In the sub-group analyses (Table 3), we found that the HDAC1 expression level was higher in the lymph node metastasis-positive group than in the negative group with gastric cancer (OR = 1.60, 95% CI = 1.07–2.40), and the group positive for distant metastasis showed higher HDAC1 expression than the negative group in patients with colorectal cancer (OR = 3.67, 95% CI = 1.38–9.79). This evidence concerns the gene HDAC1 and gastric cancer.