Radiofrequency ablation (RFA) as a technique for reduction or eradication of one or more pulmonary tumor(s), including pleura or chest wall when involved by tumor extension, may be considered medically necessary, only when determined to be indicated by the treating physician, for the following:
- As palliative treatment of medically or surgically inoperable tumor(s), and/or
- For patients who have failed, or are a poor candidate for, standard treatment such as surgical intervention, radiation, chemotherapy, or opioids.
For all patients who do not meet the above criteria, radiofrequency ablation (RFA) as a technique for reduction or eradication of one or more pulmonary tumor(s), including pleura or chest wall when involved by tumor extension is considered experimental, investigational and unproven.
This policy was originally based on an analysis of relevant literature identified in a MEDLINE search, beginning in 2003. The current policy includes a MEDLINE literature search through March 2013.
Radiofrequency ablation (RFA) has been used to treat pulmonary tumors in many studies. In a 2011 evidence-based review, 46 studies on RFA for lung tumors were evaluated, which included 2,905 ablations in 1,584 patients with a mean tumor size of 2.8 ± 1.0 cm. (4) Twenty-four studies (51.2%) reported rates of local recurrence, which ranged from 0% to 64% and occurred in 282 cases (12.2%) with a mean follow-up time of 13 months (range 3-45 months of 19 studies reporting). Primary lung cancer rates of local recurrence were not significantly different at 22.2% than for metastases at 18.1%. Twenty-one studies reported rates of overall survival, which ranged from 25% to 100% with a mean of 59.4% and a mean follow-up time of 17.7 ± 12.4 months. The mean cancer-specific survival rate was 82.6%, as reported in 24 studies with a range of 55% to 100% with a mean of 17.4 ± 14.1 months follow-up. Mean overall morbidity was 24.6% and most commonly included pneumothorax (28.3%), pleural effusion (14.8%), and pain (14.1%). Mortality related to the RFA procedure was 0.21% overall. The authors observed that RFA for the treatment of lung tumors is promising, noting better outcomes with RFA than traditional external beam radiotherapy and RFA outcomes comparable to surgery but with lower rates of procedural mortality (0.21% vs. 1%, respectively). Additionally, repeated RFA procedures can be performed without reducing lung function. The authors acknowledged the current evidence is limited to case series and indicated further prospective studies are needed to compare RFA to other local treatment options.
A 2008 systematic review of RFA for primary and secondary lung tumors included studies that reported procedure-related morbidity and mortality, rates of complete tumor ablation, local recurrence and/or overall survival (OS). (5) Seventeen studies were included for a total of 707 patients (range: 12–142), and all were observational case series with no control groups and were classified as poor quality by the authors of the systematic review. No random controlled trials (RCTs) or comparative studies were found. The definition of nonsurgical candidates differed from study to study, and there were differences in the criteria used for tumor resectability. An additional confounding factor was that in some studies, additional therapies were used with RFA, such as systemic chemotherapy. The mean size of lesions treated ranged from 1.7 cm to 5.2 cm (median: 2.2 cm). Seven of the studies reported survival; 3 reported on 3-year survival rates. One-, 2-, and 3-year survival rates ranged from 63–85%, 55–65%, and 15–45%, respectively. The authors of the systematic review concluded that there is limited evidence reporting clinical outcomes of RFA treatment of lung tumors and that the quality of the evidence is relatively low, with no RCTs or case-control trials comparing the use of RFA with conventional treatment for nonsurgical patients. Of the studies that they included in their review, there were a wide range in results of local recurrence rates, heterogeneity of the patients selected, and tumor characteristics, and relatively short follow-up in most.
In a 2012 review of evidence from 16 studies, Bilal and colleagues compared RFA to stereotactic ablative radiotherapy (SABR) in patients with inoperable early stage non-small cell lung cancer (NSCLC). (6) The authors found overall survival rates for RFA and SABR were similar in patients at 1 year (68.2–95% vs. 81–85.7%) and 3 years (36–87.5% vs. 42.7–56%, all respectively). However, survival rates at 5 years were lower with RFA (20.1–27%) than with SABR (47%). Caution must be used in interpreting these findings drawn from comparisons of results from uncontrolled, case series and retrospective reviews.
In 2010, Zemlyak and colleagues prospectively compared 3 treatments for medically inoperable patients with stage I NSCLC: RFA in 12 patients, sublobar resection in 25 patients and percutaneous cryoablation in 27 patients. (7) At 3 years follow-up, survival rates were not significantly different between groups. Overall and cancer-specific 3-year survivals were 87.5%, 87.1%, and 77% and 87.5%, 90.6%, and 90.2%, respectively. The authors concluded any of the 3 procedures were reasonable options for treatment of lung tumors in patients unfit for major surgery. The authors noted since surgeons chose the treatment option with patient input for this study, selection bias limits interpretation of his study, and further studies are warranted. In 2011, Huang and colleagues prospectively followed 329 consecutive patients treated with RFA for lung tumors (237 primary and 92 metastatic). (8) Complications were experienced by 34.3% (113) of patients and were most commonly pneumothorax (19.1%). Overall survival at 2 and 5 years was 35.3% and 20.1%, respectively. The risk of local progression was not significantly different in tumors less than 4 cm but became significant in tumors greater than 4 cm.
