The variables related to hospital stay were age (p < 0.001), diabetes (p = 0.011), non-insulin-dependent diabetes (p = 0.042), chronic renal failure (p = 0.038), ASA stage (p = 0.010), Charlson ́s index (p = 0.001), lymphocyte count (p < 0.001), lymphocyte neutrophil rate (p = 0.001), lymphocyte neutrophil lymphocyte derived rate (p < 0.002), pre and postoperative serum Hb value (p = 0.016 and p = 0.021, respectively), tumor location (p = 0.001), operative time (p = 0.002), type of suture used (p < 0.001), need for postoperative transfusion (p < 0.001), and incisional SSI (p = 0.001). This evidence concerns the gene GSTM1 and diabetes mellitus.