CLUSTERING OF COLORECTAL-CANCER IN FAMILIES OF PROBANDS UNDER 40 YEARS OF AGE

Although sporadic colorectal cancer (CRC) is relatively uncommon in th e young, it may constitute an elevated genetic risk for CRC in these i ndividuals. PURPOSE: This study was designed to determine extent of co lorectal cancer in families of probands under 40 years of age. METHODS : Medical records of all consecutive patients, 40 years of age or youn ger at the time of CRC surgery, during the time period 1986 to 1994 we re examined. Cases of familial adenomatous polyposis and ulcerative co litis were excluded. Via interviews of surviving probands or nearest r elatives, dates of birth and death, causes of death, and diagnosis of cancer were recorded on all first-degree relatives (parents, siblings, and offspring), second-degree relatives (grandparents, aunts, and unc les), and any other relatives. RESULTS: A total of 128 patients, 40 ye ars of age or less at time of CRC resection, were identified. Of these , 45 probands/families were reached by phone, and 45 detailed family h istories were obtained. Age range of these 45 probands was 19 to 40 (m ean, 33.1) years. In 25 families there was no history of CRC in first- degree, second-degree, or third-degree relatives. Eight of 45 probands (17.8 percent) had at least one first-degree relative with CRC, and t hree of these eight families fulfilled the Amsterdam criteria for here ditary nonpolyposis colorectal cancer (HNPCC). In all three families, inheritance of CRC appeared to segregate with the maternal side of the family. In addition, 5 of 43 non-HNPCC probands had at least one firs t-degree, second-degree, or third-degree relative less than 40 years o f age, at time of CRC diagnosis. CONCLUSION: Ascertainment of a detail ed family history in early age of onset CRC patients identifies freque nt familial clustering of CRC and HNPCC in 17.8 percent of cases.