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11
Dose Response Gradient
A fi nding in observational studies that increases our confi dence in a cause effect
relationship is the demonstration of a dose response effect. For example, an increased
risk of bleeding with increasing INR.
All Plausible Confounding Would Reduce the Demonstrated Effect or Increase it if No Effect Was Observed
A confounder is a factor related to both a predictor and outcome, but is not in the
causal link between the predictor and outcome. If a likely confounder acts opposite
to the way one would expect, then it is possible that the true effect is underestimated. For example if high risk patients do at least as well with a surgical procedure
as do those at low risk, it more strongly suggests that there is a true effect of the
surgical intervention and would increase our confi dence and thus the quality rating
of the evidence.
Summary of Findings
The last column is a summary of fi ndings where the estimate of relative effect, the
baseline risk of the standard therapy and the absolute effects of the intervention are
reported. A measure of the absolute effect is crucial for making a recommendation
since one intervention may be more effective in comparison to another, the overall
effect in terms of overall numbers may be small, in our example the absolute risk of
bleeding is only decreased by 1 %. Another example is if the baseline risk of pneumonia is 1 % and with the addition of preoperative antibiotics drops down to .7 %.
A change in absolute risk of .3 % is unlikely to be of clinical signifi cance despite
there being a 30 % relative risk reduction, which in many cases would be considered
of considerable “clinical signifi cance”.
The fi nal component of the GRADE system is to make a recommendation. In
assessing the quality of the evidence necessary to make the recommendation, the
ones making the recommendation should specify which of the various outcomes are
crucial to making a recommendation, in our example it is reasonable to conclude
that the evidence is low since that is the quality for the crucial outcome of perioperative mortality . It could be argued that the 5-year survival is more important in which
case the quality of evidence is moderate (Tables 1.2 ).
From determining the quality of evidence , a recommendation is made. This is a
separate process from determining quality of evidence. A recommendation is either
strong or weak where “The strength of a recommendation is defi ned as the extent to
which one can be confi dent that the desirable consequences of an intervention outweigh its undesirable consequences” [ 1 ]. A strong recommendation is one where
from the clinicians’ point of view; most patients should receive the intervention as
1 Finding and Appraising the Evidence: EBM and GRADE
12
the expected benefi ts comfortably outweigh the undesirable effects. In these situation there is usually little need for extensive discussions about the merits of the
intervention. Weak recommendations on the other hand, may be appropriate in
some patients, but requires more thorough discussions about the benefi ts and
adverse effects of the treatment (Table 1.3 ) [ 4 ].
Ultimately, decisions about the care of individual patient falls to the surgeon and
the patient which takes into account not just the external evidence for a particular
course of action but crucially the patients own preferences and values and the practical
ability for the surgeon to deliver on this decision in their own specifi c environment.
Acknowledgment I would like to acknowledge Tania Gottschalk and Gordon Guyatt for their
advice and assistance.
Other Resources
JAMA Users Guide: Guyatt and Rennie
Author Gordon Guyatt, Drummond Rennie
Series Users’ Guides to the Medical Literature
Publisher McGraw-Hill
Publication date: 2008
ISBN 978-0071590341
CEBM website: http://www.cebm.net/
GRADE website: http://www.gradeworkinggroup.org/index.htm
EPIQ: https://www.fmhs.auckland.ac.nz/en/soph/about/our-departments/epide-
miology-and-biostatistics/research/epiq.html
Table 1.3 Implications of the strength of recommendation for an intervention in the GRADE
approach
Group Strong recommendation Weak recommendation
Patients Most patients would want the
course of action recommended,
and only a small proportion
would not
The majority of patients would want the
recommended course of action, but many
would not
Clinicians Most patients should receive the
recommended course of action
Different choices will be appropriate for
different patients based on their values and
preferences. Recognizing that you must
make greater effort to help each patient to
arrive a management decision
Policy
makers
The recommendation can be
adopted as policy in most
situations
Policy making will require substantial
debate and involve many stakeholders
S.K. Srinathan
13
References
1. Andrews J, Guyatt G, Oxman AD, Alderson P, Dahm P, Falck-Ytter Y, et al. GRADE guide-
lines: 14. Going from evidence to recommendations: the signifi cance and presentation of recommendations. J Clin Epidemiol. 2013;66(7):719–25. doi:
10.1016/j.jclinepi.2012.03.013 .
