For OS, the hazard ratio of primary tumor location was 0.160 in favor of left-sided (p = 0.002, 95 % CI 0.050–0.511), 0.640 in favor of wild-type (p = 0.159, 95 % CI 0.344–1.191) for KRAS mutation, and 0.372 (p = 0.013, 95 % CI 0.171–0.810) for interaction between primary tumor location and KRAS mutation. The gene discussed is KRAS; the disease is neoplasm.