[Periodic examination of families with hereditary nonpolyposis colorectal carcinoma in The Netherlands: a study of 41 families].

OBJECTIVE

To determine characteristics of hereditary nonpolyposis colorectal cancer (HNPCC) and the implications for screening and treatment.

DESIGN

Longitudinal.

SETTING

Nationwide.

METHOD

Genealogic studies were performed in 114 families referred to the Netherlands Foundation for Detection of Hereditary Tumours because of a suspected inherited form of colorectal cancer.

RESULTS

Forty-one families met the criteria for HNPCC: These families included 194 patients with colorectal cancer (84 females and 110 males). The mean age at diagnosis was 44 years (range: 16-74). In 92% the tumour was diagnosed before the age of 60 years. Fifty-eight per cent were located in the proximal colon. Twenty-three per cent of the patients had multiple primary colorectal cancer. The cumulative risk of developing a second colorectal cancer was 23% after 10 years of follow up. Cancer of the endometrium, stomach and urinary tract were the most frequent extracolonic cancers.

CONCLUSIONS

Periodic examination of first-degree relatives of patients from HNPCC families should start between the ages of 20 and 25 years. The recommended interval between consecutive examinations is 2-3 years. After the age of 60 years screening may be performed at a lower frequency. The right colon in particular should be investigated. A subtotal colectomy is indicated at the time of diagnosis of the initial colon cancer, because of the risk of multiple primary tumours.