FDG-PET predicts Hodgkin's lymphoma chemo response

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 August 20, 2007, issue of the Journal of Clinical Oncology (25:3746-3752, 2007).

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 Andrea Gallamini, MD, a hematologist at the Azienda Ospedaliera S. Croce e Carle in Cuneo, Italy.

Dr. Gallamini and colleagues enrolled 260 advanced Hodgkin's lymphoma patients who were scheduled to receive six cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). 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.

A total of 205 patients were in complete remission after a median follow-up of about 2 years (range, 0.32 to 5.18 years), while 2 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 chemotherapy cycle recorded a 2-year progression-free survival rate of 12.8%, while the rate for patients with negative PET results was 95% (P < .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, Dr. 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 2 or 3 years, early interim PET will be routinely used in the management of advanced-stage Hodgkin's lymphoma patients," Dr. Gallamini said.

Study results confirm that FDG-PET stands up as an extraordinarily accurate predictor of outcome, according to Michael M. Graham, MD, director of the University of Iowa's nuclear medicine program and the Society of Nuclear Medicine's vice-president-elect.

In an interview, Dr. 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," Dr. Graham said.