A new study published in the American Cancer Society journal Cancer questions when a woman should begin mammogram screening if her mother, sister, or daughter has been diagnosed with breast cancer.
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Women who have a first-degree relative with breast cancer and are otherwise at average risk are often advised to get screened 10 years before the relative's diagnosis age. There is, however, little evidence to back up the long-standing recommendation.
Diana Miglioretti of the UC Davis Comprehensive Cancer Center collaborated on the study with Danielle Durham of the University of North Carolina at Chapel Hill's Department of Radiology and five other researchers. They examined data from the Breast Cancer Surveillance Consortium on screening mammograms performed between 1996 and 2016 to determine when screenings for women with a family history of breast cancer should begin.
The national study included more than 300,000 women. The researchers compared the cumulative 5-year breast cancer incidence in women with and without a first-degree family history of breast cancer based on the relative's age at diagnosis and screening age.
"The study concluded that a woman with a relative diagnosed at or before the age of 45 should consider starting screening 5-8 years earlier than their relative's diagnosis age, rather than a decade earlier, in consultation with her doctor. This puts them at the same risk as a woman of average risk who is 50 years old, the recommended age for starting mammograms "Durham stated.
Carriers of the BRCA gene mutation may benefit from starting screenings earlier. Women aged 30-39 who have more than one first-degree relative with breast cancer may benefit from genetic counseling.
Increased screening age could reduce the potential harm of starting breast cancer screenings too early. Increased radiation exposure and false positive results, which require women to return to the clinic for diagnostic imaging and possibly invasive procedures but do not result in a breast cancer diagnosis, are two examples. The earlier a woman begins receiving mammograms, the more screenings she will have over her lifetime, increasing her chances of experiencing these side effects.
"Mammography may also not perform as well in younger women because they are more likely to have dense breasts, which makes finding cancer on the images more difficult and results in more false positives," Miglioretti explained.
Linn A. Abraham, Kaiser Permanente Washington Health Research Institute; Megan C. Roberts, UNC Eshelman School of Pharmacy; Carly P. Khan, Patient-Centered Outcomes Research Institute; Robert A. Smith, American Cancer Society; and Karla Kerlikowske, UCSF Health are the other authors on this study. Miglioretti is a UC Davis Center for Healthcare Policy and Research and Kaiser Permanente Washington Health Research affiliate, investigator.
The study was funded by the National Institutes of Health's Cancer Prevention Fellowship Program, the Division of Cancer Prevention, and the National Cancer Institute (NCI). The NCI funded the Breast Cancer Surveillance Consortium's data collection (grant numbers P01CA154292, U54CA163303 and PCS-1504-30370).
Journal Reference: Danielle D. Durham, Linn A. Abraham, Megan C. Roberts, Carly P. Khan, Robert A. Smith, Karla Kerlikowske, Diana L. Miglioretti. Breast cancer incidence among women with a family history of breast cancer by relative's age at diagnosis. Cancer, 2022; DOI: 10.1002/cncr.34365