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- •Foreword
- •Preface
- •Contents
- •Contributors
- •Editors
- •Authors
- •Anal Canal Epithelium
- •External Anal Sphincter
- •Hemorrhoids
- •Perineal Body
- •Pelvic Floor Muscles
- •Puborectalis Muscle
- •Iliococcygeus Muscle
- •Pubococcygeus Muscle
- •Mesorectum
- •Presacral Fascia
- •Retrosacral Fascia
- •Waldeyer’s Fascia
- •Denonvilliers’ Fascia
- •Lateral Ligaments
- •Anorectal Spaces
- •Perianal Space
- •Intersphincteric Space
- •Submucous Space
- •Ischioanal/Ischiorectal Space
- •Supralevator Space
- •Retrorectal Space
- •Internal Anal Sphincter
- •Conjoined Longitudinal Muscle
- •Rectal Blood Supply
- •Superior Rectal Artery
- •Middle Rectal Artery
- •Inferior Rectal Artery
- •Cecum
- •The Appendix
- •Ascending Colon
- •Transverse Colon
- •Descending Colon
- •Sigmoid Colon
- •Rectosigmoid Junction
- •Blood Supply
- •Superior Mesenteric Artery
- •Inferior Mesenteric Artery
- •Venous Drainage
- •Lymphatic Drainage
- •Nervous Innervation
- •Embryology
- •Midgut Rotation
- •Non-rotation
- •Malrotation
- •Reversed Rotation
- •Omphalocele
- •Internal Hernias
- •Proximal Colon Duplication
- •Meckel’s Diverticulum
- •Hirschsprung’s Disease
- •Anorectal Malformations
- •Anal Stenosis
- •Membranous Atresia
- •Anal Agenesis
- •Anorectal Agenesis
- •Rectal Atresia or “High Atresia”
- •Persistent Cloaca
- •References
- •2: Colonic Physiology
- •Embryology
- •Colonic Anatomy
- •Introduction
- •Colonic Wall Anatomy
- •Epithelial Types
- •Sodium
- •Potassium
- •Aldosterone
- •Short-Chain Fatty Acid Absorption
- •Vitamin K Absorption
- •Colonic Innervation
- •Pain
- •Colonic Motility
- •Microbiome
- •Conclusion
- •References
- •3: Anorectal Physiology
- •Introduction
- •Anatomy
- •Physiology
- •Normal Continence
- •Patient Positioning
- •Digital Rectal Examination
- •Anoscopy
- •Proctoscopy
- •Endoanal/Endorectal Ultrasound
- •Normal Defecation
- •Physiologic Testing
- •Anal Manometry
- •Pudendal Nerve Terminal Motor Latency
- •Defecography
- •Functional Anorectal Disorders
- •Fecal Incontinence
- •Anorectal Pain
- •Urogynecological Considerations
- •References
- •4: Endoscopy
- •Introduction
- •Anorectal Examination
- •Flexible Endoscopy Techniques
- •Torque
- •Dithering/Jiggle
- •Air Aspiration
- •Slide-By
- •Flexible Sigmoidoscopy
- •Colonoscopy
- •Bowel Preparation
- •Special Considerations
- •Anticoagulated Patient
- •Sedation
- •Instrumentation
- •Colonoscopy Technique
- •Alternative Techniques
- •Chromoendoscopy
- •Narrow Band Imaging
- •Full-Spectrum Endoscopy
- •Changing Patient Position
- •Abdominal Pressure
- •Incomplete Colonoscopy
- •Complications
- •Procedural Complications
- •Perforation
- •Bleeding
- •Post-polypectomy Syndrome
- •Splenic Injury
- •Infectious Complications
- •The Endoscopy Unit
- •Endoscope Processing
- •Quality Measures
- •Withdrawal Time
- •Adenoma Detection Rate
- •Leasing vs Purchasing Endoscopy Equipment
- •Summary
- •References
- •Introduction
- •Forceps
- •Snare
- •Lifting
- •Endoscopic Mucosal Resection
- •Clip
- •Underwater EMR
- •Endoscopic Submucosal Dissection
- •ESD Complications
- •ESD Technique
- •Postoperative Care
- •Endoscopic Suturing
- •Stabilization Platforms
- •Colonic Stenting
- •Stenting Technique
- •Stenting Anastomotic Leaks
- •Conclusion
- •References
- •Abdominal Surgery
- •Anorectal Surgery
- •Preoperative Testing
- •Laboratory Studies
- •Electrocardiogram
- •Chest X-Ray
- •Advanced Diagnostic Imaging
- •Cardiac Evaluation
- •Initial Workup
- •Additional Testing
- •Preoperative Anticoagulation
- •Coronary Stent Management
- •Bridging
- •AICD/Management
- •Pulmonary Assessment
- •Perioperative Steroid Management
- •Diabetes
- •Obesity
- •Malnutrition
- •Solid Organ Transplant Recipients
- •Substance Abuse
- •Alcohol
- •Tobacco
- •Opioids
- •Other Illicit Drugs
- •Immunosuppressive Agents
- •Assessing Frailty
- •Complete Geriatric Assessment
- •Frailty Scores
- •Prehabilitation
- •Exercise
- •Nutrition
- •Psychosocial Therapy
- •Outcomes
- •Conclusion
- •References
- •Enhanced Recovery Models
- •Education
- •Preoperative Optimization
- •Smoking Cessation
- •Preoperative Nutrition
- •Preoperative Anemia
- •Perioperative Hyperglycemia
- •Bowel Preparation
- •In-hospital Preoperative Enhanced Recovery Elements
- •Multimodal Analgesia (MMA)
- •Intraoperative Enhanced Recovery Elements
- •Multimodal Analgesia
- •Intentional Fluid Management
- •Minimally Invasive Surgical Approaches
- •Postoperative Enhanced Recovery
- •Multimodal Analgesia
- •Standard Discharge Criteria
- •Future Directions
- •Summary
- •References
- •8: General Postoperative Complications
- •Introduction
- •Risk Factors
- •Morbidities
- •Nutrition
- •Smoking
