SMAD4 and colorectal cancer: When colorectal cancer was analyzed, age (OR = 1.69, 95% CI: 1.09–2.61; Pheterogeneity = 0.648) and stage (OR = 2.31, 95% CI: 1.71–3.10; Pheterogeneity = 0.218) but not gender (OR = 0.85, 95% CI: 0.30–2.44; Pheterogeneity = 0.013) were positively associated with loss of Smad4 staining.