Investigation of molecular subtypes and histopathological grading of breast cancer in young female patients: a cross-sectional study

BACKGROUND: Breast cancer is among the most common malignant tumors and the leading cause of death among women worldwide. In young women, although relatively rare, breast cancer is the most frequently diagnosed malignancy. Histopathological examination has been the gold standard of diagnosis with prognostic value, with the determination of breast cancer grading proven correlated with different outcomes. Breast cancer therapy determination is influenced by molecular subtypes and histopathological grading, among other less significant factors. This study aimed to determine the relationship between molecular subtypes of breast cancer and histopathological grading in young female patients.METHODS: This was an analytical, observational, cross-sectional study of young women with breast cancer. Breast cancer is divided into molecular subtypes, including luminal A, luminal B, triple-negative or basal, human epidermal growth factor receptor 2 (HER-2 type), claudin-low, and normal-like. The histopathological grading is divided into grade 1 (well differentiated), grade 2 (moderately differentiated), and grade 3 (poorly differentiated).RESULTS: The luminal B molecular subtype was the most prevalent (26, 32.9%). The luminal B molecular subtype had the highest grade 2 prevalence (15, 32.6%). The luminal A subtype was present in 12 samples, and the HER-2 subtype was predominantly observed in grade 2 histopathological features, with 10 samples. The luminal B subtype was discovered in 15 samples, and the triple-negative subtype was most prevalent among the rest, with nine samples.CONCLUSIONS: No statistically significant correlation existed between molecular subtypes of breast cancer and histological grading in any category.