High NNMT expression was shown to be an unfavorable postoperative prognosis in breast cancer (Wang et al., 2019), head and neck squamous cell carcinoma (Togni et al., 2021), renal cancer (Qu et al., 2022; Reustle et al., 2022), non-small cell lung cancer (Wang et al., 2022), colorectal cancer (Song et al., 2020), pancreatic cancer (Xu et al., 2016), liver cancer (Kim et al., 2009), gastric cancer (Chen et al., 2016), ovarian cancer (Eckert et al., 2019) and endometrial cancer (Akar et al., 2019). This evidence concerns the gene NNMT and gastric cancer.