The impact of obesity and endocrine therapy on the prognosis of premenopausal women with hormone receptor-positive breast cancer: A single-institute retrospective study

Background: Higher body mass index (BMI) is associated with worse prognosis in pre- and postmenopausal patients with breast cancer (BC). However, there is insufficient evidence regarding the optimal adjuvant endocrine therapy for obese premenopausal women with hormone receptor (HR)-positive BC.

Aim: To evaluate the impact of obesity and adjuvant endocrine therapy on prognosis in premenopausal patients with BC.

Methods and results: We retrospectively reviewed the medical record of premenopausal women who received curative surgery for clinical stage I-III HR-positive BC from 2007 to 2017. Patients were classified into five groups according to BMI: underweight (UW), normal weight (NW), obese 1 degree (OB1), obese 2 degree (OB2), and obese 3 degree (OB3) categories. The primary analysis was a comparison of BC-specific survival (BCSS) according to BMI (UW/NW vs. OB1-3) and adjuvant endocrine therapy (with or without ovarian function suppression [OFS]). Of 13 021 patients, the data of 3380 patients were analyzed. BCSS in OB1-3 patients was significantly worse than that in patients with UW/NW (hazard ratio [HR] 2.37; 95% confidence interval [CI], 1.40-4.02: p = .0009). In OB1-3 patients who received tamoxifen (TAM), BCSS was significantly worse than that in UW/NW patients (p = .0086); however, a significant difference was not shown in patients who received TAM and OFS (p = .0921).

Conclusion: High BMI was associated with worse prognosis in premenopausal patients with HR-positive BC who received adjuvant TAM. The role of OFS as adjuvant endocrine therapy remains unclear, and further studies are required to explore the adequate management of obese premenopausal patients.