OBJECTIVETo analyze the clinical and pathological features of patients with hereditary nonpolyposis colorectal cancer (HNPCC).

METHODSThe data of 8 HNPCC pedigrees according with Amsterdam standard II were collected and their pedigree trees were generated.

RESULTSThe morbidity of HNPCC was 1.59%. Thirty-one patients were found in the 8 HNPCC pedigrees including 25 with colorectal cancer and 6 with extraintestinal tumors. The 8 probands consisted of 6 female and 2 male patients, among whom 4 were younger than 40 years old, 2 had lesions in the right colon, 3 in the left colon, and 3 in the rectum. The tumors were histologically identified mainly as highly to moderately differentiated adenocarcinoma; all the patients were free of lymph node or distant metastasis. Of the 8 probands, 5 had abnormal expression of MMR protein and only 1 had normal expression.

CONCLUSIONThe HNPCC probands are characterized by early onset at a young age and high differentiation of the tumor. The members of the pedigrees show a high incidence of the malignancies, and regular examination and timely treatment can be effective in preventing the tumor occurrence and reducing the mortality. Detection of MMR gene mutation can be a crucial approach to raising the diagnostic rate of HNPCC.