- •Preoperative Anemia
- •Sarcopenia
- •Obesity
- •Functional Exercise Capacity
- •Open Surgical Approach
- •Assessing Risk Factors
- •Addressing Risk Factors
- •Postoperative Complications
- •Gastrointestinal Complications (#1)
- •Ileus (Functional Bowel Obstruction)
- •Postoperative Small Bowel Obstruction (Mechanical Bowel Obstruction)
- •Hematologic Complications (#2)
- •Venous Thromboembolism
- •Infectious Complications (#3)
- •Surgical Site Infection (SSI)
- •Anastomotic Leaks
- •Wound Dehiscence
- •Other Infectious Complications
- •Pulmonary Complications (#4)
- •Postoperative Respiratory Failure
- •Pneumonia
- •Pulmonary Aspiration
- •Renal Complications (#5)
- •Acute Kidney Injury
- •Postoperative Urinary Retention
- •Cardiac Complications (#6)
- •Myocardial Infarction
- •Dysrhythmias
- •Neurological Complications (#7)
- •Perioperative Cerebrovascular Accidents
- •Sexual Dysfunction
- •Postoperative Delirium
- •Conclusion
- •References
- •9: Anastomotic Construction
- •Introduction
- •Operative Planning
- •Mobilization
- •Small Bowel Mobilization
- •Colonic Mobilization
- •Splenic Flexure Mobilization
- •Special Mobilization Techniques
- •Retroileal Anastomosis or Ileal Mesenteric Window
- •Right Colon De-Rotation (Deloyer’s Procedure)
- •Perfusion
- •Low Pelvic Anastomosis
- •Sutured Anastomosis
- •Stapled Anastomosis
- •Compression Ring Anastomosis
- •References
- •10: Anastomotic Complications
- •Anastomotic Leak
- •Risk Factors
- •Diagnosis
- •Outcomes After Anastomotic Leak
- •Anastomotic Fistula
- •Blind Loop Syndrome
- •Anastomotic Bleeding
- •Anastomotic Stricture
- •References
- •Anal Fissure
- •Medical/Pharmaceutical Treatment
- •Topical Agents
- •Botulinum Toxin Injection
- •Operative Treatment
- •Lateral Internal Sphincterotomy (LIS)
- •Technique
- •Outcomes
- •Local Advancement Flaps
- •Atypical Fissures
- •Anal Fissure, Conclusion
- •Anal Stenosis
- •Symptoms
- •Evaluation
- •Treatment
- •Nonoperative Treatment
- •Surgical Treatment
- •Rectal Advancement Flap
- •Y-V Advancement Flap
- •V-Y Advancement Flap
- •Diamond (Rhomboid) Flap
- •House Flap
- •U Flap (Island Flap Anoplasty)
- •Rotational S Flap
- •Technical Aspects
- •Flap Aftercare
- •Prevention
- •Anal Stenosis, Conclusions
- •References
- •Introduction
- •Cryptoglandular Pathophysiology
- •Cryptoglandular Abscess
- •Diagnosis
- •Treatment
- •Acute Fistula Management
- •Post-drainage Care
- •Post-drainage Antibiotics
- •Anal Fistula
- •Presentation/Symptoms
- •Fistulography
- •Computed Tomography (CT)
- •Magnetic Resonance Imaging (MRI)
- •Endoanal Ultrasound (EAUS)
- •Treatment Strategies
- •Fistulotomy
- •Setons
- •Draining Seton
- •Cutting Seton
- •Fibrin Glue
- •Fistula Plug
- •Endorectal Advancement Flap (ERAF)
- •Novel Surgical Therapies
- •Fistula Tract Laser Closure (FiLaC™)
- •Video-Assisted Anal Fistula Treatment (VAAFT)
- •Stem Cell Therapy
- •Recommendation
- •References
- •Introduction
- •Etiology
- •Clinical Presentation
- •Diagnostic Evaluation
- •Transanal Approach
- •Transperineal Approach
- •Posterior Approach
- •Transabdominal Approach
- •Other Approaches
- •Conclusion
- •References
- •15: Rectovaginal Fistula
- •Obstetrical
- •Crohn’s Disease
- •Cryptoglandular
- •Radiation Injury
- •Surgical Techniques
- •Perineal Approach
- •Episioproctotomy
- •Transverse Perineal Repair
- •Transrectal Approaches
- •Rectal Sleeve Advancement
- •Vaginal Approach
- •Tissue Transposition Repairs
- •Bioprosthetic Products
- •Abdominal Approaches
- •Conclusion
- •References
- •Pilonidal Disease
- •Introduction
- •Diagnosis
- •Treatment
- •Managing Patient Expectations
- •Nonsurgical Treatment
- •Antibiotics
- •Phenol
- •Fibrin Glue
- •Surgical Treatments
- •Complex Surgical Treatment
- •Karydakis Flap
- •Rhomboid Flap (aka Limberg Flap)
- •Cleft Lift Flap (Bascom Procedure)
- •Minimally Invasive Treatments
- •Trephination
- •Wound Healing Adjuncts
- •Hidradenitis Suppurativa
- •Introduction
- •Treatment
- •Medical Therapy
- •Topical Therapy
- •Systemic Antibiotics
- •Biologics
- •Other Medical Therapies
- •Laser Therapies
- •Surgery
- •Conclusions
- •References
- •Introduction
- •Pathophysiology
- •Etiology
- •Fecal Soilage
- •Dermatologic Diseases
- •Diagnostic Approach
- •Laboratory Testing
- •Treatment
- •First Encounter
- •Conclusions
- •References
- •Introduction
- •Anorectal Immunology
- •Asymptomatic
- •Symptomatic
- •Bacterial Sexually Transmitted Infections
- •Chlamydia
- •Diagnosis
- •Treatment
- •Lymphogranuloma Venereum
- •Diagnosis
- •Treatment
- •Gonorrhea
- •Diagnosis
- •Treatment
- •Syphilis
- •Diagnosis
- •Treatment
- •Chancroid
- •Diagnosis
- •Treatment
- •Donovanosis
- •Diagnosis
- •Treatment
- •Herpes Simplex Virus
- •Genital Warts
