Report from AMI: PET/CT helps improve cervical cancer staging

Results from a prospective trial in Denmark involving 120 consecutive patients at Copenhagen University Hospital may strengthen the argument favoring F-18 FDG-PET/CT in the standard staging protocol for cervical cancer patients.

The study, reported Tuesday at the 2005 Academy of Molecular Imaging meeting in Orlando, found that PET/CT improves staging accuracy and creates opportunities for supplementary radiation therapy to treat otherwise undetected disease for cervical cancer patients

For 28 patients receiving surgery, FDG-PET/CT produced a sensitivity of 80% and a specificity of 87%. The positive and negative predictive values were 57% and 95%, respectively. Overall accuracy was 86%.

For the 78 patients who did not undergo surgery, the sensitivity and specificity of PET/CT were 100% and 88%, respectively. PPV and NPV were 76% and 100%, respectively. Accuracy was 91%.

Among the nonsurgical patients, pelvic node metastases were found in 14 patients. Metastases were also identified in the inguinal and para-aortic nodes. Distant metastases appeared in the neck, mediastinum, bone, lungs, liver, and adrenal gland. Comparative histological data were not acquired.

True positives were found in para-aortic lymph nodes in nine patients, raising the possibility of supplementary radiation treatment, according to principal investigator Dr. Annika Loft, chief physician at the hospital's Center of Diagnostic Investigations. True-positive distant foci appeared in 10 patients. A pelvic lymph node metastasis was verified with biopsy in one patient. Primary lung cancer was identified in another patient.

Seven false positives were identified. Four involved small bone lesions that were verified as normal with MRI. Two patients had histiocytosis involving high FDG uptake, and one patient had granuloma.

The results may help address problems with current standard surgical staging procedures for cervical cancer, Loft said. The consensus regimen, written by the International Federation of Gynecology and Obstetrics, involves a clinical exam, cystoscopy, urography, and x-ray.

Performing PET/CT as well would increase the probability of finding para-aortic nodal disease, known to appear in 24% of cervical cancer cases, she said. For nonsurgical patients, lesion localization data acquired with PET/CT could assist radiation therapy planning.

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