Preliminary report of using FDG-PET to detect extrapelvic lesions in cervical cancer patients with enlarged pelvic lymph nodes on MRI/CT

Purpose To evaluate, in a prospective study, the effects of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) on the detection of extrapelvic lesions, the design of whole pelvis or extended field radiotherapy, and subsequent failure patterns for patients with cervical cancer and enlarged pelvic lymph nodes (LNs) shown on MRI or CT. Methods and materials Between April and December 2001, 19 consecutive patients underwent an additional FDG-PET examination before concurrent chemoradiotherapy. The inclusion criteria for the study were at least one enlarged pelvic LN ≥10 mm in its maximal dimension as shown on radiologic images and no extrapelvic tumors detected by conventional examination. The PET findings of the primary tumor, pelvic LNs, and extrapelvic lesions were investigated and compared with the MRI/CT findings. Tumor FDG uptake was quantitated with the maximal pixel standardized uptake value. Results Except for 1 patient with diabetes mellitus who was excluded from analysis, 18 cervical tumors had significant FDG uptake (maximal pixel standardized uptake value >8). A total of 39 pelvic LNs were reported, and the agreement of positive pelvic LNs between MRI/CT and PET was 79.5%. Five patients (28%) had positive paraaortic LNs on FDG-PET, and their treatment fields were extended to include the paraaortic region. In addition to the paraaortic LNs, 1 patient also had metastasis at the left supraclavicular node. After a minimum follow-up of 12 months (median 15.9), 4 patients (22.2%) developed new extrapelvic metastases. The disease-free survival rate was 78% at 12 months. Conclusion FDG-PET is a useful tool to detect paraaortic LN metastasis and determine the appropriate treatment field for cervical cancer with enlarged pelvic LNs on MRI/CT. The preliminary data suggest that pretreatment FDG-PET can supplement conventional imaging studies, but still has limitations in the detection of microscopic disease.