Incorporating Baseline Breast Density When Screening Women at Average Risk for Breast Cancer : A Cost-Effectiveness Analysis

Abstract

Background: Breast density classification is largely determined by mammography, making the timing of the first screening mammogram clinically important.

Objective: To evaluate the cost-effectiveness of breast cancer screening strategies that are stratified by breast density.

Design: Microsimulation model to generate the natural history of breast cancer for women with and those without dense breasts and assessment of the cost-effectiveness of strategies tailored to breast density and nontailored strategies.

Data sources: Model parameters from the literature; statistical modeling; and analysis of Surveillance, Epidemiology, and End Results-Medicare data.

Target population: Women aged 40 years or older.

Time horizon: Lifetime.

Perspective: Societal.

Intervention: No screening; biennial or triennial mammography from age 50 to 75 years; annual mammography from age 50 to 75 years for women with dense breasts at age 50 years and biennial or triennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; and annual mammography at age 40 to 75 years for women with dense breasts at age 40 years and biennial or triennial mammography at age 50 to 75 years for those without dense breasts at age 40 years.

Outcome measures: Lifetime costs and quality-adjusted life-years (QALYs), discounted at 3% annually.

Results of base-case analysis: Baseline screening at age 40 years followed by annual screening at age 40 to 75 years for women with dense breasts and biennial screening at age 50 to 75 years for women without dense breasts was effective and cost-effective, yielding an incremental cost-effectiveness ratio of $36 200 per QALY versus the biennial strategy at age 50 to 75 years.

Results of sensitivity analysis: At a societal willingness-to-pay threshold of $100 000 per QALY, the probability that the density-stratified strategy at age 40 years was optimal was 56% compared with 6 other strategies.

Limitation: Findings may not be generalizable outside the United States.

Conclusion: The study findings advocate for breast density-stratified screening with baseline mammography at age 40 years.

Primary funding source: National Cancer Institute.

Appendix Figure 1.. Flow diagram of the microsimulation model and costing process.

DCIS = ductal carcinoma in situ; ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; PR = progesterone receptor.

Appendix Figure 2.. Observed versus predicted age-specific breast cancer incidence.

SEER = Surveillance, Epidemiology, and End Results.

Appendix Figure 3.. Observed versus predicted breast cancer mortality.

SEER = Surveillance, Epidemiology, and End Results.

Figure 1.. Flow diagram of the microsimulation model and the 7 screening strategies.

B50 = biennial mammography from age 50 to 75 years; SA40B50 = stratified annual mammography from age 40 to 75 years for women with dense breasts at age 40 years and biennial mammography from age 50 to 75 years for those without dense breasts at age 40 years; SA40T50 = stratified annual mammography from age 40 to 75 years for women with dense breasts at age 40 years and triennial mammography from age 50 to 75 years for those without dense breasts at age 40 years; SA50B50 = stratified annual mammography from age 50 to 75 years for women with dense breasts at age 50 years and biennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; SA50T50 = stratified annual mammography from age 50 to 75 years for women with dense breasts at age 50 years and triennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; T50 = triennial mammography fromage 50 to 75 years.

Figure 2.. Cost-effectiveness frontier.

Discounted lifetime cost versus discounted quality-adjusted life-years for each screening strategy for the base-case scenario (1970 birth cohort) (A) and 3 sensitivity analyses. The screening strategies in boxes are those along the cost-effectiveness frontier (solid line) for which ICERs were compared; strategies above the solid line were dominated (more expensive and less effective than the alternative comparator along the frontier) or extendedly dominated (a less efficient use of resources than the alternative comparator). B50 = biennial mammography from age 50 to 75 years; ICER = incremental cost-effectiveness ratio; SA40B50 = stratified annual mammography fromage 40 to 75 years for women with dense breasts at age 40 years and biennial mammography from age 50 to 75 years for those without dense breasts at age 40 years; SA40T50 = stratified annual mammography from age 40 to 75 years for women with dense breasts at age 40 years and triennial mammography from age 50 to 75 years for those without dense breasts at age 40 years; SA50B50 = stratified annual mammography from age 50 to 75 years for women with dense breasts at age 50 years and biennial mammography fromage 50 to 75 years for those without dense breasts at age 50 years; SA50T50 = stratified annual mammography fromage 50 to 75 years for women with dense breasts at age 50 years and triennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; T50 = triennial mammography fromage 50 to 75 years.

Figure 3.. Cost-effectiveness acceptability analysis.

The cost-effectiveness acceptability curve plots the probability that a strategy is optimal (that is, yields the highest net benefit compared with other competing strategies) or, in other words, cost-effective at each societal willingness-to-pay threshold. Using a societal willingness-to-pay threshold of $100000 per quality-adjusted life-year, the probability of screening strategy SA40B50 being optimal was 56% and the probability of strategy SA40T50 being optimal was 38%. None of the remaining 5 screening strategies had more than a 3% chance of being the optimal screening strategy. B50 = biennial mammography from age 50 to 75 years; ICER = incremental cost-effectiveness ratio; SA40B50 = stratified annual mammography from age 40 to 75 years for women with dense breasts at age 40 years and biennial mammography from age 50 to 75 years for those without dense breasts at age 40 years; SA40T50 = stratified annual mammography from age 40 to 75 years for women with dense breasts at age 40 years and triennial mammography fromage 50 to 75 years for those without dense breasts at age 40 years; SA50B50 = stratified annual mammography fromage 50 to 75 years for women with dense breasts at age 50 years and biennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; SA50T50 = stratified annual mammography from age 50 to 75 years for women with dense breasts at age 50 years and triennial mammography from age 50 to 75 years for those without dense breasts at age 50 years; T50 = triennial mammography fromage 50 to 75 years.