Adherence to Endocrine Therapy in Breast Cancer Adjuvant and Prevention Settings

Abstract

Adherence to oral endocrine therapy in adjuvant breast cancer settings is a substantial clinical problem. To provide current perspective on adherence to oral endocrine therapies, a comprehensive literature review was conducted. In adjuvant trials, endocrine therapy adherence is relatively high with greater adherence for aromatase inhibitors compared with tamoxifen. In contrast, adherence to adjuvant therapy in clinical practice is relatively poor, with only about 50% of women successfully completing 5-year therapy. Importantly, good adherence (>80% use) has been associated with lower recurrence risk. Endocrine therapy adherence in primary breast cancer prevention trials parallels that seen in adjuvant trials. Factors associated with nonadherence include low recurrence risk perception, side effects, age extremes, medication cost, suboptimal patient-physician communication, and lack of social support. Few prospective studies have evaluated interventions designed to improve adherence. Interventions currently proposed reflect inferences from clinical trial procedures in which clinical contacts are commonly greater than in usual practice settings. In conclusion, for optimal breast cancer outcome, adherence to endocrine therapy must improve. Although general recommendations likely to improve adherence can be made based on clinical trial results and preliminary prospective trial findings, research specifically targeting this issue is needed to establish effective intervention strategies. Cancer Prev Res; 7(4); 378-87. Ó2014 AACR.

Arthralgia induced by endocrine treatment for breast cancer: A prospective study of serum levels of insulin like growth factor-I, its binding protein and oestrogens

“…88% and 80% of our tamoxifen and AI-treated patients, respectively, stated to be fully adherent to their endocrine therapy, which was assessed by asking the patient about her adherence behaviour. This method, however, is known to largely overestimate actual adherence [29]. Nonetheless, on-treatment oestrogen levels were below the LOQ in all -but one -selfdeclared adherent AI-users.…”

Cytochrome P-450 2D6 (CYP2D6) Genotype and Breast Cancer Recurrence in Tamoxifen-Treated Patients: Evaluating the Importance of Loss of Heterozygosity

“…It is estimated that 50% of patients do not persist with tamoxifen therapy through the entire 5-year course (75,77,78). Poor adherence to tamoxifen treatment, often defined as receiving fewer than 80% of scheduled doses, is strongly associated with less effective treatment (75,(79)(80)(81), increased medical costs (75), and increased mortality (75,82).…”

2013 San Antonio Breast Cancer Symposium

“…If this strategy enters the clinical practice, however, problems of adherence to treatment will become increasingly relevant [18]. The IBIS-II trial clearly shows that menopausal symptoms are common and only slightly but significantly increased by the use of AIs.…”