Women may often lack information about breast cancer on their father's side of the family, a problem that could cloud their view of their own risk, new research suggests.

In a study of 899 women age 40 and older, the researchers found that 16 percent of the women said there was a history of breast cancer in their mother's family, while just 10 percent reported a paternal history of the disease.

The discrepancy is suspect because statistically speaking, women should generally have a similar number of maternal and paternal relatives affected by breast cancer.

The findings, according to Dr. John M. Quillin of Virginia Commonwealth University in Richmond and colleagues, have implications for both women and their doctors, who use family history to help gauge whether a woman has a higher-than-average breast cancer risk.

The researchers report their findings in the American Journal of Preventive Medicine.

Women need to find out all they can about breast cancer in their father's family, and doctors need to specifically question them about it, Dr. Quillin told Reuters Health.

Family history is one of the established risk factors for breast cancer, and most studies have indicated that this genetic risk is equally likely to be passed on from mothers or fathers, Quillin said.

It is possible, he noted, that women in his study accurately reported their family history of breast cancer. The women all volunteered for the study, Quillin explained, and if a large number of women with a maternal family history of breast cancer enrolled, that could explain the discrepancy in the findings.

It's more likely, however, that the women were less aware of breast cancer on the father's side of the family, according to the researchers.

But greater awareness isn't only a matter of women delving more deeply into their father's family history. Quillin said men need to learn about their relatives' health history, then share that information with their own family.

"Maternal and paternal family histories each only tell half of the genetic story," he noted.

SOURCE: American Journal of Preventive Medicine, September 2006.