Cervical cancers that glow brightly with positron emission tomography are more likely to be biologically aggressive than tumors that appear dim, according to an article published online September 4 by Cancer.

"We've seen that among patients with the same stage of cervical cancer, there will be some patients who don't respond to treatment as well as others," said lead author Elizabeth A. Kidd, MD, a Barnes-Jewish Hospital resident in Washington University's Department of Radiation Oncology. "Our study suggests that PET (positron emission tomography) can reliably identify patients who have a poorer prognosis."

The researchers used FDG-PET, a widely available three-dimensional scanning technique that measures how rapidly tumors take up a radiolabeled glucose tracer (FDG): High uptake corresponds with a stronger or brighter signal in the scan. The researchers found that the higher the standard uptake value (SUV) in the primary tumor, the greater the recurrence rate and the lower the survival rate of patients.

"FDG-PET is the most commonly used PET scan," Kidd said. "It's standard for patients to have this type of scan once diagnosed with cervical cancer. Oncologists use it to see the extent of the primary tumor and to look for tumors that have spread beyond the pelvis. But this study shows that the SUV obtained from FDG-PET can also tell physicians how well a patient will respond to treatment and should be part of the evaluation process."

In the current study, 287 patients with cervical cancer were treated with surgery, chemotherapy or radiation therapy following standard treatment protocols. At the time of diagnosis, the standard uptake value of their primary tumor was obtained. Their cancers were also staged under standard guidelines, with stage ranging from early (stage 1A2) to highly advanced (stage 4B).

The researchers showed that patients who had a high tumor standard uptake value were more likely to have aggressive disease: They were likely to have positive lymph nodes, persistent disease after initial treatment, recurrence of disease in the pelvis, and lower survival rates. Investigators also found that tumor standard uptake value did not depend on tumor stage or volume - large tumors could have a relatively low value, and small tumors could have a high value.

The findings suggest that standard uptake value is a more sensitive indicator of tumor aggressiveness than standard staging protocols. The study also demonstrated that it was better at predicting overall survival than tumor type or lymph node involvement, factors suspected to affect prognosis.

The patients were found to fall into three distinct risk groups. Those with the lowest uptake values had a survival rate of 95 percent at five years, those in the middle range had a 70 percent five-year survival rate, and those in the highest range had a 44 percent five-year survival rate.

A high uptake value at diagnosis could signal that a patient should be followed more closely than usual to catch recurrences earlier, according to Kidd. She also indicated that although the results suggest that patients with high uptake tumors may need more aggressive treatments, further clinical studies will be necessary to determine the best therapy in such cases.

Because high standard uptake value indicates that tumors take up glucose rapidly, the measurement may point to an important biological difference in these more aggressive cancers. "We're interested in finding out what causes that difference," Kidd said. "That could eventually lead to new methods for treating patients whose tumors have a high standard uptake value."