Complete pathological response according to hormonal status, c-erbB2 and P53 in two neoadjuvant treatments in locally advanced breast cancers.

Abstract Abstract #5107 Background: We previously showed that the p53 mutation is the major factor for response to dose-dense epirubicin-cyclophosphamide regimen (PLoS Med. 2007; Lancet 2002). Some years ago Taxanes became a standart treatment in neoadjuvant setting. We study two regimens of neoadjuvant anthracycline-based chemotherapy combined with high dose cyclophosphamide (C), or with Taxotere in locally advanced breast cancers (LABC) with respect to pathologic complete response (pCR).
 Materials and methods: Between 1990 and 2003, 219 patients (pts) with LABC and/or inflammatory breast cancers (IBC) from one institution received 6 cycles (c) of dose dense C (1.2g/m2 d1)-epirubicin (E) (75mg/m2d1) q2w (SIM regimen). From 2003 to 2008, 132 pts with LABC and/or IBC from the same institution received 4 c of E (75mg/m2 d1) C(750mg/m2 d1) q3w followed by 4c of docetaxel 100mg/m2 d1q3w (ECT regimen). Surgery was done after chemotherapy and pCR was defined as no residual invasive tumour in breast and lymph nodes.
 Results: 139/219 SIM pts (63.4 %) and 96/132 ECT (72.7 %) pts had frozen biopsies, surgery after chemotherapy, ER, c-erbB2 determination (IHC and /or RT-PCR) and p53 done by yeast functional complementation assay (FASAY) and were thus included in our study.
 
 
 
 Conclusion:The high performance of the FASAY assay allows the demonstration of p53 role in the prediction of histological response in the ECT, as previously for the SIM regimen. In p53 mutant tumors, especially in ER- and ER- c-erbB2 negative tumors, high dose cyclophosphamide combined with E seems significantly better than Taxane regimen and needs to be studied prospectively. Future trials should determine the best regimen for p53 WT tumors. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5107.