Risk stratification in diffuse large B cell lymphoma using lesion dissemination and metabolic tumor burden calculated from baseline PET/CT.

We analysed the prognostic value of a new baseline PET parameter reflecting the spread of the disease, the largest distance between two lesions (Dmax). We tested its complementarity to metabolic tumor volume (MTV) in a large cohort of diffuse large B cell lymphoma (DLBCL) patients from the REMARC trial (NCT01122472).MTVs were defined using the 41% SUVmax threshold. From the three-dimensional coordinates, the centroid of each lesion was automatically obtained and considered as the lesion location. The distances between all pairs of were calculated. Dmax was obtained for each patient and normalized with the body surface area (SDmax).290 patients were included from the REMARC trial in patients 60-80 years old; 91% had an advanced stage and 71% IPI≥3. High vs low SDmax significantly impacted PFS (P<0.0001) and OS (P=0.0027). Patients with SDmax>0.32 m-1 (n=82) had a 4y-PFS and OS of 46% and 71%, respectively, against 77% and 87%, respectively, for patients with low SDmax. High SDmax and high MTV were independent prognostic factors of PFS (P=0.0001 and P=0.0010 respectively) and OS (P=0.0028 and P=0.0004 respectively). Combining MTV and SDmax yielded three risk groups with no (n=109), one (n=122) or two (n=59) factors (P<0.0001 for both PFS and OS). The 4-year PFS were 90%, 63%, 41%, respectively, and the 4-year OS were 95%, 79%, 66%, respectively. In addition, patients with at least 2 of the 3 factors including high SDmax, high MTV, ECOG >2 had a higher number of CNS relapse (P=0.017).SDmax is a simple feature that captures lymphoma dissemination, independent from MTV. These two PET metrics, SDmax and MTV, are complementary to characterise the disease, reflecting the tumor burden and its spread. This score appeared promising for DLBCL baseline risk stratification.

View the full article @ Annals of oncology : official journal of the European Society for Medical Oncology

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