Radiofrequency ablation as an adjunct to systemic chemotherapy for colorectal pulmonary metastases

Abstract

We read with interest the article by Chua et al and would like to share the belief that the combination of chemotherapy and radiofrequency ablation (RFA) offers the potential for disease control in patients with colorectal pulmonary metastases. In fact, in our institution, 74 (94.9%) of 78 consecutive patients with colorectal cancer who received RFA for the treatment of pulmonary metastases received systemic chemotherapy after RFA. The 1year and 3-year overall survival rates were 83.9% (95% confidence interval [95% CI], 92.7%-75.2%) and 56.1% (95% CI, 70.5%-41.7%), respectively, and the median survival time was 38.0 months in all patients. In the article by Chua et al, the survival curve was plotted only between patients treated with and without adjunctive systemic chemotherapy (the median survival times were 59 months and 21 months, respectively, as shown in Figure 5 in their article), although the presence of extrapulmonary metastases at the time of RFA treatment, identified as a negative predictive factor for patient survival in both studies, was found to be significantly dominant (P 1⁄4 .019 using the chi-square test) in our study cohort compared with that of Chua et al (24 of 78 patients and 16 of 100 patients, respectively). This finding might also support the benefit of systemic chemotherapy as an adjunct to RFA in patients with pulmonary metastases from colorectal cancer in multimodality therapy. With regard to a prospective randomized trial to compare metastasectomy and RFA, which Chua et al mentioned as a valid trial in the last part of their discussion, we launched a multicenter randomized controlled trial of surgical metastasectomy versus RFA in patients with resectable colorectal lung metastases in October 2008 in Japan. However, the recruitment of candidates was troublesome because most of the patients preferred RFA to surgical treatment and refused to join in this phase 3 trial. Therefore, we changed it to a 1-arm phase 2 clinical trial for RFA in patients with resectable colorectal lung metastases in October 2009 (NCT00776399). We are expecting a favorable survival outcome in this ongoing trial compared with previous studies of multimodality therapy including pulmonary resection because patients with extrapulmonary metastases at the time of RFA or lymph node swelling are excluded from enrollment.