Adherence to tamoxifen over the five-year course.
OBJECTIVE
To estimate the proportion of older women who fail to complete 5 years of tamoxifen therapy and to identify predictors of non-adherence.


METHODS
We followed 462 women 65-years-old or older with stage I-IIIA breast cancer diagnosed in four US regions between 1996 and 1999 and who initiated tamoxifen therapy. We interviewed patients annually to assess tamoxifen adherence and collected information about predictors of adherence by medical record review, patient interview, and physician questionnaire.


RESULTS
Thirty-one percent of patients who started tamoxifen failed to complete the recommended 5-year course. Patients who had initial severe side effects [hazard ratio (HR) per side effect=1.2, 95% confidence interval (CI) 0.97, 1.5] or developed them (HR per new side effect=1.3, 95% CI 1.0, 1.6) were more likely to discontinue. Patients with more prescription medications at baseline were less likely to discontinue (HR per baseline prescription equaled 0.90, 95% CI 0.81, 0.99), whereas patients who added a prescription were more likely to discontinue (HR per new prescription equaled 1.2, 95% CI 1.0, 1.4). Patients with positive views of tamoxifen at baseline (HR for a 10-point higher score=0.93, 95% CI 0.83, 1.0) and an improving view over follow-up (HR for a 10-point positive change=0.93, 95% CI 0.87, 1.0) were less likely to discontinue.


CONCLUSIONS
Five years of tamoxifen confers a significant benefit beyond 1-2 years of tamoxifen, so physicians should ask patients about side effects, other prescriptions, and beliefs about tamoxifen and should educate them about the benefits of completing adjuvant therapy.
Department of Epidemiology, Boston University School of Public Health, Boston, MA 02118, USA. tlash@bu.edu
Timothy L
TL
Lash
Matthew P
MP
Fox
Jennifer L
JL
Westrup
Aliza K
AK
Fink
Rebecca A
RA
Silliman
D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001294:Attitude to Health; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D010349:Patient Compliance; D010353:Patient Education as Topic; D012307:Risk Factors; D013629:Tamoxifen / Q000627:therapeutic use*; D013997:Time Factors
D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen