Most women do not have an accurate understanding of their breast cancer risk – a finding that has important implications for prevention and early detection, as well as psychological well-being, according to a survey of nearly 10,000 women undergoing mammography screening.

When asked to estimate their lifetime personal breast cancer risk, just 9.4% of the women gave a value that was within 10% of their actual calculated risk, according to data reported in a press briefing held in advance of the breast cancer symposium sponsored by the American Society of Clinical Oncology, where the study will be presented in full.

"Despite all the ongoing media attention, awareness campaigns, pink ribbons, breast cancer walks, and breast cancer month, most women lack accurate knowledge of their own breast cancer risk," maintained first author Dr. Jonathan D. Herman, an ob.gyn. at Hofstra University, New Hyde Park, N.Y. This tells us that "our education messaging is far off and we should change the way breast cancer awareness is presented."

"We began to think: What happens to women when they underestimate their risk of breast cancer? Well, they probably don’t get the necessary or most accurate treatment," he said. In particular, this group could benefit from a tailored plan of chemoprevention and early detection. On the other hand, "we think that women who overestimate their risk are worrying about getting breast cancer more than they really have to."

In the study, the investigators surveyed 9,873 women aged 35-70 years who were about to undergo screening at 21 Long Island mammography centers. The anonymous questionnaire included many questions adapted from the National Cancer Institute’s Breast Cancer Risk Assessment Tool, which is available online and typically used by physicians.

The women’s subjective estimate of risk was compared with their risk as calculated with the tool. Their estimate was considered inaccurate if it differed from their calculated risk by more than 10%.

Most of the women were at average calculated risk, with 35% having a 5%-10% lifetime risk and 40% having a 10%-15% lifetime risk.

Just 9.4% of the women, however, accurately estimated their risk, while 46% overestimated their risk and 45% underestimated their risk.

The predominant direction of estimation error varied by race/ethnicity. Of the white women, 10% accurately estimated their risk, 39% underestimated, and 51% overestimated their risk. Women of other ethnicities were more likely to underestimate their breast cancer risks. Just 9% of African American women were in line with their risk, with 58% underestimating and 34% overestimating. Asian women had similar assessments. Hispanic women’s inaccurate assessments were more balanced, with 50% underestimating and 41% overestimating risk. Although these differences were statistically significant, it is more important to note that the overall level of understanding was very low, Dr. Herman said.

Ideally, patients should learn of their breast cancer risk from their physician, he said, but the study data told another story. "All of these women were about to have mammography, so they obviously had some interest in their breast health," but when asked when they last spoke to their doctor about their personal breast cancer risk, "we were shocked to find that 40% of women said they never ever had a conversation with a health care provider," he reported.

The findings suggest a need to improve communication about risk by primary care providers, especially as the U.S. Preventive Services Task Force is now putting greater emphasis on informed decision making, Dr. Herman acknowledged.

But patients could be spurred to action as well, by moving beyond the pink ribbons and asking their physician, "What are my breast cancer numbers? I need to know that," he proposed.

Dr. Steven O’Day, director of clinical research at the Beverly Hills (Calif.) Cancer Institute and moderator of the press briefing, noted that the study has important implications for making use of guidelines for women at elevated risk. "To make decisions about chemoprevention, an accurate understanding of prognosis and risk both from the patient’s perspective and the physician’s is going to be essential to making good decisions in terms of surveillance and chemoprevention," he said.

A follow-up study planned by Dr. Herman will be important for informing efforts to improve risk communication, according to Dr. O’Day. "It’s a huge hurdle, yet how we are going to implement this [in primary care], as well as the tertiary-care oncology setting?" he commented. "If we don’t, the implications are huge; interventions by increased surveillance or chemoprevention are not trivial in terms of cost as well as potential side effects and morbidity. And these are difficult decisions even with accurate information. And without the information, you really can’t make any decision, in my mind."

Dr. Herman disclosed no relevant conflicts of interest. Dr. O’Day disclosed no relevant conflicts of interest.

Most women misestimate their breast cancer risk