2. Atkins D, Best D, Briss PA, Eccles M, Falck-Ytter Y, Flottorp S, et al. Grading quality of evi-
dence and strength of recommendations. BMJ (Clin Res Ed). 2004;328(7454):1490.
doi:
10.1136/bmj.328.7454.1490 .
3. Balshem H, Helfand M, Schünemann HJ, Oxman AD, Kunz R, Brozek J, et al. GRADE guide-
lines: 3. Rating the quality of evidence. J Clin Epidemiol. 2011;64(4):401–6. doi:
10.1016/j.
jclinepi.2010.07.015
.
4 . B r o żek JL, Akl EA, Compalati E, Kreis J, Terracciano L, Fiocchi A, et al. Grading quality of
evidence and strength of recommendations in clinical practice guidelines Part 3 of 3. The
GRADE approach to developing recommendations. Allergy. 2011;66(5):588–95.
doi:
10.1111/j.1398-9995.2010.02530.x .
5. Evidence-Based Medicine Working Group. Evidence-based medicine. A new approach to
teaching the practice of medicine. JAMA. 1992;268(17):2420–5. doi:
10.1001/
jama.1992.03490170092032
.
6. GATE in ACP. 2013. GATE in ACP, 1–4.
7. Grimes DA, Schulz KF. An overview of clinical research: the lay of the land. Lancet.
2002;359(9300):57–61. doi:
10.1016/S0140-6736(02)07283-5 .
8. Grimes DA, Schulz KF. Bias and causal associations in observational research. Lancet.
2002;359(9302):248–52. doi:
10.1016/S0140-6736(02)07451-2 .
9. Guyatt GH, Oxman AD, Kunz R, Vist GE, Falck-Ytter Y, Schünemann HJ, GRADE Working
Group. What is “quality of evidence” and why is it important to clinicians? BMJ (Clin Res Ed).
2008;336(7651):995–8. doi:
10.1136/bmj.39490.551019.BE .
10. Haynes RB. Optimal search strategies for retrieving scientifi cally strong studies of treatment
from Medline: analytical survey. BMJ (Clin Res Ed). 2005;330(7501):1179. doi:
10.1136/
bmj.38446.498542.8F
.
11. Karanicolas PJ, Davies E, Kunz R, Briel M, Koka HP, Payne DM, et al. The pylorus: take it or
leave it? Systematic review and meta-analysis of pylorus-preserving versus standard whipple
pancreaticoduodenectomy for pancreatic or periampullary cancer. Ann Surg Oncol.
2007;14(6):1825–34. doi:
10.1245/s10434-006-9330-3 .
12. Sackett DL. Evidence-based medicine. Semin Perinatol. 1997;21(1):3–5.
13. Sackett DL, Rosenberg WMC, Gray JAM, Haynes RB, Richardson WS. Evidence based medi-
cine: what it is and what it isn’t. BMJ (Clin Res Ed). 1996;312(7023):71–2. doi:
10.1136/
bmj.312.7023.71
.
1 Finding and Appraising the Evidence: EBM and GRADE
15© Springer International Publishing Switzerland 2016
J.M. Millis, J.B. Matthews (eds.), Diffi cult Decisions in Hepatobiliary
and Pancreatic Surgery, Diffi cult Decisions in Surgery: An Evidence-Based
Approach, DOI 10.1007/978-3-319-27365-5_2
Chapter 2
Is Surgery Indicated for Asymptomatic
Giant Hepatic Hemangioma?
John Seal
Abstract Liver hemangiomas are the most common benign neoplasms of the liver
and are often diagnosed incidentally on abdominal imaging. Most liver hemangiomas are small (<4 cm) indolent lesions that do not require further intervention or
surveillance in the absence of symptoms. The management of giant liver hemangiomas (>4 cm), however, remains controversial. The natural progression of giant hemangiomas is not well defi ned and the risk of life-threatening complications, namely
rupture and bleeding, is not clearly established. The development of symptoms such
as abdominal pain, mass effects or life-threatening events such as rupture, bleeding
or consumptive coagulopathy is an indication for surgical resection or intervention.
