RESUMEN
BACKGROUND: Squamous cell carcinoma of the oral cavity (OSCC) is the sixth most common malignancy. Surgery is mainstay treatment for oral cancers. Surgery in locally advanced OSCC presents many challenges primarily because the head and neck have critical structures that can be damaged by tumor or treatment. It is thought that neoadjuvant chemotherapy (NC) in locally advanced OSCC is able to shrink tumor size. Chemoresistancy is a problem due to hypoxic microenvironment characterized by increased expression of HIF-1α. It is also regulated by miR-210 as well as increased expression of CD44 and CD133. Melatonin has a powerful antioxidant and oncostatic effects that are expected to improve tumor hypoxia and clinical response. Fifty patients with OSCC were included and randomized. miR-210 and CD44 expression were measured before and after intervention using qRT-PCR absolute quantification, and clinical response was evaluated according to RECIST 1.1 criteria. This study aims to determine the effect of melatonin in improving the clinical response of patients with locally advanced oral squamous cell carcinoma (OSCC) after neoadjuvant chemotherapy to miR-210 and CD44 expression. RESULTS: Melatonin administration reduced miR-210 levels but not significant (p = 0.767). CD44 expression also decreased in the melatonin group compared with placebo yet was not significant (p = 0.103). There was a decrease in the expression of miR-210 and CD44 followed by a decrease in the percentage of residual tumor but not significant (p = 0.114). CONCLUSION: In OSCC, the addition of 20-mg melatonin to neoadjuvant chemotherapy (NC) reduced the expression of miR-210 and CD44 and decreased the percentage of tumor residue; however, no statistically significant result was observed. TRIAL REGISTRATION: This study is registered to ClinicalTrials.gov under trial registration number: NCT04137627 with date of registration on October 22, 2019-retrospectively registered, accessible from: https://clinicaltrials.gov/ct2/show/NCT04137627.