83P - Repeatability evaluation of PET/CT imaging using [18F]fluorothymidine (FLT) and [18F]fluorodeoxyglucose (FDG) in primary triple negative breast canc...

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Breast Cancer
Imaging, Diagnosis and Staging
Presenter Jennifer Glendenning
Citation Annals of Oncology (2015) 26 (suppl_3): 27-28. 10.1093/annonc/mdv119
Authors J.L. Glendenning1, S. Barrington2, H. Tovey3, J. Parikh4, J. Dunn2, A. Tutt1
  • 1Breakthrough Breast Cancer Research Unit, King's College London Guy's Hospital, SE1 9RT - London/UK
  • 2Pet Imaging Centre, St Thomas' Hospital, SE17EH - London/UK
  • 3Icr-ctsu, Institute of Cancer Research ICR, SM25NG - London/UK
  • 4Radiology, Guy's and St. Thomas' Hospital NHS Trust, SE19RT - London/UK

Abstract

Body

Introduction: Pathological response to neo-adjuvant chemotherapy in TNBC is an independent predictor of survival. PET/CT imaging of proliferation & metabolism is of interest for early response but response criteria need defining. The test-re test performance of PET/CT in TNBC is unknown, the optimal SUV response parameter is unclear and it is likely EORTC and PERCIST criteria overestimate response. TNPET01 is a 2 part phase II imaging feasibility and response prediction study in TNBC intended to relate baseline and therapy induced changes in PET tracers after 1 cycle of neoadjuvant docetaxel to mid and end-of-treatment MRI, biopsy and pCR to sequential taxane-anthracycline. Part A (presented here) provides baseline repeatability assessment prior to selection of a single tracer for further response evaluation in part B.

Methods: 10 patients with T2 TNBC and planned neoadjuvant chemotherapy were randomised to FLT or FDG imaging prior to and in week 3 after cycle 1 docetaxel. Patients had 2 scans at baseline. Dynamic imaging was followed by static scans at 90, 120, 180 mins (FDG) or 90 mins (FLT). SUV max, mean, peak & SULpeak were measured using HERMES software. Repeatability was evaluated by Bland Altman plots of the pre-chemotherapy log-transformed SUV/SUL measurements.

Results: 9 patients completed part A (5FDG, 4FLT), 1 patient withdrew. Mean interval between baseline scans was 3.7 days (s.d 0.7). 3 patients had axillary nodal uptake (2FLT, 1FDG). SUVmax and mean were evaluable in all patients. Baseline SUV and SUL peak were non-evaluable in 2 FDG imaged tumours despite clinical size >2cm. On per-patient analysis, repeatability coefficients for FDG were 15% for SUVmax and SUVmean. FLT repeatability coefficients were 13% and 14% for SUVpeak and SULpeak but 25% for SUV max and 20% for SUVmean. PET scans at day 17 ± 3 after the first docetaxel cycle showed a drop of >20% in all SUV parameters in patients with CR/PR or SD (8/9 patients).

Conclusion: Repeatability coefficients for FDG & FLT in TNBC are within ±15%. 2 FDG imaged breast tumours were not evaluable with SULpeak. The more widely used SUVmax may be a better parameter for tumour evaluation in TNBC.

Clinical trial identification: EUDRACT 2011-004220-34

Disclosure: All authors have declared no conflicts of interest.