Post-therapy PET imaging predicts outcome in cervical cancer

November 21, 2007

NEW YORK (Reuters Health) - Positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) performed 3 months after treatment for cervical cancer is helpful in determining response to treatment and predicting outcome, a study shows.

"For follow-up of patients treated for advanced cervical cancer, there has never been a good 'test' to perform to detect persistent or recurrent cancer or no cancer," Dr. Perry W. Grigsby, of the Mallinckrodt Institute of Radiology, Washington University, St. Louis, told Reuters Health.

"Our study demonstrates that a post-therapy PET is an excellent test to determine the patient's tumor status," he added. "If the test shows that cancer is still present, further treatment can be performed. If the PET shows absence of cancer then the patient can be reassured that they will have an excellent prognosis and long-term cure."

In the November 21 Journal of the American Medical Association, Dr. Grigsby and colleagues report results of 92 women with advanced cervical carcinoma who underwent whole-body FDG-PET an average of 3 months after completion of external irradiation, brachytherapy, and concurrent chemotherapy.

"The concept of using FDG-PET to assess tumor response to therapy is based on in vitro studies that associate decreases in tumor cell glucose uptake with decreases in the fraction of viable tumor cells," they explain.

FDG-PET showed a complete metabolic response in 65 patients (70%), a partial metabolic response, as indicated by persistent FDG uptake in the irradiated region, in 15 (16%), and progressive disease, as indicated by new sites of FDG uptake outside of the irradiated region, in 12 patients (13%). The 3-year progression-free survival rates were 78%, 33%, and (0%), respectively.

In multivariate analysis, women with progressive disease on the 3-month post-therapy FDG-PET had a hazard ratio for recurrence of 32.57. Women showing a partial metabolic response on the 3-month FDG-PET had a hazard ratio of 6.30.

Results of FDG-PET were significantly more predictive of survival than the pretreatment lymph node status.

The fact that "all of this information is obtained just 3 months after completing treatment, is really a new and powerful concept in the treatment of cancer patients," Dr. Grigsby noted. "They no longer need to wait the classic 5 years to see if they are cured of their cancer."

Dr. Grigsby said that he has also demonstrated similar findings in patients with anal cancer. Those findings are currently in press.