Pulmonary metastasectomy for colorectal cancer: Prognosis analysis disaggregated by the origin of the primary tumor

Background: The metastatic pattern differs between colon cancer and rectal cancer because of the distinct venous drainage systems. It is unclear whether colon cancer and rectal cancer are associated with different prognostic factors based on the anatomic difference. Methods: We assessed the prognostic factors and survival outcomes of patients with colorectal cancer who underwent pulmonary metastasectomy (PM), disaggregated by the location of primary colorectal cancer. The Cox proportional hazards model was used to identify variables that influenced the outcomes of pulmonary metastasectomy. Results: Between 2008 and 2017, 179 patients underwent PM classified into colon cancer and rectal cancer groups based on the site of origin of metastasis. The median postoperative follow-up was 2.3 years (range, 0.1–10.6). The post-PM 5-year survival rate in the colon cancer and rectal cancer groups was 42.5% and 39.9%, respectively (p = 0.310). On multivariable Cox proportional hazards analysis, presence of previous liver metastasis [hazard ratio (HR), 2.32; 95% confidence interval (CI), 1.19–4.51; p = 0.013], numbers of tumors (≥2; HR, 6.56; 95% CI, 2.07–20.79; p = 0.001), and abnormal preoperative carcinoembryonic antigen (CEA) level (HR, 2.50; 95% CI, 1.34–4.64; p = 0.001) were independent prognostic factors in patients with metastatic rectal cancer. Conclusions: Prognostic correlates of post-PM survival differ between colon and rectal cancer. Rectal cancer patients have worse prognosis if they have a history of liver metastasis, multiple pulmonary metastases, or abnormal preoperative CEA. These results may help assess the survival benefit of PM and facilitate treatment decision-making.