5-year adherence to adjuvant endocrine treatment in Dutch women with early stage breast cancer: A population-based database study (2006–2016)

Article type: Research Article

Authors: van den Biggelaar, Yannick J.P.G.^a | Kuiper, Josephina G.^b | van der Sangen, Maurice J.C.^c | Luiten, Ernest J.T.^d | Siesling, Sabine^e | van Herk-Sukel, Myrthe^f | Voogd, Adri C.^g | Mesters, Ilse^h;

Affiliations: [a] Faculty of Health Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands | [b] PHARMO Institute for Drug Outcomes Research, Utrecht, the Netherlands | [c] Department of Radiation Oncology, Catharina Hospital, Eindhoven, the Netherlands | [d] Department of Surgery, Breast Care Center Tawam Hospital, Abu Dhabi, United Arab Emirates | [e] Department of Research and Development, Netherlands Comprehensive Cancer Organization, Utrecht, the Netherlands | [f] Department of Internal Medicine and Dermatology, University Medical Center Utrecht, Utrecht, the Netherlands | [g] Department of Epidemiology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands | [h] Department of Epidemiology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands

Correspondence: [*] Corresponding author: Ilse Mesters, Department of Epidemiology, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands. E-mail: ilse.mesters@maastrichtuniversity.nl

Abstract: BACKGROUND:Hormonal receptor (HR) positive breast tumors are common. Adjuvant hormonal therapy (AHT) with tamoxifen or Aromatase Inhibitors (AIs) is beneficial depending on the stage of the tumor. Despite the fact that AHT has been shown to improve survival and recurrence, Dutch adherence rates, which were mostly dependent on Tamoxifen prescriptions until 2006, plummeted from 80% after one year to 50% after five years. Nonadherence with AHT reduces its effectiveness. This research presents more recent adherence statistics (from 2006 to 2016), on a larger sample (7,996 vs 1,451), as well as factors that influence AHT adherence. In addition to tamoxifen data, AIs are now included. OBJECTIVE:As low use of adjuvant endocrine therapy is a potentially important and modifiable risk factor for poor outcome, it is important to monitor the rate as an indicator of women’s burden of disease and the direction of adherence trends. METHODS:The Netherlands Cancer Registry (NCR) was used to find women with early-stage breast cancer who started AHT within a year of surgery and were linked to the PHARMO Database Network (n = 8,679). The Kaplan-Meier approach was used to measure AHT adherence five years after treatment was started, with a 60-day gap between refills as our primary outcome. Furthermore, the Medication Possession Rate (MPR) was determined using a cutoff of ≥80%. Analysis was performed on influential factors of adherence. RESULTS:The proportion of persistent women declined over time to reach 46.6% at the end of the fifth year and 53.3% of the women had a MPR ≥80% during the fifth year. Older and being diagnosed in 2006-2010 were associated with AHT adherence. CONCLUSION:Dutch 5-year AHT adherence appears to remain poor. Improving AHT adherence in HR+ breast cancer survivors is a critical medical need.

Keywords: Breast cancer, compliance, survival, survival analysis, adjuvant hormonal therapy

DOI: 10.3233/BD-230024

Journal: Breast Disease, vol. 42, no. 1, pp. 331-339, 2023