Radiation-Induced Breast Cancer Incidence and Mortality From Digital Mammography Screening: A Modeling Study

Abstract

Background: Estimates of risk for radiation-induced breast cancer from mammography screening have not considered variation in dose exposure or diagnostic work-up after abnormal screening results.

Objective: To estimate distributions of radiation-induced breast cancer incidence and mortality from digital mammography screening while considering exposure from screening and diagnostic mammography and dose variation among women.

Design: 2 simulation-modeling approaches.

Setting: U.S. population.

Patients: Women aged 40 to 74 years.

Intervention: Annual or biennial digital mammography screening from age 40, 45, or 50 years until age 74 years.

Measurements: Lifetime breast cancer deaths averted (benefits) and radiation-induced breast cancer incidence and mortality (harms) per 100,000 women screened.

Results: Annual screening of 100,000 women aged 40 to 74 years was projected to induce 125 breast cancer cases (95% CI, 88 to 178) leading to 16 deaths (CI, 11 to 23), relative to 968 breast cancer deaths averted by early detection from screening. Women exposed at the 95th percentile were projected to develop 246 cases of radiation-induced breast cancer leading to 32 deaths per 100,000 women. Women with large breasts requiring extra views for complete examination (8% of population) were projected to have greater radiation-induced breast cancer risk (266 cancer cases and 35 deaths per 100,000 women) than other women (113 cancer cases and 15 deaths per 100,000 women). Biennial screening starting at age 50 years reduced risk for radiation-induced cancer 5-fold.

Limitation: Life-years lost from radiation-induced breast cancer could not be estimated.

Conclusion: Radiation-induced breast cancer incidence and mortality from digital mammography screening are affected by dose variability from screening, resultant diagnostic work-up, initiation age, and screening frequency. Women with large breasts may have a greater risk for radiation-induced breast cancer.

Primary funding source: Agency for Healthcare Research and Quality, U.S. Preventive Services Task Force, National Cancer Institute.

Figures

Figure 1

Schematic of two modeling approaches used to simulate mammography events and outcomes associated with the eight screening strategies. Estimates of the number of screening exams and false-positive screens from the MISCAN-Fadia model were combined with the mean radiation dose from the Radiation Exposure Model to estimate mean radiation-induced breast cancer incidence. Estimates of the distribution of cumulative radiation dose at each age across women from the Radiation Exposure Model were used to estimate the distribution of radiation-induced breast cancer incidence. Radiation-induced breast cancer incidence was combined with breast cancer survival estimates from the MISCAN-Fadia model to estimate radiation-induced breast cancer mortality.

Figure 2

Screening mammography process. Short interval follow-up (SIFU) examinations included unilateral, diagnostic views on the recalled breast at 6 months after the initial SIFU recommendation, and both unilateral, diagnostic views on the recalled breast plus bilateral routine screening views at 12 and 24 months after the initial SIFU recommendation for annual screeners and 24 months after the initial SIFU recommendation for biennial screeners. The routine screening views could result in recall for additional imaging to work up a new finding, followed by a recommendation for another SIFU examination, or tissue biopsy.