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Abstract P2-12-07: Fdg PET/CT early response prediction for triple negative breast cancer neoadjuvant chemotherapy with addition of carboplatin


 Introduction. The addition of carboplatin to standard neoadjuvant chemotherapy (NAC) including dose-dense (dd) anthracycline-cyclophosphamide (AC) combination followed by taxanes in triple negative breast cancer (TNBC) is the most intense routinely used approach, not widely accepted and potentially of increased toxicity. Fluorodeoxyglucose PET/CT ealy response assessment may aid to decide about treatment intensification. The aim of our study was to define the optimal cut-off of SUVmax decrease for pathological complete response (pCR) prediction after one cycle of AC regimen, in patients who received further AC and taxane plus carboplatin. Material and Methods. 122 patients with TNBC were enrolled into neoadjuvant chemotherapy (NAC) within STRATEGMED 2/267398/4/NCBR/2015 research project in our center between Jan 2018 and Dec 2020, upon approval of Ethics Commitee. Among them 15 patients still continued neoadjuvant treatment at the time of data cut-off, 3 patients did not receive anthracyclines because of lifetime cumulative dose with previous treatments, in 2 patients treatment was interrupted during first cycles of anthracycline-based treatment and in one patient there was no evident (18)F-fluorodeoxyglucose uptake. Remaining 101 patients were enrolled into this study. Baseline PET/CT study before NAC was performed in all patients, 73 patients had baseline PET/CT as well as additional study performed after 1st cycle of chemotherapy. Majority of patients received ddAC followed by docetaxel plus every-three-week carboplatin or weekly paclitaxel plus weekly carboplatin. Patients with residual disease received 8 cycles of capecitabine treatment adjuvantly. Radiation therapy was performed according to guidelines, concurrently or before capecitabine treatment. Mann-Whitney U test was used to assess differences in variables, predictive value was evaluated by receiver-operating characteristic (ROC) curve analysis. Results. 54 patients (53,5%) achieved pCR after neoadjuvant chemotherapy. At baseline, median of SUVmax in breast was 10.2 (IQR 7.2-14.4), whereas median of SUVmax in lymph nodes was 3.7 (IQR 0-10.0). In 16 patients (16%) baseline SUVmax in lymph nodes was higher than in breast (ratio>1). Higher baseline value of SUVmax was associated with pCR achievement (p=0.037). Median SUVmax decrease in breast after one cycle of chemotherapy was 33% (IQR 11%-52%) and was predictive for pCR (p=0.000021). Median decrease of 18-FDG uptake in lymph nodes was more pronounced than in breast (53%; IQR 29%-84%) and was also associated with pCR achievement (p=0.012). For pCR prediction SUVmax decrease cut-off of 40% provided optimal trade-off between sensitivity and specificity, with positive likelihood ratio 2.35, negative likelihood ratio 0.33, positive predictive value 80% and negative predictive value 64%. By ROC analysis, AUC for the prediction of pCR was 0.7604 (p=0.036). Conclusions. While high decrease of SUVmax relatively strongly indicates high pCR chance in TNBC neoadjuvant chemotherapy, lower decrease does not preclude pCR occurrence when intensive four-drug sequential regimen with carboplatin is used. Studies assessing response in reverse sequence chemotherapy with carboplatin are warranted. The study was supported by the Polish National Center of Research and Development MILESTONE project - Molecular diagnostics and imaging in individualized therapy for breast, thyroid and prostate cancer, grant no. STRATEGMED 2/267398/4/NCBR/2015.
 Citation Format: Marcin Kubeczko, Anna Michalik, Agnieszka Badora-Rybicka, Anna Polakiewicz-Gilowska, Andrea d'Amico, Michał Kalemba, Aleksandra Leśniak, Katarzyna Świderska, Marta Mianowska-Malec, Agnieszka Pasierbek, Barbara Łanoszka, Konstanty Chomik, Barbara Bobek-Billewicz, Michał Jarząb. Fdg PET/CT early response prediction for triple negative breast cancer neoadjuvant chemotherapy with addition of carboplatin [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-07.