[Clinical phenotype of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) families].

OBJECTIVE: To characterize the clinical features of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) families and to evaluate the value of Chinese HNPCC criteria.

METHODS: Twenty-six families were involved in this study. Eight families fulfilled both the Amsterdam criteria and the Chinese HNPCC criteria (named group A), while the other 18 families fulfilled the Chinese HNPCC criteria only (named group B). The clinical features of these HNPCC families were compared with those of 509 sporadic colorectal cancers (CRC) cases. Features of families in group A and in group B were also compared and analyzed.

RESULTS: A total of 86 colorectal carcinomas developed in 77 patients in these 26 families. Synchronous or metachronous colorectal cancers developed in seven (9.1%) patients. Thirty-nine percent of colorectal carcinomas were developed in the proximal colon. Fifty-one out of 71 patients (71.8%) were diagnosed before the age of 50. A total of 24 extracolonic malignancies were identified in these families. Gastric carcinoma was the most common type of extracolonic malignancy (37.5%). Compared with sporadic CRCs, HNPCC patients were significantly younger at the age of diagnosis, namely, higher proportion of patients less than 50 years old, and more frequent development of multiple colorectal cancers. Except for the average number of colorectal carcinomas developed per family (4.5:2.3, P = 0.022), there was no significant difference between group A and B regarding the age of diagnosis, the location of colorectal cancer, the development of multiple colorectal cancers and the distribution of extra-colonic malignancies.

CONCLUSION: Chinese HNPCC families have certain specific clinico-pathological features. Families in accord with the Chinese HNPCC criteria have similar clinical features as those with the Amsterdam criteria. The Chinese criteria are, however, more suitable for the diagnosis of patients from small families.