Risk factors and clinicopathological features of young women with breast cancer: An observational study.

e13114 Background: Breast cancer in young women presents as an aggressive disease with advanced clinical stages and worse prognosis. Understanding the influence of risk factors on the characteristics of this population is crucial. This study aimed to identify common risk factors and their relationship with clinicopathological features of a cohort of young Mexican women. Methods: We included 58 patients diagnosed with breast cancer before the age of 40 at our center. The evaluated risk factors comprised body mass index (BMI), alcohol consumption, smoking status, diet quality, age at menarche, parity, contraceptive use, family cancer history, and BRCA1/2 mutation status. Clinicopathological parameters included age at diagnosis, clinical stage, tumor grade, and molecular subtype (ER, PR, HER2, Ki-67). Statistical analyses encompassed chi-square tests for categorical data, Mann-Whitney U tests for non-parametric data, and logistic regression for histopathological predictors. Results: The mean BMI was 25 [14.2–39.0], alcohol consumption before 21 was reported in 46.6%, and smoking in 25.9% of the patients. Poor/regular diet was noted in 37.5%. The mean age at menarche was 12.8 years, and the mean parity was 1.22. Previous contraceptive use was documented in 28.3%, while BRCA1 and BRCA2 mutations were present in 12.5% and 15.6%, respectively. The mean age at diagnosis was 34.3 years. The most common clinical stage was IV (25%), followed by IIA (19.2%), with grade 3 tumors accounting for 50%. Luminal B was the most frequent subtype (41.1%), followed by triple-negative (30.4%). ER+, PR+, and HER2+ tumors were observed in 61.4%, 47.4%, and 33.9%, respectively, with a mean Ki-67 index of 39.9%. Family cancer history correlated significantly with triple-negative histology (p = 0.048), while alcohol consumption was associated with more aggressive molecular subtypes (p = 0.023). Patients without a family cancer history showed higher Ki-67 levels (p = 0.010). Logistic regression identified BMI (p = 0.017) and BRCA1 mutations (p = 0.022) as predictors of more aggressive histopathological patterns. Conclusions: This study highlights the prominence of familial cancer history, early alcohol consumption, and elevated BMI (≥25 kg/m²) as key risk factors in our population. Elevated BMI and BRCA1 mutations were independent predictors of aggressive molecular profiles. Larger, prospective studies are warranted to validate these findings and guide tailored interventions for young women with breast cancer. Ordinal logistic regression to predict histopathological patterns. Predictor Estimator Standard Error t Value p Value DX Age -0.156 0.211 -0.738 0.461 Menarche 0.151 0.455 0.331 0.740 # Children 1.893 1.051 1.801 0.072 BMI -0.521 0.219 -2.385 0.017 AHF (1–0) -2.587 1.417 -1.826 0.068 BRCA1 (1–0) -5.963 2.610 -2.284 0.022 BRCA2 (1–0) -3.463 3.357 -1.031 0.302