Abstract
Multiple primary malignant tumors (MPMT) can be defined as more than two different tumors synchronously or metachronously forming in the same organ or different organs. The incidence of MPMTs varies dramatically between antemortem and postmortem examinations, becoming a serious medical issue. Evidence shows that the overall incidence of MPMTs is between 2.4% and 17%. Double primary malignancy (DPM) is considered the most common type of MPMT. In this case series, we present three cases of MPMT. The first case involved the colon and the breast, the second case involved the colon and the kidney, and the third case involved rectum and kidney.