Population-based retrospective trial of clinical factors associated with patterns of endocrine therapy adherence in premenopausal breast cancer patients

Patients with hormone receptor postive breast cancer (HR+ BC) are recommended at least five years of adjuvant endocrine therapy (AET), but adherence to this treatment is often suboptimal. A population-based retrospective study among stage I to III premenopausal HR+ BC patients in Denmark identified three AET adherence patterns. Women with stage I disease (versus stage II: OR 1.9; 95% CI 1.5-2.5), without chemotherapy (versus with chemotherapy: 4.3; 3.0-6.1), with prevalent comorbid disease (CCI score ≥ 1 versus 0: 1.6; 1.1-2.3), and with a history of chronic non-cancer medication use (versus no history: 1.3; 1,0-1.8) were more likely to be rapid decliners compared with high adherers. The authors conclude that taking steps to promote adherence in these groups may reduce risk of recurrence of HR+ BC at population level.