Background: Head and neck squamous cell carcinoma (HNSCC) exhibit considerable heterogeneity, complicating the prediction of disease progression and treatment response. Consequently, researchers are actively investigating reliable biomarkers to forecast disease trajectories and inform therapeutic decisions. This study examines the role of BAG3, a protein involved in cell survival and stress response, as a potential predictive marker in HNSCC. The objective is to analyze BAG3 expression across various HNSCC types and correlate it with disease-free survival (DFS), aiming to elucidate the influence of BAG3 positivity on cancer progression. Methods: A multi-institutional retrospective study was conducted by analyzing BAG3 expression by immunohistochemistry in 104 tissue samples from patients with head and neck squamous cell carcinoma (HNSCC). The data were then correlated with DFS to assess the impact of BAG3 positivity on prognosis. Results: Immunohistochemical analysis of primary tumor samples collected from therapy-naive patients showed that BAG3 positivity was widespread across different head and neck cancer sites, with no significant correlation to sex, smoking status, HPV infection, tumor location, grade, or TNM parameters. However, BAG3 high positive patients had shorter DFS (median 23.2 months) compared to BAG3-negative patients (median 31.3 months). Cox analysis revealed that BAG3 high expression by IHC was associated with a more than 3-fold increased risk of disease recurrence. Conclusions: This study is the first to explore BAG3 as a biomarker for HNSCC recurrence. While preliminary findings suggest a link between BAG3 positivity and increased recurrence risk, further research is needed to validate these results. Prospective studies could help establish BAG3’s prognostic value and potentially lead to more personalized treatment approaches for HNSCC.

The expansion of neoadjuvant immune checkpoint blockade, chemoimmunotherapy, and targeted therapies in oncogene-driven tumors is reshaping the management of resectable non-small cell lung cancer (NSCLC). Major pathologic response (MPR) and pathologic complete response (pCR), defined respectively as 10% or less residual viable tumor (RVT) within the primary tumor bed and the complete absence of viable tumor in both the resected primary tumor and sampled regional lymph nodes, have become widely adopted early efficacy endpoints. Both are consistently associated with favorable survival outcomes at the patient level, although their validity as trial-level surrogates for long-term outcomes remains incompletely established. Accurate pathologic response assessment requires rigorous standardization of gross specimen handling, tumor bed sampling, and microscopic quantification of viable tumor, necrosis, and stroma. International recommendations have improved methodological harmonization, and reproducibility studies have demonstrated good interobserver agreement when standardized protocols are applied. Increasing evidence also indicates that RVT behaves as a continuous prognostic variable and that integration of primary-tumor and nodal response may improve postoperative risk stratification. Beyond quantification of RVT alone, additional histologic characteristics of the residual tumor, together with stromal and immune therapy-related features, may provide complementary prognostic information. Digital pathology and artificial intelligence may support more reproducible quantitative assessment, whereas circulating tumor DNA-based molecular residual disease evaluation may capture systemic risk not represented by the resection specimen. These emerging approaches remain investigational and require prospective validation. This review critically examines the methodological standardization, biological interpretation, and prognostic validation of pathologic response in resectable NSCLC, and discusses future strategies integrating histopathologic, digital, and molecular variables into post-neoadjuvant risk assessment.