Barriers to Optimal Adherence to Adjuvant Hormonal Therapies
These studies provide clear evidence that nonadherence is common among breast cancer patients prescribed hormonal adjuvant treatments. Recognizing nonadherence as a problem and quantifying its scope is a precondition for the problem to be solved; furthermore, understanding the barriers to optimal adherence will allow the problem to be addressed. While this is easily said, it is far less easily done, as the barriers to adherence will vary among patients, providers and demographics. As previously stated, investigators have identified some correlates of adherence, but these factors do not fully identify those at risk of nonadherence.
What is currently known is that factors such as treatment side effects contribute to nonadherence. While both tamoxifen and AIs are generally well-tolerated, each has a distinct pattern of medical toxicity based on the mechanism of action, and furthermore, each has a side-effect profile that may limit patient use of these treatments based on symptoms and impact on quality of life. As Perez discusses, both tamoxifen and AIs are associated with hot flashes and mood disturbances. Tamoxifen confers benefits, such as lowering serum cholesterol and protecting against bone and cardiovascular disease, while at the same time increasing risks for endometrial cancer and stroke. AIs do not increase these risks, but are associated with musculosketal effects such as arthralgia and bone loss. Many of these side effects can be mitigated: for example, by ensuring that patterns of vaginal bleeding are monitored, and providing support for symptom management. If side effects are contributing both to nonadherence as well as a diminished quality of life, then their management should be a priority.
Patient perceptions reinforce the importance of side effects for adherence. For example, in a cohort of 451 women, 42% attributed not taking hormonal therapy to side effects, most frequently hot flashes, which were cited by 35% of tamoxifen and 30% of AI users; 22% of AI users also cited muscle aches. The poignant title of a paper by Winters and colleagues – "I feel like I am 100 years old!" – vividly conveys the arthralgia experience of some AI patients and points to why nonadherence may be likely.
The Y-ME National Breast Cancer Organization conducted an internet survey that was completed by 328 breast cancer patients who had been prescribed adjuvant hormonal therapy. This survey identified provider communication as a primary contributor to nonadherence, with less than half of respondents (44%) reporting that they had received instructions about the importance of taking oral medication as directed at each office visit. Only 57% of the women indicated that they had not missed a single dose during the previous month. These women indicated that adherence to oral medications could be increased by raising their awareness of the importance of adherence for improved clinical outcomes (89%), and by better management of treatment-related side effects (60%). Similarly, Kahn et al. cite both the physician's input into the treatment decision and being told about side effects as affecting adherence. Davidson and colleagues observed actual office encounters between community oncologists and breast cancer patients beginning or receiving hormonal therapy; they found that possible challenges to long-term adherence were not discussed.
Patients' personal beliefs about their susceptibility to disease, its severity, drug benefits, barriers to treatment, and self-efficacy also influence the degree to which they are adherent. Patients who believe that nothing can be gained from taking tamoxifen are far more likely to be nonadherent. Cost has also been cited as a barrier to adherence, with more costly drugs representing a greater barrier.[24,26] Addressing various patient perceptions and misperceptions requires skillful clinical communications.
Expert Rev Pharmacoeconomics Outcomes Res. 2011;11(6):709-715. © 2011 Expert Reviews Ltd.