Annual mammograms starting at age 40 and continuing until age 84 will achieve the greatest reductions in breast cancer deaths, according to a modeling study published in Cancer.

Researchers used Cancer Intervention and Surveillance Modeling Network (CISNET) breast cancer models to compare three current mammography-based screening approaches for women at average risk of breast cancer. The first approach is for annual screening from ages 40-84 years, the second is a hybrid approach with annual screening from ages 45 to 54 then biennial screening from ages 55 to 79, and the third approach involves biennial mammograms from ages 50 to 74.

The modeling suggested that the largest mean reduction in mortality – 36.9% – was associated with annual screening starting at age 40. The second largest reduction of 30.8% occurred with the hybrid screening approach starting at age 45, while the smallest reduction in mortality – 23.2% – occurred with biennial screening starting at age 50 ( Cancer 2017 Aug 21. doi: 10.1002/cncr.30842 ).

Annual screening also averted the most deaths from breast cancer – 11.9 per 1,000 women screened – and gained the most life-years (189 per 1,000 women screened, compared with 149 for the hybrid approach and 110 for biennial screening), reported Elizabeth K. Arleo, MD, of Weill Cornell Imaging at New York–Presbyterian, New York, and her coauthors.

The number needed to screen to avert one death was 84 for the annual screening, 108 for the hybrid approach, and 144 for the biennial screening approach.

However, the annual screening approach was also associated with the largest number of benign recalls and benign biopsies. The model suggested that a woman starting annual screening from age 40 could expect on average to be recalled for a benign diagnostic work-up every 13 years and undergo a benign biopsy every 187 years.

Overall, using a single-year cohort of women born in 1960 who were 100% compliant with screening, the model predicted that 44,671 would still die of breast cancer with annual screening, 51,211 would die under the hybrid screening model, and 56,887 would die under the biennial screening model.

“If the goal is to avert the most breast cancer deaths and gain the most life-years, CISNET modeling shows that the optimal age of initiation for screening mammography is 40 years, the optimal screening frequency is annual, and the optimal stopping age is when a woman’s life expectancy is less than 5-7 years,” the researchers wrote. “Individual women should continue to have the choice to reduce their risk of dying from breast cancer as much as possible, and as CISNET models show, annual mammography starting at age 40 years is the best way to do so.”

Two of the researchers reported consulting or institutional support from GE Healthcare. No other conflicts of interest were reported.