title: Use of hormonal therapy in senior breast cancer patients treated with or without radiotherapy.
abstract: OBJECTIVE
  Breast cancer treatment guidelines state that radiotherapy (rt) can reasonably be omitted in selected women 70 years of age and older if they take adjuvant endocrine therapy (aet) for 5 years. We aimed to assess persistence and adherence to aet in women 70 years of age and older, and to examine differences between rt receivers and non-receivers.
  
  
  METHODS
  Quebec's medical service and pharmacy claims databases were used to identify seniors undergoing breast-conserving surgery (1998-2005) and initiating aet. Cox proportional hazards models were used to identify predictors of aet non-persistence.
  
  
  RESULTS
  Of 3180 women who initiated aet (mean age: 77.5 years), 28% did not receive rt. During the subsequent 5 years, 32% of patients who initiated aet did not persist, 2% filled only a single prescription, and 22% switched medications. Compared with rt receivers, non-receivers discontinued more often (35.5% vs. 30.1%) and earlier (1.4 years vs. 1.6 years). They also became nonadherent earlier (medication possession ratio < 80% at year 3 vs. at year 5). Predictors of nonpersistence included rt omission [hazard ratio (hr): 1.26; 95% confidence interval (ci): 1.09 to 1.46]; age (hr per decade increase: 1.15; 95% ci: 1.01 to 1.31); new medications (hr per medication: 1.01; 95% ci: 1.00 to 1.02); and hospitalizations during aet, (hr per hospitalization: 1.08; 95% ci: 1.05 to 1.11). In a subanalysis of rt non-receivers, significant predictors included hospitalizations (hr: 1.07; 95% ci: 1.02 to 1.12) and medications at aet start (hr: 0.94; 95% ci: 0.91 to 0.97).
  
  
  CONCLUSIONS
  Suboptimal use of aet was observed in at least one third of women. In rt non-receivers, aet use was worse than it was in rt receivers. Initiation of new medications and hospitalizations increased the risk of non-persistence.
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC.
authors: S P
authors: SP
authors: Krotneva
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC. ; Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC.
authors: A
authors: A
authors: Ramjaun
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC.
authors: K E
authors: KE
authors: Reidel
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC. ; Department of Medicine, McGill University, Montreal, QC.
authors: T
authors: T
authors: Eguale
authors: Department of Surgery, McGill University, Montreal, QC. ; Department of Surgery, King Abdul-Aziz University, Saudi Arabia.
authors: N
authors: N
authors: Trabulsi
authors: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC. ; Department of Medicine, McGill University, Montreal, QC. ; School of Physical and Occupational Therapy, McGill University, Montreal, QC.
authors: N
authors: N
authors: Mayo
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC. ; Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC. ; Department of Medicine, McGill University, Montreal, QC.
authors: R
authors: R
authors: Tamblyn
authors: Clinical and Health Informatics Research Group, McGill University, Montreal, QC. ; Department of Oncology, McGill University, Montreal, QC.
authors: A N
authors: AN
authors: Meguerditchian
keywords: Adjuvant endocrine therapy; adherence; breast cancer; persistence; radiotherapy; seniors