OBJECTIVES: To identify prevalence and impact of adherence to oral breast cancer treatments based upon the 2003 WHO framework.

METHODS: A targeted literature review was conducted for oral breast cancer treatments from 2014-2019. Eleven oral breast cancer specific articles studied across 5,752 patients were categorized using the WHO classification and ranked by type, prevalence, and level of impact on adherence. Outcomes for adherence were measured by the following: interviews/surveys, symptom burden questionnaires, Rx refill data, pill count, and assessment scales such as, memorial symptom assessment scale (MSAS) and Morisky medication adherence scale (MMAS-8).

RESULTS: Data analysis showed that 25 WHO factors attributed to higher (7/25) or lower adherence (18/25). Of the 25 adherence factors, 52% (13/25) were patient-related factors, 16% (4/25) were social economic related factors, 16% (4/25) were therapy-related factors, 12% (3/25) were health care system related, and 4% (1/25) were condition-related factors. Furthermore, our analysis showed higher adherence outcomes were seen when both patient-related and social economic factors were positively impacted. Key factors amongst both being the patients’ disease and medication beliefs and perceptions, lifestyle, health literacy, and insurance coverage. However, lower adherence outcomes were seen across all 5 dimensions with the majority being patient and therapy-related factors. Which include negative psychological stress and emotional problems; poor perception and attitude towards medication; logistical issues; and perceived and / or experienced treatment emergent adverse events. Some studies did not achieve statistically significant adherence outcomes that directly attributed to higher or lower adherence.

CONCLUSIONS: When creating medication adherence strategies for patients taking oral breast cancer treatments, these adherence drivers should be incorporated into the design of patient support programs. Furthermore, designing well controlled adherence interventional studies are necessary to provide methodological standardization across adherence factors.