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103

9 Thoracic Ablation: Primary Lung Cancer, Metastases, Chest Wall Disease

system to system. For example, the table height should be low for obese patients,

for noncoaxial or non ﬂ exible systems, and for super ﬁ cial lesions.

Prone positioning or the location of the scapula may change access route com-•

pletely. Position of the arms above the head or alongside the body will also

change the scapular position. If in doubt, it is useful to perform a CT in the

desired position prior to the GA.

In prone patients, suitable support to ensure abdominal breathing is required to •

prevent ventilatory compromise. Other pressure points also need protection.

If lateral access is contemplated, it is good to ensure that enough space is present •

between gantry and the patient to accomodate the electrode apparatus outside the

body. This can be done by placing the patient off-center on the CT table. This is

particularly true if a noncoaxial system is used.

Performing the Procedure

Technique

Skin preparation: A chlorhexidine or betadine skin preparation is used. A wide •

area is prepped as a pneumothorax drain may have to be placed at a site remote

from the electrode entry site.

Local anesthesia: This is not required in GA patients. Nevertheless, a 21-G nee-•

dle with some anesthetic is used to assess needle angle and location prior to the

larger electrode. Do not hover at the pleural surface with this needle – it is quite

easy to do so with this needle in thin cachectic patients and giving them a pneu-

mothorax prior to start of the procedure !!

A small skin incision is made •

The electrode is inserted in the desired angle to the appropriate depth. I use a •

clock face and take the help of an assistant to monitor the angle of entry from the

foot end of the CT table. The precise location of the needle tip within the lesion

also depends on the electrode and its ablation geometry. The more rounded tines

of the LeVeen electrode means that the needle tip should be just beyond the mid-

point of the lesion, while the forward pushing tines of the Starburst electrode

means that the tip should be short of the midpoint of the lesion.

If a coaxial needle is used, a biopsy can be performed at this stage through the •

same needle. A core biopsy can and does cause hemorrhage. So, only perform

this, if, it is absolutely necessary.

Hemorrhage from the biopsy or the needle tract can obscure a lesion very quickly. •

It is useful to get a quick needle entry into the lesion and commence ablation.

This is a good way to stop the bleeding.

If a pneumothorax occurs during entry, it is usually possible to drain it and com-•

plete the ablation.

The electrode is partially deployed (in case of tined electrodes) and its position •

checked with a volume CT acquisition. An MPR of this is performed at the

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workstation to ensure that the needle is appropriately centered in all planes before

full deployment (see Fig. 9.2 ). Ideally, tines going through the tumor into normal

lung tissue should not be withdrawn, without ablating, for fear of seeding.

The electrode is fully deployed and its position checked with CT. Once deployed, •

tined electrode does not move in relation to the lesion.

Ablation is commenced and continued according to the manufacturer’s algo-•

rithm. Unlike solid organ ablation, it is necessary to keep a close eye at the needle

position, the compliance graph of the Boyle’s apparatus, etc. as a pneumothorax

may happen mid-procedure and the needle position can change in the lungs.

A second or subsequent ablation cycles are performed as deemed ﬁ t to ensure •

that there will be an adequate margin all around the tumor.

Fig. 9.2 The electrode is partially deployed (in case of tined electrodes) and its position checked

with a volume CT acquisition ( a ). An MPR of this is performed at the workstation to ensure that

the needle is appropriately centered in all planes before full deployment ( b ). End point of ablation

in two different patients ( c & d ) with a ground glass opacity all around the tumour. This needs to

be checked in all three planes. Sometimes the ablated area appears as bubble lucencies ( e ) that

disappear by three months

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9 Thoracic Ablation: Primary Lung Cancer, Metastases, Chest Wall Disease

The pads can heat up during prolonged ablation. Frequent checks or use of an •

ice-pack may be useful.

Track ablation is performed within the lungs, but not across the pleural surface. •

The needle entry site is covered by a small dressing. •

Tips

For lesions close to the pleural surface, or, on the diaphragm, hydrodissection •

can be used to protect the chest wall or to ensure complete treatment. Algorithms

are also different for lesions with pleural contact.

Often, a signi ﬁ cant change in needle angle can be made within the lung without •

having to withdraw the needle across the pleural surface.

A small lesion may be enveloped in tines rather than trying to penetrate it by put-•

ting the needle tip next to it.

The 14-G electrodes cause signi ﬁ cant ﬂ are artefact on CT. Using thicker sections •

to view or using a bone window can be useful.

With tined electrodes, angulation of the shaft prior to deployment can change the •

coverage by the tines considerably.

With tined electrodes, it is possible to pull the deployed tines away from a vital •

structure during ablation.

Hypervascular chest wall lesions and certain parenchymal metastasis can be pre-•

embolized (intercostal or internal mammary) prior to ablation.

Pneumothorax may happen at the time of needle withdrawal. A check CT should •

be performed prior to reversal of the patient.

