Abstract
BACKGROUND: The rising incidence of breast cancer and the growing number of survivors underscore the need for further research into quality of life. The BREAST-Q is one of the most comprehensive tools for assessing quality of life (QL) in patients undergoing breast surgery. Although translated into multiple languages, it has only been fully validated in English. MATERIAL AND METHODS: This longitudinal study was conducted to validate and evaluate the psychometric properties of the BREAST-Q in Brazilian Portuguese. Breast cancer-related modules were assessed in 195 patients, mastectomy modules in 66 patients, breast-conserving therapy (BCT) modules in 79 patients, and reconstruction modules in 50 patients. Patient characteristics were analyzed using the mastectomy, BCT, and breast reconstruction modules, along with surgical data on complications and cosmetic outcomes. The psychometric properties of the questionnaires were evaluated for reliability using Cronbach's α. Test-retest reproducibility was analyzed using the intraclass correlation coefficient (ICC). Construct validity was evaluated using Spearman's correlation coefficient. Responsiveness to change was assessed using the Wilcoxon test. Comparisons among independent groups, performed using the Kruskal-Wallis test. Convergent and discriminant validity analysis was achieved by comparing the results with those of the BCTOS and EORTC QLQ questionnaires. RESULTS: A total of 195 patients were recruited from the outpatient breast surgical oncology clinic. The sample was divided into five groups: mastectomy without reconstruction, mastectomy with reconstruction (short form), mastectomy with reconstruction (long form), BCT, and BCT with radiotherapy (RT). Internal reliability, measured by Cronbach's α, was greater than 0.7 in most modules across all groups. Reproducibility, assessed by ICC, ranged from 0.23 to 0.97, with the lowest values observed in the expectation modules, particularly expectations regarding appearance in the long-form questionnaire. The BREAST-Q exhibited good convergent and discriminant validity, with ρ ≥ 0.4 (positive correlations) or ρ ≤ -0.4 (negative correlations). Responsiveness showed that the mastectomy without reconstruction group had worse quality of life. Comparisons among independent groups demonstrated, in the postoperative phase, highest QL in the BCT with radiotherapy group. CONCLUSION: The findings indicate that all breast cancer-related modules of the BREAST-Q effectively measured QL in Brazilian patients.