Familial cancer: consequences for the oncological practice.

Pedigree data were systematically collected from patients with newly diagnosed malignant diseases in hospital outpatient services and private offices in Basel. Special efforts were made to verify every tumor diagnosis. The families of 380 adult cancer patients (greater than 16 years; 160 men and 220 women) were evaluated. The mean number of relatives per family tree was 33 (5.9 first degree) in men and 39 (6.4 first degree) in women. There were 29% of families with one, 11% with two, and 6% with three or more first-degree relatives who had cancer. In 6% of the families there was one or more first-degree relative with cancer of the same site as in the proband. Hereditary cancer syndromes were detected in several families. Fifty-four percent of all families showed no tumor occurrence in first-degree relatives. Our program clearly demonstrates that a carefully obtained family history can lead to the recognition of persons with high cancer risk in oncological practice.