Adherence to endocrine therapy in women with breast cancer in a clinical practice setting.
Authors: Friedman LC , Schluchter M , Silverman P , Baar J , Wolff B , Cooper B , Moore L , Krishnamurthi S , Lanese R , Panneerselvam A , Brell J , Owusu C , Lyons J 
Published: December 2010

Abstract #3108

Background: Recommendations for treatment of estrogen receptor-positive (ER+) breast cancer include tamoxifen for 5 years or, in postmenopausal women, an aromatase inhibitor either as the primary treatment, sequentially after 2 to 3 years of tamoxifen, or after 5 years of tamoxifen. Despite the demonstrated efficacy of endocrine therapy in reducing both recurrence of and mortality from breast cancer, studies suggest that adherence to recommended treatment has been poor. Studies of patients with 4 or more years of follow-up show that patients in clinical trials terminate therapy early 23% to 28% of the time, and in clinical settings 30% to 50% of the time. This study sought to determine the rate of adherence to and predictors of discontinuation of endocrine therapy in a cohort of early-stage breast cancer patients treated in an academic clinical setting.&#x2028; Material and Methods: Subjects in this preliminary study were women with ER+ breast tumors for whom endocrine therapy was prescribed between December, 2000 and December, 2002. Eligibility criteria included being female and &gt;18 years of age, having ER+ Stages I to IIIA breast cancer and having no prior history of breast cancer. Women were eligible with any type of breast surgery with or without axillary surgery and with or without radiation to the breast or chest wall. Patients were identified from the Ireland Cancer Center tumor registry. Eligible patients received letters from their oncologists describing the study and asking them to participate. Those who agreed completed questionnaires, either online or by mail, assessing demographic and medical variables (including length of endocrine therapy), adherence and health beliefs. Self-reported discontinuation of therapy was validated by medical records.&#x2028; Results: To date, 86 potential subjects were eligible with valid contact information and were sent letters requesting their participation. Sixty subjects completed questionnaires (8 online), a response rate of 70%. Subjects' mean age was 65 years (SD=12). Most (85%) were Caucasian and 15% were African-American. Sixty-two per cent were married, 55% were employed, 93% had at least a high school education and 73% had some prescription drug coverage. Thirteen per cent reported discontinuing therapy while it still was precribed. Seventy per cent took endocrine therapy for &gt;5 years. Women who discontinued therapy prematurely were more likely to be married (Fisher's exact test;p=0.04), less likely to perceive the benefits of endocrine therapy (Wilcoxon exact test; p=0.0024) and reported more vaginal symptoms and bone pain (Cochran-Armitage trend test; p=0.028 and p=0.0035, respectively).&#x2028; Conclusion: This preliminary study suggests that most women follow their physicians' recommendation of endocrine therapy for treatment of ER+ breast cancer. Interventions designed to educate women about the benefits as well as side-effects of endocrine therapy may further increase adherence.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3108.