# Risk models for breast cancer and their validation

## TL;DR

This paper reviews the development and validation of the IBIS (Tyrer-Cuzick) breast cancer risk model, emphasizing calibration methods and demonstrating its application on a large screening cohort.

## Contribution

It introduces updated methods for assessing calibration of comprehensive breast cancer risk models with competing mortality considerations.

## Key findings

- The IBIS model effectively stratifies breast cancer risk in screening populations.
- Calibration assessment methods improve model accuracy evaluation.
- Demonstrated model performance on over 132,000 women in Washington.

## Abstract

Strategies to prevent cancer and diagnose it early when it is most treatable are needed to reduce the public health burden from rising disease incidence. Risk assessment is playing an increasingly important role in targeting individuals in need of such interventions. For breast cancer many individual risk factors have been well understood for a long time, but the development of a fully comprehensive risk model has not been straightforward, in part because there have been limited data where joint effects of an extensive set of risk factors may be estimated with precision. In this article we first review the approach taken to develop the IBIS (Tyrer-Cuzick) model, and describe recent updates. We then review and develop methods to assess calibration of models such as this one, where the risk of disease allowing for competing mortality over a long follow-up time or lifetime is estimated. The breast cancer risk model model and calibration assessment methods are demonstrated using a cohort of 132 139 women attending mammography screening in Washington, USA.