Clinicopathological characteristics of colorectal metastases from lung cancer: systematic review of the case reports in the Japanese literature

Since colorectal metastases from primary lung cancer are rare, the location of metastatic lesion and prognostic factors have not been well evaluated. Therefore, we carried out a systematic review and meta-analysis to assess the clinicopathological characteristics and prognostic factors of Japanese patients with colorectal metastasis from lung cancer. We searched the Ichushi-Web database from January 1964 to December 2020. We found 59 colorectal metastases in 52 cases for this meta-analysis. Small cell carcinoma was shown to have significantly more metastases to the appendix than non-small cell carcinoma. However, there was no significant correlation between location and histology when classified into right and left colons ( P = 0.247). The median overall survival after diagnosis was 6 months. Univariate analysis showed that adenocarcinoma (Hazard Ratio (HR) 0.383, P = 0.024), simultaneous metastasis (HR 0.325, P = 0.046), and chemotherapy group (HR 0.482, P = 0.044) were good prognostic factors. Multivariate analysis confirmed that chemotherapy (HR 0.38, P = 0.02) was an independent good prognostic factor for overall survival. In conclusion, although there was no statistical difference, right colon metastases were more frequent than left colon metastases. Chemotherapy may be effective for colorectal metastases from lung cancer.