Women know that if their mother, sister or daughter has been diagnosed with breast cancer, they may need to be more vigilant about screening.
But a large new study using data from the Women’s Health Initiative has found that women whose fathers, brothers and sons had prostate cancer may also have a higher risk for breast cancer.
In one of the largest — if not the largest — study to examine the association between prostate and breast cancer, researchers at the Barbara Ann Karmanos Cancer Institute at Wayne State University in Detroit showed that if a woman’s first-degree relative — her father, brother or son — had prostate cancer, then she has a 14 percent higher risk of developing breast cancer.
What’s more, the study found a family history of both prostate and breast cancer among first-degree relatives was associated with a 78 percent increase in a woman’s breast cancer risk.
African-American women had the highest risk of all. According to researchers, black women with a family history of breast and prostate cancer among first-degree relatives were nearly 2.5 times more likely to develop breast cancer than black women without a family history of both diseases.
According to the American Cancer Society, about one in eight women in the U.S. will develop invasive breast cancer during her lifetime.
Dr. Garnet Anderson, director of the Public Health Sciences Division at Fred Hutchinson Cancer Research Center, said the study raises intriguing questions about the role of genes and environment on the risk of breast and prostate cancer.
“These are rather modest associations and lead us to ask [about] attribution — what is the source of this common risk?” she said. “There is limited overlap in the genetic factors identified as risk factors for breast and prostate cancer. The degree of association reported here could be consistent with a small number of genetic risk alleles but it could also be explained by the large set of shared environmental factors that exist between family members. The analysis shown here was not designed to tease apart those two aspects. But that would be an interesting next step.”
The new study also demonstrates the enduring value of Women’s Health Initiative data. Fred Hutch is the Clinical Coordinating Center for the WHI. Anderson is its principal investigator.
In the prostate-and-breast-cancer study, researchers used data from more than 78,000 participants enrolled in the WHI Observational Study for their analysis. From 1993 to 1998, the study gleaned a wealth of data from the participating women — including family health histories — then followed them for between six and 10 years. None of the 78,000 participants included in this analysis had been diagnosed with breast cancer when they were first enrolled in in the observational study. After follow up years later, however, more than 3,500 had been diagnosed with breast cancer.
Wayne State University researchers looked at the family histories of these women and determined the risks associated with both prostate and breast cancer.
Dr. Jennifer Beebe-Dimmer, lead author of the study, said that these new findings highlight the need for doctors to ask about all cancer diagnoses among family members — even cancers found in the opposite sex.
“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.
She also stressed the need for further research to understand why, exactly, a link exists between the two cancers.
“Families with clustering of different tumors may be particularly important to study in order to discover new genetic mutations to explain this clustering.”
Diane Mapes is a staff writer at Fred Hutchinson Cancer Research Center. She has written extensively about health issues for NBC News, TODAY, CNN, MSN, Seattle Magazine and other publications. A breast cancer survivor, she also writes the breast cancer blog doublewhammied.com. Reach her at firstname.lastname@example.org.
Solid tumors, such as those of the breast and prostate, are the focus of Solid Tumor Translational Research, a network comprised of Fred Hutchinson Cancer Research Center, UW Medicine and Seattle Cancer Care Alliance. STTR is bridging laboratory sciences and patient care to provide the most precise treatment options for patients with solid tumor cancers.