Pulmonary metastasectomy for colorectal cancer: analysis of prognostic factors affecting survival

Background: Pulmonary metastasectomy is considered a standard procedure in the treatment of metastatic colorectal cancer (CRC). Different prognostic factors including multiple metastatic nodules, the presence of extra-pulmonary metastases and BRAF mutation status have been associated with poor survival. The aim of this study was to evaluate which factors influenced survival in CRC patients undergoing pulmonary metastasectomy by studying primary tumors and pulmonary metastases. Methods: All patients treated for primary CRC who presented pulmonary metastases in a 10-year period were considered (group A). A control group treated for primary CRC who did not develop any pulmonary or extra-pulmonary metastases was taken for comparison (group B). Different prognostic factors including gender, age, tumor location, histological type, inflammatory infiltrate, BRAF, CDX2 and extra-pulmonary metastases were analyzed. Overall survival (OS) and patients’ survival after pulmonary metastasectomy were also considered. Results: Fifty-four patients were evaluated in group A and twenty-three in group B. In group A, BRAF immunohistochemistry did not significantly differ between primary tumors and pulmonary metastases; no difference of BRAF expression was found between group A and B. Even the expression of CDX2 was not significantly different in primary tumors and metastases. Similarly, in group B CDX2 did not significantly differ from primary CRC of group A. The most significant prognostic factor was the presence of extra-pulmonary metastases. Patients with extra-pulmonary metastases experienced a significant shorter survival compared to patients with pulmonary metastases alone (P=0.001 with log-rank test vs. P=0.003 with univariate Cox regression). Interestingly, patients with right pulmonary metastases presented a significant longer survival than those with left pulmonary metastases (P=0.027 with log-rank test vs. 0.04 with univariate Cox regression). Conclusions: The main prognostic factor associated with poor survival after lung resection of CRC metastases is a history of extra-pulmonary metastases. BRAF and CDX2 did not have a significant role in this small series of patients.