# Quality‐adjusted life years in the presence and absence of organized mammographic screening using data from BreastScreen Norway

## TL;DR

The study finds that mammographic screening for breast cancer in Norwegian women aged 50–69 leads to a net gain in quality-adjusted life years, even with high overdiagnosis rates.

## Contribution

The study introduces a new method to estimate net QALYs from mammographic screening using real-world data and alternative assumptions on mortality and overdiagnosis.

## Key findings

- Biennial mammographic screening resulted in 2446–7444 net QALYs gained per 100,000 women.
- Net QALYs remained positive even with high overdiagnosis and low mortality reduction assumptions.
- BC mortality reduction assumptions had the largest impact on net QALYs.

## Abstract

Benefits and harms of breast cancer (BC) screening with mammography have been debated and, although most studies reported positive effects, some studies found a negative effect in terms of net quality‐adjusted life years (QALYs). We aimed to estimate net QALYs associated with biennial mammographic screening for women aged 50–69 years offered to 100,000 women followed until age 85, using various assumptions on BC mortality reduction, overdiagnosis and mortality transfer (the extent to which a reduction in BC mortality results in a reduction in all‐cause mortality). Individual‐level data from women invited to BreastScreen Norway during 1996–2020 were used to perform the calculations. The three baseline scenarios included (1) Model Microsimulation Screening Analysis (MISCAN): MISCAN prediction for mortality reduction and overdiagnosis proportion; (2) Model A: 40% BC mortality reduction and 15% overdiagnosis; and (3) Model B: 20% BC mortality reduction and 50% overdiagnosis. For all scenarios, an 80% mortality transfer was assumed. An online tool was developed to illustrate the impact of alternative assumptions. Biennial organized mammographic screening for women aged 50–69 years who were followed until the age of 85 years was associated with 6819, 7444 and 2446 net QALYs gained per 100,000 women for Model MISCAN, A and B, respectively. Assumptions on BC mortality reduction exhibited the largest impact on net QALYs. To conclude, even when assuming a high overdiagnosis proportion and low BC mortality reduction, net QALYs remained positive, reinforcing the value of offering BC screening with mammography to Norwegian women and showing its potential to improve health outcomes.

Although mammographic screening can reduce breast cancer mortality and extend life, some studies have found a negative impact on net quality‐adjusted life years (QALYs). Here, the authors estimated net QALYs associated with biennial mammographic screening for women aged 50–69 years in Norway under various scenarios. The screening program resulted in a gain of 2446–7444 net QALYs per 100,000 women when followed up until 85 years of age. Even when assuming a high overdiagnosis proportion and low breast cancer mortality reduction, net QALYs remained positive, reinforcing the value of offering mammographic screening and its potential to improve health outcomes.