ALDH2 and neoplasm: After excluding 22 pathological non-SCC, 12 without available tissues, and 2 without clinical data for evaluation, we found no significant difference in the average ALDH2 protein levels between 101 tumor specimens and 15 normal samples (24.46 ± 21.73 vs. 28.70 ± 21.60, P = 0.3921, Mann-Whitney U test).