Modeling Shows Digital vs Film Mammography Screening for Breast Cancer Produces Small Benefit at Increased Cost
A study reported in the Journal of the National Cancer Institute by Stout et al suggests that the switch from film to digital mammography screening in the United States has produced a small health benefit at increased cost and with an increased false-positive rate. Biennial digital screening beginning at age 40 vs 50 years is cost-effective but associated with a high false-positive rate. Annual digital screening does not appear to be cost-effective.
In the study, five independent models for breast cancer screening and treatment were used to compare annual, biennial, or breast density–based digital screening strategies starting at age 40 or 50 years with biennial film screening from ages 50 to 74 years and with no screening.
Biennial Screening
The models estimated that biennial film screening of women aged 50 to 74 years would result in a median reduction in breast cancer mortality of 21% vs no screening, yielding an estimate of 32 (discounted) life-years gained per 1,000 women. The median lifetime cost of screening and treatment was estimated at $2.71 million per 1,000 women, with a median within-model increase of $0.49 million in cost compared with no screening. Biennial digital screening would result in a median 22% mortality reduction with 38 life-years gained per 1,000 women vs no screening.
The median within-model increase in life years with digital vs film screening was approximately 2 life-years per 1,000 women (0.73 days per woman) with prevention of 0.27 additional deaths per 1,000 women; however, digital screening was associated with an additional 220 false-positive results and an additional cost of $0.35 million per 1,000 women.
Annual Digital Screening
Reserving annual digital screening for women with high breast density was slightly more effective than performing annual screening in women aged 40 to 49 years (57 vs 56 life-years gained per 1,000 women), but was more expensive ($4.48 vs $4.41 million per 1,000 women) and associated with more false-positive findings (2,379 vs 2,225 per 1,000 women). Annual screening from age 40 to 70 years produced the maximum number of life-years gained across all models (median 61 per 1,000 women) but was associated with the highest cost and false-positive rate, with medians of $5.26 million and 3,014, respectively, per 1,000 women.
Incremental Cost-Effectiveness Analysis
Three digital screening strategies were efficient in all models. Starting biennial screening at age 40 vs 50 to 74 years was associated with incremental cost-effectiveness ratios ranging from $33,200 to $113,300 per quality-adjusted life-year (QALY) gained across the five models. For the other two strategies, there was variability in the incremental cost-effectiveness ratios reflecting the relatively small incremental benefits of screening. Thus, annual screening of women with Breast Imaging Reporting and Data System (BI-RADS) category 3 or 4 breast density resulted in incremental ratios between $59,300 and $264,700 per QALY gained compared to biennial screening of all women aged 40 to 74 years.
Annual screening of all women aged 40 to 74 years was associated with greatest benefit, but ratios ranged from $74,400 to $582,000 per additional QALY compared with annual screening of women with BI-RADS 3 or 4 breast density. The strategies of annual screening for women aged 50 to 74 years and annual screening for women aged 40 to 49 years with biennial screening in those aged 50 to 74 years were dominated in all models.
Inclusion of short-term negative quality-of-life effects from screening participation and positive test results reduced the relative incremental benefits between strategies. For example, the median cost-effectiveness ratio in a strategy including biennial screening for women aged 40 to 49 years increased from $55,100 to $96 200 per QALY compared with biennial screening from ages 50 to 74 years. Strategies that included more frequent screening intervals were dominated in three of the five models compared with biennial screening from ages 40 to 74 years.
A reduction in cost of digital screening to that of film screening would make screening of women aged 40 to 49 years more cost-effective. Changing the specificity of digital screening or the relative risk for breast cancer based on breast density had little effect on results of cost-effectiveness analysis.
The investigators concluded, “The transition to digital breast cancer screening in the United States increased total costs for small added health benefits. The value of digital mammography screening among women aged 40 to 49 years depends on women’s preferences regarding false positives.”
Natasha K. Stout, PhD, Harvard Medical School and Harvard Pilgrim Health Care Institute, is the corresponding author for the Journal of the National Cancer Institute article.
The study was supported by the National Cancer Institute.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
