Estrogen receptor as the predictive factor for response to chemotherapy in breast cancer

It has generally been accepted that breast cancer (BC) cells are equally responsive to chemotherapy (C�T) irrespective of ER status. �owever, subset analyses of disease outcome in recently reported trials on neoadjuvant and adjuvant C�T brought new information about the issue. The subject of this paper is to review these data and to communicate our own results. NSABP B27 was designed to evaluate if adding of docetaxel (D) to conventional neoadjuvant doxorubicin-cyclophosphamide (AC) C�T improves the clinical response rate (cRR) and pathological RR (pRR) in BC patients treated with 4 AC cycles only. Although the adding of D to AC C�T significantly improved RR in both ER-negative and ER-positive BC patients, the pCR was significantly higher in ER-negative than in ER-positive group (16.7% vs. 8.3%) irrespective which regimen was used. ECTO trial and several neoadjuvant studies confirmed the significantly inferior RR to neoadjuvant C�T in ER-positive compared to ER-negative BC patients. Three large randomized Cancer and Leukemia Group B (CALGB) studies (CALGB 8541, CALGB 9344, and CALGB 9741) compared the efficacy of different adjuvant anthracycline-containing or anthracycline/taxane-containing regimens in BC patients. The absolute benefit in 5-year disease-free survival in ER-negative and ER-positive BC patients treated with adjuvant C�T were 22.8% and 7.0%, while corresponding absolute benefits in overall survival were 16.7% and 4.0%. The concept of equal sensitivity of ER-negative and ER-positive BC to C�T has been changing. The future task is to find BC patients with ER-positive BC with no benefit from C�T in whom endocrine therapy is the therapy of first choice. KEY WORDS: Breast Neoplasms; Receptors, Estrogen; Antineoplastic Agents; Treatment Outcome; Chemotherapy, Adjuvant Dept. for Medical Oncology, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia; Address correspondence to: Snežana Šušnjar, Institute for Oncology and Radiology of Serbia, Pasterova 14, 11000 Beograd, Serbia; E-mail: [email protected]; The manuscript was received: 22.10.2006, Provisionally accepted: 26.10.2006, Accepted for publication: 07.11.2006 © 2006, Institute of Oncology Sremska Kamenica, Serbia