ALDH1, a prognostic marker in oral neoplasms: A systematic review

Introduction: Oral squamous cell carcinoma is one of the most common malignancies of the head and neck region. Despite advances in therapeutic options, the disease high rate of mortality hasn’t been changed markedly. The prediction of disease behavior is difficult to evaluate solely using conventional parameters. Therefore, studies on molecular biomarkers have performed as potential tools to predict the prognosis of patients with OSCC. ALDH1 is an enzyme responsible for oxidizing endogenous and exogenous aldehydes into their corresponding carboxylic acids. It plays a detoxifying and self-protective role and therefore seems to influence the chemotherapy resistance in cancer stem cells. Thus, it can be a potential biomarker in determination of OSCC prognosis. Methods: We performed a systematic review to identify all the primary research studies that evaluated potential role of ALDH1 as a prognostic marker in OSCC. We searched the MEDLINE/PubMed medical literature database from 2009 to 2018. The search strategy was based on combination of following key words: “mouth neoplasms” [MeSH] and “aldehyde dehydrogenase 1” [MeSH] and “prognosis” [MeSH] Results : Analysis of data shows a significant correlation between ALDH1 expression and lower survival rates, increased hazard ratio, poor tumor differentiation grade, increased invasion ability and recurrence after chemotherapy and radiotherapy. High correlation between ALDH1 expression and lymph node metastasis has been proved. No relation between expression of ALDH1 and tumor size has been found as well as with age, gender and tumor location. Conclusion : These data indicate that expression of ALDH1 can be an effective marker to evaluate prognosis. In particular, it is a potential biomarker for prediction of lymph node metastasis in OSCC patients.