Impact on survival of the patients
For disease-free survival, no differences were found between individuals with GSTM1-null genotype and those with positive-GSTM1 genotype (P =0.8094). Accordingly, no impact for RNA GSTM1 expression on disease-free survival (P = 0.8991 and P = 0.9096 for before and after treatment, respectively) was observed (Table 2). In contrast, the absence of hormone receptors (P = 0.0020) and the presence of p53 gene mutations (P = 0.0098) had an impact on disease-free survival. With multivariate analysis, hormone receptors status (P = 0.0002, OR=3.99, 95% CI = 1.92-8.29) and p53 gene mutations (P = 0.0138, OR = 2.36, 95% CI=1.22-4.59) remained significantly associated with metastasis recurrence risk.
No impact was also found (P = 0.9729) for GSTM1-null genotype on overall survival (Table 2), or for RT-PCR RNA expression (P = 0.1667 and P = 0.9637 for before and after treatment, respectively). Only the absence of hormone receptors (P = 0.0018), the presence of p53 gene mutations (P = 0.0071) and no response to primary chemotherapy (P = 0.0086) were associated with reduced overall survival of the patients. In multivariate analysis, hormone receptors status (P = 0.0003, OR = 5.23, 95% CI = 2.03-13.49) and p53 gene mutations (P = 0.0037, OR = 3.62, 95% CI = 1.53-8.53) were strongly related to the risk for death. Absence of clinical response to chemotherapy was less related to the overall survival (P = 0.0530, OR = 2.31, 95% CI = 1.02-5.26).