Immunohistochemical Expression of Cyclin D1 and p16 in Invasive Breast Carcinoma and Its Association with Clinicopathological Parameters.

Invasive breast cancer (IBC) is a significant health concern globally, contributing to substantial morbidity and mortality among women. Dysregulated cellular proliferation, a hallmark of malignancy, involves molecular pathways modulated by proteins such as cyclin D1 and p16. Understanding their roles in IBC pathogenesis and their association with prognostic parameters is crucial for refining treatment strategies. This retrospective study included 50 female IBC patients who underwent modified radical mastectomy. Histopathological evaluation and immunohistochemical staining for cyclin D1 and p16 were conducted. Associations between protein expression and clinicopathological parameters were analyzed using statistical tests. Cyclin D1 was expressed in 76% of cases, significantly associated with lower tumor grade and lower Ki-67 proliferation index. It also correlated with luminal A/B molecular subtypes. p16 expression was observed in 48% of cases, significantly associated with higher tumor grade, higher Ki-67 index, and triple-negative/Her-2 neu-enriched subtypes. Co-expression of cyclin D1 and p16 was noted in 60% of cases. No significant association was found between protein expression and other parameters. Cyclin D1 and p16 exhibit potential as prognostic markers in IBC. Cyclin D1 expression correlates with less aggressive tumor features and luminal subtypes, suggesting a favorable prognosis and potential predictive value for CDK4/6 inhibitor therapy. Conversely, p16 expression associated with aggressive phenotypes, indicating poor prognosis. Further studies are warranted to validate these findings and explore their clinical implications. Integrating these biomarkers into clinical practice may enhance risk stratification and treatment decisions, ultimately improving outcomes for IBC patients.