Evaluation of Cyclin D1 and Human Epidermal Growth Factor Receptor 2 Neu Protein Expression in Head and Neck Squamous Cell Carcinoma

Background Head and neck cancers are highly aggressive, frequently occurring cancers that are prevalent worldwide. The mainstay of their treatment is surgery, followed by adjuvant therapy. Various studies have documented the usefulness of molecular markers in carcinogenesis and have proven helpful in the diagnosis and treatment of head and neck cancers. Cyclin D1 is a proto‑oncogene, overexpression of which leads to the accelerated entry of cells in the S phase of the cell cycle, causing uncontrolled proliferation of the cells. The dysregulation of human epidermal growth factor receptor 2 (HER2) neu is also related to multiple features of malignancy, including loss of cell cycle control, induction of angiogenesis, and resistance to apoptotic stimuli. This study seeks to identify a subset of patients with a bad prognosis who may require aggressive treatment strategies. Aim This study aims to determine the proportion of the expression of cyclin D1 and HER2 neu in head and neck squamous cell carcinoma (HNSCC) and analyze the association between the expression of cyclin D1 and HER2 neu using histological grading, tumor, node, and metastasis (TNM) staging, and nodal status of the tumor. Furthermore, this study also aims to document clinical outcomes, such as locoregional control, depth of invasion (DOI), and regional metastasis regarding the expression of cyclin D1 and HER2 neu in HNSCC. Setting and design This study is a laboratory-based observational study. Materials and methods Seventy histologically proven cases of HNSCC were studied for various histopathological parameters, and further immunohistochemistry (IHC) was performed for cyclin D1 and HER2 neu. The expression and intensity of cyclin D1 were multiplied, and the total score was derived. The College of American Pathologists/American Society of Clinical Oncology (CAP/ASCO) guidelines for HER2 neu testing in breast cancer were used for scoring. Result Out of 70 cases, 52 (75%) demonstrated strong and moderate positivity for cyclin D1, and the p-values were 0.017, 0.001, and 0.032 for depth of invasion, TNM stage, and lymph node metastases, respectively, for cyclin D1, which was considered statistically significant. For HER2 neu, five out of 70 cases were positive, and the p-value was significant for depth of invasion (0.008). Conclusion The expression of the above marker cyclin D1 increases with stage, DOI, and positive lymph node status. Hence, cyclin D1 immunoexpression can be helpful in the early assessment of HNSCC behavior and can serve as an independent prognostic marker. Furthermore, it was observed that HER2 neu was significant with an increase in depth of invasion of tumor, which, in the American Joint Committee on Cancer (AJCC) eighth edition, is considered an important factor for determining the stage of the tumor. Further research is needed to examine whether HER2 neu can act as a prognostic factor for HNSCC and if it can be targeted for treatment options.