When it comes to physical traits, such as eye color or body type, many women are well aware that these can be inherited from either parent-but not so many realize that a genetic risk for breast or ovarian cancer is as likely to be passed down from your dad's side of the family as from your mom's.

Most inherited genetic predispositions to breast and ovarian cancers are caused by mutations in the BRCA1 and BRCA2 genes, and men are just as likely as women to pass on these mutations to their children. Yet, when researchers at Princess Margaret Hospital in Toronto examined records from their cancer clinic, they found that women were five times more likely to be referred for genetic counseling due to having a maternal history of cancer than they were if the disease occurred in their paternal line.

Fathers Helping Daughters

This has important implications-not only for women worried about their own health but also for fathers who want to be sure that their daughters are doing all that they can to protect themselves. J. Leonard Lichtenfeld, MD, deputy chief medical officer at the national office of the American Cancer Society in Atlanta, stressed the importance of learning as much as possible about both parents' family history, "Many fathers don't realize that they can be carrying genes for breast and ovarian cancer," he said, adding the surprising news that many healthcare providers don't know this either!

Of the 700,000 women worldwide diagnosed with breast cancer each year, 5% to 10% have a genetic predisposition, usually a mutation in one of the BRCA genes. Women with these mutations have a 55% to 87% risk for breast cancer and a 20% to 44% risk for ovarian cancer. In a commentary on the study published online in The Lancet Oncology, the researchers pointed out that if doctors don't ask about the medical history on the paternal side, women may not realize that they could be at high risk for breast or ovarian cancer-and that could prevent them from seeking genetic testing.

What You Can Do

Dr. Lichtenfeld urged women to invest some time in learning their family medical history—from both sides of the family tree. Ask questions of your relatives, and follow through to get as much information as you can. Be alert to other cancers connected to breast cancer on your father's side, such as colon and ovarian cancers.

"As you get older and relatives pass away, you'll find that the memory of the diseases they had and the causes of death disappear with them," Dr. Lichtenfeld pointed out. "If you discover a history of breast or ovarian cancer, especially premenopausal, on either side of your family, it's very important to get a consultation with an experienced genetic counselor who will discuss whether a test for the BRCA1 or BRCA2 mutation is appropriate and the implications of the results."

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