Incidence of pulmonary metastasis among patients with colorectal adenocarcinoma: Correlation between sidedness and RAS mutations.

527Background: Sidedness alongside with RAS status in colorectal adenocarcinoma has been proved to correlate with survival and response to systemic therapy. There are few data reporting how these clinical characteristics can predict the dissemination of metastasis. We hypothesize that lung metastasis were more common among those with RAS mutations and left colon primary cancers. Methods: In this study, 609 patients with stage I to IV colorectal adenocarcinoma were enrolled retrospectively. Patients were divided by sidedness, right and left and were also classified according to KRAS and NRAS status. The frequencies of lung metastasis were analyzed among the different groups. Results: Of the 609 patients analyzed, 129 (21.1%) had recurrent disease and 206 (33.8%) had synchronous metastasis. RAS status was available in 311 (92.8%) of the metastatic patients and 138(44.4%) were wild type. We found that 60 (34.7%) of the patients with RAS mutated tumors presented with metachronic or synchronous lung metastasis...