MILAN, ITALY. Breast cancer is relatively uncommon in women under 40 years of age (less than 10 per cent of all cases). This explains why most work on defining risk factors has centered on older women. A team of Italian researchers has released the results of a major study aimed at determining the risk factors for younger women. The study involved 579 women aged 22 to 39 years who had been diagnosed with breast cancer and 668 age-matched controls without breast cancer. The women who started menstruating at 15 years of age or older were found to have half the risk of the women who had their first period before the age of 12 years. The women who had their first child when 30 years or older had a five times greater risk of breast cancer than the women who gave birth before the age of 20 years. The women who had never given birth had about half the risk of breast cancer than did the women who had given birth to one or two children. NOTE: This association is contrary to that found for older women.
Use of oral contraceptives and abortions, whether induced or spontaneous, did
not have a statistically significant impact on breast cancer risk. A family
history of breast cancer, a history of benign breast disease, and higher
education levels were associated with an increased risk whereas a high body mass
index (overweight) conferred a decreased risk.