Endpoint

The endpoint is dictated by the algorithm of the generator when a treatment cycle is

completed. Usually, more than one ablation cycle is necessary to encompass the

entire tumor with a satisfactory margin. A ground glass halo, around the tumor,

measuring at least 5 mm indicates satisfactory endpoint of treatment. (Fig. 9.2 )

Larger margins are desirable for adenocarcinomas.

Immediate Postprocedure Care

Usual anesthetic recovery principles apply. An additional anesthetic assistant is

invaluable for this period, particularly if more than one case is scheduled for the list.

Oxygen saturation is monitored continuously, particularly if a pneumothorax had

occurred at the time of treatment.

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106

S. Roy-Choudhury

Follow-up and Postprocedure Medications

A chest radiograph is performed 4 h after the procedure. Good communication •

with the admitting team is essential.

A 5-day course of antibiotics is prescribed only in high-risk cases (previous •

radiotherapy, poor lung function, etc.).

Patients usually recover very fast and are encouraged to sit up and have a meal in •

the evening.

A visit by the operating team on the ﬁ rst post-op day is essential. Pain control, •

particularly for pleural-based lesions is important. It is important to impress on

the clinical team and the admitting nurses that in spite of no apparent scars, etc.

the procedure can be painful !!

Uncomplicated cases may be discharged on the ﬁ rst post-op day with suitable •

advice regarding postembolization syndrome and pain due to pleural reaction

that may be delayed till day 5. Preemptive analgesia is useful. Drained pneu-

mothoraces and lesions close to the pleural surface or those with potential bron-

chial communication are kept for at least one additional day as delayed

pneumothoraces can occur.

Imaging follow - up schedule includes a pre- and postcontrast CT at 1, 4, 7, 12, 18,

24, 36, 48, and 60 months. In cases of renal dysfunction, diffusion-weighted MRI is

useful. We use PET as a problem-solving tool, but there is increasing evidence to

perform a routine PET at 3–6 months. Interpreting imaging appearances can be

complex, but a pattern-based approach can help, as outlined below.

Immediate Postprocedure Appearances on CXR and CT

These include dependent hypostatic changes (normal), a ground glass opacity

(GGO) encompassing the tumor, hemorrhage, pleural reactions, etc.

Appearances of Complete Response

A GGO encompassing the tumor in all planes is the best predictor for complete •

treatment. This may evolve into an area of atelectasis, the size of which is typi-

cally larger than the original tumor at the 1-month scan, which is taken as the

baseline for follow-up. The size of the atelectasis reduces over time and eventu-

ally becomes a scar. (Fig. 9.3 )

Lack of enhancement between an unenhanced and a postcontrast scan signi ﬁ es •

complete necrosis. Ideally, the postcontrast scan should be performed at around

60 s rather than in the arterial phase. (Fig. 9.4 )

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9 Thoracic Ablation: Primary Lung Cancer, Metastases, Chest Wall Disease

Cavitation can be seen in 25% cases and appears between 1 and 4 months. •

Linear strands or bubble lucencies may appear within the treated area (Fig. • 9.2 ) .

Appearances of Incomplete Response or Recurrence

Local recurrence is characterized on CT by

Enlargement of the ablation zone after 1 month, •

Increased enhancement (by at least 15 HU from the unenhanced scan). •

Nodular excrescence from the smooth outline of the treated atelectasis (Fig. • 9.5 ).

Recurrence can also be due to satellite nodules, needle tract seeding, mediastinal •

node involvement, further lung nodules, or extrathoracic metastasis.

Results

Detailed literature review is outside the scope of this text, but a summary of the

important papers is given in Table 9.1 . Complete tumor necrosis and good local

control is the goal of ablative therapy. If small tumors are chosen and a good margin

of groundglass opacity is obtained at the end of ablation, a local recurrence rate of

less than 10% can be achieved, which is similar to the rates achieved by sublobar

resection of small lung tumors. Lung function is well preserved after tumor abla-

tion. In a recent paper by Lee H et al., median survival times for patients treated

with surgery alone and RFA alone for stage I–II primary lung cancer were 33.8 and

28.2 months, respectively ( p = 0.426). Median survival times for patients treated

with chemotherapy alone and RFA with chemotherapy for stage III–IV cancer were

29 and 42 months, respectively ( p = 0.03).

Alternative Therapies

Surgery: Lobectomy with node sampling is the gold standard for operable and ﬁ t •

Stage 1 and 2 NSCLC, but has higher morbidity and a mortality rate of around

2.5%. Sublobar resections are limited to less ﬁ t patients or patients with metas-

tasis. Neoadjuvant therapies may render higher-stage tumors operable.

External beam radiotherapy: For medically inoperable patients and early stage •

disease. High local recurrence rate.

Chemotherapy: For higher-stage disease or used in the neoadjuvant setting. •

Stereotactic radiotherapy: Excellent recent results. May have equivalent survival •

to lobectomy for small lung cancers with very low morbidity and mortality.

