BREAST-CANCER RISK-ESTIMATION IN FAMILIES WITH HISTORY OF BREAST-CANCER

Among 288 breast cancer patients (118 with bilateral disease and 165 w ith diagnosis before 40 years of age), we identified 26 families with a history of breast cancer, including a minimum of three first-or seco nd-degree relatives. Complete pedigrees with verified malignancy data from the Finnish cancer registry were constructed for 22 families. The median age at breast cancer diagnosis of the young probands (< 40 yea rs of age) was 35 years and of bilateral probands was 54 years. The re latives of the young probands were diagnosed with breast cancer at a y ounger age (median age 54 years) than the relatives of the older (bila teral) probands (median age 60 years). Standard life-table methods wer e used to compare the risk of breast cancer in the family members with that of the general population. Among the relatives of the young prob ands, the increased breast cancer risk occurred in the early post-meno pausal period, whereas the risk estimate for the relatives of the bila teral probands closely followed that of the general population. In bot h groups, however, those family members reaching the age of 80 years h ad a cumulative probability of over 50% of developing breast cancer. T he standard life-table method proved useful when assessing the age-spe cific risk for familial breast cancer, taking into account numerous fa mily members as well as their age at disease onset. This kind of analy sis can be performed in populations for which reliable cancer registry data are available, It provides a useful tool for selecting individua ls for imaging and mutation screening, counselling and experimental ch emoprevention programmes.