Report from SNM: FLT-PET predicts survival in patients with brain tumors

In the first study of its kind, researchers have found that fluorothymidine PET can predict which patients with primary brain cancer will react positively to therapy with antiangiogenic agents. Findings could have implications for the development of new drugs to treat brain malignancies.

Prevention or slowing of angiogenesis shows promise in oncology, but no reliable means can predict response to treatment with antiangiogenic agents. With MRI, the standard imaging test used to monitor treatment for malignant brain tumors, it could take months to know if patients are responding. That poses an important limitation when survival is a matter of weeks, not years.

FLT-PET could tell within one or two weeks if patients are responding to treatment, said principal investigator Dr. Wei E. Chen, an assistant professor in the department of molecular and medical pharmacology at the University of California, Los Angeles, David Geffen School of Medicine. Chen spoke at the 2007 SNM meeting in Washington, DC.

"Our research paves the way for developing drugs that could improve the lives of those with malignant brain tumors," she said.

Chen and colleagues prospectively evaluated the predictive value of FLT-PET in 19 patients with recurrent malignant gliomas treated biweekly with bevacizumav and irinotecan. Patients underwent FLT-PET scanning at baseline, at one or two weeks, and after six weeks of treatment. Investigators defined a reduction in standardized uptake value of more than 25% as a metabolic response and compared FLT-PET response with MRI response and patient survival.

They found that metabolic responders survived twice as long as nonresponders (p = 0.003). They also observed a prolonged progression-free survival in these patients. Early and late FLT-PET responders were more significant predictors of survival (one to two weeks: p = 0.006 and six weeks: p = 0.002) than MRI responders (p = 0.06 overall).

A lack of reduction in FLT uptake six weeks after the initiation of treatment increased the hazard ratio of death fivefold, even after adjusting for variables such as age, recurrence, tumor grade, and time and type of treatment.

"No matter one's age, number of times cancer recurred, or number of prior drug treatments, FLT-PET was the most powerful independent predictor of survival," Chen said.

For more information from the Diagnostic Imaging archives:

PET brings new definition to brain tumor diagnosis

Hybrid imaging makes headway in cardiac and oncology imaging, but caveats persisty

PET registry boost coverage outlook for rare cancers

Anatomic, functional imaging collaborate in cancer detection