Cancer
Longitudinal change in endocrine therapy adherence patterns in the Carolina Breast Cancer Study using latent class analysis Srijon Mukhopadhyay* Srijon Mukhopadhyay Mukhopadhyay Mukhopadhyay Mukhopadhyay UNC Chapel Hill
Background Lower endocrine therapy (ET) adherence worsens survival in less aggressive breast cancers and adherence barriers may change over time. We hypothesized that adherence patterns vary longitudinally and shifts are influenced by clinical and social characteristics.
Methods We identified women with Stage I-III HR+ tumors in the Carolina Breast Cancer Study who completed ET use surveys at 25 months and 84 months follow-up (n = 837). Surveys quantified adherence and assessed barriers such as affordability, side-effects, and risk tradeoffs. We applied latent class analysis at 25 and 84 months to identify adherence patterns. Adherence patterns at the two time points were compared to categorize shifts as “favorable” [improved adherence], or “unfavorable” [worsened adherence]. We estimated prevalence differences (PD) between adherence shifts and social and clinical factors using logistic regression with post-hoc estimated marginal means, adjusting for age, stage, and grade.
Results We identified 3 adherence patterns, consistent across time points: “High Adherence (HA)”, “Adherence Variability (AV)”, and “Substantial Barriers (SB)”. At 84 months, Black women were less represented in the HA group (PD= -8.4%; -15.5%, -1.3%) and experienced more unfavorable shifts (PD= 7.4%; -0.1%, 14.8%) than non-Black women. Chemo use was associated with more unfavorable shifts among non-Black women (PD= 13.5%; 5.8%, 21.2%) but not Black women. Compared to ≥50 women, younger women had higher unfavorable shifts, a trend observed in both Black (40-50: PD= 19.1%; 5.7%, 32.5%, <40: PD= 26.3%; 1.4%, 51.1%) and non-Black women (40-50: PD= 11.8%; 4.3%, 19.4%; <40: PD= 21.3%; 7.3%, 35.2%). Social factors did not influence adherence shifts.
Conclusion Longitudinal analyses show that latent adherence subtypes are stable across time, though individuals may transition between adherence states. Black women and younger women face more barriers maintaining adherence in later survivorship.