Predictive value of neoadjuvant chemotherapy failure in breast cancer using FDG-PET after the first course.

Abstract

563 Background: To prospectively evaluate the predictive value of FDG-PET to detect the absence of clinical and pathological response to preoperative chemotherapy in patients (pts) with breast cancer. Methods: 63 consecutive pts with nonmetastatic, noninflammatory advanced breast cancer, eligible for neoadjuvant chemotherapy (3 FEC 100 followed by 3 docetaxel) were enrolled. Fifty-two were assessable (4 non eligible, 7 non evaluable). Median age of assessed pts was 49 years. There were 63% T2 and 37% T3, with 98% invasive ductal carcinomas. FDG-PET was performed before the first and the second course. Metabolic activity (tumor FDG uptake) was measured by standardized uptake value (SUVmax). Patients were classified as non responders (NR) when the decrease of SUVmax in the primary tumor was less than 15% at the time of the second PET (EORTC 1999 criteria). The metabolic response in FDG-PET was correlated with WHO criteria (clinical evaluation and ultrasound and/or mammography) evaluated after 3 cycles, pathologic complete response (pCR) after surgery (according to Sataloff classification) and patient disease free survival. Results: Out of the 38 patients with a PET response (SUV decrease more than 15%), 25/38 (66%) had a clinical response after the third cycle and 10/33 (30%) had a pCR. Out of the 14 patients with no PET response, (SUV decrease less than 15%), only 1/14 (7%) had a clinical response after the third cycle and no pCR was observed. The 3-year disease-free survival (DFS) rate was significantly longer for metabolic responders than for non responders (respectively 94±4% vs. 69±13%; p = 0.0008). In this population the pCR, as expected, was also a significant prognostic factor on 3 year- DFS rate (p = 0.02). Conclusions: This prospective study shows that a decrease in the SUV less than 15% after the first chemotherapy course is a very potent predictor of failure to neoadjuvant chemotherapy, especially of pCR. It is interesting to note that this has been shown despite the fact that the chemotherapy regimen was changed after the third course. No significant financial relationships to disclose.