Background: Cancer diagnosis and prognosis remain a serious challenge in clinical oncology. Immunohistochemistry (IHC) has become a powerful tool for characterizing tumors on the basis of stages, providing valuable information on specific protein expression to guide diagnosis and predict treatmentoutcomes. The aimof this study was to comprehensively investigate the role of IHC in cancer diagnosis and prognosis in a tertiary hospital setting.Methods: A retrospective analysis was conducted on a group of cancer patients admitted to a tertiary hospital from August 2022 to December 2023. Tissue samples are collected and immunohistochemically stained to detect key biomarkers associated with various cancers. The expression patterns of these biomarkers are then correlated with clinical and pathological data to assess their diagnostic and prognostic significance.Results:These findingsreveal distinct patterns of biomarker expression in different cancer types, which enables precise sub typing and aids in accurate diagnosis of malignancies. Furthermore, IHC features show strong correlation with clinical outcomes and may improve prognostic stratification. In particular, certain biomarkers show potential as predictors of treatment response and guides for personalized treatment strategies.Conclusion: IHChas become acrucial tool for cancer diagnosis and prognosis in tertiary hospitals, providing a precise and personalized approach to patient management. Identification of specific biomarkers by IHC improves diagnostic accuracy, aids in prognostic stratification, and facilitates tailored therapeutic interventions. This study highlights the importance of incorporating IHCinto routine clinical practice for optimal care of cancer patients.