The role of obesity in the clinicopathologic variables and treatment of early stage breast cancer.

e12555 Background: Breast cancer (BC) is the second most common cancer among women in the United States. Studies have found obesity to be a key risk factor for BC, in which obese patients have higher recurrence and mortality. With 40% of the United State population being obese, we studied the differences in clinicopathological variables and treatment of normal-weight (NW) and obese patients with BC in a community-based cancer center within Florida. Methods: In this retrospective study, 535 patients with non-metastatic breast cancer (NMBC) diagnosed between January 1st, 2015 and December 31st, 2021 were identified. A Two Proportion Z test was done to evaluate the association between body mass index (BMI) groups of NW (BMI 30) patients amongst several independent variables. Variables included are histology, grade, estrogen and progesterone receptor status (ER/PR), human epidermal growth factor receptor 2 (HER2) status, chemotherapy, and surgical modality. Results: Results demonstrated that only Grade 2 histology was statistically more prevalent in NW vs obese patients (p < 0.01). 218 patients underwent mastectomy with 54% in the obese BMI. 317 patients were treated with lumpectomy with 65% in the obese BMI. Of the 211 NW patients, 97% were HER2 negative or low compared to 96% in the obese group. Only 3% and 4% of patients were HER2 positive in NW and obese groups, respectively. Of the obese patients, 40% were treated with neoadjuvant/adjuvant chemotherapy compared to 33% of NW patients (p=0.05). Factors such as mean age, smoking status and other demographic information were not statistically different between the groups. Conclusions: This study demonstrates that obese NMBC patients required chemotherapy more often than NW patients and that histologic characteristics cannot explain this difference in treatment. Factors such as stage at diagnosis or BC prognostic scores may contribute to the increased use of chemotherapy in obese patients. A limitation of this study is that the stage of disease at diagnosis was not abstracted, as a new staging system for BC was implemented in 2018. Furthermore, studies have suggested that, in obese patients, difficulty in identification of a mass in clinical or self -breast exam and poor compliance with screening guidelines may delay diagnosis of BC at an earlier stage. Obesity has many negative health effects, and with the increased use of novel weight loss medications, it will be important in the future to study the impact this may have on breast cancer development, histopathologic features, and treatment of patients with breast cancer. Table: see text