Younger women at increased risk for breast cancer may benefit from mammography screening performed once every 2 years beginning at age 40 years, according to two studies funded by the National Cancer Institute.
In one project, data synthesized from 66 published studies showed that having extremely dense breasts on mammography or first-degree relatives with breast cancer doubled the risk of breast cancer for a woman aged 40 to 49 years. Risk was even higher among women with two or more first-degree relatives with breast cancer or a first-degree relative with a diagnosis before age 40 years.
Having a prior benign breast biopsy result, second-degree relatives with breast-cancer, or heterogeneously dense breasts was associated with a 1.5-fold to 2-fold increased risk. Women who currently used oral contraceptives, who had never given birth, or who were at least 30 years old at first birth had an increased risk of 1.0-fold to 1.5-fold.
Although most women who develop breast cancer have no known risk factors, information about risk may be particularly useful when making decisions about screening women in their 40s, noted the investigators (Annals of Internal Medicine. 2012;156: 635-648).
The second study, published along with the first (pp. 609-617) and conducted by several authors of the first study, revealed that for women aged 40 to 49 years with a 2.0-fold increased risk for breast cancer, the harm-benefit ratio of biennial screening with film mammography was similar to that of biennial screening of average-risk women aged 50 to 74 years. This suggests that for that group of younger women, biennial screening at age 40 years has more benefits than harms. ONA