P3-14-10: Early Predictive Value of Non-Responder to Docetaxel in Neoadjuvant Chemotherapy in Breast Cancer Using 18F- FDG-PET.

Abstract Background; Clinical response is determined after several cycles of chemotherapy by changes in tumor size in imaging procedures including ultrasound, MRI or CT. The aim of this prospective study was to early detect non-responder to docetaxel (DTX) in neoadjuvant chemotherapy using 18F- FDG-PET in patients with breast cancer. Method; 41 patients were eligible for this study. 37 were assessable (4 were not eligible or not evaluable) with Invasive carcinoma (T1:10%, T2: 83%). All 37 patients were treated with 4 cycles of docetaxel (75mg per square meter) followed by 4 cycles of FEC(cyclophosphamide/epirubicin/fluorouracil: 500/75/500 mg per square meter) before surgery. 18F-FDG-PET response rate was evaluated between before and after the first cycle of DTX. 18F-FDG-PET images were analyzed by standardized uptake value, SUVmax. Clinical response is determined by reduction rate in tumor size with MRI (RECIST criteria) between before the first cycle and after the fourth cycle of DTX. Pathological response evaluated by core needle biopsy after the fourth cycle of DTX. Result; 18F-FDG-PET response rate after the first cycle of DTX showed correlation with tumor size reduction rate with MRI image after the fourth cycle of DTX (r=0.746)(P <.001). 0 out of 8 patients (0%) revealed cPR with MRI changes in SUV decrease less than 18% (p <.001). 8 out of 13 patients (62%) showed cPR (cCR = 0) with MRI in SUV decrease over 19 to 44% (P <.001). 9 out of 16 patients (56%) were cPR, and 7 out of them (44%) showed cCR with MRI in SUV decrease over 45% (P <.001). Conclusion; Changes of 18F-FDG SUVs in tumors were statistically significantly different between responding and nonresponding (P <.001). SUV decrease less than 18% after the first cycle indicated potential failure to DTX in neoadjuvant chemotherapy. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-14-10.