Survival of cancer with BRAF mutations, often associated with right-sided colon cancer, may have resulted in poorer survival than cancer with KRAS mutations, often seen in left-sided colon cancer.35–37 The increased mortality rate for rectal cancer after 6 months (online supplemental table 6) may suggest the local recurrence, which is common in rectal cancer compared with cancer of the rectosigmoid junction. This evidence concerns the gene KRAS and cancer.