Association between Pathological Complete Response and Outcome Following Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer Patients

Abstract

Purpose: 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.

Conclusion: 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.

Keywords: Antineoplastic combined chemotherapy protocols; Breast neoplasms; Neoadjuvant therapy; Surgery; Treatment outcome.

Figure 1

Consort diagram. There were 237 patients who treated with chemotherapy followed by surgery between January 1, 2007 and September 31, 2011. Data of 179 patients met the inclusion criteria and were used in this study.

Figure 2

Disease-free survival (DFS) and overall survival (OS) according to intrinsic breast cancer subtypes. Compared with luminal A like tumor, luminal B like tumors, human epidermal growth factor receptor 2 (HER2) and triple-negative tumors were associated with a shorter DFS (A) and OS (B).

Figure 3

Disease-free survival (DFS) and overall survival (OS) according to pathological complete response (pCR). Patients who achieved pCR showed significant positive associations with DFS (A) and OS (B) compared to those without a pCR (5-year DFS: 80% vs. 53%, log-rank test, p=0.030; 5-year OS: 86% vs. 54%, log-rank test, p=0.042). NSABP=National Surgical Adjuvant Breast and Bowel Project.