Abstract

BackgroundNeoadjuvant endocrine therapy (NET) has shown efficacy in terms of clinical response and surgical outcome in postmenopausal patients with estrogen receptor-positive / HER2-negative breast cancer (ER+/HER2- BC) but monitoring of tumor response is challenging. The aim of the present study was to investigate the value of an early metabolic response compared to morphological and pathological responses in this population.MethodsThis was an ancillary study of CARMINA 02, a phase II clinical trial evaluating side-by-side the efficacy of 4 to 6 months of anastrozole or fulvestrant. Positron Emission Tomography/Computed Tomography using 2-deoxy-2-[18F]fluoro-D-glucose (FDG-PET/CT) scans were performed at baseline (M0), early after 1 month of treatment (M1) and pre-operatively in 11 patients (74.2 yo ± 3.6). Patients were classified as early “metabolic responders” (mR) when the decrease of SUVmax was higher than 40%, and “metabolic non-responders” (mNR) otherwise. Early metabolic response was compared to morphological response (palpation, US and MRI), variation of Ki-67 index, pathological response according to the Sataloff classification and also to Preoperative Endocrine Prognostic Index (PEPI) score. It was also correlated with overall survival (OS) and recurrence-free survival (RFS).ResultsTumor size measured on US and on MRI was smaller in mR than mNR, with the highest statistically significant difference at M1 (p = 0.01 and 7.1 × 10− 5, respectively). No statistically significant difference in the variation of tumor size between M0 and M1 assessed on US or MRI was observed between mR and mNR. mR had a better clinical response: no progressive disease in mR vs 2 in mNR and 2 partial response in mR vs 1 partial response in mNR. One patient with a pre-operative complete metabolic response had the best pathological response. Pathological response did not show any statistically significant difference between mR and mNR. mR had better OS and RFS (Kaplan-Meier p = 0.08 and 0.06, respectively). All cancer-related events occurred in mNR: 3 patients died, 2 of them from progressive disease.ConclusionsFDG-PET/CT imaging could become a “surrogate marker” to monitor tumor response, especially as NET is a valuable treatment option in postmenopausal women with ER+/HER2- BC.

Highlights

  • Neoadjuvant systemic therapies have been developed to achieve “tumor shrinkage” in locally advanced breast cancer in inoperable patients or to avoid radical mastectomy in patients with a tumor too large for primary breast-conserving surgery (BCS) [1] and to monitor tumor response

  • Pathological complete response is the “gold standard” for evaluation of tumor response to neoadjuvant chemotherapy (NCT), as it is correlated with prognosis, differences are observed among breast cancer subtypes [2]

  • Secondary endpoints were tumor response on US and Magnetic resonance imaging (MRI) according to RECIST 1.0 criteria, baseline and ontreatment Ki-67 index, BCS rate, pathological response assessed by the Sataloff classification, with partial pathological response defined as TB and Pathological complete response (pCR) as TA [13], and survival parameters, with overall survival (OS), recurrencefree survival (RFS) and PEPI score (Preoperative Endocrine Prognostic Index, [14])

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Summary

Introduction

Neoadjuvant systemic therapies have been developed to achieve “tumor shrinkage” in locally advanced breast cancer in inoperable patients or to avoid radical mastectomy in patients with a tumor too large for primary breast-conserving surgery (BCS) [1] and to monitor tumor response. Pathological complete response (pCR) is the “gold standard” for evaluation of tumor response to neoadjuvant chemotherapy (NCT), as it is correlated with prognosis, differences are observed among breast cancer subtypes [2]. PCR is uncommon after NET in ER+/HER2- BC [4] and is not a suitable primary endpoint in NET clinical trials. Monitoring response to NET is challenging and, despite a poor reproducibility, clinical response is used as a primary endpoint in most clinical trials [5]. Neoadjuvant endocrine therapy (NET) has shown efficacy in terms of clinical response and surgical outcome in postmenopausal patients with estrogen receptor-positive / HER2-negative breast cancer (ER+/HER2- BC) but monitoring of tumor response is challenging. The aim of the present study was to investigate the value of an early metabolic response compared to morphological and pathological responses in this population

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