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


CONCLUSIONS
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.
Wieder
Hinrich A
HA
Department of Nuclear Medicine, Technische Universität München, München, Germany. h@wieder.de
Geinitz
Hans
H
Rosenberg
Robert
R
Lordick
Florian
F
Becker
Karen
K
Stahl
Alexander
A
Rummeny
Ernst
E
Siewert
Jörg R
JR
Schwaiger
Markus
M
Stollfuss
Jens
J
D000328:Adult; D000368:Aged; D049109:Cell Proliferation; D015224:Dideoxynucleosides / Q000494:pharmacology*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000494:pharmacology*; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000628:therapy*; D016896:Treatment Outcome
D015224:Dideoxynucleosides; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C002854:alovudine