Other highlights in the May 13 JNCI

Familial Breast Cancer Risk Continues Throughout a Woman’s Life

Women who have a sister diagnosed with breast cancer are at an increased risk of developing the disease throughout their lives. The increased risk is most pronounced in younger women, regardless of the age at which the first sister was diagnosed.

Women who have a first degree relative affected by breast cancer are at increased risk for the disease, but it is unclear how a woman’s risk varies with her current age and the age at which her relative was diagnosed.

To find out, Marie Reilly, Ph.D., and colleagues at the Karolinska Institute in Stockholm analyzed a national family database that is linked to the national cancer register. They compared the breast cancer incidence between 1958 and 2001 in 23,654 sisters of breast cancer patients and in 1,732,775 women who did not have a sister with breast cancer.

The familial risk was highest for young women, aged 20 to 39, with a 6.6-fold increase in the risk of breast cancer diagnosis, compared with similarly aged women who did not have a sister with breast cancer. The excess risk declined to approximately two-fold for women aged 50 and older. For the sisters of a breast cancer patient, the risk of diagnosis was similar regardless of whether she was approaching the age at which her sister had been diagnosed or had already passed it.

“Sisters of women diagnosed with breast cancer still have an increased risk of breast cancer 20 years after diagnosis of the sister, suggesting that women live with the burden of familial breast cancer for their lifetime,” the authors write.

Contact: Marie Reilly, , 46852483982

Exercise in Adolescent and Young Women Is Associated With a Lower Risk of Premenopausal Breast Cancer

Women who engaged in leisure-time exercise between the ages of 12 and 35 have a lower risk of developing premenopausal cancer than do women who were less active.

Several studies have shown that regular exercise is associated with a lower risk of postmenopausal breast cancer, but few studies have looked at the impact of exercise on premenopausal disease.

In this cohort study, Graham Colditz, M.D., of Washington University School of Medicine in St. Louis and colleagues examined exercise and the likelihood of developing breast cancer in a group of 64,777 women participating in the Nurses’ Health Study II. The researchers asked participants to fill out questionnaires on their physical activity starting from age 12. With six years of follow-up, 550 participants have been diagnosed with breast cancer.

The age-adjusted incidence rates for breast cancer was 194 cases per 100,000 person-years in the least active women versus 136 cases in the most active. Women whose activity was equivalent to 3.25 hours per week of running or 13 hours per week of walking had a relative 23 percent reduced risk of disease compared with women who had been less active.