Explanation model using pathological data for treatment outcome of patients with early-stage breast cancer with hormonal receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative.

Abstract

e12006 Background: The decision to initiate adjuvant chemotherapy for early-stage breast cancer patients with HR+ and HER2- is still unclear. Although the 21-gene Recurrence Score (RS) assay is a validated testing and becomes an emerging decision-making tool; it is still controversial guidance on adding adjuvant chemotherapy for patients with intermediate RS. This study aimed to develop the explanation model by using pathological information for prediction of the best outcome from adjuvant systemic treatment in these patients.Methods: Early-stage breast cancer patients with HR+, and HER2- who underwent complete resection registered within electronic medical record from 2003 to 2013 were included. Patient’s characteristics and pathological information were collected and analyzed. Univariate and multivariate analysis were conducted by using stepwise logistic regression. The explanation model was explored by using association between multivariate models and overall survival (OS).Results: 236 patients who underwent complete surgery treatment were included. 121 patients (51%) were treated with sequential adjuvant treatment, and 115 patients (48%) with anti-hormonal therapy alone. Clinicopathological parameters between two groups were demonstrated in Table1. Tumor size (≥2 – 5 cm), Estrogen receptor-negative/ Progesterone receptor-positive (ER-/PgR+), and Ki-67 expression were statistically significant multivariate independent prognostic factors for OS. When we adjusted for tumor size, HR status, and Ki-67 expression, the explanation model predicted 10-year OS was 99.2% for patients with sequential adjuvant treatment, whereas 89.5% for patients with adjuvant anti-hormonal alone (difference: 9.7%); p-value = 0.01.Conclusions: We found substantial discordance in 10-year OS benefit between early-breast cancer patients with HR+, HER2- with sequential adjuvant therapy and adjuvant hormonal therapy alone. Adjuvant chemotherapy should be considered in early-breast cancer patients with 2-3 cm in tumor size, ER-/PgR+, and Ki 67 expression.