Earlier Breast Screening May Reduce Mortality in Survivors of Childhood Cancer

A study published in Annals of Internal Medicine suggested that instituting annual breast cancer screening with MRI, with or without mammography, at ages 25 to 30 years may reduce breast cancer mortality by 50% or more in survivors of childhood cancer.

“Our findings highlight the importance of MRI in reducing deaths from breast cancer among young women previously exposed to chest radiation,” the authors wrote. “Identifying effective policies and interventions to reduce barriers to screening should be a priority for policymakers to ensure comprehensive and coordinated care for these high-risk survivors.”

Researchers used data from the Childhood Cancer Survivor Study (CCSS) and 2 Cancer Intervention and Surveillance Modeling Network (CISNET) breast cancer simulation models to estimate the clinical benefits, harms, and cost-effectiveness of breast cancer screening among childhood cancer survivors previously treated with chest radiation. The models evaluated 3 strategies, including no screening, digital mammography with MRI screening starting at age 25 (current Children’s Oncology Group [COG] recommendations), 30, or 35 years and continuing to age 74 years, and MRI only starting at age 25, 30, or 35 years and continuing to age 74 years.

Notably, digital mammography alone was not studied because no current guideline recommends mammography alone as a surveillance strategy in this patient population.

Lifetime breast cancer mortality risk without screening was found to be 10% to 11% across the models. Compared with no screening, starting at age 25 years, annual mammography with MRI prevented the most deaths (56% to 71%) and annual MRI (without mammography) prevented 56% to 62%. Moreover, both screening strategies had the most screening tests, false-positive screening results, and benign biopsy results.

For all of the studied strategies, the number of false-positive screening results per death prevented ranged from 31 to 85 per 1000 women and the number of benign biopsy results per death prevented was 11 to 27 per 1000 women across models. In addition, estimates of overdiagnosed cases per death prevented were also lower than average-risk benchmarks.

“Although not directly comparable given differences in strategies evaluated, our findings are consistent with those of previous studies showing that early initiation of screening among survivors reduces breast cancer mortality and is cost-effective,” the authors wrote.

When researchers examined the COG recommendations, the incremental cost-effectiveness ratio (ICER) for annual mammography with MRI starting at age 25 years versus no screening was cost-effective at the common threshold of less than $100,000 per quality-adjusted life-years (QALY) gained. Even further, when all screening and starting age strategies falling below this threshold were considered, the preferred screening method was mammography with MRI starting at age 30 years.

In sensitivity analyses, assuming lower screening performance, the benefit of adding mammography to MRI increased in both models, although the conclusions about preferred starting age remained unchanged.

“Our findings underscore the importance of making sure that young women previously treated with chest radiation are informed about their elevated breast cancer risk and the benefits of routine screening,” the authors wrote. “Both primary care providers and oncologists who care for survivors should discuss breast cancer screening with these patients.”

Notably, the researchers did not account for the risk for radiation-induced breast cancer from mammography screening, because the additional radiation exposure from mammograms between ages 25 and 39 years is small (<0.3%) relative to the total radiation dose in women previously treated with 20 Gy of chest radiation. However, the current findings suggest that even without accounting for these possible added risks, the benefit of adding mammography to MRI screening at these young ages is uncertain, and MRI alone may be a reasonable screening strategy at younger ages.

“Future planned analyses include the use of modeling to understand how this information can refine and inform screening guidelines for at-risk survivors,” the authors wrote.

Reference:

Yeh JM, Lowry KP, Schechter CB, et al. Clinical Benefits, Harms, and Cost-Effectiveness of Breast Cancer Screening for Survivors of Childhood Cancer Treated With Chest Radiation. Annals of Internal Medicine. doi: 10.7326/M19-3481.