Factors Influencing Locoregional Recurrence and Disease-Free Survival in Buccal Mucosal Squamous Cell Carcinoma

Abstract

Oral cancers are the most common malignancy affecting Indian population with buccal mucosa being the frequent subsite. This study is to evaluate the histopathological factors influencing locoregional recurrence (LRR) and disease-free survival (DFS) in buccal mucosal squamous cell carcinoma (BSCC). One hundred and twenty patients treated surgically for BSCC with a curative intend between January 2014 and December 2015 were retrospectively analyzed. Histopathological factors like tumor stage, grade of differentiation, tumor front, skin involvement, bone involvement, depth of invasion, perineural invasion, lymphovascular emboli, primary resection margin in frozen section, nodal stage, extracapsular extension, and lymph node ratio were analyzed and compared for LRR and DFS. With a median follow-up of 41 months, LRR occurred in 34 patients (28.3%) and a 2-year DFS was 75.8%. Multivariate analysis identified that the factors that independently influenced the LRR were pathological nodal stage (p < 0.0001) and primary resection margin in frozen section (p < 0.0001). A single neck node involvement increases risk by 6.8 times for LRR compared to no nodal involvement (95% CI 2.897-15.888, p < 0.0001). Frozen section studies on primary tumor excision margin showed that close margin had 2.3 times chance of LRR (95% CI 1.020-5.035, p < .045) and involved margin showed 20.9 times risk of LRR compared to clear margin(95% CI 6.529-67.021, p < 0.0001). Primary resection margin on frozen section and pathological nodal status are the most important factors influencing LRR and DFS. This study highlights importance of aggressive treatment and close follow-up even with a single node involvement and when frozen section margin clearance is less than 5 mm.