- •Giant Condyloma
- •Molluscum Contagiosum
- •Ectoparasitic Sexually Transmitted Diseases
- •Conclusion
- •References
- •19: Anal Intraepithelial Neoplasia
- •Introduction
- •Incidence
- •Epidemiology
- •Progression
- •Diagnosis
- •Treatment
- •Expectant Management
- •Topical Therapies
- •Trichloroacetic Acid (TCA)
- •5-Flurorouracil (5FU)
- •Cidofovir
- •Imiquimod
- •Local Ablative Therapies
- •Wide Local Excision
- •Treatment Summary
- •Surveillance/Prevention
- •Conclusion
- •References
- •20: Anal Cancer
- •Physical Examination
- •Radiologic Evaluation
- •Anal Anatomy
- •Perianal Squamous Cell Carcinoma
- •Anal Canal Squamous Cell Carcinoma
- •Chemotherapy
- •Radiation Therapy
- •Inguinal Lymph Node Metastases
- •Surgery
- •Surveillance
- •Anal Adenocarcinoma
- •Verrucous Carcinoma
- •Melanoma
- •Perianal Paget’s Disease (Intraepithelial Adenocarcinoma)
- •Basal Cell Carcinoma
- •Gastrointestinal Stromal Tumor (GIST)
- •Conclusion
- •References
- •21: Presacral Tumors
- •Introduction
- •Anatomic Considerations
- •Clinical Presentations
- •Physical Examination
- •Imaging Studies
- •Preoperative Biopsy
- •Tailgut Cysts
- •Enterogenous Cysts
- •Teratomas
- •Chordomas
- •Meningoceles
- •Neurogenic Tumors
- •Osseous Tumors
- •Miscellaneous Lesions
- •Currarino Syndrome
- •Management
- •Multidisciplinary Team
- •Neoadjuvant Therapy
- •Preoperative Considerations
- •Surgical Approach
- •Posterior Approach
- •Minimally Invasive Approaches
- •Outcomes
- •Conclusions
- •References
- •Introduction
- •Sporadic Versus Inherited Colorectal Cancer
- •Sporadic Colorectal Cancer
- •Mutations
- •Chromosomal Alterations
- •Right vs. Left CRC
- •Young Onset CRC
- •Epidemiology
- •Management
- •Inherited CRC
- •Lynch Syndrome (Hereditary Non-polyposis CRC)
- •Genetic Mutation
- •Lynch Syndrome Variants
- •Turcot Syndrome
- •Muir-Torre Syndrome
- •Familial CRC X
- •Screening Recommendations
- •Surgical Treatment
- •Medical Treatment
- •POLE/POLD1-Related Hereditary Cancer
- •Familial Adenomatous Polyposis
- •Genetic Mutations
- •Extracolonic Manifestations
- •Screening Recommendations
- •Attenuated FAP
- •Gardner Syndrome
- •Surgical Treatment
- •MUTYH-Associated Polyposis
- •Serrated Polyposis Syndrome
- •Diagnosis
- •Treatment
- •Hamartomatous Polyposis Syndromes
- •Juvenile Polyposis
- •Peutz-Jeghers Syndrome
- •Cowden Syndrome
- •Conclusion
- •References
- •Overview
- •Colorectal Cancer Precursor Lesions
- •Adenomas
- •Serrated Polyps
- •Colorectal Cancer Carcinogenic Pathways
- •Adenoma-Carcinoma Pathway
- •Serrated Pathway
- •Lesion Assessment
- •Endoscopic Mucosal Resection (EMR) Technique
- •Endoscopic Submucosal Dissection Technique
- •Recurrence Following Endoscopic Resection
- •Surveillance After Endoscopic Resection
- •Conclusion
- •References
- •Fecal Sampling
- •Flexible Sigmoidoscopy
- •Computed Tomography (CT) Colonography
- •Colonoscopy
- •Delineating Colon Versus Rectum
- •TNM Staging
- •History
- •Physical Examination
- •Proctoscopy
- •Colonoscopy
- •Tumor Localization
- •Blood Work
- •Imaging
- •Computed Tomography (CT) Scan
- •PET-CT
- •Endorectal Ultrasound
- •Preoperative Evaluation
- •Pathologic Features: Pre-Resection
- •Lymphovascular Invasion (LVI)
- •Perineural Invasion (PNI)
- •Tumor Budding
- •Tumor Grade
- •Histologic Type
- •Pathologic Factors: Post-Resection
- •Extranodal Tumor Deposits
- •Mesorectal Grade
- •Tumor Regression Score
- •Clinical or Imaging-Based Factors
- •Extramural Vascular Invasion (EMVI)
- •Circumferential Radial Margin (CRM) Status
- •Tumor Location
- •Conclusion
- •References
- •Introduction
- •Preoperative Tumor Localization
- •General Surgical Principles
- •No-Touch Technique
- •Lymphadenectomy
- •Mesocolic Excision
- •Adjacent Tissue or Organ Invasion
- •Technical Aspects
- •Hepatic Flexure Colon Cancer
- •Technical Aspects
- •Transverse Colon Cancer
- •Technical Aspects
- •Technical Aspects
- •Sigmoid Colon Cancer
- •Technical Aspects
- •Special Circumstances
- •References
- •26: Rectal Cancer: Neoadjuvant Therapy
- •Introduction
- •Rectal Cancer Staging
- •Adjuvant Radiation
- •Neoadjuvant Radiation
- •The Foundation Trials
- •Short- vs Long-Course Radiation
- •Total Neoadjuvant Chemoradiation Therapy (TNT)
- •Rationale
- •Systemic Chemotherapy Alone
- •Pathologic Complete Response
- •Consolidation vs Induction Chemotherapy
- •Conclusion
- •References
- •27: Rectal Cancer: Local Excision
- •Introduction
- •Patient Selection
- •T1N0
- •Predicting Lymph Node Metastasis
- •Tumor Budding
- •Techniques
- •Transanal Excision
- •Transanal Endoscopic Microsurgery
- •Transanal Minimally Invasive Surgery (TAMIS)
- •Complications
- •Oncologic Results
- •T1 Cancer
- •T2 Cancer
- •Salvage Surgery
