A major mitochondrial enzyme for protecting cells from acetaldehyde toxicity is aldehyde dehydrogenase 2 (ALDH2).The correlation between ALDH2 dysfunction and tumorigenesis/growth/metastasis has been widely reported.Either low or high ALDH2 expression contributes to tumor progres-sion and varies among different tumor types.Furthermore,the ALDH2* 2 polymorphism (rs671) is the most common single nucleotide polymorphism (SNP) in Asia.Epidemiological studies associate ALDH2 * 2 with tumorigenesis and progression.This study summarizes the essential functions and poten-tial ALDH2 mechanisms in the occurrence,progression,and treatment of tumors in various types of can-cer.Our study indicates that ALDH2 is a potential therapeutic target for cancer therapy.