A prospective, single-arm, multicenter trial from 7 centers in Europe, the U.S., and Australia reported the technical success, safety, response of tumors, and survival in 106 patients with 183 lung tumors. (9) All patients were considered to be unsuitable for surgery and unfit for radiotherapy or chemotherapy. Tumors measured less than 3.5 cm (mean 1.7 cm; standard deviation [SD]: 1.3) and included patients with NSCLC (n=22), colorectal metastases (n=41), and other metastases (n=16). Technical success rate was 99%. Patients were followed for 2 years, and a confirmed complete response lasting at least 1 year was observed in 88% of assessable patients, with no differences in response rate between patients with primary and metastatic tumors. Overall survival in patients with NSCLC was 70% at 1 year (95% confidence interval [CI]: 51–83%; cancer-specific survival, 92% [78–98%], and 48% at 2 years (95% CI: 30–65%; cancer-specific survival, 73% [54-86%]). Overall survival in patients with metastatic colorectal cancer was 89% at 1 year (95% CI: 76–95%; cancer-specific survival, 91% [78–96%]) and 66% at 2 years (95% CI: 53–79%; cancer-specific survival 68% [54–80%]). Overall survival in patients with other metastases was 92% at 1 year (95% CI: 65–99%; cancer-specific survival, 93% [67–99%]) and 64% at 2 years (43–82%; cancer-specific survival, 67% [48–84%]). Patients with stage 1 NSCLC (n=13) had OS rates of 75% (45–92%) at 2 years (cancer-specific, 92% [66–99%]). No differences in response were seen between patients with NSCLC or lung metastases. The authors concluded that RFA yields high proportions of sustained complete response in selected patients and RCTs that compare RFA with standard non-surgical treatment options are warranted. Comparison of patient survival rates with those from other studies in which different modalities were used are unreliable due to the heterogeneity of the study population and the severe pulmonary impairment and significant comorbidities of the patients in this study.
Zhu and colleagues reported on a study to assess the incidence and risk factors of various complications after RFA of pulmonary neoplasms. (10) The authors prospectively evaluated the clinical and treatment-related data regarding 129 consecutive percutaneous RFA treatment sessions for 100 patients with inoperable lung tumors. In this study, there was no post-procedural mortality. The overall morbidity rate was 43% (n=55 of 129). The most common adverse effect was pneumothorax, occurring in 32% (n=41 of 129) of treatment sessions. Other significant complications included pleuritic chest pain (18%), hemoptysis (7%), pleural effusions (12%), and chest drain insertion (20%). Both univariate and multivariate analyses identified more than 2 lesions ablated per session as a significant risk factor for overall morbidity, pneumothorax, and chest drain insertion. Length of the ablation probe trajectory greater than 3 cm was an additional independent risk factor for overall morbidity and pneumothorax. The authors concluded that RFA for lung tumors could be considered safe and technically feasible, with an acceptable incidence of complications.
In 2009, Pennathur et al. reported on 100 patients with inoperable lung tumors. (11) Forty-six patients had primary lung neoplasm, 25 had recurrent cancer, and 29 had pulmonary metastases. Mean follow-up was 17 months. Median OS for all patients was 23 months. The probability of 2-year OS for primary lung cancer patients, recurrent cancer patients, and metastatic cancer patients was 50% (95% CI: 33–65%), 55% (95% CI: 25–77%), and 41% (95% CI: 19–62%), respectively. In a retrospective review, Beland et al. reviewed recurrence patterns in patients with primary NSCLC treated with RFA between 1998 and 2008. (12) Ninety-one patients were identified and 10 excluded because of lack of post-treatment imaging results or multiple treated lung cancers (n=2). Mean tumor size was 2.5 cm (range: 1-5.5 cm). Nineteen patients had adjuvant external beam radiation, and 9 had brachytherapy. At follow-up imaging at a mean of 17 months (range: 1–72 months), 45 patients demonstrated no evidence of recurrence. Recurrence after RFA was local in 13 cases, intrapulmonary in 6, nodal in 6, mixed in 2, and distant metastases in 7 cases. Median disease-free survival was 23 months. Increasing tumor size and stage were related to risk of recurrence. The most common pattern of recurrence was local, suggesting that more aggressive initial RFA and adjuvant radiation may offer better outcomes. In another series with 31 consecutive patients with NSCLC deemed ineligible for resection, RFA was performed 38 times. (13) Mean tumor size was 2.0 cm (range: 0.8–4.4 cm). Recurrence was confirmed radiographically after 32% of treatments. Two of these patients were successfully retreated for technical failures related to pneumothorax, and 3 underwent radiotherapy with stable disease. After mean follow-up of 17 months, 23 of the 31 patients were alive. Three patients died of metastatic disease, and 5 died of pneumonia remote from treatment. Two-and 4-year survivals were 78% and 47%, respectively. Local tumor progression appeared to be related to tumors larger than 3 cm. The authors concluded that RFA of inoperable early-stage lung cancer in carefully selected patients yields encouraging results and that computed tomography (CT) and positron emission tomography (PET) need further validation for the early identification of local tumor progression following RFA.