- •Conclusion
- •References
- •28: Rectal Cancer: Nonoperative Management
- •Introduction
- •Rationale
- •Accidental Versus Intentional WW
- •Baseline Stage
- •Tumor Location
- •Endoscopic Features
- •Radiological Studies

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rence, survival, and quality of life relative to radical resection? Ann
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Rectal Cancer: Nonoperative Management
JulioGarcia-Aguilar andRodrigoOlivaPerez
28
Key Concepts
• A proportion of patients with rectal cancer managed by
neoadjuvant chemoradiation may achieve complete disappearance of the primary tumor (complete clinical
response) during assessment of response after treatment
completion.
• Establishing a complete clinical response requires the
combination of clinical, endoscopic, and radiological
ndings consistent with the absence of residual cancer at
the site of the original cancer.
• Patients that achieve a complete clinical response have
been considered for organ preservation strategy with strict
surveillance and no immediate surgery (Watch and Wait)
to avoid the potential morbidity, mortality, requirement
for stomas, and functional consequences of a
proctectomy.
• Patients that achieve a complete clinical response and are
managed by the Watch and Wait strategy have a 25% risk
for developing local regrowth of the primary tumor.
• The majority of local regrowths are amenable to successful
salvage proctectomy with negative resection margins (R0).
• Patients that achieve a cCR and are managed by Watch
and Wait have similar overall survival rates when compared to patients with pCR managed by radical proctectomy. Disease-free survival rates are superior for patients
undergoing radical proctectomy due to the 25% risk of
Supplementary Information The online version of this chapter
(https://doi.org/10.1007/978- 3- 030- 66049- 9_28) contains supplementary material, which is available to authorized users.
J. Garcia-Aguilar (*)
Department of Surgery, Memorial Sloan Kettering Cancer Center,
New York, NY, USA
e-mail: garciaaj@mskcc.org
R. O. Perez
Department of Surgical Oncology, Angelita and Joaquim Gama
Institute, Benecencia Portuguesa de Sao Paolo, Alemao Oswaldo
Cruz, Sao Paulo, Brazil
local regrowth following WW requiring salvage
proctectomy.
• Functional outcomes and quality of life appear to be
improved among patients with complete clinical response
managed by Watch and Wait when compared to
proctectomy.
Introduction
The introduction of neoadjuvant therapy has led to signicant changes in the management of rectal cancer. The observation of a variable degree of tumor response to neoadjuvant
therapy has challenged the previously standard practice of
proctectomy and has prompted the introduction of new treatment algorithms. The assessment of tumor response after
neoadjuvant therapy, previously considered unnecessary, is
now an integral part of contemporary rectal cancer management algorithms. Patients found to have clinical, endoscopic,
and radiological evidence of complete disappearance of the
primary tumor are considered candidates for deferral of surgery and active surveillance, with the ultimate goal of achieving sustained organ preservation, a strategy known as Watch
and Wait (WW). In this chapter we will review rectal cancer
management with an emphasis on baseline staging, neoadjuvant treatment regimens, timing and methods for assessment
of tumor response, and surveillance protocols relevant for
the effective and safe implementation of WW strategies that
will result in optimal organ preservation. We will also provide an overview of the evidence supporting the WW strategy for rectal cancer patients who achieve a clinical complete
response to neoadjuvant therapy.
Terminology andDenitions
Organ preservation strategies in the management of rectal
cancer require new terms and denitions.
© Springer Nature Switzerland AG 2022
S. R. Steele et al. (eds.), The ASCRS Textbook of Colon and Rectal Surgery, https://doi.org/10.1007/978-3-030-66049-9_28
491

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J. Garcia-Aguilar and R. O. Perez
The nal histologic stage of the tumor after neoadjuvant
therapy should follow the nomenclature of the AJCC/IUCC
TNM classication [1]. ypT0 indicates no residual tumor in
the bowel wall in the primary tumor bed (within the rectal
wall), whereas ypN0 means negative nodes in the mesorectum when part of the surgical specimen. The term pathologic
complete response (pCR) should be reserved for ypT0N0
tumors in patients who had a proctectomy or for ypT0 tumors
after a full-thickness local excision (LE) without radiological evidence of mesorectal positive nodes or deposits.
