FDG-PET imaging for the assessment of physiologic volume response during radiotherapy in cervix cancer.
OBJECTIVE
To evaluate the physiologic tumor volume response during treatment in cervical cancer using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET).


METHODS
This was a prospective study of 32 patients. Physiologic tumor volume in cubic centimeters was determined from the FDG-PET images using the 40% threshold method.


RESULTS
The mean pretreatment tumor volume was 102 cm3. The mean volume by clinical Stages I, II, and III were 54, 79, and 176 cm3, respectively. After 19.8 Gy external irradiation to the pelvis, the reduction in tumor volume was 29% (72 cm3). An additional 13 Gy from high-dose-rate (HDR) brachytherapy reduced the mean volume to 15.4 cm3, and this was subsequently reduced to 8.6 cm3 with 13 Gy additional HDR brachytherapy (26 Gy, HDR). Four patients had physiologic FDG uptake in the cervix at 3 months after the completion of therapy. The mean time to the 50% reduction in physiologic tumor volume was 19.9 days and after combined external irradiation and HDR to 24.9 Gy.


CONCLUSIONS
These results indicate that physiologic tumor volume determination by FDG-PET is feasible and that a 50% physiologic tumor volume reduction occurs within 20 days of starting therapy.
Department of Radiation Oncology, Department of Radiology, Mallinckrodt Institute of Radiology, St. Louis, MO, USA.
Lilie L
LL
Lin
Zhiyun
Z
Yang
Sasa
S
Mutic
Tom R
TR
Miller
Perry W
PW
Grigsby
D018262:Adenocarcinoma, Clear Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D000328:Adult; D000368:Aged; D001918:Brachytherapy; D018196:Carcinoma, Adenosquamous / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D005240:Feasibility Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18