Authors of 2 recent case series from Japan reported outcomes at median follow-up periods of 2 years. Yamakado et al. report on a series of 78 patients with 198 pulmonary metastases of colorectal cancer with median follow-up of 24.6 months. (14) The respective 1-, 3-, and 5-year local tumor progression rates were 10.1% (95% CI: 2.9–17.3%), 20.6% (95% CI: 8.9–22.2%), and 20.6% (95% CI: 8.9–22.2%), respectively. The 1-, 3-, and 5-year survival rates were 83.9% (95% CI: 75.2–92.7%), 56.1% (95% CI: 41.7–70.5%), and 34.9% (95% CI: 18.0–51.9%), respectively, with median survival time of 38.0 months. Lack of extrapulmonary metastasis and normal carcinoembryonic antigen (CEA) level were significant independent prognostic factors. In the smaller series, 39 patients with unresectable pulmonary metastases of renal cell cancer were treated with RFA. (15) Patients with 6 or fewer lung metastases measuring 6 cm or smaller that were confined in the lung, had all lung tumors ablated (curative ablation). Patients with extrapulmonary lesions, 7 or more lung tumors, or large tumors of greater than 6 cm, had mass reduction (palliative ablation). Overall survival rates in the curative and palliative groups were 100% versus 90% at 1 year, 100% versus 52% at 3 years, and 100% versus 52% at 5 years (p<0.05), respectively. Maximum lung tumor diameter was a significant prognostic factor. In the curative ablation group, the recurrence-free survival rates were 92% at 1 year, 23% at 3 years, and 23% at 5 years.
However, these results are compromised by the retrospective nature of the data; the potential confounding effects of undefined prior and adjuvant chemo- or radiotherapy; lack of histopathologic proof of treatment completeness; substantial patient and disease heterogeneity; and failure to separate overall survival rates according to disease.
In summary, while available studies are limited by study design, accumulating evidence from case series suggests that RFA may be a treatment option in selected patients with primary, non-small cell lung cancer and metastatic pulmonary tumors. Although complications have been reported with the use of RFA in the lung, evidence suggests RFA may have survival rates and have rates of procedure-related complications and mortality similar to surgery. Surgical resection remains the treatment of choice, but in patients unable to tolerate surgery due to medical comorbidities, RFA may be considered a treatment option.
National Comprehensive Cancer Network (NCCN) Guidelines for the treatment of non-small cell lung cancer state that “studies suggest that RFA may be an option for node-negative patients who either refuse surgery or cannot tolerate surgery” and that “optimal candidates for RFA include patients with an isolated peripheral lesion less than 3 cm.” (16) The NCCN guidelines for colon cancer indicate that ablative techniques can be considered in those whose primary colon tumor was resected for cure when metastatic lung tumors are unresectable but amenable to complete ablation [category 2A]. (17)
National Institute for Clinical Excellence (NICE) 2010 Guidance on RFA for primary and secondary lung cancers states, “[C]urrent evidence on the efficacy of percutaneous radiofrequency ablation (RFA) for primary or secondary lung cancers is adequate in terms of tumor control.” (18) The NICE Guidance also indicates RFA may “be used in patients with small, early-stage lung cancers or small numbers of lung metastases who are unsuitable for, or prefer not to undergo, surgery. It may also have a place in multi-modality treatment of more advanced primary lung cancers.”
In a search of the National Cancer Institute Clinical Trials Database (PDQ®) (19) online at ClinicalTrials.gov, 4 ongoing, non-randomized studies of RFA and lung tumors were identified. RFA combined with external-beam radiation therapy will be evaluated in patients with medically inoperable stage 1a or 1b NSCLC (NCT00499447). RFA will be evaluated for resectable colorectal lung metastasis (NCT00776399). RFA combined with stereotactic body radiotherapy will be evaluated for lung tumors near the central airway (NCT01051037). And an additional study assessing short- and long-term outcomes after RFA of pulmonary malignancies in patients who are not candidates for surgical resection is ongoing (NCT00280189).
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