KRAS and colonic neoplasm: Under normal circumstances, the rate of KRAS wild-type is expected to be higher in left-sided colon cancer than in right-sided colon cancers.[16] Yoon et al[15] found a statistically higher rate of RAS wild-type in patients with left-sided colon cancer than in those with right-sided colon cancer, with a longer PFS value in left-sided colon cancers (P = .04).