Phospholipase C gamma 1 is a potential prognostic biomarker for patients with locally advanced and resectable oral squamous cell carcinoma

The aim of this study was to investigate the prognostic and predictive values of phospholipase C gamma 1 (PLCG1) expression in patients with locally advanced and resectable oral squamous cell carcinoma (OSCC), who were treated in a prospective, randomized, phase 3 trial evaluating standard treatment with surgery and postoperative radiation preceded or not by induction docetaxel, cisplatin, and 5-fluorouracil (TPF). Immunohistochemical staining for PLCG1 was performed on the biopsies of 232 out of 256 OSCC patients at clinical stage III/IVA; the PLCG1 positive score was determined by immunoreactive scoring system. The survival analysis was performed by Kaplan–Meier method; hazard ratios were calculated using the Cox proportional hazards model. Patients with a low PLCG1 expression had a significantly better overall survival (P = 0.022), and a trend towards better disease-free survival (P = 0.087), loco-regional recurrence-free survival (P = 0.058), distant metastasis-free survival (P = 0.053), and a high response rate to TPF induction chemotherapy with regard to clinical response (P = 0.052) and pathological response (P = 0.061), compared to those with high PLCG1 expression. Our results suggest that PLCG1 expression could be used as a prognostic biomarker for patients with advanced OSCC; however, it was not an adequate predictive biomarker for TPF induction chemotherapy.