Survival After Multimodal Treatment for Breast Cancer in Brazil: The Predominant Role of Clinical Stage and Treatment Response

Background Neoadjuvant systemic therapy (NST) enables early systemic disease control and assessment of treatment response in breast cancer. However, survival outcomes after NST are also shaped by subsequent local-regional treatment, including surgery and radiotherapy. We evaluated the impact of clinical and selected nonclinical factors on survival among Brazilian women treated with NST followed by surgery and radiotherapy as part of multimodal care. Methods This subanalysis of the LACOG 0115 Amazona III cohort included women (≥18 years) with nonmetastatic breast cancer treated with NST, surgery, and radiotherapy at 22 Brazilian centers between 2016 and 2018. Overall survival (OS) and disease-free survival (DFS) were estimated using Kaplan-Meier methods and assessed with multivariable Cox regression. Results Of 2,972 enrolled patients, 582 met inclusion criteria. Median age was 49 years (range, 25-87); 74.1% were treated in the public health care system, 57.2% were non-White, and 58.9% had stage III disease. After recoding the multivariable model for clinically intuitive interpretation, stage III disease was associated with worse OS (HR, 1.96; 95% CI, 1.05-3.70; p = 0.034) and DFS (HR, 1.69; 95% CI, 1.02-2.86; p = 0.041) compared with stage II disease. Absence of pCR was strongly associated with inferior OS (HR,3.53;95% CI,1.27-9.77; p=0.015) and DFS (HR,2.24;95%CI, 1.11-4.52; p=0.024). Educational level, race, and insurance status were not independently associated with OS or DFS after adjustment. Conclusions Among Brazilian women treated with NST, surgery, and radiotherapy, tumor stage and achievement of pCR were the principal independent prognostic factors. After multivariable adjustment, socioeconomic and health care-related variables were not independently associated with survival, suggesting that their influence may operate indirectly through disease stage, access to treatment, and treatment response. These findings should be interpreted within the context of a selected cohort that completed multimodal therapy. MicroAbstract In this subanalysis of the LACOG 0115 Amazona III cohort, we evaluated early- to intermediate-term overall and disease-free survival and their clinical and selected nonclinical correlates among Brazilian women with nonmetastatic breast cancer treated with neoadjuvant systemic therapy, surgery, and radiotherapy at 22 centers between 2016 and 2018. Among 582 eligible patients (median age, 49 years; 74.1% treated in the public health care system; 57.2% non-White; 58.9% stage III), with a median follow-up of 30.7 months, clinical stage and pathologic complete response (pCR) were independently associated with outcomes. Stage III disease compared with stage II disease and absence of pCR were associated with inferior overall and disease-free survival. In this selected treatment-complete cohort, educational level, race, and insurance status were not independently associated with survival after multivariable adjustment; however, this finding should be interpreted cautiously and is hypothesis-generating, suggesting that their prognostic influence may operate through upstream pathways related to disease stage, access to multimodal treatment, and treatment response.