Abstract P5-01-05: Prognostic Value at 4 Years of FDG PET, after the First Course of Neoadjuvant Chemotherapy in Breast Cancer

Abstract

Abstract FDG-PET may be a powerful examination to evaluate the effectiveness of neoadjuvant chemotherapy: it appears to be possible to predict the preoperative histological response after the first cycle of chemotherapy. The aim of this prospective study was to investigate the prognostic value of the early decrease of tumoral glucidic metabolism, evaluated with FDG-PET, after the first cycle of neoadjuvant chemotherapy in breast cancer. Material and methods: FDG-PET was performed before and after the first cycle of neoadjuvant chemotherapy in 92 patients with large or locally advanced, non inflammatory, breast cancer. The change of 18F-FDG tumoral uptake was calculated from the maximum Standard Uptake Value corrected for body surface and glycemia (ΔSUVmax). Disease free survival (DFS) was assessed, and the prognostic value of ΔSUVmax was first studied among all patients. Using immunohistochemistry as a surrogate for expression profiling, patients were then classified according to tumoral phenotypes as follow: triple negative (defined by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression), luminal (ER positive or PR positive, HER2 negative) and HER2 positive. Results: The median follow-up was 46.3 months (range: 37–52 months). Twenty one patients had recurrent disease, 9 of whom died. Using univariate Cox regression analysis with all patients, DFS showed significant correlation with initial tumor size measured with ultrasound scan (p=0.03), and ΔSUVmax after the first cycle of neoadjuvant chemotherapy (cut-off = -45%, p=0.01). Using multivariate cox regression analysis, only ΔSUVmax remained an independent prognostic factor of DFS at four years (p=0.028). According to tumoral phenotypes, ΔSUVmax was a prognostic factor of DFS for the 50 patients with a luminal cancer : the risk of relapse was 8.7 times higher in women whose SUVmax decreased less than 24% after the first course of chemotherapy (p=0,04). No significant correlation between ΔSUVmax and DFS was shown in the 22 triple negative phenotypes. For the 31 patients overexpressing HER2, a tumoral SUVmax lower than 1,8 after one cycle of chemotherapy tended to be a favorable prognostic factor with a lower risk of relapse (p = 0,058) but ΔSUVmax had no significant prognostic value (p=0.08). Conclusion: Using immunohistochemistry, the change of tumoral FDG uptake after the first cycle of neoadjuvant chemotherapy in operable breast cancer patients appears to be an early surrogate marker of disease free survival for luminal tumors in this study. For HER2 positive tumors, FDG-PET seems to provide prognostic information but, as for the triple negative tumors, it was not statistically significant. FDG-PET might be useful to guide the early therapeutic choice for breast cancer treated with neoadjuvant chemotherapy. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-01-05.