# Impact of screening on late-stage breast cancer in the Netherlands: a population-based cohort study (2007-2016)

## TL;DR

Breast cancer screening in the Netherlands is linked to fewer late-stage diagnoses, across all cancer subtypes.

## Contribution

This study shows that screen-related breast cancers are consistently diagnosed at an earlier stage across all HR/HER2 subtypes.

## Key findings

- Non-screen-related breast cancers are significantly more likely to be late-stage compared to screen-related cancers.
- Screen-detected cancers have much lower odds of being metastatic compared to non-screen-detected cancers.
- The association between screening and earlier diagnosis holds true across all breast cancer subtypes.

## Abstract

Breast cancer (BC) screening can detect BC early to reduce mortality. This study evaluated the impact of BC screening on the incidence of late-stage BC in a population-based setting in the Netherlands.

All Dutch women aged 50–74 years diagnosed with invasive BC or ductal carcinoma in situ (DCIS) between 2007 and 2016 (n = 108,253) were included from the Netherlands Cancer Registry. BC was classified as screen-related if diagnosed within 24 months the last screening attendance, and as screen-detected if diagnosed within 12 months after positive screening result. Late-stage BC was defined in two ways: advanced BC, including TNM stages T3, T4, or N2, N3, or M1, and metastatic BC, defined as M1 disease. Multivariable logistic regression adjusted for age and socioeconomical status was used to assess associations between screen-related and screen-detected BC and late-stage BC. Analyses were done overall and stratified by HR/HER2-defined subtypes.

BC incidence increased between 2007 and 2013 and decreased slightly thereafter. Advanced BC incidence decreased between 2007 and 2016, while metastatic BC rates remained stable. Non-screen-related BCs were significantly more likely to be present as late disease compared with screen-related (advanced BC: aOR = 3.24, 95%CI = 3.12–3.37; metastatic BC: aOR = 6.40, 95%CI = 5.98-6.85). Similarly, non-screen-detected BCs had substantial higher odds of being late than screen-detected BCs (advanced BC: aOR = 5.54, 95%CI = 5.31–5.78; metastatic BC: aOR = 12.66, 95% CI = 11.41-14.05) than screen-detected BCs. These associations were observed across all HR/HER2-defined subtypes.

Population-based screening is strongly associated with earlier-stage breast cancer at diagnosis, consistently across all immunohistochemistry subtypes.

•This nationwide study used individual-level data to assess screening effectiveness.•Non-screen-related breast cancers are more likely to be late-stage breast cancers.•Screen-related breast cancers have an earlier stage in all immunochemistry subtypes.

This nationwide study used individual-level data to assess screening effectiveness.

Non-screen-related breast cancers are more likely to be late-stage breast cancers.

Screen-related breast cancers have an earlier stage in all immunochemistry subtypes.