Patients without evidence of tumor on clinical, endoscopic, and radiological exams are considered to have a clinical complete response (cCR) [2]. The key to determining
whether a WW strategy will likely be successful is based on
the assumption that cCR after neoadjuvant therapy correlates
with pCR after proctectomy [3].
The goal of the WW strategy is to identify patients who
have no residual disease in the bowel wall after neoadjuvant
therapy who can avoid surgery and preserve the rectum [4].
Therefore, the term Watch and Wait was originally used
exclusively for patients who achieved a cCR and were offered
no immediate surgery with strict and close surveillance [4].
This means that achieving a cCR is a prerequisite for entering a WW program.
Considering the lack of a “perfect” correlation between
cCR and pCR, some patients with a cCR entering a WW
program are at risk of local regrowth during follow-up [5].
The reappearance of the tumor in the rectal wall or in the
regional lymph nodes after an apparent cCR is called local
regrowth [6]. Regrowths occur more often in the bowel wall
compared to the regional lymph nodes and therefore are
more easily detected by digital rectal examination (DRE)
and/or exible sigmoidoscopy. Most local regrowths are
potentially salvageable by surgery [7–12]. Any tumor reappearance in the pelvis after a curative-intent surgery is considered “local recurrence.” Distant metastases can occur in
patients with a sustained cCR but are more frequent in
patients with tumor regrowth.
Historically, most rectal cancer patients entered in a
WW protocol had received standard long-course chemoradiation therapy (CRT) [4, 12, 13]. As treatment strategies
evolved over time, systemic chemotherapy was progressively added to standard neoadjuvant CRT regimens.
Chemotherapy that is given before CRT is called induction
chemotherapy, and chemotherapy given during and after
CRT (before surgery) is called consolidation chemotherapy
[14–17]. The full regimen of induction or consolidation
chemotherapy (eight cycles of FOLFOX [leucovorin, uorouracil, oxaliplatin] or ve cycles of CapeOX [capecitabine,
oxaliplatin]) in combination with CRT is called total neo-
adjuvant therapy [18].
Radiation therapy delivery has also evolved over time.
Originally, most treatment regimens included external beam
radiotherapy (EBRT), with or without intensity modulation
techniques (IMRT). In addition to the mode of delivery, fractionation of doses may encompass two different regimens:
long-course with hyperfractionation or short-course with
hypofractionation. Even though a detailed description of
these different approaches is beyond the scope of this chapter, sufce to say that both regimens may result in pCR and/
or cCR [19, 20]. In an attempt to increase the total dose of
radiation delivery, techniques have been developed to provide maximal dose (dose escalation) with minimal toxicity.
Therefore, additional doses (boosts) to the primary tumor
may be delivered by EBRT, endorectal high-dose-rate
brachytherapy (HDBRT) or contact radiation (Papillon technique) [16, 17, 21, 22].
Rationale
The possibility of a permanent stoma has always been one of
the main concerns of patients diagnosed with rectal cancer.
Even though patients’ perspectives may vary across different
geographical areas and cultures, a permanent end-colostomy
impacts body image and impairs quality of life [23]. The
concept of avoiding surgery in rectal cancer patients treated
with neoadjuvant chemoradiation was driven by the observation of pCR in patients treated with abdominal-perineal
resection (APR) with permanent colostomy [4]. Following
similar observations from anal cancer treatment, where
patients with complete tumor regression after neoadjuvant
chemoradiation (nCRT) avoided radical surgery with surprisingly favorable oncological outcomes, initial attempts
were made to identify rectal cancer patients who had
achieved a pCR, by means of clinical, endoscopic, and radiological examination [24]. However, most rectal cancer
patients have more surgical options than anal cancer patients,
for whom APR is the main radical surgical alternative.
Depending on tumor stage, anatomy, and relation to the anal
sphincter complex, many rectal cancer patients are candidates for sphincter preserving procedures. Although avoiding a permanent stoma, restorative proctectomy is often
associated with signicant bowel dysfunction, particularly
worsened by previous exposure to ionizing radiation to the
pelvis. A sizeable fraction of patients who undergo a restorative procedure with their temporary diverting stoma reversed
are left with variable degrees of fecal incontinence and a
constellation of symptoms known as “low anterior resection
syndrome,” some requiring conversion to a permanent stoma
or creation of cecostomy/appendicostomy for anterograde
colon lavage [25–27]. In addition, proctectomy, with or without sphincter preservation, has signicant consequences in
terms of sexual and urinary function [28, 29].
Despite recent advances in minimally invasive approaches
to the surgical management of rectal cancer, proctectomy is
also associated with immediate postoperative morbidity and
mortality [30]. One of the main drivers of postoperative mor-

28 Rectal Cancer: Nonoperative Management
493
bidity among these patients is the risk of postoperative anastomotic leak. Prospective randomized clinical trials have
shown the benets of diverting stomas in decreasing the risk
of clinically relevant leaks and the need for urgent reoperations among these patients [31]. However, the creation of a
diverting stoma often results in direct morbidity associated
with high-output syndromes (with ileostomy) and with subsequent stoma reversal [32]. Altogether, avoidance of
potentially unnecessary proctectomy among patients with
complete tumor regression after nCRT could have the potential benets of sparing patients from the need of a permanent
or temporary stoma, risk of immediate and late morbidity,
chance of postoperative mortality, and negative functional
consequences in bowel, urinary, and sexual functions [30–
35]. In addition, patients undergoing proctectomy for rectal
cancer will have potentially signicant long-term nancial
and social burdens beyond the clinical aspects of the disease
and its treatment. These patients will need resources to
nance surgical treatment as well as its potential complications, the cost of supplies for the stoma, and assistance dealing with the impact of proctectomy on the activities of daily
living and professional life [36].