Asymptomatic giant hemangiomas present a management dilemma as the risk of
life-threatening complications is unknown. Several single centers studies have demonstrated the safety of expectant management of even very large asymptomatic
hemangiomas. There is no evidence to support using size alone as an indication for
resection. Although morbidity and mortality of liver resection for hemangioma has
improved, the risks of surgical intervention need to be balanced against the rare risk
of adverse events during expectant observation.
Keywords Hemangioma • Liver resection • Observation • Complications • Liver •
Giant hemangioma • Cavernous hemangioma • Surgery • Resection
Introduction
Liver hemangiomas are the most common benign neoplasms of the liver and are
often diagnosed incidentally on abdominal imaging. Most liver hemangiomas are
small (<4 cm) indolent lesions that do not require resection or routine follow-up in
the absence of symptoms or complications. The management of giant liver
J. Seal (*)
Multi-Organ Transplant Institute , Ochsner Medical Center ,
1514 Jefferson Highway , New Orleans , LA 70121 , USA
e-mail:
johnsealmd@gmail.com
16
hemangiomas (>4 cm), however, remains controversial [ 1 – 3 ]. In contrast to smaller
lesions, giant hemangioma s can become quite large (>40 cm), symptomatic and
even cause life-threatening complications. The most common symptoms of giant
hemangiomas are abdominal pain and mass effects of the tumor such as biliary
obstruction [ 4 , 5 ], Budd Chiari syndrome [ 6 ], vena cava compression [ 7 ], and gas-
tric outlet obstruction [ 8 ]. Although spontaneous rupture is very rare, traumatic rup-
ture or intra-tumoral bleeding often necessitates emergency resection, trans-arterial
embolization or both [ 9 ]. In some cases when hepatic resection is not anatomically
feasible, both deceased and living donor liver transplant ation have been reported for
treatment of symptomatic giant hemangioma [ 10 – 12 ].
In the absence of signifi cant symptoms, however, the rationale for surgical resection is less clear. The natural progression of hemangiomas and the risk of lifethreatening complications, namely rupture and bleeding, is not well established.
Several authors have advocated for preventive surgical resection or enucleation
based on tumor size, rate of growth and perceived risk of rupture despite a lack of
supporting evidence. Also, progress in surgical technique, anesthesia and perioperative care has reduced the risk of death and major complications following liver
resection , further lowering the risks associated with surgical intervention. An
evidence- based approach to surgical management of asymptomatic giant hemangioma s must balance an estimate of the risk of expectant management in the absence of
well-defi ned natural history of the disease with peri-operative morbidity and risks of
surgical intervention.
Search Strategy
A literature search of English language publications from 1990 to 2014 was used to
identity published data on management of liver hemangiomas using the PICO outline (Table 2.1 ). PubMed database was searched using the following terms [number
of results]: “liver, hemangioma, surgery , observation ” [ 36 ], “liver, giant, hemangioma, surgery, observation” [ 12 ], “surgical, approach, liver, hemangioima” [80],
“giant, liver, hemangioma, surgery, technique” [ 17 ]. Articles that did not present
new data with respect to observation versus surgical management were excluded.
Retrospective studies of benign liver lesions were included if a separate analysis of
hemangiomas was provided. In an effort to be more comprehensive in the analysis,
studies that included smaller hemangiomas (<4 cm) were considered in the review.
Table 2.1 PICO table for management of giant liver hemangioma
P (Patients) I (Intervention)
C (Comparator
group) O (Outcomes measured)
Patients with giant liver
hemangioma (>4 cm)
without symptoms
Surgical resection
(anatomic resection,
enucleation, liver
transplanta tion )
Observation Post operative
complications, persistent
or recurrent symptoms, life
threatening adverse events
J. Seal
17
No prospective randomized studies comparing surgical resection and observation of
asymptomatic giant hemangioma s were identifi ed. The PubMed search yielded six
single institution and one multicenter retrospective study comparing surgical resection and observation of hemangiomas and four single center retrospective reviews
of benign liver lesions that included analysis of hemangiomas. An additional two
retrospective single center reviews of resection for hemangioma were included to
better assess the rate of complications following resection. The data were classifi ed
using the GRADE system.
