SOD2 POLYMORPHISM IS A POSSIBLE PREDICTOR OF EARLY-STAGE BREAST CANCER (HR +, HER2 -) RECURRENCE DURING ADJUVANT TAMOXIFEN

Introduction: About 30% of early-stage breast cancer patients with hormonal receptor tumors show resistance to tamoxifen during adjuvant treatment, which may result in local or distant recurrence. It is known that the development and aggressiveness of tumors are associated with oxidative stress and antioxidant enzymes such as SOD2. The evaluation of the Val16Ala-SOD2 polymorphism is a possible predictor of recurrence during adjuvant treatment, helping in the therapeutic and prognostic definition of these patients. Objective: To evaluate the association between genotypes of SOD2 polymorphism and the risk of recurrence in patients with luminal breast cancer using adjuvant tamoxifen. Methodology: Retrospective cohort study of patients with early-stage breast cancer (HR + / Her2-) using adjuvant tamoxifen and follow-up at a reference center. The genotypes AA, AV and VV were evaluated by real-time PCR. The study of the different genotypes were performed through a Cox-regression multivariate analysis of (backward wald) adjusted for age in diagnosis, histology, grade and clinical staging. Results: In a sample of 72 patients, 58.21% were older than 40; 85% presented ductal histological type; 29.21% presented histological grade 3 and 30.3% presented clinical stage III. In this cohort, 25 patients (35%) had shown recurrence (12 patients with local recurrence and 13 patients with distance recurrence). The genotypic frequencies of SOD2 were AA = 35%, VV = 35% and AV = 30%. In the multivariate analysis, the presence of the V allele showed a tendency to be a risk factor for recurrence (RR = 2.56 95% CI 0.930-7.07 – p = 0.069). When we stratified the analysis by clinical staging (CS), it was observed that in patients with CS = III, the presence of the V allele was an independent risk factor for recurrence (RR = 7.56 95% CI 2.48-23.01 – p < 0.001). Conclusion: In general, despite not being statistically significance, the presence of the V allele in early-stage breast cancer patients using adjuvant tamoxifen showed a tendency of recurrence. When only patients with CS = III were analyzed, the presence of the V allele showed significant association with disease recurrence.