Nearly 9 out of 10 women overestimate how likely they are to develop breast cancer in their lifetimes, according to a new study.

In the study, a group of 175 women estimated that the chance of developing breast cancer was, on average, 46 percent - much higher than the actual average risk of 13 percent.

Previous research has shown that women who speak to a counselor about their risk of breast cancer tend to become less motivated to schedule regular Mammograms - perhaps because, during counseling, they learn the actual risk of breast cancer is much lower than they expected.

Clinicians are thus faced with a “dilemma,” the authors write in the journal Patient Education and Counseling: should they be honest with women about the odds of breast cancer, and risk that this information makes them lackadaisical about screening?

A woman’s risk of breast cancer “is not as high as you think it is, but that doesn’t mean the risk is zero,” study author Dr. Angela Fagerlin of the University of Michigan in Ann Arbor told. “You definitely need to have your screening every year,” she added.

During the study, Fagerlin and her team asked 175 out of 356 women to estimate the average risk of breast cancer, then told all the women that the actual risk was 13 percent.

Only 7 percent of women asked to estimate their risk came close to the actual number.

Among the women not asked to estimate their risk, on the other hand, 37 percent said they thought 13 percent was close to “what they expected.”

In an interview, Fagerlin noted that people likely don’t “carry a number in their head of their risk of breast cancer.” Women asked to pinpoint their risk likely are influenced by the fact that people often talk about breast cancer, making it seem more common than it is, she said.

In contrast, if they are told outright that it’s 13 percent, that sounds okay. “Everything makes sense after you’ve heard about it,” Fagerlin noted.

Fagerlin cautioned that the risk of 13 percent is an “average,” and each woman might have a higher or lower risk depending on family history and other factors. A woman’s individual risk “is something only (she and her) doctor can determine,” Fagerlin said.

She added that she and her team have found similar findings in men about their risk of Prostate cancer.

SOURCE: Patient Education and Counseling, June 2005.