Early ¹⁸fluorodeoxyglucose PET Scan as a Prognostic Tool in Diffuse Large B-Cell Lymphoma Patients Treated with An Anthracycline-Based Chemotherapy Plus Rituximab.

¹⁸Fluorodeoxyglucose PET has been quickly integrated to the diagnostic and therapeutic armamentarium in diffuse large-B cell lymphoma (DLBCL). Moreover, early PET appears a promising prognostic tool for tailoring treatment strategies. We evaluated the predictive value of early PET in a large prospective cohort of patients treated with immunochemotherapy.

112 previously untreated patients from three institutions were treated between January 2000 and October 2008 for DLBCL using an anthracycline-based regimen plus Rituximab. Chemotherapy was either an R-CHOP21 regimen (n=57) or a dose-dense regimen (R-ACVBP, n=31 or R-CHOP14, n= 24). PET was performed at diagnosis and after two cycles of treatment. Early PET results were interpreted visually as positive (PET2p) or negative (PET2n), as previously described¹, but did not modify the scheduled therapy.

Median age at diagnosis was 59 years (range 20–79 years) and 67% of patients were males, 44% were over 60 years, 81% presented with an advanced Ann Arbor stage (III–IV), 29% had a poor performance status (ECOG 2-4), 36% had more than one extra-nodal site involved and LDH were elevated in 68%. The repartition on the basis of the International Prognosis Index was the following: low=5%, low-intermediate =35%, intermediate-high=37% and high risk=23%. After two cycles, 70 patients (63%) were PET2n and 42 (38%) were PET2p (38 patients in partial response and 4 with stable disease). Median follow-up was 38 months for living patients. Ten of 70 (14%) PET2n patients showed progression versus 22 of 42 (52%) PET2p patients. The estimated 5-year progression free survival (PFS) was 81% for PET2n and 47% for PET2p patients (log rank test, p<0.0001). Prognostic value of early PET was significant in terms of PFS whether patients were treated with R-CHOP21 (p=0.0006) or with dose-dense regimens (p=0.0056). Nine of 70 (13%) PET2n and 15 of 42 (36%) PET2p patients died. The estimated 5-year overall survival (OS) was 88% for PET2n and 62% for PET2p patients (log rank test, p<0.0034). Prognostic value of early PET was significant in terms of OS for patients treated with R-CHOP21 (p=0. 0225) but not for those treated with dose-dense regimens (p=0.133).

Early PET after 2 cycles of treatment is a powerful tool to predict outcome in DLBCL patients treated with Rituximab combined with an anthracycline-based chemotherapy. It brings promising opportunities in the designing of new treatment strategies for DLBCL.

Reference : ¹ Haioun et al. Blood 2005; 106(4):1376–81.

No relevant conflicts of interest to declare.