Predictors of increased risk for early treatment non-adherence to oral anti-estrogen therapies in early-stage breast cancer patients

Purpose: Non-adherence to the oral anti-estrogen therapies (AET) tamoxifen and aromatase inhibitors in early-stage hormone receptor-positive breast cancer is associated with numerous negative clinical outcomes. Prior studies have identified that non-adherence is associated with psychological and menopause-related factors which are present during AET, but the presence of these characteristics prior to AET initiation has not been investigated.

Methods: Psychological and menopause symptoms (depression, generalized anxiety, insomnia, somatosensory amplification, hot flash frequency, and hot flash-related interference) were assessed pre-AET initiation as predictors of subsequent non-adherence in 73 participants (M_age = 55.0, SD = 10.1 years). Participants self-reported treatment adherence after three and 6 weeks on AET. Participants who did not initiate treatment were excluded from the analysis.

Results: Discriminant function analyses revealed that the hypothesized set of psychological and menopause symptoms at baseline (pre-AET) together statistically distinguished between those who were non-adherent (n = 19; 26.0%) from adherent (n = 54; 74.0%) at 6 weeks. Model classification accuracy was statistically significant (Wilks' ƛ = 0.782, χ²(6) = 15.50, p = 0.017) at the 6-week timepoint. Results were consistent at 3 weeks. Pre-AET psychological and menopause symptoms correctly classified 6-week treatment adherence 77.9% of the time. Depression contributed most to distinguishing between adherers and non-adherers.

Conclusions: The presence of a composite profile of psychological and menopause symptoms prior to AET initiation may help to identify early treatment non-adherence. Results can be used to identify patients at risk for non-adherence and to guide psychological and symptom management interventions.