Abstract P4-03-39: Breast density and Body Mass Index association with breast cancer molecular subtypes in early breast cancer Spanish population

Abstract Obesity is a major health problem and is closely related to the incidence and progression of breast cancer (BC). Likewise, mammogram breast density (MBD) is a risk factor for breast cancer. This study aims to analyze the potential association between BMI (Body Mass Index) and MBD with different molecular subtypes of BC. The interaction with cholesterol, vitamin D, insulin levels, and lifestyle, will also be evaluated. Materials and methods: This is a transversal, descriptive, multicenter study involving women with a recent diagnosis of early BC for one-year duration (November 2019 to October 2020). BMI was classified as obesity (BMI >=30 kg/m2), overweight (>=25 kg/m2), and normal weight (18-25 Kg/m2). American college of radiology was used to classify MBD into 4 categories: A, B, C, and D. Data of weight, height, MBD, molecular subtype (according to 13th St Gallen International Breast Cancer Panel), cholesterol, insulin, vitamin-D, hypertension, diabetes, exercise, and lifestyle were collected at the moment of diagnosis. Results: 162 women with a recent diagnosis of early BC have been successively evaluated in 3 Spanish hospitals. The median age was 52 years, and 49.1% were postmenopausal. Molecular subtypes were: 43% luminal-A, 25% luminal-B, 17% HER2+, and 15% triple-negative. 7% of patients were MBD type A, 17% type B, 55% type C, and 21% type D. 52% were normal weight, 32% overweight, and 16% obese. 48% of women had normal cholesterol levels and 60% normal vitamin D. There was not association between BMI and molecular subtype, however considering menopausal status, BMI was significantly higher in postmenopausal patients with Luminal A subtype (p= 0.011) and HER2+ subtype (p= 0.027). There was no association between MBD and molecular subtype. However, there were significant differences between BMI and MBD (p< 0.001) with lower BMI in patients who had MBD type C or D. Patients with higher BMI had lower HDL-Cholesterol (p< 0.001) and higher levels of insulin (p< 0.001). Conclusion: This study showed a higher BMI in Luminal A and HER2 positive postmenopausal BC patients. Higher BMI was shown in patients with low MBD independently of menopausal status. More studies are needed to understand the role of obesity and molecular subtype of breast cancer. Citation Format: Isabel Calvo, Marta González, Fernando Neria, Isabel Gallegos, Lourdes García-Sánchez, Silvia Pérez, Laura G. Estévez. Breast density and Body Mass Index association with breast cancer molecular subtypes in early breast cancer Spanish population. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-39.