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The hereditary colonic cancer syndrome without polyposis, hereditary non-polyposis colorectal cancer (HNPCC), is usually divided into 2 main categories: hereditary site-specific colorectal cancer (Lynch syndrome I) and colorectal cancer in association with other forms of cancer (Lynch syndrome II). One problem associated with Lynch II is the uncertainty as to which types of cancer form part of the hereditary tumour spectrum. The present study was performed to obtain more information about the tumour spectrum of HNPCC. In the 24 HNPCC families studied, 104 patients had colorectal cancer (mean age at diagnosis: 46 years) and in 4 of the families this was the only type of cancer to occur. Sixty-five extra-colonic tumours were diagnosed in 20 families. Endometrial carcinoma was found in 16 patients belonging to 12 families. Cancer of the stomach occurred in 10 patients representing 5 families, and mainly in the older generations. Urinary-tract tumours were found in 8 patients from 4 families. Second primary tumours were diagnosed in 13 of the 16 patients with endometrial cancer, in 4 of the 10 patients with stomach cancer and in 7 of the 8 patients with a urinary-tract tumour. Many other types of carcinoma were found as well, but less frequently. In our families, the trait appears to be transmitted by patients with cancer of the stomach, endometrium or urinary tract, because some of their children have developed colorectal cancer. The findings suggest that, in these 24 HNPCC families, carcinomas of the endometrium, stomach and urinary tract belong to the hereditary tumour spectrum. Definite assignment of tumours to this spectrum will become possible only after a sensitive and specific biomarker becomes available. The screening programme should depend on which and how many extra-colonic tumours occur in a family.

In 1984 a national registry of families with familial adenomatous polyposis was set up in The Netherlands to promote screening in those families. Eight-two families had been registered by the end of 1988. Analysis of the pedigrees showed that 204 family members at risk had not yet been screened. The diagnosis of familial adenomatous polyposis was histologically confirmed in 230 patients. These patients were subdivided into two groups. Group A comprised patients with familial adenomatous polyposis referred because they were symptomatic, and Group B relatives of these patients who were found by screening to have familial adenomatous polyposis. The authors compared these groups with respect to the occurrence of colorectal carcinoma. Fifty-four patients were found to have a colorectal carcinoma at the time of diagnosis of familial adenomatous polyposis, i.e., 49 of the 104 patients in Group A (47 percent) and five of the 126 patients in Group B (4 percent). The average age at diagnosis of the 104 patients in Group A was 35 years (range, 13 to 66 years) and that of the 126 patients in Group B was 24 years (range, 8 to 59 years). By the age of 40 years, 90 percent of the patients in group B had been diagnosed. Late onset of familial adenomatous polyposis was found in four families. Endoscopy and/or radiography of the upper digestive tract were (was) performed in 44 of the 230 patients. Nineteen patients (43 percent) were found to have polyps in the stomach or duodenum, or both. In our series, only one patient died from cancer of the upper digestive tract (ampullary carcinoma). These results show conclusively that screening leads to the early detection of familial adenomatous polyposis. The value of a national registry is proved by the finding of many at-risk family members who had not previously been screened. Screening should start between the ages of 10 and 12 and should continue up to the age of 50. In the rare cases of families with an apparently late onset of familial adenomatous polyposis, screening should be continued up to age 60. More studies are needed to determine the natural history of polyps in the upper digestive tract.