Significance of Pathologic Response in Patients With Early and Locally Advanced Breast Cancer Treated With Neoadjuvant Chemotherapy in a Middle-Income Country. A Real-World Historical Cohort.

Breast cancer (BC) is the most frequent neoplasm in women in Colombia and is associated with a higher mortality rate than in other countries and regions. Neoadjuvant chemotherapy (NACT) has become a standard treatment in locally advanced BC and provides an opportunity to improve clinical outcomes in BC. This study aims to describe characteristics, treatment patterns, and outcomes after NACT in a cohort of Colombian patients with BC. We performed a retrospective cohort study. We included adult patients with BC treated with NACT. Clinical charts were retrospectively reviewed. Descriptive statistics and time to event for overall survival analyses were performed. Recursive partitioning was performed for survival curves to assess the complex relationship between survival times and other variables. Three hundred and fourteen patients were included for analysis. The pathologic complete response after neoadjuvant chemotherapy (ypCR) rate was 34.4%, with a higher ypCR in triple-negative BC (TNBC; 46.9%) and human epidermal growth factor receptor 2-positive BC (72.7%). Those who did not achieve ypCR had a higher percentage of death and relapse. The median follow-up was 4.9 years, with an 88.2% 5-year overall survival (OS). A total of 62.6% of the total patients identified were not treated with NACT, indicating a low utilization. Our global ypCR rate was higher when compared with similar studies in Colombia, likely because of differences in the NACT treatment regimens. ypCR was only associated with OS in the TNBC subgroup, emphasizing the importance of pursuing ypCR in these patients. We consider the use of NACT a valuable opportunity to implement innovative treatment approaches that improve outcomes in Colombian patients with BC.