Second primary tumors and myeloperoxidase expression in buccal mucosal squamous cell carcinoma.

Objective The present study investigated the relationship between the expression of manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase (GP x ), and myeloperoxidase (MPO) in buccal mucosal squamous cell carcinoma (SCC), and the risk of second primary tumors (SPTs). Study design Immunohistochemistry was performed to examine the expression of MnSOD, GP x , catalase, and MPO in tissue microarray slides of 173 male patients with buccal mucosal SCC who had undergone potentially curative resections. Results Forty-five (26.01%) patients developed SPTs. The prevalent subsites of SPTs were buccal mucosa (48.89%), tongue (13.33%), and lip (11.11%). High expression level of MPO was correlated with an increased risk of SPTs, even after adjustment for development of clinicopathologic parameters (high vs. low expression, adjusted hazard ratio = 3.89; 95% confidence interval, 1.33-11.41; P  = .013). Conclusions SPTs are common in male buccal mucosal SCC patients. Higher MPO expression in buccal mucosal SCC is a risk factor for SPTs.