Familial risk of colo-rectal cancer in a low incidence area in southern Italy.

The risk of colo-rectal cancer (CRC) in subjects with a positive family history (FH+) for malignancy has been assessed by means of a case-control study carried out between 1987-89 in an area of about 215,000 inhabitants in Southern Italy. One hundred and nineteen CRC cases were compared with 119 sex- and age-frequency matched population controls. Detailed pedigrees were collected at the family homes of both cases and controls. The odds ratio (OR) of CRC, adjusted by means of logistic regression for age, sex and number of first-degree relatives, increased with the number of any kinds of cancers in first-degree relatives with a significant linear trend (p = 0.042), while there was no risk with a FH+ for digestive cancer excluding CRC or for other cancers excluding large bowel and digestive organs. The OR (and 95% confidence interval) for CRC was 5.9 (1.64-21.23) for at least one first-degree relative with CRC. After a mutual adjustment between CRC and the other cancers in the families of cases and controls, the risk of CRC with a FH+ for other cancers did not change, revealing a strong association (p = 0.002) for CRC alone. From the analysis of the family history of cancer in the case group, the relative frequency of families that satisfied the criteria for so-called hereditary non-polyposic colo-rectal cancer (HNPCC) was 2.6%. The increased relative risk of CRC observed only in families with FH+ for CRC is a supportive finding for organizing and planning prevention and genetic counselling for these families, whose members should be referred for further assessment.