Abstract P1-11-14: Neoadjuvant Chemotherapy in Lobular and Ductal Carcinoma: Comparison of Clinical, Pathological Response Rates and Survival

Abstract

Abstract Introduction: Neoadjuvant chemotherapy is a standard of care in locally advanced breast carcinomas. The major purpose of neoadjuvant chemotherapy is breast conserving surgery. Advantages in survival have only been shown in patients undergoing achieving pathological complete response (pCR). Lobular carcinomas seem less chemosensitive than ductal carcinomas to neoadjuvant chemotherapy (NCT). Purpose: To compare the clinical and pathological response rate and the outcome of lobular (ILC) versus ductal (IDC) invasive breast carcinomas after NCT. Patients and methods: Between 1985 and 2010, 385 patients with locally advanced and/or inflammatory breast carcinomas from Saint Louis hospital received neoadjuvant chemotherapy. Forty-four (11, 4%) ILC and 341 (88, 6%) IDC were diagnosed by surgical or core needle biopsy before CT. All patients received anthracyclines based CT,181 (47%) additionally received a taxane (four cycles of epirubicin 75 mg/m2 and cyclophosphamide 750 mg/m2 then four cycles of taxotere 100mg/m2 or six cycles of a dose dense regimen of 75 mg/m2 epirubicin and 1200mg/m2 cyclophosphamide, every 14 days),and underwent breast surgical excision (lumpectomy or mastectomy) and axillary node dissection.Clinical response was defined by the lack of palpable tumor in the breast before surgery.Pathological complete response was defined by no residual invasive tumor in breast. Radiotherapy and hormonotherapy were delivered to patients, when appliable. Results: Clinical response to NCT was higher for ILC (27, 3%) than IDC (13,4%). ILC with clinical response tended to have higher histological grade 2 (91,6 % versus 30,4% for IDC),more estrogens receptors (RE) positivity (91,6% vs 45,6%), p53 wild type (66,6% vs 30,4%) and HER2- negative tumors (91,6% vs 76%) Pathologic response (pCR) rate was lower for ILC than for IDC (2, 7% vs 9, 3%). Only one ILC (grade 2, RE+, HER2 negative, p53 wild type) underwent pCR. Thirty two (9, 3%) IDC haved pCR: 15,6% haved histological grade 2, 15,6% RE positivity,9,3% p53 wild type, 62,5% HER2 negative. Thirteen percent of ILD and 9 % of ILC haved breast conservating surgery .At a median follow up of 60 months, ILC patients tended to have longer overall survival (55% vs 48%) and recurrence free survival (44% vs 36,8%) than IDC. Conclusions: ILC was characterized by better clinical response rates but lower pathologic response and breast conservating surgery rates .Despite the low pCR rate, patients with ILC tended to have better outcomes than did patients with IDC. Pathological complete response to NCT in ILC did not seem to have prognostic significance. Further data are warranted to help clarify the characteristics genomics and proteomics of ILC which explains this better outcome. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-11-14.