Malignant neoplasms usually occur in the elderly. Common cancers in elderly men are gastric, lung, colorectal and prostate, whereas they are colorectal, gastric, lung and biliary in elderly women. Compared with malignant neoplasms in younger patients, several characteristic features exist in the neoplasms of the elderly, such as tumor location, histology, biological behavior, and the pathway of tumor carcinogenesis. The incidence of multiple cancers increases with aging. Although it is generally recognized that carcinoma in the elderly is well -differentiated and shows slow growth, a low incidence of metastases and favorable prognoses, tumors do not always evidence such features. Regarding biological behavior of malignant tumors in the elderly, age-related alterations of the host, such as stromal weakness and decreased immune response against cancer cell invasion should be considered, as well as the characteristics of the tumor cell itself.