Perioperative supplementation with probiotics did not improve weight loss (MD 0.73 kg; 95% CI: −0.56, 2.02) or serum prealbumin levels (MD 9.48 mg/L 95% CI: −3.43, 22.40), but did reduce the incidence of postoperative infectious complications (RR 0.46, 95% CI 0.28, 0.77), shorten the time to first exhaust (MD −11.27 h; 95% CI: −16.83, −5.70), the time to first defecation (MD −15.71 h; 95% CI: −25.62, −5.79), and the length of hospital stay (MD −0.94 days; 95% CI: −1.33, −0.55), and increase serum albumin levels (MD 0.73 g/L; 95% CI: 0.01, 1.46) in gastric cancer patients undergoing surgery. This evidence concerns the gene TTR and gastric cancer.