KRAS and rectal cancer: With regard to K-ras mutations, two case–control studies with colon cancer patients, one with 2418 patients and 2410 controls (Slattery et al, 2000), the other with 185 patients (Voskuil, 1999; Kampman et al, 2000), and one cross-sectional case–case study with rectal cancer patients (O'Brien et al, 2000) have previously been conducted and have reported on the association between meat consumption and K-ras mutations.