, Volume 34, Issue 9, pp 1339-1347
Date: 02 Mar 2007

Imaging early changes in proliferation at 1 week post chemotherapy: a pilot study in breast cancer patients with 3′-deoxy-3′-[18F]fluorothymidine positron emission tomography

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3′-Deoxy-3′-[18F]fluorothymidine positron emission tomography ([18F]FLT-PET) has been developed for imaging cell proliferation and findings correlate strongly with the Ki-67 labelling index in breast cancer. The aims of this pilot study were to define objective criteria for [18F]FLT response and to examine whether [18F]FLT-PET can be used to quantify early response of breast cancer to chemotherapy.


Seventeen discrete lesions in 13 patients with stage II–IV breast cancer were scanned prior to and at 1 week after treatment with combination 5-fluorouracil, epirubicin and cyclophosphamide (FEC) chemotherapy. The uptake at 90 min (SUV90) and irreversible trapping (K i) of [18F]FLT were calculated for each tumour. The reproducibility of [18F]FLT-PET was determined in nine discrete lesions from eight patients who were scanned twice before chemotherapy. Clinical response was assessed at 60 days after commencing FEC.


All tumours showed [18F]FLT uptake and this was reproducible in serial measurements (SD of mean % difference = 10.5% and 15.1%, for SUV90 and K i, respectively; test–retest correlation coefficient ≥0.97). Six patients had a significant clinical response (complete or partial) at day 60; these patients also had a significant reduction in [18F]FLT uptake at 1 week. Decreases in K i and SUV90 at 1 week discriminated between clinical response and stable disease (p = 0.022 for both parameters). In three patients with multiple lesions there was a mixed [18F]FLT response in primary tumours and metastases. [18F]FLT response generally preceded tumour size changes.


[18F]FLT-PET can detect changes in breast cancer proliferation at 1 week after FEC chemotherapy.