The major findings of the present study demonstrate that: (i) the rate of SULF2M in human gastric cancer is around 30%; (ii) the first evidence for the SULF2U is associated with cisplatin sensitivity in cancer; (iii) evidence for the SULF2M is associated with irinotecan sensitivity in gastric cancer; (iv) a retrospective study and validation for SULF2 methylation in a cohort of 56 patients with gastric cancer, which allowed us to discover that SULF2U is an independent prognostic biomarker in gastric cancer patients treated with a modified FOLFOX regimen. The gene discussed is SULF2; the disease is gastric cancer.