Impact of old age, comorbidity, and polypharmacy on adjuvant endocrine therapy for patients with early-stage breast cancer.

Objectives

To explore effects of adjuvant endocrine therapy (ET) among women with early-stage hormone receptor positive breast cancer aged 70+ years, with comorbidities or experiencing polypharmacy.

Methods

Women diagnosed with breast cancer in 2006-2022 were identified from the Te Rēhita Mate Ūtaetae - Breast Cancer Foundation National Register in New Zealand. Patients with pathological stage I-III, hormone receptor positive disease, and had surgery within 1 year after diagnosis were included. All-cause survival, breast cancer-specific survival and disease-free survival were explored between women with adjuvant ET and women without using Kaplan-Meier methods, after propensity score matching on key factors.

Results

Only half patients completed 5 years of adjuvant ET, and the rate declined with cancer stage. Women with stage I cancer aged 70+ years, with comorbidities or experiencing polypharmacy had excellent relapse-free survival and breast-cancer specific survival but poor all-cause survival. The 10-year all-cause mortality rate (26.1%-37.2%) were more than 10 times the breast cancer-specific mortality rate (0.7%-3.2%) and more than three times the cancer relapse rate (6.0%-10.3%). Among these women, no significant difference was found in all-cause survival, breast cancer-specific survival or disease-free survival between those receiving and not receiving adjuvant ET.

Conclusions

Women with stage I hormone receptor-positive breast cancer who were older, had comorbidities or polypharmacy showed excellent breast cancer-specific and disease-free survival but poorer all-cause survival. These patients with stage I cancer may derive limited benefit from adjuvant ET with high competing mortality. Further research should be performed to verify these findings.