Results
Resection Versus Observation for Giant Hemangiomas
Evidence comparing resection versus observation of asymptomatic giant hemangioma s is limited to retrospective single institution studies (Table 2.2 ) [ 13 – 20 ] and
sub-analyses within single center retrospective studies of benign liver tumor s
(Table 2.3 ) [ 21 – 24 ]. The primary outcomes in most of these studies included peri-
operative morbidity and mortality , resolution of symptoms in the treatment group or
development of new symptoms and adverse events in the observation cohorts. None
of the studies describe deliberate changes in treatment algorithms during the study
period and no explicit comparison of practices in different eras. Thus, the interpretation of the data is limited to center specifi c and often ill-defi ned practices in the
management of giant hemangiomas. Nevertheless, the cumulative trends in outcomes offers insight into the risks and morbidity of resection compared with observation and the natural history of giant hemangiomas.
Table 2.2 Resection versus observation for liver hemangioma
Author (year)
N
(total)
Resection Observation
N % Complication N Finding
Yedibela (2013) 246 103 17 % 143 56 % new symptoms, 2 deaths
from rupture
Giuliante (2010) 74 40 10 % 34 No signifi cant increase in size of
asymptomatic tumors during
observation
Schnelldorfer
(2010)
289 56 14 % 233 Size not associated with adverse
events
Yoon (2003) 115 52 25 % 63 36 % resected patients to exclude
presence of malignancy
Terkivatan (2002) 49 11 27.3 % 38 Symptoms resolved in 12 patients
Pietrabissa (1996) 78 16 NA 62 No rupture in observation group
Yamagata (1991) 33 13 23 % 20 Observation group tumors <5 cm
diameter
2 Is Surgery Indicated for Asymptomatic Giant Hepatic Hemangioma?
18
The most recent report comparing resection and observation by Yedibela et al.
[ 14 ] reviewed 307 hemangiomas referred for evaluation. Elective surgery was per-
formed in 103 patients, 62 of which were symptomatic and 41 asymptomatic. Of the
asymptomatic patients undergoing resection, 11 were for diagnostic uncertainty, 9
for tumor enlargement and 21 for patient fear of future complications. There was no
mortality in the post-operative period and symptom resolution was achieved in
88 % of symptomatic patients. In contrast to other studies, they report a 9 % rate of
major complications in the observation group with two fatalities from traumatic
hemangioma rupture. In this study, the overall trend was toward lower rates of complications in the surgical treatment group.
Giuliante et al. [ 13 ] reviewed 74 consecutive referrals for hemangioma evalua-
tion, with 34 undergoing observation and 40 treated surgically. As a regional hepatobiliary referral center, the authors discuss the bias that most giant hemangioma s
were referred for symptoms, large size or diagnostic uncertainty and that the overall
operative rate of 54 % is likely infl ated with underrepresentation of asymptomatic
lesions. The primary indications for resection were abdominal symptoms, diagnostic uncertainty and tumor growth. Tumor growth has been used by some centers as
an indication for resection, but the trajectory of growth over long term follow-up
and its implication for risk of tumor rupture is uncertain. In this study, only 7 of 14
tumors demonstrating growth underwent resection, 5 of which had additional indications for resection (abdominal pain and Kasabach-Merritt syndrome). Of the
seven tumors demonstrating growth in the observation group, the tendency to
enlarge decreased over time and among all tumors in the observation group, there
was no signifi cant increase in mean tumor size or development of new symptoms
during the follow-up period.
Another single institution review by Terkivatan et al. [ 19 ] supported the safety of
expectant management of asymptomatic giant hemangioma s. During the study
period, 11 patients were treated with resection , all of whom had abdominal symptoms attributed to the hemangioma except for one asymptomatic lesion that exhibited
5 cm of growth over 36 months follow-up. Thirty-eight patients were managed with
observation . Importantly, there was no signifi cant difference in the mean diameter
of tumors in the resection group compared with the observation group. Twelve of
the observation patients had abdominal pain on initial assessment that was not
Table 2.3 Studies of benign liver lesions: analysis of hemangiomas
Author (year)
N
(total)
Resection Observation
N % Complication N Finding
Mezhir (2013) 151 60 NA 91 4.4 % of observed tumors were
ultimately resected
Terkivatan (2001) 103 25 24 % 78 25 cm tumor followed without
need for resection
Charny (2001) 97 39 21 % 58 63.3 % of pre-operative biopsies
were indeterminate or incorrect
Weimann (1997) 238 103 18.8 % 135 No episodes of bleeding in
observation group
J. Seal
19
attributed to the hemangioma and, in each case, the pain resolved during follow-up.
