Abstract P2-08-02: Trends in survival and the introduction of novel systemic therapies for locoregional and metastatic breast cancer in the Netherlands, 1989-2017
Authors: Luyendijk Marianne , Visser Otto , Blommestein Hedwig , de Groot Carin Uyl- , Siesling Sabine 
Published: March 2020

Objective:The introduction of innovations in breast cancer care such as screening and new systemic treatments may influence the proportions of patients with metastatic and locoregional disease as well as their survival outcomes. Aim of this study is to provide insight in trends in relative survival for locoregional versus metastatic breast cancer over the period 1989-2017 in relation to innovations introduced in the Netherlands.

Methods: We used data from the population-based Netherlands Cancer Registry (NCR) which contains demographic and tumor information (e.g. stage at diagnosis, initial treatment) which is abstracted from the medical records by trained data managers. Information on patient’s last available vital status was retrieved by merging the NCR with the Municipal Personal Records Database (last update 31-01-2019). All patients with breast cancer were selected from the NCR and stratified into locoregional (TNM stage I-III) or metastatic disease (TNM stage IV) at time of diagnosis. 1-year and 5-year relative survival rates were calculated for the entire population and for patients with locoregional and metastatic disease separately. Relative survival rates were estimated by using the Ederer II method and plotted over time. Along with the annual survival rates the introduction of innovations were projected. The date of introduction of screening and the registration of new medicines was obtained from the literature, the medicines evaluation board the Netherlands (CBG) and the European Medicines Association.

Results: In total 342.017 breast cancer patients were included in the study. The number of newly diagnosed patients increased from 7.741 in 1989 to 14.958 in 2017. Meanwhile, the proportion of patients with metastatic breast cancer at diagnosis decreased from 7.0% in 1989 to 5.4% in 2017. One year relative survival increased from 94% to 98% for all patients, from 97% to 99% for locoregional disease and from 60% to 76% for metastatic disease. Five year relative survival increased from 75% to 89% for all patients, from 80% to 92% for locoregional disease and from 16% to 33% for metastatic disease. The survival increase in metastatic disease was most prominent after 2010. Over the past three decades, several systemic therapies were introduced including taxanes, monoclonal antibodies and CDK 4/6 inhibitors. Taxanes were introduced for metastatic breast cancer in the 1990s. Trastuzumab was introduced for metastatic breast cancer in 2000 and for locoregional breast cancer in 2006. CDK 4/6 inhibitors were introduced for metastatic breast cancer from 2016 onwards.

Conclusion: Breast cancer survival gradually improved during 1989-2017, both for patients with locoregional and metastatic disease. Nevertheless, a large though slightly shrinking gap in survival between the two groups was observed over the entire period. During the study period, many innovative systemic therapies were introduced. These are likely to have contributed to the increase in breast cancer survival, especially in metastatic disease after 2010. However, other innovations such as in surgery and radiotherapy may also have contributed to the higher survival rates, especially in locoregional disease. The most recent introductions of new drugs are not yet visible in our results, but might result in a further reduction in the gap in survival rates between locoregional and metastatic breast cancer.

Citation Format: Marianne Luyendijk, Otto Visser, Hedwig Blommestein, Carin Uyl- de Groot, Sabine Siesling. Trends in survival and the introduction of novel systemic therapies for locoregional and metastatic breast cancer in the Netherlands, 1989-2017 [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-08-02.