Clinicopathological and molecular characteristics of gastric and colorectal carcinomas in the elderly.

The occurrence of malignant neoplasms increases with advancing age. Although aging and carcinogenesis are basically different processes, there are phenomena common to each such as accumulation of DNA damage and abnormal proteins. Gastric and colorectal carcinomas are representative tumors in which the prevalence and the number of patients increase significantly with age. Compared with gastric and colorectal cancers occurring in younger patients, those occurring in older patients have clinicopathological differences in tumor location, gender distribution, histological type, histological diversity, multiplicity, incidence of lymph node metastasis, and prognosis. In the elderly there are peculiar types of carcinoma such as medullary-type poorly differentiated colorectal adenocarcinoma and solid-type poorly differentiated gastric adenocarcinoma, both of which occur in older women. Methylation, apoptosis, and telomere dysfunction play important roles in the development of gastric and colorectal cancers in the elderly.