Which Breast Cancer Patients Are Least Likely to Adhere to Endocrine Therapy?

A new study examined factors associated with non-adherence to endocrine therapy among breast cancer patients.

“For women with hormone receptor positive breast cancer, long‐term endocrine therapy (ET) can greatly reduce the risk of recurrence, yet adherence is low‐ particularly among traditionally underserved populations,” the study authors established.

The study, which was published in Psycho-Oncology, examined data from the Carolina Breast Cancer Study, which included an oversample of black women and women aged younger than 50 years. Patients filled out a survey related to their endocrine therapy medication adherence, particularly assessing the reasons for non-adherence. Principal factor analysis was used to establish latent factors that indicated non-adherence, and multivariable regression was used to identify which characteristics—both demographic and clinical—predictive of each endocrine therapy non-adherence factor.

Final analysis included 1,231 women. Of the total cohort, more than half (59%) identified at least one obstacle that kept them from adhering to endocrine therapy. Three latent factors were observed, which the researchers defined as barriers associated with:

• Habit (challenges developing medication‐taking behavior)
• Tradeoff (high perceived side effect burden and medication safety concerns)
• Resource (challenges related to cost or accessibility)

Women who were aged 50 years and older were less likely to report habit (adjusted risk ratio [aRR]=0.54; 95% confidence interval [CI], 0.43–0.69) and resource (aRR=0.66; 95% CI, 0.43–0.99) barriers, but older age was not correlated with tradeoff barriers. Women who were insured through Medicaid, compared to those with private insurance, were more likely to report tradeoff (aRR=1.53; 95% CI, 1.10–2.13) or resource (aRR=4.43; 95% CI, 2.49–6.57) barriers. Black women were more likely to report all three barriers: habit (aRR=1.29; 95% CI, 1.09–1.53), tradeoff (aRR=1.32; 95% CI, 1.09–1.60), and resource (aRR=4.43; 95% CI, 2.49–6.57).

“Endocrine therapy can offer a big benefit for breast cancer survivors, but many of the strategies we use to help women who are struggling with medication adherence are only designed to address one barrier at a time,” said Jennifer Spencer, PhD, of the University of North Carolina at Chapel Hill, lead author of the study, in a press release. “Our study finds that there are at least three distinct kinds of barriers that women might experience when taking endocrine therapy–suggesting that intervention strategies that can help address multiple barriers at once might be more effective, especially for Black women.”

The authors summarized, “Barriers to ET adherence were described by three distinct factors, and strongly associated with sociodemographic characteristics. Barriers to ET adherence appear inadequately addressed for younger, Black, and publicly‐insured breast cancer survivors. These findings underscore the importance of developing multi‐faceted, patient‐centered interventions that address a diverse range of barriers to ET adherence.”