Primary Tumor Assessment andSelection
Criteria
Baseline tumor assessment for patients being considered for
organ preservation is of paramount importance and is based
primarily on clinical ndings of DRE, endoscopic features,
and radiological imaging. Neoadjuvant therapy should only
be instituted after these studies are complete, and conrmatory biopsies of adenocarcinoma have been obtained and
properly documented.
Accidental Versus Intentional WW
The occasional eradication of rectal cancer by radiation therapy has been known for decades. Attempts to cure rectal cancer with radiation alone were popular at the beginning of the
twentieth century, when the mortality and morbidity of rectal
cancer surgery were prohibitive [37]. The difculty in identifying patients with a true complete response and increased
safety of surgery ultimately led to the abandonment of the
idea of treating cancer with radiation alone. Over the years,
some surgeons have omitted surgery in some patients with an
apparent complete or near-complete response because of
advanced age, high surgical risk from comorbid conditions,
or patient refusal of a permanent stoma. This “accidental”
approach to WW, still the only one accepted at many institutions, should be distinguished from the systematic or “intentional” approach, in which patients with distal rectal cancer
likely requiring restorative proctectomy with low colorectal
anastomosis or non-restorative proctectomy with permanent
colostomy are treated with optimal neoadjuvant therapy,
restaged, and selectively entered in a WW protocol with the
intention of achieving permanent organ preservation [38].
Chances of achieving a cCR are now anticipated, and consideration of WW is discussed prior to treatment with nCRT.The
intentional WW approach is relatively straightforward in
patients with locally advanced rectal cancer requiring nCRT
before proctectomy for oncological purposes. However,
patients with less advanced disease, not necessarily requiring
nCRT before proctectomy for oncological reasons, may also
be considered for WW and undergo nCRT for the primary
purpose of achieving a cCR [38].
Baseline Stage
Baseline tumor stage is an important predictor of tumor
response to nCRT.In general, more advanced tumors are less
likely to completely respond to nCRT compared to earlystage tumors. Therefore, clinical stage has potential implications for the selection of patients for WW.Current guidelines
recommend nCRT for patients with locally advanced tumors
that have baseline features indicative of high risk of local
recurrence following proctectomy alone [39]. A distance of
the primary tumor to the mesorectal fascia of ≤1 mm
(mrCRM≤1mm including T3c,d or T4), extramural venous
invasion (EMVI), extensive nodal disease (N1c/N2), or lateral pelvic sidewall nodes (LPNM) have been associated
with the risk of local recurrence after proctectomy alone and
therefore are currently indications for nCRT.While the presence of these features is not a contraindication for WW, a
cCR is less likely in patients with such advanced tumors. In
addition, clinical and radiological identication of a cCR
may be quite challenging in the presence of extensive disease, where it may be difcult to ascertain whether palpable
or radiographic extraluminal abnormalities are due to brotic
changes versus remaining tumor following neoadjuvant
therapy.
The indication for nCRT in patients with intermediate disease—those with mrT3a,b or N0/1 and no additional highrisk features (CRM≤1 mm, EMVI+, LPNM+)—is
controversial. While such patients are still considered candidates for nCRT in international guidelines that use the TNM
classication system as the basis for risk stratication (such
as the guidelines of the National Comprehensive Cancer
Network; www.nccn.org), data from the MERCURY trial
suggest that these patients are at low risk for local recurrence
after proctectomy, casting doubt on the need for nCRT [40].
While the debate about the benets of nCRT for all
intermediate- risk rectal cancer patients is beyond the scope
of this chapter, offering nCRT to patients with more distal
intermediate stage tumors offers the possibility of a cCR and
potential organ preservation [41].

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J. Garcia-Aguilar and R. O. Perez
A similar treatment algorithm may be considered for
patients with early-stage disease (mrT1/T2N0). As the local
recurrence rate with proctectomy alone is very low, earlystage tumors are typically not considered candidates for
nCRT.However, nCRT followed by local excision has been
proposed as an alternative for patients with early-stage distal
rectal cancer who otherwise would need a coloanal anastomosis or a permanent colostomy. Several phase II trials have
shown that the rate of pCR for these patients is higher than in
patients with more advanced disease [3, 42]. It is therefore
reasonable to offer WW to patients with early-stage rectal
cancer who seek to avoid a permanent stoma and start treatment with nCRT in an attempt to achieve a cCR.
Tumor Location
Tumor location is also important when selecting patients for
WW.While any rectal cancer patient with a cCR after CRT
is a potential candidate for WW, those more likely to benet
from a WW approach that may result in organ preservation
are patients with tumor located in the distal rectum who may
otherwise need a low colorectal or coloanal anastomosis or a
permanent colostomy. Tumors in this location are also more
likely to be accessible to monitoring by DRE [2].
Tumor location in the distal rectum is particularly important when considering nCRT with the goal of achieving cCR
in early-stage tumors. mrT2 cancers beyond the reach of
DRE are probably surrounded by mesorectal fat and are less
likely to have CRM positivity and local recurrence if treated
by up-front proctectomy. As most of these patients are candidates for sphincter-saving surgery, they are less likely to benet from organ preservation. However, an exception to this
rule is an obese patient with a long anal canal in whom a
tumor located immediately above the anorectal ring may be
just beyond the reach by DRE but who may still be a candidate for a WW strategy.
Magnetic resonance imaging using dedicated rectal cancer protocols provides valuable information about the location of the tumor in relation to other anatomical structures,
such as the sphincter complex, the levator muscles, the prostate and seminal vesicles, the vaginal wall and cervix, as well
as the anterior peritoneal reection and helps the surgeon
anticipate the need for a permanent stoma, the ability to perform a sphincter-saving procedure and even the type of anastomosis in case proctectomy is undertaken. This information
is also very useful for the selection of patients for WW [43].
