OBJECTIVETo explore the prevalence, clinical features and prognosis of multiple primary neoplasms in patients with colorectal carcinoma (CRC).

METHODSData of colorectal cancer patients admitted to our hospital from June 1994 to June 2002 were analyzed retrospectively. Patients were divided into multiple-cancer group (MCG) and single- cancer group (SCG). Clinical features and prognosis were compared between two groups.

RESULTSThe incidence of multiple cancers was 7.4 % (83/ 1125). Forty- seven patients had multiple colorectal cancers metachronous CRC(S) in 12 and synchronous CRC(S) in 35. Thirty- six patients 5 patients with synchronous cancers had malignant tumors outside colorectal tract,12 of whom were gastric carcinomas. No significant differences were found between MCG and SCG regarding gender, onset age, Dukes stage and differentiation of index CRC. Cancer family history (P=0.002) and colorectal adenoma (P=0.036) were significantly more common in MCG than those in SCG. The local recurrence or distant metastasis in MCG was significantly higher than that in SCG (P=0.047), though there was no significant difference in survival between the two groups. Forty- one percent of index tumors were located in right colon in MCG, significantly higher than that in SCG (P=0.048). The secondary tumors were mainly adenoma cancerization in MCG.

CONCLUSIONCancer family history and colorectal adenoma seems to be at high risk for developing multiple cancers in CRC patients. Gastric cancer and colorectal adenoma cancerization were common secondary tumors of multiple primary neoplasms in patients with colorectal carcinoma.