Dados do Trabalho

Título

RELAPSE-FREE SURVIVAL AMONG ESTROGEN RECEPTOR LOW-POSITIVE BREAST CANCER PATIENTS SUBMITTED TO NEOADJUVANT CHEMOTHERAPY.

Introdução

Estrogen receptor(ER) is the most important predictive and prognostic biomarker in breast cancer. ER positivity is considered when at least 1% of tumor cell nuclei are immunoreactive in immunohistochemistry(ICH). ER low-positive(ER-low) is an uncommon subtype of luminal tumors, with a controversial behavior.

Objetivo

To compare the relapse-free survival(RFS) between ER-low and non-low(nlER), in a modern cohort undergoing neoadjuvant chemotherapy(NAC). Secondarily, to compare the pathological complete response(pCR) and overall survival(OS) between the groups.

Método

All consecutive ER-positive (≥ 1%) HER2-negative breast cancer patients treated with NAC from January 2007 to December 2018 in a single center were retrospectively recruited. Data were retrieved from medical records. ER expression was evaluated according to ASCO/CAP guidelines. ER-low was defined by 1-10% estrogen expression. RFS: time from breast surgery to local/distant recurrence or death by any cause. Categorical variables were compared by chi-squared test or Fisher. Time-to-event variables were analyzed with Kaplan-Meier curves and the Log-rank test. Prognostic factors were adjusted by Cox regression and logistic regression. p<0.05 were considered significant.

Resultado

508 patients were included. The median follow-up was 54 months. 42 (8.3%) had ER-low. Most were premenopausal, had invasive ductal carcinoma, clinical stage III, and positive axillary lymph nodes, irrespective of ER positivity. ER-low was associated with higher histologic grade (grade III: 64.3% vs 24.1%,p<0.0001), more neoadjuvant carboplatin (26.2% vs 0.6%,p<0.001), and adjuvant capecitabine (15.0% vs 1.8%,p<0.001) prescriptions. pCR was achieved in 23.8% of ER-low vs 8.2% of nlER (p=0.003). Minimal residual cancer burden (RCB 0-I) rates were also superior for ER-low (37.8% vs 18.3%,p<0.001). ER-low experienced more recurrence (40.5% vs 26.0%, p=0.048), including locoregional disease (19.0% vs 3.9%,p=0.001), lung (16.7% vs 5.8%,p=0.02) and CNS metastasis (7.1% vs 2.6%,p=0.119). The median RFS and OS were not reached. ER-low was associated with worse RFS and OS in both univariate and multivariate analysis (HR 1.85, 95%CI 1.03-3.33; and HR 2.34 95%CI 1.10-5.0,respectively).

Conclusão

ER-low incidence in this cohort was higher than literature reports. Despite acquiring higher pCR rates, ER-low patients experienced more recurrence and death. Our results support a distinct biological behavior and worse prognosis for the subset of patients with ER-low tumors.