PET imaging with [18F]3'-deoxy-3'-fluorothymidine for prediction of response to neoadjuvant treatment in patients with rectal cancer

Eur J Nucl Med Mol Imaging. 2007 Jun;34(6):878-83. doi: 10.1007/s00259-006-0292-2. Epub 2006 Dec 29.


Purpose: Positron emission tomography (PET) using 18F-labelled 3'-deoxy-3'-fluorothymidine (FLT) was assessed for therapy monitoring in patients with rectal cancer undergoing neoadjuvant chemoradiotherapy.

Methods: Ten patients with locally advanced rectal cancer were included and underwent long-course preoperative chemoradiotherapy (total dose 45 Gy, 1.8 Gy/day, concomitant 250 mg/m2 5-fluorouracil) followed by surgery. FLT-PET was performed prior to chemoradiotherapy, 2 weeks after initiation of chemoradiotherapy and preoperatively (3-4 weeks post chemoradiotherapy). FLT uptake was correlated with histopathological tumour regression and changes in T stage.

Results: Mean tumour FLT uptake was 4.2+/-1.0 SUV before therapy and decreased significantly to 2.9+/-0.6 SUV 14 days after initiation of chemoradiotherapy (-28.6%+/-10.7%, p=0.005). The preoperative scan showed a further decrease to 1.9+/-0.4 SUV (-54.7%+/-7.6%, p=0.005). However, the degree of change in FLT uptake 2 weeks after initiation and after completion of neoadjuvant therapy did not correlate with histopathological tumour regression.

Conclusion: FLT-PET did not seem to be a promising method for assessment of tumour response in the studied chemoradiotherapy regimen in patients with rectal cancer.

MeSH terms

  • Adult
  • Aged
  • Cell Proliferation
  • Dideoxynucleosides / pharmacology*
  • Female
  • Fluorodeoxyglucose F18 / pharmacology*
  • Humans
  • Male
  • Middle Aged
  • Neoadjuvant Therapy / methods
  • Positron-Emission Tomography / instrumentation*
  • Positron-Emission Tomography / methods*
  • Prognosis
  • Radiopharmaceuticals / pharmacology*
  • Rectal Neoplasms / diagnosis*
  • Rectal Neoplasms / diagnostic imaging*
  • Rectal Neoplasms / therapy*
  • Treatment Outcome


  • Dideoxynucleosides
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • alovudine