Loss of heterozygosity of D9S162: molecular predictor for treatment response in oral carcinoma.

Inspite of improvements in treatment regimen of oral cancer, locoregional recurrence rates and overall mortality have remained unchanged over the years. This study therefore focused on microsatellite alterations in 9p21 loci, as a possible molecular prognostic marker in oral cancer and to identify the correlation between allelic imbalance, if any, with the recurrence in oral cancer. Eighty-one patients, treated with radiation or combination of surgery with radiotherapy/chemotherapy, were investigated for LOH/MSI at the 9p21 locus using microsatellite assay. Correlations between allelic alterations and prognostic outcomes were assessed. LOH was noted at D9S161 (56%), followed by D9S162 (31%). Both markers were found to be associated with decreased recurrence free survival, D9S162 showed a significant association with overall survival as well. Only LOH at D9S162 was an independent predictor of recurrence free survival and overall survival. Patients positive for LOH at D9S162 were 6 times more likely to experience recurrence than those without LOH irrespective of treatment modality. LOH at D9S162 is a significant molecular alteration in oral carcinoma with unfavorable repercussions for recurrence and overall survival.