An hypothesis can be proposed to explain the molecular mechanisms responsible for higher levels of expression of GSTP1 in patients with better DFS, as the very variable levels of expression of GSTP1 cannot be explained by the presence of variant genotypes previously implicated in the pathogenesis of breast cancer in patients treated with chemotherapy (Yang et al, Cancer 2005; 103: 52–58), as these variants are mainly related to variations of enzyme catalytic activity (Sweeney, Cancer Res 2000; 60: 5621–5624). The gene discussed is GSTP1; the disease is breast cancer.