Gene polymorphisms and post-treatment toxicity and treatment response in head and neck squamous cell carcinoma: A scoping review

Variations in toxicity and treatment response are observed among patients with head and neck squamous cell carcinomas (HNSCCs) despite similar clinicopathologic characteristics that are attributed to gene polymorphisms. This study aimed to review the literatures about the impact of gene polymorphisms on post-treatment toxicity and treatment response in HNSCCs. A systematic search of all original articles about impact of gene polymorphisms on toxicity and response rate in HNSCCs was done till September 2021 using Google Scholar and PubMed databases. Of 15 345 initial searched articles, 25 articles were finally found to be eligible for inclusion in this review. A total of 41 genes and 69 polymorphisms were examined in these studies. Twenty-nine genes with 42 polymorphisms for treatment response and 21 genes with 33 polymorphisms were examined for post-treatment toxicity. Because each of the Asp312Asn ERCC2, lle105Val GSTP1, and Phe31lle AurkA polymorphisms has been associated with significant results in two studies, these polymorphisms are more likely to be associated with a treatment response. In the same way, the R521K EGFR polymorphism is more likely to be associated with a post-treatment toxicity. Because some polymorphisms such as R521K EGFR, *4 or *6 CYP2D6, and rs396991 Fc gamma RIlla have been associated with significant results in one study (without contradictory study), it is likely that they will be associated with a treatment response by further studies. Due to the paucity of studies, definitive conclusions are impossible, so further studies with meta-analysis in the future are recommended.