HER2-positive breast cancer: Combined 18F-FDG PET and CGFL/Curie nomogram to predict pathologic complete response after preoperative chemotherapy with trastuzumab

e12095 Background: The aim of this study was to compare the value of 18F-fluorodesoxyglucose positron emission tomography (18F-FDG PET/CT) with CGFL/Curie nomogram to predict a pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) in women with human epidermal growth factor 2 (HER2)-positive breast cancer treated by trastuzumab. Methods: Fifty-one women with HER2-positive breast cancer treated with trastuzumab plus taxane-based NAC, were retrospectively included from January 2005 to December 2015. For 18F-FDG PET/CT, the analyzed predictor was the maximum standardized uptake value of the primary tumor and axillary nodes after the first course of NAC (PET2.SUVmax). pCR was defined by no residual infiltrative tumor but in situ tumor was accepted. Accuracy of CGFL/Curie nomogram and PET2.SUVmax was evaluated measuring sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV). For each predictor, receiver operating characteristic (ROC) curve was created. To evaluate the correlation between predictors, the Spearman coefficient was calculated. Combined prediction was evaluated testing predictor’s associations. Results: For CGFL/Curie nomogram’s performances, Se, Sp, PPV and NPV were respectively: 76% (CI95%: 58-90%), 57% (CI95%: 43-66%), 55% (CI95%: 42-65), 77% (CI95%: 59-90%). For PET2.SUVmax’s performances, Se, Sp, PPV and NPV were respectively: 67% (CI95%: 48-81%), 77% (CI95%: 64-97%), 67% (CI95%: 48-82%), 77% (CI95%: 64-87%). ROC curves for these predictors were similar; the areas under the curve were 0.6 (CI95%: 0.56-0.64) for PET2.SUVmax and 0.55 (CI95%: 0.50-0.59) for CGFL/Curie nomogram. Spearman coefficient was 0.23. Combined prediction was more efficient with Se at 80%, VPN at 76%, Sp at 78% and VPP at 81 %. Conclusions: CGFL/Curie nomogram and PET2.SUVmax were two efficient predictors of pCR in patients with HER2-positive breast cancer. Combined prediction has an improved accuracy.