In summary, patients with lower tumors requiring a low
colorectal or a hand-sewn coloanal anastomosis or an APR
are more likely to benet from a WW strategy and organ
preservation. Patients with more proximal tumors that carry
a low risk of local recurrence and unlikely to benet from
CRT will derive minimal benet from organ preservation
and may be better treated with up-front proctectomy.
Endoscopic Features
Some endoscopic features such as pit pattern and submucosal vascular architecture can help identify benign lesions or
even supercially invasive rectal cancers that fulll the criteria for endoscopic submucosal resection (see Chap. 23) or
transanal local excision (see Chap. 27) without the need for
proctectomy or nCRT [44].
Endoscopic and some DRE features related to tumor morphology have not been associated with differences in
response rates to neoadjuvant treatment. Therefore, qualities
commonly associated with more advanced disease, such as
ulceration and tethered lesions, are not necessarily exclusion
criteria for entering WW. Size has been associated with
response, suggesting that smaller tumors are more likely to
respond completely to treatment [45]. Still, even patients
with large circumferential tumors may also achieve a cCR
and successfully undergo WW.Proper documentation of the
endoscopic characteristics of the tumor at baseline—ideally
through endoscopic images—is important for subsequent
evaluations during the assessment of tumor response. Some
large, circumferential, ulcerated tumors develop a concentric
scar that narrows the lumen of the rectum and prevents
proper endoscopic evaluation of tumor response. Patients
with such tumors may not be ideal candidates for WW
because complete endoscopic assessment and surveillance
are not possible.
In summary, patients being considered for nCRT with the
hope of entering a WW program should have conrmation of
invasive adenocarcinoma, a tumor that is (preferably) accessible to DRE, endoscopic features consistent with invasive
cancer not suitable for endoscopic submucosal dissection,
and an MRI showing a tumor located in the distal rectum.
Baseline staging features may be useful for estimating the
probability of a tumor achieving a cCR and selecting a treatment plan that will potentially include a WW strategy to
achieve organ preservation.
Assessment ofTumor Response
Most rectal cancers respond to some degree to chemotherapy
and radiation. The degree of response depends on intrinsic
tumor characteristics, such as size, stage, and some genomic
features and treatment variables, including the fractionation
dose of the radiation and the time from completion of radio-

28 Rectal Cancer: Nonoperative Management
495
therapy to assessment of response. In a WW program, tumor
response is assessed with the same diagnostic tools as for the
initial staging: DRE, endoscopy, and radiology (preferably
MRI).
The 6-week interval between the end of the neoadjuvant
therapy and surgery in patients with stage II-III rectal cancer
treated with CRT and proctectomy has been proven to be
effective in terms of surgical technical difculty and perioperative morbidity and is associated with a pCR rate of
approximately 18% [46]. Retrospective studies have suggested that longer intervals between the end of radiotherapy
and surgery result in higher pCR rates [47, 48]. These data,
along with the growing body of evidence from patients
entered in WW protocols, suggest that tumor response is
time-dependent and probably nonlinear [49–51]. These ndings have implications for the design of WW strategies:
tumors that have responded signicantly but have not
achieved a cCR at the time of the initial evaluation 6–8weeks
after completion of CRT may still achieve a cCR with longer
observation. Several prospective studies suggest that adding
chemotherapy during the longer observation period increases
the likelihood of cCR and the probability of organ preservation [15, 18].
Our current WW strategy is to assess tumor response
6–8weeks after completion of neoadjuvant therapy. Based
on the degree of tumor response, patients are stratied in one
of three treatment groups (Table28.1) [52]. Patients with an
incomplete clinical response (iCR) and a clearly visible
tumor, even if the tumor has decreased in size signicantly
from baseline, typically undergo surgery (Table 28.1,
Fig. 28.1). Patients with a cCR can enter a standard WW
surveillance protocol with repeat assessments every
3–4months (Table28.1, Fig.28.2). Patients with a very signicant response that does not meet all criteria of a cCR—
termed a near-complete clinical response (nCR)—can be
entered in an intensive surveillance protocol, with a repeat
exam after 6–8 additional weeks (Table 28.1, Fig. 28.3).
Continued observation at similar intervals may be appropriate as long as the tumor continues showing signs of ongoing
response until all strict criteria of a cCR are achieved. Most
patients should achieve all strict criteria within 28–34weeks
following completion of radiotherapy. While not the norm, it
may take up to a year (52weeks) for some tumors to achieve
a cCR.A lack of evidence of continued response in any of
the three diagnostic modalities or any sign of tumor regrowth
is an indication for surgery.
Criteria foraComplete Clinical Response
The criteria of a complete clinical response are based on
three pillars of assessment. Clinical evaluation with DRE
should reveal a regular mucosal surface, with only minor
induration of the rectal wall and no signicant abnormalities. Endoscopic assessment is typically characterized by
whitening of the mucosa with telangiectasias and absence
of ulceration, mass, or stenosis of the rectum (Figs. 28.4
and 28.5). Radiological assessment should include the
presence of an area of low-signal intensity at the original
tumor location on MRI-T2W [magnetic resonance tumor
regression grade 1 (mrTRG1)] (Fig. 28.6); restriction to
diffusion on MRI-DW should be absent, corresponding to
the area of low-signal intensity on T2-weighted images
(Fig.28.7).
