Study Finds Increased Risk of Breast Cancer After False-Positive Screening Mammography
Studies show that an estimated 67% of women aged 40 and older undergo screening mammography every 1 to 2 years. Over the course of 10 screening mammograms, the estimated cumulative probability of at least one false-positive result is 61% for women screened annually and 42% for women screened biennially. Now, a new study investigating the relationship between a history of having a false-positive screening mammogram result and the risk of developing breast cancer found that women with a false-positive result had a 39% higher risk of developing beast cancer during 10-year follow-up than women with a true-negative result. Women referred for breast biopsy after a false-positive result had a 76% increased chance of developing subsequent breast cancer compared with women with a true-negative result.
The study by Henderson et al suggests that a woman’s prior false-positive screening history may be useful to include in risk prediction models to personalize breast screening and primary prevention strategies for individual women. The study was published in Cancer Epidemiology, Biomarkers & Prevention.
Study Methodology
The researchers analyzed data from the Breast Cancer Surveillance Consortium from 1994 to 2009 to evaluate the association between false-positive mammograms with differing follow-up recommendations, either workup with imaging alone or involving biopsy, and breast cancer risk overall. The study included 2.2 million screening mammograms performed in 1.3 million women, aged 40 to 74 years.
Women who had a prior breast cancer diagnosis or who lacked knowledge of their family history of breast cancer, their history of breast biopsy, or their Breast Imaging Reporting and Data System (BI-RADS) mammography breast density assessment were excluded from the study.
After the initial screening, women were tracked over 10 years to evaluate their breast cancer risk over time.
Study Results
The researchers found that during 12,022,560 person-years of follow-up, 48,735 cancers were diagnosed. Compared with women with a true-negative examination, women with a false-positive result with additional imaging recommendation had an increased risk of developing breast cancer (adjusted hazard ratio [aHR] = 1.39, 95% confidence interval (CI) = 1.35–1.44), as did women with a false-positive with a biopsy recommendation (aHR = 1.76, 95% CI = 1.65–1.88). Results stratified by breast density were similar to the overall results except among women with almost entirely fatty breasts in which adjusted hazard ratios were similar for both the false-positive groups. Women with a false-positive result had a persistently increased risk of developing breast cancer 10 years after the false-positive examination.
Absolute Risk Still Modest
In a statement announcing the study results, Louise M. Henderson, PhD, Assistant Professor of Radiology at the University of North Carolina School of Medicine and lead author of this study, cautioned that the findings should not increase anxiety over mammograms and breast health because the increase in absolute risk with a false-positive mammogram is modest.
“Our finding that breast cancer risk remains elevated up to 10 years after the false-positive result suggests that the radiologist observed suspicious findings on mammograms that are a marker of future cancer risk. Given that the initial result is a false-positive, it is possible that the abnormal pattern, while noncancerous, is a radiographic marker associated with subsequent cancer,” said Dr. Henderson. However, she cautioned, “We don’t want women to read this and feel worried. We intend for our findings to be a useful tool in the context of other risk factors,” such as age, race, and family history of breast cancer.
Funding for this study was provided by the Breast Cancer Surveillance Consortium and the National Institutes of Health.
The study authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
