P3-14-05: Evaluation of Residual Cancer Burden Index (RCBI) as a Predictor of Disease Free Survival in a Non-Selected Cohort of Breast Cancer Patients Treated in the Neoadjuvant Setting.
Authors: Perez-Fidalgo J-A , Martinez M , Ferrer J , Pons V , Burgues O , Bermejo B , Furriol J , Eroles P , Lluch A 
Published: June 2012

INTRODUCTION: Pathologic complete response (pCR) is associated with long-term survival and is considered as the primary endpoint in neoadjuvant trials. Definition of pCR includes patients without residual disease of the breast, however the presence of nodal metastasis, minimal residual cellularity and residual in situ carcinoma were not consistently defined as pCR. These observations, lead Symmans et al to construct a new prognostic index, the RCBI, in which these important issues were incorporated. RCBI is classified into 4 different response subgroups, from RCB-0 or pCR to RCB-III or absence of response. The aim of our study was to assess the prognostic value for recurrence free survival of the RCBI in a cohort of unselected breast cancer patients treated in our institution.

PATIENTS AND METHODS: We performed a retrospective evaluation of samples of breast cancer patients treated with neoadjuvant treatment. RCBI was assessed by two highly trained pathologists. Patients included had a histological diagnosis of breast carcinoma before neoadjuvant treatment and were considered candidate for neoadjuvant therapy. Clinical variables including date and type of recurrence were obtained from clinical records. Prognostic accuracy of RCBI index was evaluated by comparison of the Kaplan-Meier survival curves of the 4 different groups of response by RCBI. Differences were assessed with log-rank.

RESULTS: Samples from 70 patients treated in the neoadjuvant setting from January 2003 to December 2006 were included in the analysis. Median age was 54.6 years (range 31–80), histhologic subtype was ductal carcinoma (87.1%), lobular carcinoma (8.5%), and other (4.2%). In biopsy, rate of estrogen receptor positive was 72.7%, progesterone receptor positive 62.1%, and rate of HER2 overexpression was 26.2%. Neoadjuvant therapy administered was anthracycline+taxanes chemotherapy (CT )in both sequential or combination schedules in 71.4%, anthracycline-based CT in 15.7%, and other in 12.9%. Most patients received from 6–10 cycles of neoadjuvant CT. 3 patients treated with only 4 cycles received adjuvant complementary CT. All patients with hormone-sensible tumors received adjuvant endocrine therapy and 20 patients received adjuvant trastuzumab. Number of responses by RCB-group was 5 patients (7.1%) with RCB-0, 12 patients (17.1%) with RCB-I, 35 (50%) with RCB-II, and 18 (25.7%) with RCB-III. With a median follow-up of 41.2 months (range 12.7−120.9 months) 22 patients (31.4%) have relapsed. Ratio of events/patients in each RCB group was 0/5 in RCB-0, 2 /12 in RCB-I, 8/35 in RCB-II and 15/18 in RCB-III. Differences in recurrence-free survival in each group was statistically significant with p=0.0002.

CONCLUSIONS: Our results suggest that RCBI might be an appropriate prognostic tool to predict disease-free survival in a non-selected population of breast cancer patients. Further validation of our results with a bigger sample size is needed.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-14-05.