Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study

Abstract

Introduction: Breast cancer is the most common cancer among women worldwide. Neoadjuvant therapy (NAC) aims to reduce tumor size before surgery and assess the tumor's biological response to treatment. Pathological complete response (pCR) is an important marker of oncological outcomes, but its evaluation in the Colombian population is limited. This study aimed to evaluate pCR and its relationship with overall survival in breast cancer patients who received NAC at a hospital in Medellín. Methodology: This is a retrospective cohort observational study conducted at Clínica Vida, Medellín, between 2017 and 2023, including 1,008 breast cancer patients treated with NAC. Sociodemographic, histological, and treatment variables were evaluated. Bivariate analyses and the Kaplan-Meier test were used to assess survival. Results A total of 36.2% of the patients achieved pCR, which was associated with better overall survival (95.1% vs. 91.1%). Factors associated with pCR included younger age, higher histological grade, elevated Ki67, negative hormone receptors, and lower lymph node involvement. The use of anthracycline-based chemotherapy, taxanes, and Trastuzumab was more common in pCR. Most patients with pCR underwent conservative surgery and sentinel lymph node biopsy. Conclusions Factors such as tumor biology and therapeutic regimen significantly influence the likelihood of achieving pCR and improving long-term survival. This highlights the importance of personalizing NAC in breast cancer, guided by specific biological characteristics of the tumor to optimize clinical outcomes.