Abstract 135P
Background
Clinical trials have shown that adjuvant hormone therapy-related hot flashes can predict better breast cancer outcomes. Using a population-based cohort, this study aimed to investigate whether this result can be generalized to a real-world setting.
Methods
By linking the Quality Register for Breast Cancer, Prescribed Drug Register, and Cause-of-death Register, we identified 7,152 chemotherapy-free breast cancer patients who initiated adjuvant hormone therapy in Stockholm, Sweden during 2006-2019 and followed them until September 2020. Hot flashes were defined as new use of drugs for hot flashes within 6 months after initiating adjuvant hormone therapy. Cox models were used to compare disease-free survival and treatment discontinuation among patients with and without hot flashes.
Results
Patients who newly used drugs for hot flashes shortly after adjuvant hormone therapy initiation had worse disease-free survival, with an adjusted hazard ratio (HR) of 1.67 (95% CI, 1.11-2.52). A higher discontinuation rate of adjuvant hormone therapy was also found among patients with newly prescribed drugs for hot flashes, with an adjusted HR of 1.47 (95% CI, 1.21-1.78). The association between drugs for hot flashes and discontinuation of adjuvant hormone therapy differed by patient characteristics, with stronger associations found among patients with low income [HR, 1.91 (95% CI, 1.41-2.59)] and those who did not have first-degree relatives having cancer [HR, 1.81 (95% CI, 1.39-2.35)] or dying from cancer [HR, 1.71 (95% CI, 1.37-2.12)].
Conclusions
Adjuvant hormone therapy-related hot flashes predict worse – rather than better – breast cancer outcomes among patients treated in clinical routine, which may potentially be due to the higher discontinuation rate observed in these patients. These findings suggest that the result from clinical trials may not be readily generalizable to clinical practice.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Swedish Research Council; Swedish Cancer Society; FORTE; China Scholarship Council.
Disclosure
All authors have declared no conflicts of interest.