A large-scale survey of Long Island women undergoing mammography screening indicates that the majority (90.6%) either under- or over-estimate their lifetime risk for developing breast cancer (Abstract 4). Furthermore, four in 10 women surveyed reported they had never discussed their personal breast cancer risk with a doctor. Although some doctors have suspected that women have misconceptions about their own breast cancer risk, this is the first study to quantify the magnitude of this knowledge gap. The authors hope these findings will prompt more doctors to perform breast cancer risk assessments for their patients and encourage woman to ask for a breast cancer risk estimate.
“Women are surrounded by breast cancer awareness messages, through pink ribbons, walks, and other campaigns, yet our study shows that fewer than one in 10 women have an accurate understanding of their breast cancer risk—that means that our education messaging is far off, and we should change the way breast cancer awareness is presented,” said lead study author Jonathan Herman, MD, an obstetrician and gynecologist at Hofstra North Shore-LIJ Medical School, New Hide Park, NY. “If a patient doesn’t have a formal estimation, she will just be guessing her risk.”
Women need to have accurate knowledge about their own breast cancer risk to make appropriate decisions regarding screening and prevention. Women at greater than 1.66% 5-year risk and those at a greater than a 20% lifetime risk may benefit from chemoprevention with medications such as tamoxifen, raloxifene, or anastrozole and/or additional surveillance that might include annual MRI screening. Conversely, overestimation of risk can lead to unnecessary anxiety, testing, and interventions.
Researchers surveyed 9,873 women, 35-70 years of age, who were undergoing breast cancer screening at 21 mammography centers on Long Island, NY. The survey also asked women to estimate their own risk of developing cancer over the next 5 years and over their lifetime. In addition, the survey included questions about patient demographics (race/ethnicity, religious affiliation, education, marital status, household income, and health insurance), breast cancer risk factors (age at the time of first menstrual period, age at the time of giving birth for the first time, personal and family history of breast cancer, and breast cancer biopsy findings), and any prior breast cancer risk assessments and discussions. Many of the questions were adapted from the National Cancer Institute’s Breast Cancer Risk Assessment Tool, an interactive tool that doctors use to estimate a woman’s risk of developing invasive breast cancer, allowing researchers to calculate the respondents’ breast cancer risk.
For each survey respondent, researchers compared the calculated actual lifetime risk with her subjective risk estimate. If a woman’s personal estimate differed from the calculated value by more than 10%, it was labeled as inaccurate. As an overall group, 707 women (9.4%) accurately estimated their risk, 3,359 (44.7%) underestimated risk, and 3,454 (45.9%) overestimated risk. When parsed by ethnicity, Caucasian women were more likely to overestimate their risk, whereas African American, Asian, and Hispanic women were more likely to underestimate their risk. Although these differences between groups were statistically significant, the overall understanding of breast cancer risk among all subgroups in the study was low. One can speculate that the understanding might be even lower in the general population of U.S. women, as women participating in this study were already concerned about their breast cancer risk.
According to Dr. Herman, increasing knowledge about breast cancer is everybody’s responsibility—primary care doctors, gynecologists, breast cancer foundations, and patients themselves all need to take initiative to improve women’s understanding of their risk. Breast cancer risk assessment tools are available to doctors online free of charge. “It takes a minute to go through the questions, but that minute is not being spent often enough in doctors’ offices. Women should be aware of their breast cancer risk number, just as they know their blood pressure, cholesterol, and BMI numbers,” he said. Health insurance plans will cover the cost of additional screening only if women have a documented increased breast cancer risk.
Prior studies have suggested certain lifestyle factors that may reduce a woman’s risk of developing breast cancer. For young women who are at average risk, the most significant ways to reduce risk are to have children early in life, breastfeed, and maintain a healthy BMI.