Discordance of KRAS Mutational Status between Primary Tumors and Liver Metastases in Colorectal Cancer: Impact on Long-Term Survival Following Radical Resection

If KRAS mutation status of primary colorectal tumor is representative of corresponding\r\ncolorectal liver metastases (CRLM) mutational pattern, is controversial. Several studies have\r\nreported different rates of KRAS discordance, ranging from 4 to 32%. Aim of this study is to assess\r\nthe incidence of discordance and its impact on overall survival (OS) in a homogenous group of\r\npatients. KRAS mutation status was evaluated in 107 patients resected for both primary colorectal\r\ntumor and corresponding CRLM at the same institution, between 2007 and 2018. Discordance rate\r\nwas 15.9%. Its incidence varied according to the time interval between the two mutation analyses\r\n(p = 0.025; Pearson correlation = 0.2) and it was significantly higher during the first 6 months from\r\nthe time of primary tumor evaluation. On multivariable analysis, type of discordance (wild‐type in\r\nprimary tumor, mutation in CRLM) was the strongest predictor of poor OS (p < 0.001). At\r\nmultivariable logistic regression analysis, the number of CRLM >3 was an independent risk factor\r\nfor the risk of KRAS discordance associated with the worst prognosis (OR = 4.600; p = 0.047). Results\r\nof our study suggested that, in the era of precision medicine, possibility of KRAS discordance\r\nshould be taken into account within multidisciplinary management of patients with metastatic\r\ncolorectal cancer.