Moreover, when we performed multivariable analysis to evaluate the risk factors of SNE in total, cancer stage III and basal Hb < 12 g/dL were significant risk factors of SNE (cancer stage III: OR 13.96, 95% CI 4.82–40.46; basal Hb < 12 g/dL: OR 2.41, 95% CI 1.21–4.78) (Table 2). This evidence concerns the gene GSTM1 and cancer.