None of the asymptomatic patients developed new symptoms during a mean follow up period of 59 months.
Schnelldorfer et al. [ 16 ] report the only contemporary series to assess the impact
of hemangioma management on quality of life . A quality of life survey was administered with responses from 289 of 492 patients treated for hemangioma at their
center, including patients treated with surgical resection or observation . In the
observation group, 20 % of patients developed new-onset symptoms with 2 % being
life-threatening. Post-operative complications occurred in 14 % of resected patients
with 7 % being life threatening. Interestingly, the size of the hemangioma was not
associated with adverse events in either group, lending credence to the notion that
risk of rupture is not necessarily related to tumor size or rate of growth. The subjective quality of life survey was similar for resected and observed patients leading the
authors to conclude that observation is preferred in most patient and surgical resection should be reserved for patient with symptoms or hemangioma-related
complications.
The consideration of tumor size and rate of growth have both been proposed as
risk factors for tumor rupture and, thus, indications for resection in asymptomatic
patients. Iwatsuki et al. [ 25 ] suggested benign hepatic lesions exceeding 10 cm
should be resected based increased risk for internal bleeding, further growth or rupture, although this was not based on conclusive prospective observational data. In
the more recent literature, an absolute size threshold as an indication for resection is
not favored. The indication for resection of giant hemangioma was most often the
development of symptoms. The rate of growth of the tumor remains a controversial
indication for resection, although such recommendations are made without a clearly
defi ned relationship between rate of growth and risk of rupture. Pietrabissa et al.
[ 17 ] proposed resection for “rapidly growing” asymptomatic hemangiomas defi ned
as a minimum 25 % increase in largest diameter over a period of 6 months. The
rationale is based on the speculation that the risk for tumor rupture or diagnostic
error is higher in patients with rapid growth. Although well reasoned, no clinical
support is provided to substantial the claim of increased risk of rupture or diagnostic
error with rapid growth, leaving the natural disease course of giant hemangiomas
unresolved.
Diagnostic uncertainty has been used as an indication for resection of vascular
lesions of the liver when a defi nitive diagnosis cannot be made from radiologic
studies, particularly in the setting of known extra-hepatic malignancies or risk
factors for the development of liver malignancy ( cirrhosis , hepatitis, steatosis).
With advances in imaging modalities and experience at high-volume centers,
diagnostic uncertainty is much less common. In a subgroup analysis of a retrospective review of benign liver lesions at Memorial Sloan-Kettering Cancer
Center, Mezhir et al. [ 22 ] report diagnostic uncertainty as the indication for surgi-
cal resection in 53.3 % of asymptomatic hemangiomas from 1992 to 2009.
Importantly, though, only 12.5 % of patients resected for diagnostic uncertainty
were seen in the last 10 years of the study, suggesting a signifi cant impact of
advances in medical imaging.
2 Is Surgery Indicated for Asymptomatic Giant Hepatic Hemangioma?
20
Treatment of Giant Hemangiomas: Operative Approaches and Non-surgical Therapies
The morbidity and mortality of hemangioma resection is an important consideration when determining appropriate treatment for giant hemangioma s, particularly asymptomatic lesions. Complications following surgical resection range
from 10 % to 27.3 % in recent studies comparing resection and observation . In
a recent multi- institutional review of surgical management of hepatic hemangiomas [ 26 ], the overall rate of Clavien grade 3 complication or higher was 5.7 %
and included bile leak s and bleeding. The 30-day post-operative mortality was
0.8 % (N = 2). Although hepatic resection s for hemangioma can be performed
safely, post-operative complications can be signifi cant with a nearly 1 % risk of
death. The documented risks of surgery must be carefully weighted against the
severity of symptoms and the very low risk of complications associated with
observation.
