Response rate by molecular subtypes and p53 expression in neoadjuvant therapy for breast cancer with TAC regimen: a single-centre experience

Abstract

Background: Pathologic complete response (pCR) is a surrogate of survival in breast cancer (BC), although its value seems to be restricted to specific subtypes. The aims of our study were to determine the response rate (RR) and pCR according to BC subtypes and p53 expression in neoadjuvant setting. Materials and methods: From January 2000 to December 2016 we retrospective analyzed 87 consecutive patients (pts) treated with TAC regimen (docetaxel 75mg/mq, doxorubicin 50mg/mq, cyclophophamide 500mg/mq, d1q21) for locally advanced BC between 2004 and 2016. RR > 50% and pCR (defined as no evidence of residual cancer or residual in situ component only in the primary tumour and lymph-nodes) were compared to St. Gallen 2015 molecular subtypes and p53 expression, considered positive with a nuclear staining>10%. Results: 87 patients (pts), median age 44.7 years (24-78), were classified as follows: luminal A 13.7% (12/87), luminal B-HER2-ve 29.8% (26/87), luminal B-HER2+ve 10.3% (9/87), HER2+ve 4.5% (4/87), triple negative 40.2% (36/87). p53 was negative in 49% pts and positive in 51%. All pts received 6 cycles of TAC regimen before surgery that was conservative in 37 cases (42.5%) and modified or radical mastectomy in the others. After surgery patients HER2+ve underwent adjuvant treatment with Trastuzumab for an year. RR was 75.8% (67/87) and pCR 19.5% (17/87). pCR rate by molecular subtypes was: luminal A 0%, luminal B-HER2-ve 11.7% (2/17), luminal B-HER2+ve 17.6% (3/17), triple negative 70.5% (12/17).p53 expression was determined in 77/87 pts. RR was 77.5% in p53+ve tumours and 69% in p53-ve, pCR was 50% in both p53+ve and p53-ve. At a median follow-up of 55.5 months (15-104), 74 pts are still alive. All pts that achieved pCR are alive and disease free at a median follow-up of 63 months (24-102). Conclusions: Our results are in agreement with the literature. TAC regimen is highly effective in neoadjuvant setting especially in triple negative BC. p53 expression doesn’t seem to be an independent predictor for response.