Characterization of Conversion Chemotherapy for Secondary Surgical Resection in Colorectal Cancer Patients with Lung Metastases

Objective: Clinical trials demonstrated that 6-37% of the patients with colorectal liver-limited metastases underwent surgical resection after first-line chemotherapy. However, limited information is available on the conversion of colorectal cancer patients with lung metastases to resection by systemic chemotherapy. Methods: We retrospectively investigated 156 patients with unresectable colorectal cancer who received oxaliplatin- or irinotecan-based first-line systemic chemotherapy with or without antibodies in our department between January 2007 and December 2015. The conversion rate to surgery and chemotherapeutic regimens and periods were analyzed with respect to the target organ. Results: In addition to 4 patients who achieved complete response, 73 exhibited tumor shrinkage of any extent. Twenty patients underwent secondary surgery, all of whom received targeting antibodies. In 75 patients with liver metastases, 18 (24%) were converted to resection after chemotherapy for a median of 110 days. In contrast, 4 (7%) out of 56 patients with lung metastases underwent resection after chemotherapy for a median of 449 days. Conversion was an independent prognostic factor in patients with lung metastases. Conclusion: The conversion rate to resection was lower for colorectal cancer patients with lung metastasis by systemic chemotherapy, which required a longer duration than for those with liver metastases.