Evolution in operative techniques and application of non-surgical therapies may
lead to a less invasive and safer approach to management of hemangiomas in the
future. Though technical aspects of resection may vary greatly between centers, a
single center study by Lerner et al. [ 27 ] documented an intra-institutional evolution
toward enucleation over resection for large hemangiomas over time with more liberal use of infl ow occlusion, less intra-operative blood loss and less complications.
Liver transplantation [ 10 – 12 , 28 ] for life threatening symptoms attributed to giant
hemangioma s has been reported, further expanding therapeutic options to include
lesions anatomically unresectable by conventional approaches. Laparoscopic [ 29 –
32 ] and robotic [ 33 ] approaches have been reported by several centers, although the
impact of a minimal access approach in reducing operative risk or complications is
not defi ned.
The use of several non-surgical therapies for symptomatic giant hemangioma s
has been reported. Transarterial embolization is widely used both in the setting of
acute management of ruptured hemangiomas and as a pre-operative treatment to
reduce vascular infl ow and decrease size [ 34 – 38 ]. Radiofrequency ablation has
also been reported for symptomatic control of giant hemangiomas with promising
results. Gao et al. [ 39 ] report a single institution initial experience with RFA
treatment in giant hemangiomas. In this series, use of RFA in lesions >10 cm
diameter had a 100 % complication rate including life-threatening complications
of lower esophageal fi stula and acute respiratory distress syndrome. In smaller
lesions (5–10 cm diameter), RFA was successful at controlling symptoms with
only minor complications. Medical therapies such as the anti-angiogenic agent
bevicizumab and the tyrosine kinase inhibitor sorafenib have also been reported
to decrease the size of large hemangiomas, though published data is limited to
case reports. Overall, even less invasive modes of treating giant hepatic hemangiomas will have some risk of complication that must be carefully considered in
asymptomatic patients.
J. Seal
21
Recommendations
Surgical resection is a well established and accepted treatment of symptomatic giant
hemangioma s. The relative risk of surgical intervention is balanced by a benefi t to
the patient with expected improvement or resolution of symptoms. Management of
asymptomatic giant hemangiomas remains controversial as the natural progression
of the disease in not well described. The hypothesis that tumor size contributes to
the risk of rupture is not supported in the literature and should not be used alone as
an indication for surgical resection . Retrospective studies from many centers demonstrate that expectant management of asymptomatic giant hemangiomas is safe.
Surgical resection or an alternative treatment modality should be considered if
symptoms develop. Though several centers consider rapid growth of tumors during
observation periods as an indication for resection, there is no evidence to suggest
that growth alone presents additional risk to the patient if a defi nitive radiographic
diagnosis has been made.
A Personal View of the Data
Surgical resection of giant symptomatic hemangiomas is widely accepted as the
risks of surgery are balanced by a direct benefi t of symptom relief. Though resolution of symptoms after resection is not universal and varies in published reports, it is
reasonable to expect a high rate of symptom resolution if the initial symptoms were
appropriately attributed to the hemangioma. To that end, symptomatic patients with
giant hemangioma s should be carefully assessed to ensure the symptoms, in particular non-specifi c abdominal pain , can be attributed to effects of the mass. The retrospective series highlighted in this chapter support the safety and prudence of deferring
surgical resection in asymptomatic patients with giant hemangiomas. Yedibela et al.
reported a higher rate of adverse events in patients under observation including two
deaths from rupture, compared with other contemporary series that report no adverse
events. Overall, the evidence indicates observation of even very large hemangiomas
is safe. There is no evidence to support size alone as an indication for surgical resection in asymptomatic lesions. Impending complications such as vascular compression or gastrointestinal obstruction may be appropriate. Patient anxiety has been
reported as an indication for surgical resection of asymptomatic lesions in some
series. While anxiety can certainly be a signifi cant symptom, it is the responsibility
of the surgeon to reassure patients regarding the very low risk of adverse events
associated with observation and to manage patient anxiety non-operatively. Finally,
the risk of rupture related to tumor growth is unclear, but to date no series has demonstrated that rapid growth of hemangiomas presents an increased risk if a defi nitive
radiologic diagnosis has been made. Rapid growth may prompt further investigation
to confi rm the diagnosis and exclude concern for malignancy, but there is insuffi cient
evidence to support surgical resection on the basis of growth alone.
2 Is Surgery Indicated for Asymptomatic Giant Hepatic Hemangioma?