[298] Evaluation of Incomplete Tumor Regression Scores for Neoadjuvant Chemotherapy of Breast Cancer and Predictive Value of Immunohistology

HP Sinn, Z Elsawaf, P Schirmacher. University Hospital Heidelberg, Heidelberg, Germany

Background: Neoadjuvant chemotherapy is an important modality for locally advanced breast cancers. However, because of the difficulties to evaluate partial regression, there is no agreement how to evaluate the partial tumor response.
Design: A series of 102 patients cases that received neoadjuvant chemotherapy in a clinical trial were evaluated for histological regression scores using four different systems (Miller-Payne, Sataloff, residual cancer burden [RCB] score, and Sinn). Tumours underwent assessment before and after 2 cycles of chemotherapy by core needle biopsy, and after resection of the tumor bed using breast conserving therapy or mastectomy. Regression scores were compared with each other and with predictability by immunohistology (ER,PR,HER2,bcl2,Ki67,p53) before chemotherapy.
Results: In 17 patients a complete histological tumor regression was observed (pCR according to RBC score or Miller-Payne regression grade 5), but near total or total regression was seen in 27 cases (TA according to Sataloff). Only 9 cases achieved complete regression of invasive and intraductal carcinoma (score 5 according to Sinn). Regression scores were very similar with the Miller-Payne system and RCB scores, but did not well correlate with the Sataloff scores with 57% of RCB incomplete regression (classes 1,2,3) being in Sataloff categories TA or TB (good responders). With lymph-node negative patients, 24% showed evidence of complete regressed lymph node metastases (Sataloff NA), while 61% of lymph-node positive patients had evidence of regressive changes (Sataloff NC). When compared with immunohistology before chemotherapy, predictive parameters were similar for complete and near complete remission (HER2 overexpression, high proliferative index, ER negativity).
Conclusions: With the use of a regression grading system it is possible to better describe the effect of neoadjuvant chemotherapy, but there is only limited correlation between the four most commonly used scoring systems. The most important difference is the definition of complete tumor regression. For statistical purposes the regression is best evaluated with the continuous residual cancer burden (RCB) score. The Sataloff score is offers the benefit to classify regression in lymph node metastases.
Category: Breast

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 16, Wednesday Afternoon