Very early detection of response to imatinib mesylate therapy of gastrointestinal stromal tumours using 18fluoro-deoxyglucose-positron emission tomography.
OBJECTIVE
To investigate whether 18F-FDG-PET allows early assessment of response to imatinib mesylate in GIST patients.


METHODS
Five gastrointestinal stromal tumour (GIST) patients and one patient with a KIT-positive small cell cancer were studied. Treatment consisted of 400 mg imatinib mesylate daily. 18F-deoxyglucose-positron emission tomography (18F-FDG-PET) scans were done before and one week after starting imatinib mesylate therapy.


RESULTS
Metabolic responses were detected after only one week of therapy in all GIST patients (four partial and one complete response). The mean decrease of the standardised uptake value was 60% (range 43 to 77%). In contrast, the tumour of the non-GIST patient was metabolically stable. Four of the 5 GIST patients achieved a partial response on CT after a mean duration of 23 weeks (range 6 to 48 weeks).


CONCLUSIONS
18F-FDG-PET is a valuable method for the detection of response to imatinib mesylate in patients with KIT-positive tumours as early as one week after starting therapy.
Heinicke
T
T
Departments of Internal Medicine I, University of Bonn, Bonn, Germany. thomas.heinicke@ukb.uni-bonn.de
Wardelmann
E
E
Sauerbruch
T
T
Tschampa
H J
HJ
Glasmacher
A
A
Palmedo
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D005260:Female; D019788:Fluorodeoxyglucose F18; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D049268:Positron-Emission Tomography / Q000379:methods; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis; D011743:Pyrimidines / Q000627:therapeutic use*; D019275:Radiopharmaceuticals
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit