Abstract 3559: Racial and ethnic disparities in medication adherence between Black and Caucasian cancer survivors using oral anticancer medications: A Blinder-Oaxaca decomposition analysis
Authors: Meng-Jung Wen, Olayinka O. Shiyanbola
Journal: Cancer Research (2025)

Abstract Background: About half of cancer survivors do not adhere to prescribed oral anticancer medications (OAMs), leading to higher relapse rates, hospitalizations, and healthcare costs. Nonadherence disproportionately impacts Black cancer survivors, often due to barriers such as limited healthcare access, healthcare mistrust and health literacy challenges. However, limited research has examined adherence among Black cancer survivors using OAMs, highlighting the need to explore factors contributing to nonadherence for future interventions. This study aimed to (1) assess disparities in medication adherence among Black and Caucasian cancer survivors on OAMs, and (2) examine the extent to which these disparities may be attributed to patient demographics and psychosocial factors. Methods: A total of 335 cancer survivors currently taking OAMs were recruited through two online panels. Participants completed a survey on medication adherence, psychosocial factors, and demographics. Medication adherence was measured with the 12-item Adherence to Refills and Medications Scale, designed to assess the extent of adherence to OAMs. Independent t-tests and multiple linear regression analyses examined differences and predictors of nonadherence between Black and White patients. A two-fold Blinder-Oaxaca decomposition analysis was used to further decompose the disparities in medication adherence identified within the regression model. Results: Compared to Caucasian patients, Black patients had significantly lower adherence (-2.06 points, p = .04) to OAMs. The model attributed a total of 2.77 points (SE = .64) of adherence disparities to socio-demographic and psychosocial factors. Specifically, age and metropolitan residence explained 1.18 points (51.5%) and 0.18 points (7.9%) of the variance, respectively. Health literacy emerged as the most significant psychosocial factor, accounting for 1.24 points (54.2%) of the observed disparities in medication adherence. Conclusion: Blinder-Oaxaca decomposition analysis offered a nuanced way to assess disparities in medication adherence and their contributing behavioral factors. The results indicate that younger Black cancer survivors and those who live in metropolitan areas showed lower engagement in medication use. Future interventions should adopt a multi-faceted approach to address modifiable factors, such as enhancing health literacy and providing support for OAM adherence among Black cancer survivors. Citation Format: Meng-Jung Wen, Olayinka O. Shiyanbola. Racial and ethnic disparities in medication adherence between Black and Caucasian cancer survivors using oral anticancer medications: A Blinder-Oaxaca decomposition analysis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3559.