title: Association between Pathological Complete Response and Outcome Following Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer Patients.
abstract: OBJECTIVE
  We aimed to determine the rate of pathological complete response (pCR), clinicopathological factors associated with pCR, and clinical outcomes following neoadjuvant chemotherapy in locally advanced breast cancer.
  
  
  METHODS
  Medical records of patients who had undergone neoadjuvant chemotherapy for breast cancer between January 2007 and September 2011 were retrospectively reviewed, and the pCR rates were calculated according to three sets of criteria: the National Surgical Adjuvant Breast and Bowel Project (NSABP), the MD Anderson Cancer Center (MDACC), and the German Breast Group (GBG). Tumors were classified as luminal A like, luminal B like, human epidermal growth factor receptor 2 (HER2), or triple-negative. pCR and clinical outcome, including overall survival (OS) and disease-free survival (DFS) rates were analyzed at the median follow-up of 54.2 months.
  
  
  RESULTS
  Of a total of 179 patients who had received neoadjuvant chemotherapy, 167 patients (93.3%) had locally advanced breast cancer and 12 patients (6.7%) had early-stage breast cancer. The majority of patients (152 patients, 89.4%) received anthracycline-based neoadjuvant chemotherapy. The objective clinical response rate was 61.5%, comprising clinical partial response in 5.5% and clinical complete response in 3.9% of patients. Twenty-one (11.7%), 20 (11.2%), and 17 patients (9.5%) achieved pCR according to NSABP, MDACC, and GBG definitions, respectively. pCR rates, as defined by NSABP, according to breast cancer subtype were 4.4%, 9.7%, 24.2%, and 19.2% in luminal A like, luminal B like, HER2, and triple-negative subtypes, respectively. Patients who achieved pCR had significantly better DFS (5-year DFS rates, 80% vs. 53%, p=0.030) and OS (5-year OS rates, 86% vs. 54%, p=0.042) than those who did not.
  
  
  CONCLUSIONS
  The pCR rate following neoadjuvant chemotherapy for breast cancer in Thai women attending our institution was 11.7%; pCR was more frequently observed in HER2 and triple-negative breast tumor subtypes. Patients who achieved pCR had significantly improved survival.
authors.affiliation: Division of Medical Oncology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Sutima
authors.initials: S
authors.lastname: Luangdilok
authors.affiliation: Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Norasate
authors.initials: N
authors.lastname: Samarnthai
authors.affiliation: Division of Medical Oncology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Krittiya
authors.initials: K
authors.lastname: Korphaisarn
keywords: Antineoplastic combined chemotherapy protocols; Breast neoplasms; Neoadjuvant therapy; Surgery; Treatment outcome