Most inherited cases of breast cancer are associated with two abnormal genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two). Men are just as likely as women to have an abnormal breast cancer gene. If they have an abnormal gene, men are also just as likely to pass it on to both their daughters and their sons.
So a woman who has a strong family history of breast or ovarian cancer on her father's side (her dad's mother or sisters) has the same risk of having an abnormal breast cancer gene as a woman with a strong family history on her mother's side.
Still, a study suggests that women are much more likely to be referred for genetic counseling if the family history of breast or ovarian cancer is on their mother's side rather than their father's.
This could mean that doctors aren't recognizing that paternal (father's) family history of breast and ovarian cancer is equally important as maternal (mother's) family history when considering abnormal breast cancer gene risk. It's also possible that women themselves don't consider paternal family history equal to maternal family history when talking about risk and family history with their doctors.
Having an abnormal BRCA1 or BRCA2 gene has health implications for both men and women.
Women with a BRCA1 or BRCA2 genetic mutation:
- have up to a 72% lifetime risk of developing breast cancer
- have a much higher-than-average lifetime risk of ovarian cancer; estimates range from 17% to 66%
Men with an abnormal BRCA1 or BRCA2 gene are 80 times more likely to develop breast cancer than men who don't have an abnormal gene. Breast cancer in men without an abnormal gene is rare. Still, one study found that:
- men with an abnormal BRCA1 gene had a 1.2% risk of developing breast cancer by age 70
- men with an abnormal BRCA2 gene had a 6.8% risk of developing breast cancer by age 70
Other research has found a link between an abnormal BRCA2 gene in men and a higher risk of aggressive prostate cancer.
Both women AND men with an abnormal breast cancer gene have a 50% risk of passing the abnormal gene on to their children.
All women should tell their doctors about the health histories of their mother's AND their father's families, especially any history of breast and ovarian cancer. Having a family history of breast or ovarian cancer in first-degree relatives on either side may be an indicator of an abnormal breast cancer gene and higher-than-average risk for breast or ovarian cancer. If your mother or father's family has a strong family history, you may want to consider BRCA1 and BRCA2 testing. Knowing the results can help you develop the best cancer screening and risk-reduction strategies, as well as inform other family members about their risk of an abnormal breast cancer gene.
Editor’s Note: This article was updated on Jan. 22, 2019, with updated information on cancer risks associated with BRCA mutations.