Overall survival of neoadjuvant versus adjuvant systemic treatment for breast cancer in Brazil.

Abstract

Objective: Compare the overall survival of women with non-metastatic breast cancer who received neoadjuvant systemic therapy followed by surgery versus those who underwent surgery followed by adjuvant systemic therapy.

Methods: A nationwide retrospective cohort study was conducted using real-world data from 2008 to 2015 available on the Brazilian Unified Health System (SUS). Women aged ≥ 18 years with breast cancer undergoing surgery or neoadjuvant systemic therapy as their first treatment between 2008 and 2010 were included. Cohorts were matched using propensity score matching in a 1:1 ratio and assessed 5-year overall survival using Kaplan-Meier, compared by log-rank test and hazard ratios (HR) using Cox proportional HR model.

Results: A total of 23,331 women began treatment for breast cancer in SUS with neoadjuvant systemic therapy (n = 6,040) and surgery (n = 17,291). In the matched cohorts (n = 6,040 in both groups), more deaths occurred among those who received neoadjuvant systemic therapy compared with surgery as first treatment (37.3% and 19.6%, respectively; p < 0.001). Overall survival after five years was 0.641 in neoadjuvant systemic therapy and 0.816 in the surgery group (p < 0.001). For both groups, older patients (≥ 70 years) living in northern and midwestern Brazil, in municipalities with low and medium HDI, and self-declared as Black presented the lowest overall survival probabilities. Use of hormone therapy after surgery and conservative surgery instead of mastectomy were associated with higher survival. HR was 5.13 (95%CI: 2.95-8.88) in stage I, 1.57 (95%CI: 1.27-1.95) in stage II, and 1.38 (95%CI: 1.26-1.50) in stage III.

Conclusion: Women who underwent surgery as first treatment had a significantly higher 5-year overall survival compared with those who received neoadjuvant systemic therapy. Socioeconomic and demographic factors influenced survival outcomes.