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

Abstract

527 Background: 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 compared with 31 (22.5%) of the wild-type population (p = 0.019). Focusing only on sidedness, excluding rectal cancer since its already described increased incidence of lung metastasis, 47 (29.7%) of the patients with left sided colon cancer had lung metastasis compared with 8 (11.1%) of the right sided primary population (p = 0,002). It was observed similar frequencies of RAS mutations among patients with left (54.1%) and right (57.6%) sided tumor. Conclusions: RAS mutated colorectal adenocarcinoma is associated with an increased incidence of lung metastasis as well as left sided tumors where this finding seems to be independent of RAS status.