FDG-PET predicts response of Hodgkin’s lymphoma to chemotherapy

FDG-PET performed after two cycles of standard chemotherapy can accurately predict which patients with Hodgkin's lymphoma will respond or relapse, according to a multicenter international study published in the Aug. 20 issue of the Journal of Clinical Oncology.

The study confirms previous findings by smaller single-center trials. It also shows that FDG-PET can be a useful prognostic tool that will help sort out patients into appropriate management paths, according to a team of Italian and Danish researchers led by Dr. Andrea Gallamini, a hematologist at the Azienda Ospedaliera S. Croce e Carle in Cuneo, Italy.

Gallamini and colleagues enrolled 260 advanced Hodgkin's lymphoma patients who were scheduled to receive six cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine. They underwent F-18 FDG-PET imaging before the first and after the second cycle of chemotherapy. Two observers interpreted the PET results, while a third expert reviewed positive-only scans. Investigators recorded progression-free survival and compared PET results against the International Prognostic Score (IPS) standard to determine the best predictor of disease progression or relapse.

Two hundred five patients were in complete remission after a median follow-up of about two years (range, 0.32 to 5.18 years), while two patients were in partial remission. Cancer progression was observed for 43 patients during or immediately after therapy, and 10 patients relapsed.

Patients with positive FDG-PET results at the second chemo cycle recorded a two-year progression-free survival rate of 12.8%, while the rate for patients with negative PET results was 95%. The finding was statistically significant (p<0.0001).

Trials from England and Italy in this setting show it is possible to adjust patient management based on PET results after two cycles of chemotherapy, Gallamini said. German researchers are moving in this direction as well. Nuclear medicine experts from these countries are working to develop PET interpretation protocols that provide positive or negative scan results within 72 or 96 hours.

"In two or three years, early interim PET will be routinely used in the management of advanced-stage Hodgkin's lymphoma patients," he said.

Study results confirm that FDG-PET stands up as an extraordinarily accurate predictor of outcome, according to Dr. Michael M. Graham, director of the University of Iowa's nuclear medicine program and the SNM's vice president-elect. In an interview, Graham expressed hope that the trial will influence Medicare reimbursement policy for the application of FDG-PET to assess the response of Hodgkin's lymphoma to chemotherapy.

"FDG-PET is so accurate that we should be able to move patients to a different treatment scheme after two cycles of chemotherapy if PET shows persistent disease," Graham said.

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