In addition, loss of Smad4 staining was more likely to be found in older (OR = 1.69, 95% CI: 1.09–2.61; Pheterogeneity = 0.648) colorectal cancer patients with a late tumor stage (OR = 2.31, 95% CI: 1.71–3.10; Pheterogeneity = 0.218) and in gastric cancer patients with lymph node metastasis (OR = 2.11, 95% CI: 1.03–4.34; Pheterogeneity = 0.038). The gene discussed is SMAD4; the disease is gastric cancer.