For example, there may be a preferential development of CMS4 and BRAF peritoneal tumours in colorectal cancer, contrasting with the increased frequency of CDH1 and TAF1 mutations observed in gastric cancer.20, 21, 22 Differences in prognosis among different tumour types may also be explained by variations in the immune system. The gene discussed is BRAF; the disease is colorectal cancer.