TORONTO--Intensive chemotherapy can cure patients with high-grade
non-Hodgkins lymphoma (NHL), but many patients fail to enter
complete remission or relapse after a complete response.
A study presented at the 45th annual meeting of the Society of
Nuclear Medicine shows that use of whole-body fluorine-18-fluorodeoxyglucose
positron emission tomography (FDG-PET) after two chemotherapy cycles
may help to predict which patients will achieve a complete response
and which patients will respond poorly to chemotherapy and might
benefit from alternative treatment modalities.
"Patients with early response to chemotherapy (indicated by a
normal FDG-PET scan after two or three cycles) have a high
probability of progression-free survival," said Pierre Rigo, MD,
professor of nuclear medicine, University Hospital, Liège, Belgium.
In this study, from the Divisions of Hematology and Nuclear Medicine,
20 patients with confirmed non-Hodgkins lymphoma were imaged
with FDG-PET before treatment and again after two to three cycles of
chemotherapy. The absence or presence of abnormal radiotracer (FDG)
uptake was correlated to clinical outcome.
FDG-PET imaging after two to three chemotherapy cycles showed that
seven patients still had increased FDG uptake in one or more of the
tumor sites active at diagnosis.
Of these seven patients, four did not achieve a complete response
after completion of chemotherapy and eventually had disease
progression. Two patients who did enter complete remission relapsed
at 12 and 20 months, respectively; and one patient remains in
complete remission at 30 months. Five of these patients have died.
The remaining 13 patients all had negative FDG-PET results after two
to three cycles of chemotherapy (Figure 1),
and all entered into complete response. Of these, 11 remain in
complete response at up to 36 months after their cancer diagnosis,
and two have relapsed at 6 and 14 months, respectively, and have died
of thier lymphoma.
Lower CR Rate With Positive PET
The probability of achieving a complete response was lower in
patients with a positive FDG-PET scan (43% vs 100% for those with
negative PET scans), Dr. Rigo said. Overall survival and
progression-free survival were also significantly different between
the two groups (Figure 2).
"Patients with positive PET scans after chemotherapy is
initiated need more frequent monitoring and probably additional
treatment," Dr. Rigo said. "However, more experience and
confirmation of these results are needed before we recommend any
change in patient management based on FDG-PET during chemotherapy."
If PET is not available, he said, monitoring of chemotherapy in
patients with non-Hodgkins lymphoma could be undertaken with
FDG and positron coincidence-detection systems. Such systems use
dual-head scintillation cameras to perform both conventional nuclear
medicine imaging (such as SPECT) and PET.
"We conclude that FDG-PET after 2 to 3 chemotherapy cycles for
high-grade NHL is predictive of outcome," he said.