Insights Into Breast Cancer Screening: A Computer Simulation of Two Contemporary Screening Strategies.

Abstract

The debate over the value of screening mammography is rekindled with each new published study or guideline. Central to the discussion are the uncertainties about screening benefits and harms and the criteria used to assess them. Today, the magnitude of benefits for a population is less certain, and the evolving concept of harm has come to encompass false-positives (FPs), unnecessary biopsies, overdiagnosis, and overtreatment. This study uses a Monte Carlo computer simulation to study the balance of benefits and harms of mammographic breast cancer screening for average-risk women. This investigation compares the American Cancer Society's 2015 mixed annual-biennial guideline with the U.S. Preventive Services Task Force's 2016 fixed biennial guideline. Screening strategies are compared using cost-effectiveness acceptability curves, an economic analysis describing uncertainty in evaluating costs and health outcomes. Strategy preference is examined under changing assumptions of willingness to pay for a quality-adjusted life-year. Additionally, comparative effectiveness analysis is performed using FP screens and unnecessary biopsies per life-year gained. Alternative scenarios are compared assuming a reduced mortality benefit of screening. In general, results using both cost-effectiveness and clinical measures indicate that American Cancer Society's 2015 mixed annual-biennial guideline is preferred. Assuming decreases in the mortality benefit of mammography, no screening may be reasonable. The use of a mixed annual-biennial strategy for population screening takes advantage of the nonuniformity of occurrence of mammography benefits and harms over the duration of screening. This approach represents a step toward improving guidelines by exploiting age dependencies at which benefits and harms accrue.