Abstract P6-05-03: Evaluation of predictive markers for clinical outcome after neoadjuvant radiochemotherapy in breast cancer

Abstract BACKGROUND: Neoadjuvant radiochemotherapy (NRT-CHX) in locally advanced noninflammatory breast cancer (LABC) is an innovative method in treating patients. Proliferation markers make up the majority of genes included in RNA-based prognostic gene signatures applied for breast cancer patients. In this subgroup analysis long-term clinical outcome data and predictive factors were analyzed. PATIENTS AND METHODS: During 1991-1998, a total of 315 LABC patients (cT1-cT4/cN0-N1) were treated with NRT-CHX. Preoperative radiotherapy (RT) consisted of external beam radiation therapy (EBRT) of 50 Gy (5 × 2 Gy/week) to the breast and the supra-/infraclavicular lymph nodes combined with an electron boost in 214 cases afterwards or -in case of breast conservation- a 10-Gy interstitial boost with (192)Ir after loading before EBRT. Chemotherapy was administered prior to RT in 192 patients, and concomitantly in 113; 10 patients received no chemotherapy. The impact of age, tumor grade, nodal status, hormone and growth factor receptor status (ER, PR, EGFR), p53, ki-67, HER2/neu, and bcl-2 on pathological complete response pCR and disease-free survival were examined in uni- and multivariate terms. RESULTS: Hormone receptor status, proliferative activity, bcl-2, EGFR-status and clinical tumor size had a significant impact on predicting neoadjuvant therapy success. Age, cN, grading, p53, and HER2/neu status failed to reach a significant correlation to complete remission. All examined immunohistochemical factors with the exception of EGFR, and all clinical factors displayed an univariately significant impact on DFS (disease free survival). Particularly, while HER-2/neu had no predictive value for pCR it displayed the highest impact on DFS after complete response (n = 92), even in a multivariate setting with clinical tumor size and nodal status. Complementary, p53 was the most superior immunhistochemical factor for prognosis after neoadjuvant incomplete remission (n = 223). CONCLUSION: Her2/neu is a predictive marker for overall survival independent from the pCR. It has no predictive value for the pCR. P53 is a prognostic marker for patients with incomplete remission. Prospective studies are needed to evaluate their use for decisions to further individualize adjuvant treatment after neoadjuvant radiochemotherapy. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-03.