Assessment of cancer associated fibroblasts amongst different histological variants of oral squamous cell carcinoma

Cancer associated fibroblasts are heterogenous activated fibroblasts that form the central component of the tumor microenvironment. These cells influence the behavior of the tumor by activating various signaling pathways and initiating epithelial mesenchymal transition. CAFs have been reported in oral squamous cell carcinomas (OSCC), however, very few studies have evaluated the role of CAFs in different variants of OSCC. The aim of this study was to compare the role of CAFs in conventional OSCC and different variants of OSCCs. Eight each of well differentiated, moderately differentiated and poorly differentiated OSCC, 5 each of verrucous carcinoma and verrucous carcinoma turning into OSCC, three each of spindle cell carcinoma, basaloid OSCC and OSCC with clear cell differentiation and 2 cases of papillary OSCC were retrieved, and immunohistochemistry was performed with α-SMA to identify and evaluate the CAFs. Kaplan Meier analysis was carried out to evaluate the overall survival of the patients. Progressive increase in the CAF immunostaining was noted from papillary squamous cell carcinoma [mean - 1] to basaloid squamous cell carcinoma [1.6 ± 0.5] to spindle cell carcinoma and squamous cell carcinoma with clear cell changes [2.6 ± 0.5] (p = 0.00 - statistically significant). Patients with abundant CAF expression showed lesser survival rate when compared to patients with scanty or focal CAF immunohistochemical staining. Increased CAF immunoexpression was noted in PDSCCs, VCs turning into SCC, OSCC with clear cell changes and spindle cell carcinoma. This highlights the aggressive nature of these tumors. Screening these tumor for the presence of CAFs will help in treatment planning and will aid in treatment planning and survival analysis. • Increased CAF expression was correlated with lower survival in OSCC and its variants. • CAF could predict invasive behaviour of tumor.