Blinded Mid-Treatment FDG-PET in Newly Diagnosed Aggressive Non-Hodgkin Lymphoma (NHL): First Results of a Prospective Multicenter Study.

In aggressive B-cell NHL, determination of early response to induction therapy by FDG-PET may improve risk stratification. In a multicenter prospective trial in patients with aggressive NHL (stage II–IV) treated with 2 or 3 weekly (R)CHOP chemotherapy, FDG-PET was performed after the third cycle of chemotherapy. Both clinicians and nuclear medicine physicians were blinded for PET and clinical outcome, respectively. Clinical decisions were based on conventional diagnostic methods (CDM) only. In total 114 patients were included of which 95 were evaluable. 19 patients were excluded because of patient refusal (n=7), early progression (n=7) or logistical reasons (n=5). Median age was 55 yrs (range 20–82), 72% had DLBC-NHL, 76% IPI<3. The majority (85%) of patients completed chemotherapy according to protocol. 14(15%) went off protocol because of less than PR after 3 cycles of (R)CHOP or progression on treatment based on CDM or excess toxicity. CR(u) was reached in 60% of the patients. 34 (36%) patients relapsed and 2 patients died of NHL after a median follow-up of 26 months. PET was scored qualitatively using a Likert scale. PET after 3 courses was negative in 45 patients and positive in 50. 24/50 (48%) PET positive patients progressed or relapsed as compared to 10/45 (22%) PET negative patients. Median progression free survival (PFS) for PET positive versus PET negative patients was 19.8 months versus not yet reached (p=.0087). In a multivariate analysis, IPI and PET were independent predictors for PFS.

These results corroborate and extend the evidence that mid-treatment FDG-PET is highly predictive for PFS and may be a useful tool for risk-adapted management of aggressive NHL.