TACE or arterial infusion therapies: Encouraging results but limited data. •

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S. Roy-Choudhury

Table 9.1 Literature review

Author (year) Patients (tumors) Modality Pathology

Local recurrence/residual

disease (%) Survival Complications

deBaère (2006) 60 (100) RFA NSCLC 12 71% OS at 12 m 9% treated Ptx

Mets

Lencioni (2008) 106 (183) RFA NSCLC 12 92%, 70% 25% Ptx, 4% pleural

effusion

Mets

Hiraki et al. (2007) 128 (342) RFA Mets N/A 84%, –, 66%

NSCLC

Chua et al. (2010) 100 RFA Colorectal met N/A 87%, 66%, 50%

30%

23% treated Ptx, 1

emphysema

Hiraki et al. (2011) 50 RFA NSCLC 31 100%, 93%, 80% 12% grade 2, 6% grade

3 toxicity

Wolf et al. (2008) 50 (82) MWA 26 83%, 73%, 61% Ptx (30%), hemoptysis,

skin burns

Chan et al. (2011) 19 (23) CRA N/A 21.7 N/A 15% Ptx

Survival is cancer speci ﬁ c and at 1,2, 3, and 5 years unless stated

MWA microwave ablation, RFA radiofrequency ablation, CRA cryoablation, Ptx pneumothorax

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9 Thoracic Ablation: Primary Lung Cancer, Metastases, Chest Wall Disease

Combination treatments: Multimodality combination therapies seems to be the •

future of lung cancer management.

Complications

Lung is perhaps the riskiest organ to ablate. Prior experience in liver or kidney abla-

tion is useful.

Pneumothorax is the most common complication (median 28%), occurs more •

commonly in emphysema and with positive pressure ventilation. It requires

drainage/aspiration in around 15% cases. Most pneumothoraces are minor, non-

progressive, and do not require any treatment. Rarely, a surgical chest drain is

necessary for persistent pneumothorax or a broncho-pleural communication.

Almost always, the ablation treatment can be completed with a chest drain in

situ. In most cases, it resolves within 24–48 h of chest drainage. Occasionally, it

can be delayed, particularly if the GGO is in contact with the pleural surface.

Infection: Can take the form of pneumonia or lung abscess and is the major cause •

of mortality following ablation. Previous DXT and age are risk factors.

Bleeding. Life-threatening in 0.4%. Less severe hemoptysis is seen in around •

5%. More with multitined electrode, in basal and mid-zone nodules, with longer

needle tracts, and low platelets.

Postembolization syndrome: Relatively less common following lung ablation. •

Can be controlled with paracetamol.

Pleural effusion and aseptic pleuritis: Most common cause for readmission postab-•

lation. Puncture numbers and previous chemotherapy are signi ﬁ cant risk factors.

Air embolism, diaphragm injury, brachial plexus or phrenic nerve injury (usually •

transient), skin burn (usually with microwave), grounding pad burn, tumor seed-

ing, or GA-related ventilatory complications are rare.

In a large Japanese series of 1,000 ablation procedures in 420 patients, four

deaths (0.4%) related to RFA procedures was reported, most from interstitial pneu-

monia. The major complication rate was 9.8%. Frequent major complications were

aseptic pleuritis (2.3%), pneumonia (1.8%), lung abscess (1.6%), bleeding requir-

ing blood transfusion (1.6%), pneumothorax requiring pleural sclerosis (1.6%), fol-

lowed by bronchopleural ﬁ stula (0.4%), brachial nerve injury (0.3%), tumor seeding

(0.1%), and diaphragm injury (0.1%).

How to Avoid

Prepare a good team including a dedicated nurse, an anesthetist, and a CT •

technologist

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S. Roy-Choudhury

Appropriate patient and lesion selection •

Treat one lung at a time •

Keep at risk patient or lesion admitted for longer •

Key Points

Support from and prior discussion with the thoracic multidisciplinary team •

is critical

Multiplanar review of the preprocedure CT is essential to plan access and •

treatment volumes

GA is useful but not mandatory •

Overtreatment is the key to success – a ground glass margin of 1 cm or •

greater all around the tumor reduces risk of recurrence. Complete tumor

necrosis and good local control is the goal of ablative therapy.

Rigorous imaging follow-up is critical – CT is usually performed, although •

PET at 3–6 months could be better.

Local nodular recurrence, if detected early, can be successfully retreated. •

Complications (most commonly pneumothorax) do occur, more than RFA •

of other sites.

Although less used, microwave ablation, cryoablation, or sequential radiof-•

requency ablation may offer several advantages over standard unipolar

radiofrequency ablation in the lungs.

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9 Thoracic Ablation: Primary Lung Cancer, Metastases, Chest Wall Disease

Fig. 9.3 Typical evolution of atelectasis following successful ablation of a small renal cell carci-

noma metastasis ( a ). The ablation volume is usually largest at 1 month ( b ) which should be taken

as the baseline. From there, the ablation volume should reduce on subsequent follow up ( c ) to

eventually become a linear scar ( d )

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