Purpose: To investigate the effects of cognitive function on discontinuation of hormonal therapy in breast cancer survivors ages 65+ ("older").
Methods: Older breast cancer survivors with invasive, non-metastatic disease, and no reported cognitive difficulties were recruited from 78 Alliance sites between 2004 and 2011. Eligible survivors (n = 1280) completed baseline interviews; follow-up was conducted annually for up to 7 years. Survivors with estrogen-receptor-positive (ER+) cancers who initiated hormonal therapy (n = 990) were included. Self-reported cognitive function was measured using the EORTC-QLQ30 scale; a difference of eight points on the 0-100 scale was considered clinically significant. Based on varying rates of discontinuation over time, discontinuation was evaluated separately for three time periods: early (<1 year); midpoint (1-3 years); and late discontinuation (>3-5 years). Cox models for each time period were used to evaluate the effects of cognition immediately preceding discontinuation, controlling for age, chemotherapy, and other covariates.
Results: Survivors were 65-91 years old (mean 72.6 years), and 79% had stages 1 or 2A disease. Overall, 43% discontinued hormonal therapy before 5 years. Survivors who reported lower cognitive function in the period before discontinuation had greater hazards of discontinuing therapy at the treatment midpoint (HR 1.22 per 8-point difference, CI 1.09-1.40, p < 0.001), considering covariates, but cognition was not related to discontinuation in the other periods.
Conclusions: Self-reported cognitive problems were a significant risk factor for discontinuation of hormonal therapy 1-3 years post-initiation. Additional research is needed on the temporality of cognitive effects and hormonal therapy to support survivorship care needs of older survivors.
Trial registration: ClinicalTrials.gov NCT00068328.
Keywords: Adjuvant therapy; Aging; Cognition; Cognitive function; Survivorship.