Given the random distribution of cancer cells in the different layers in the rectal wall after nCRT [53, 54], endoscopic
biopsies are not very useful in the assessment of rectal cancer
response to CRT.A negative biopsy is not a requirement for
patients with a cCR entering a WW protocol. Conversely, a
negative endoscopic biopsy cannot exclude residual tumor in
patients with near-complete or incomplete clinical response.
Therefore, endoscopic biopsy in patients with an incomplete
Table 28.1 Clinical response and suggested management
Clinical
response Endoscopic features Clinical features Radiological features (MR) Suggested management
Incomplete Deep ulcerations, elevated
Nearcomplete
Complete Only whitening of the
borders, signicant
distortion of rectal wall
No visible mass, only
supercial/shallow ulcer
mucosa and/or
telangiectasias
Hard palpable
mass, signicant
stenosis
Minimal/
questionable
irregularity
Smooth surface in
DRE
mrTRG3-5, mixed or high-signal
intensity, restriction to diffusion in the
corresponding area of the primary
tumor
mrTRG 2 Reassessment in 8–12weeks;
Low-signal intensity (T2-weighted
images), absence of diffusion
restriction (corresponding area),
mrTRG1
Surgical management
further response should be
documented in subsequent
reassessment
WW, reassessment in 12weeks

496
ab
c d
J. Garcia-Aguilar and R. O. Perez
Fig. 28.1 Partial response (not near-complete). Endoscopic view of a
rectal cancer at baseline (a) and exhibiting a clear large and necrotic
residual ulcer (≤70% response) by endoscopy at 6weeks (b). Similar
response, for the purpose of convincing patients that they
have residual cancer in the setting of incomplete clinical
response, is risky because a negative biopsy may give the
patient a false sense of security and an argument to refuse a
recommended operation [55].
One of the challenges for broad implementation of WW is
establishing uniform and reproducible criteria for tumor
response. Each modality is accurate but imperfect.
Combining modalities increases accuracy [56]. In their
investigation of the accuracies of DRE, endoscopy, and MRI
in predicting pCR or sustained cCR, Maas etal. found that
ndings can be seen in baseline MR showing a mrT3N0 (c, dotted yellow line) and ≤70% response (mrTRG3, dotted yellow line) at 6weeks
(d). Achievement of a cCR is unlikely
clinical assessment was the most accurate. When all three
modalities were consistent with absence of residual tumor,
the accuracy of predicting complete response was 98% [56].
A three-tiered response assessment schema currently being
tested in the OPRA trial (organ preservation in rectal adenocarcinoma) consists of DRE, endoscopy, and T2- and
diffusion- weighted MRI [52]. Based on that assessment,
patients are considered complete responders, incomplete
responders, or near-complete responders. Studies aimed at
validating the reproducibility of that response assessment
schema are underway.

28 Rectal Cancer: Nonoperative Management
a
c d
497
b
Fig. 28.2 Near-complete response followed by cCR.Endoscopic view
of a rectal canvcer at baseline (a) and exhibiting near-complete/major
(>70%) response by endoscopy at 6weeks (b). Similar ndings can be
seen in baseline MR showing a mrT2/T3aN0 (c) and >70% response
Endoscopic andClinical Assessment
Historically, the rst experiences of WW were reported
prior to the development and standardization of radiological
imaging in rectal cancer. Therefore, assessment of tumor
response relied mostly on clinical (DRE) and endoscopic
assessment [4].
DRE may seem like a simple and a rather straightforward
tool for assessment of tumor response. However, DRE may
be quite challenging for distinguishing between cCR and
residual disease in many clinical scenarios. In this setting, it
is recommended that the colorectal surgeons involved in
organ-preserving programs be able to examine patients by
DRE at baseline and during assessment of response. A DRE
assessment of the baseline features of the primary tumor may
(mrTRG2) at 6weeks (d). Achievement of a cCR is more likely, and
patients should be reassessed in 6–8-week intervals. Further reassessment of response at 16weeks showed cCR by endoscopy and MR
aid the interpretation of response to treatment. Usually, cCR
should result in a smooth and regular mucosal surface of the
rectum. Even though slight induration of the rectal wall may
often be palpated, ulcerations, nodules, stenosis, and masses
should always raise the suspicion for residual cancer, and
patients with these characteristics are thought not to be
appropriate candidates for WW [2].
Endoscopic assessment may be equally challenging. Even
though rigid proctoscopy may sufce for the identication of
a cCR with strict criteria (see above), exible endoscopy provides additional benets in terms of improved visualization,
more accurate documentation, training, and patient comfort.
In addition, exible instruments may provide the opportunity
for retroexion and more precise examination of the areas
immediately adjacent to the dentate line. Finally, magnifying

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J. Garcia-Aguilar and R. O. Perez
a
b
Fig. 28.3 Complete clinical response. Endoscopic view of a rectal cancer at baseline (a) and exhibiting strict criteria of cCR by endoscopy at 6weeks
(b). Similar ndings can be seen in baseline MR showing a mrT2 (c, dotted yellow line) and mrTRG1 (d, dotted yellow line) at 6weeks
endoscopic features including narrowband imaging may provide additional advantages during the assessment of tumor
response after nCRT (Fig.28.8).
in baseline staging for rectal cancer and was also used for
the assessment of tumor response to nCRT.This imaging
modality provides good accuracy for the identication of
complete response in the primary cancer (ypT status).
However, patient discomfort and the difculties in assess-
Radiological Studies
ing mesorectal disease away from the rectal lumen contributed to the replacement of ERUS by alternative radiological
Several radiological tools have been tested in clinical practice for the assessment of tumor response to
nCRT.Endorectal ultrasound (ERUS) was originally used
imaging modalities [57, 58].
Magnetic resonance is currently the imaging modality of
choice for baseline staging and assessment of response to
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