Prostate Cancer in First-Degree Relative May Raise Breast Cancer Risk

Jennifer L. Beebe-Dimmer, PhD, MPH

Having a family history of prostate cancer among first-degree relatives may also increase a women’s risk of developing breast cancer, according to a new study.

The study, published early online in CANCER, provides more evidence of the importance of taking into account a patient’s complete family history of all cancers when assessing their risk of developing cancer.

“The increase in breast cancer risk associated with having a positive family history of prostate cancer is modest; however, women with a family history of both breast and prostate cancer among first-degree relatives have an almost twofold increase in risk of breast cancer,” said lead study author Jennifer L. Beebe-Dimmer, PhD, MPH, of the Barbara Ann Karmanos Cancer Institute and Wayne State University School of Medicine in Detroit, in a statement.

The study looked at 78,171 women who enrolled in the Women’s Health Initiative Observational Study between 1993 and 1998 who were free of breast cancer at the start of the study. During follow-up, which ended in 2009, a total of 3506 breast cancer cases were diagnosed.

When looking at the family history of prostate cancer in first-degree relatives of those diagnosed with breast cancer, the study showed that prostate cancer was linked with a 14% increase in breast cancer risk for women, even after adjusting for various patient factors.

Separate analyses examining the joint impact of both cancers found that a family history of both breast and prostate cancer was linked with a 78% increase in breast cancer risk.

The study also found that risks associated with a family history of both breast and prostate cancers were higher among African American women than white women.

Beebe-Dimmer noted that patients and physicians might not consider certain cancer diagnoses among family members, especially those in members of the opposite sex, in their assessments of cancer risk.

“These findings are important in that they can be used to support an approach by clinicians to collect a complete family history of all cancers—particularly among first degree relatives—in order to assess patient risk for developing cancer,” she said. “Families with clustering of different tumors may be particularly important to study in order to discover new genetic mutations to explain this clustering.”