Current imaging theory maintains that FDG-PET can potentially offer an early warning about the effectiveness of cancer therapies while standard measures of tumor size do not detect early response. Evidence supporting that perspective has emerged from a prospective trial using fluorine-18 FDG-PET to measure the effect of neoadjuvant therapy on patients with resectable high-grade soft tissue sarcoma.
Neoadjuvant therapy is highly toxic and frequently ineffective. If FDG-PET shows the therapy isn't working, the oncologist can halt treatment and prescribe a potentially more effective alternative.
Dr. Frederick C. Eilber, a surgical oncologist at the David Geffen School of Medicine at the University of California, Los Angeles, found that measuring the standard uptake rate of F-18 FDG can reliably identify sarcoma patients who are responding to therapy. Eilber was senior researcher of the study written by Dr. Matthias R. Benz and published in the April 15 issue of Clinical Cancer Research.
All responders and 14 of the nonresponders had a greater than 35% reduction in SUV between baseline and early follow-up. The test's sensitivity and specificity were 100% and 67%, respectively. At late follow-up, 60% reductions in SUV peak showed a sensitivity of 88% and a specificity of 68%.
Nothing could be determined about the effectiveness of treatment from the small changes in tumor size as seen on CT before and after therapy.
The study sets the stage for larger multicenter trials to confirm the results and to more closely examine their implications for patient survival, said Dr. R. Edward Coleman, director of nuclear medicine at Duke University.
