Abstract P4-11-06: Effect of suppressed ovarian function on prognosis of premenopausal obese women with hormone receptor-positive breast cancer: A single-institute retrospective study

Abstract

Abstract Background: Obesity is related to poor prognosis in pre- and postmenopausal patients with breast cancer. However, there is insufficient evidence regarding the optimal adjuvant hormone therapy for obese premenopausal women with hormone receptor-positive breast cancer. We examined the impact of ovarian function suppression (OFS) on the prognosis of obese women with primary hormone receptor-positive breast cancer. Methods: We retrospectively reviewed premenopausal women who received curative surgery for clinical stage I-III hormone receptor (HR)-positive breast cancer at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research from January 2007 to December 2017. All patients were classified into five groups according to body mass index (BMI): underweight (UW), BMI <18.5 kg/m2; normal weight (NW), 18.5-24.9 kg/m2; obese 1 degree (OB1), 25.0-29.9 kg/m2; obese 2 degree (OB2), 30.0-34.9 kg/m2; and obese 3 degree (OB3), ≥35 kg/m2. The primary analysis was a comparison of breast cancer-specific survival (BCSS) according to BMI (UW/NW vs. OB1-3) and adjuvant hormonal therapy (with or without OFS). Secondary endpoints included overall survival (OS). Results: Overall, the total number of patients was 13,021 and the data of 3,380 patients were analyzed, which included patients who received adjuvant tamoxifen (TAM) without OFS (n = 1,836) or with OFS (n = 670). The median follow-up duration was 5.9 years (range, 0.2-12.9). The numbers of patients with UW, NW, OB1, OB2, and OB3 were 404 (12%), 2,482 (73%), 399 (12%), 78 (2%), and 17 (1%), respectively. Obesity was significantly associated with higher stage of breast cancer (p <0.0001). Nuclear grade of breast cancer in OB1-3 patients was significantly higher than that in UW/NW patients (p = 0.0323). 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 = 0.0009). In OB1-3 patients who received TAM as adjuvant hormone therapy, BCSS was significantly worse than that in UW/NW patients (p = 0.0086); however, a significant difference was not shown in patients who received TAM and OFS (p = 0.0921). Multivariate analysis revealed that OB3 was an independent prognostic factor compared with NW in patients with stage II/III breast cancer (p = 0.0162).Conclusion: High BMI was associated with worse prognosis in premenopausal patients with HR-positive breast cancer. The negative impact of obesity might be canceled by adding OFS to TAM as adjuvant hormone therapy. Further studies are required to explore the adequate management of obese premenopausal patients. Citation Format: Yukinori Ozaki, Jun Masuda, Akemi Kataoka, Takahiro Kogawa, Tomomi Abe, Hidetomo Morizono, Lina Inagaki, Fumikata Hara, Toshimi Takano, Takayuki Ueno, Shinji Ohno. Effect of suppressed ovarian function on prognosis of premenopausal obese women with hormone receptor-positive breast cancer: A single-institute retrospective study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-11-06.