OBJECTIVETo study the epidemiological, pathological, clinical features and therapy of collision carcinoma.

METHODSSeven patients were studied retrospectively against the background of the literature from 1980 to 2001, including the incidence, age of onset, sex ratio, predilection sites, clinical signs, pathological features and therapies.

RESULTSCollision carcinoma is rare, but more common in males than in females. The peak onset age is more than 65 years. It is found frequently in the stomach, liver, uterine, esophagogastric junction, and lung. Without special clinical features, it is difficult to diagnose. Pathological findings are the only way to make a correct diagnosis before operation. Operation is the major therapy, assisted by chemotherapy or/and radiotherapy when necessary. Collision carcinoma represents a coexistence of two adjacent but histologically different malignant neoplasmas without histological admixture in an organ.

CONCLUSIONSCollision carcinoma is rare but composed of mosaics of two malignant tumours. The clinical features of collision carcinoma need further investigation.