Ovarian function recovery in breast cancer patients receiving adjuvant anastrozole treatment: updated results from the phase 3 DATA trial

PURPOSE: Patients with chemotherapy-induced ovarian function failure (CIOFF) may experience ovarian function recovery (OFR). Earlier, we showed that OFR during treatment with anastrozole impacted the prognosis of hormone receptor-positive (HR+) breast cancer (BC) patients with CIOFF. Here, we present the long-term follow-up results. METHODS: Postmenopausal women with HR+ BC who were 45-57 years of age and received chemotherapy were identified from the phase 3 DATA study (NCT00301457) on the extended use of anastrozole. Eligible patients were categorised into two groups: patients with CIOFF and definitely postmenopausal patients. Patients with CIOFF were monitored for OFR. Disease-free survival (DFS), distant recurrence-free survival (DRFS), and overall survival (OS) were compared between patients with OFR and patients without OFR using multivariable Cox regression analyses, including OFR as a time-dependent covariate. BC-specific mortality (BCSM) was compared between groups using the Fine and Gray method. RESULTS: This study included 656 patients: 395 patients with CIOFF and 261 definitely postmenopausal patients. OFR occurred in 39 (12%) of 329 patients with CIOFF who were monitored for OFR. The median follow-up time was 13.3 years. Patients with OFR experienced a deterioration in DFS (hazard ratio (HR) = 1.54; 95% confidence interval (CI) 0.85-2.81), DRFS (HR = 1.51; 95% CI 0.73-3.11), OS (HR = 1.64; 95% CI 0.75-3.55), and BCSM (subdistribution HR = 1.98; 95% CI 0.84-4.63) when compared with patients without OFR. CONCLUSION: In patients with CIOFF, OFR during treatment with anastrozole was associated with a deterioration in BC outcomes. These findings underscore the importance of adequate ovarian function suppression in this subgroup of patients.