Women aged 40 to 49 years with a twofold increased risk for breast cancer have similar harm–benefit ratios for biennial screening mammography as average-risk women aged 50 to 74 years, according to study results published in the Annals of Internal Medicine.
To determine the threshold RR at which the harm–benefit ratio of screening women aged 40 to 49 years equals that of biennial screening for women aged 50 to 74 years, researchers used four independent, well-established simulation models that were part of the NCI’s Cancer Intervention and Surveillance Modeling Network (CISNET) collaborative.
“Mainly, we wanted to find out the tipping point: what level of increased risk women in their 40s needed to have to reach the same benefit-to-harm ratio for screening mammography as women aged 50 to 74,” researcher Diana L. Miglioretti, PhD, a senior investigator at Group Health Research Institute in Seattle, said in a press release.
To estimate the benefits and harms of mammography screening for women in their 40s, the CISNET models used data from the Breast Cancer Surveillance Consortium and other information on large populations of US women.
In the absence of screening, the study models estimate that a median of 153 cases of breast cancer would be diagnosed and 25 deaths from breast cancer would occur among 1,000 women aged 40 years followed during their lifetimes.
According to study results, the harm–benefit ratios for adding screening between ages 40 and 49 years are less favorable than those for biennial screening starting at age 50 years. In all study models, adding annual to biennial screening led to minor increases in additional life-years gained and breast cancer deaths avoided, but at the cost of greater increases in incremental harm.
Additionally, although digital mammography screening was observed to increase life-years gained and avert more breast cancer deaths than with film mammography, due to the lower specificity of digital mammography for women in their 40s, it also yielded more false-positive results. In the study models, there was greater harm relative to benefit from digital than from film mammography in women aged 40 to 49 years
“Our results provide important information toward more individualized, risk-based screening, suggesting that starting biennial screening at age 40 years for women with an increased risk for breast cancer (RR >1.9) has a balance of benefits and harms similar to that of biennial screening for average-risk women aged 50 to 74 years,” the researchers said. “For women below this level of risk, the harm–benefit ratio of starting screening at age 40 years is less favorable than that of biennial screening between ages 50 and 74 years. Reducing the false-positive rate is crucial to improving the balance of benefits and harms for screening regimens for women of all ages.”
Disclosure: The study was funded by a supplement from the NCI.