Session: 626. Aggressive Lymphomas: Clinical and Epidemiological: Poster I
Hematology Disease Topics & Pathways:
Clinical trials, Research, Adult, Lymphomas, Clinical Research, B Cell lymphoma, Diseases, Aggressive lymphoma, Treatment Considerations, Lymphoid Malignancies, Technology and Procedures, Human, Imaging
A newly proposed SUV≥4 fixed threshold (Boellaard et al, J Nucl Med 2024, in press) might standardize MTV and TLG estimation and facilitate clinical application across various lymphomas, including follicular lymphoma, diffuse large B-cell lymphoma, and Hodgkin lymphoma. This new method reduces observer interaction and inter-operator variability but has not yet been tested in PMBCL.
Aim: To compare the prognostic value of TLG, estimated using both the current standard (25% of SUVmax) and the newly proposed segmentation thresholds (SUV≥4), in a large cohort of PMBCL patients.
Methods: Baseline 18FDG PET scans from 501 PMBCL patients enrolled in the IELSG37 study (NCT01599559) were evaluated. Lesion contouring was performed by a single operator using a dedicated commercial software with the two thresholds (SUV≥4 and 25% of SUVmax). PET-metrics were estimated with both thresholds.
Results: The SUV value used for segmentation with the 25% of SUVmax threshold was higher than 4 in over 75% of patients (median SUV 5.37, IQR 4.40-6.70). Consequently, the median MTV estimated with the 25% SUVmax threshold was lower than that obtained with the SUV≥4 threshold (331 ml, IQR 201-530 vs. 396 ml, IQR 229-635; p < 0.0001). Similarly, the estimated TLG showed a difference (3387, IQR 1894-6070 vs. 3750, IQR 1953-6425; p < 0.0001). Despite this, there were strong correlations between MTV values (r=0.95; p<0.001) and even higher correlations for TLG (r=0.99; p<0.001) calculated with each method. ROC analysis identified different optimal cutoff points for TLG estimated with the 25% of SUVmax threshold (3858, ROC-AUC 0.648, p=0.0008) and the SUV≥4 threshold (4225, ROC-AUC 0.649, p=0.0008), both effectively identifying patients with different outcomes. Univariate analysis showed significant differences in PFS between patients with low and high TLG, regardless of the method used (96% vs. 86%, log-rank test, p<0.0001 with the 25% of SUVmax method, and 95% vs. 86%, log-rank test, p=0.0002 with the SUV≥4 method). Only 27 of 501 patients (5%) were categorized differently by the two methods. The comparable prognostic performance of TLG obtained using these two segmentation methods was then confirmed in the 103-patient cohort from the IELSG26 study, previously used to demonstrate the superiority of the 25% threshold in PMBCL. In this cohort, TLG's capacity to discriminate patients with significantly different progression-free survival (98% at 5 years for low TLG vs. 77% for high TLG, p=0.015) was maintained with the SUV≥4 method, even using the TLG cut-point generated by ROC curves in the IELSG37 study population.
Conclusions: Optimal cutoffs for distinguishing between high and low-risk patients depend on population characteristics and the segmentation method used on PET images. Our findings support the routine use of the SUV≥4 threshold for volumetric measurements in PMBCL. The prognostic utility of TLG is maintained with the new method, allowing its use in PMBCL similarly to other lymphoma subtypes.
Disclosures: Di Rocco: ROCHE: Honoraria, Speakers Bureau; NOVARTIS: Speakers Bureau; GILEAD: Honoraria, Speakers Bureau; JANSSEN: Honoraria; ABBVIE: Honoraria; TAKEDA: Speakers Bureau; INCYTE: Speakers Bureau. Davies: Bristol Myers Squibb, Roche Pharma, AstraZeneca, MSD, Cellcentric: Research Funding; Bristol Myers Squibb, Roche Pharma, Sobi, AstraZeneca, AbbVie, Johnson & Johnson,: Honoraria; Bristol Myers Squibb, Roche Pharma, Sobi, AstraZeneca, AbbVie,: Membership on an entity's Board of Directors or advisory committees; Roche Pharma,: Other: Travel. Zucca: AbbVie, AstraZeneca, BeiGene, and Gilead: Other: Travel grants; Abbvie: Honoraria; AbbVie, BeiGene, BMS, Curis, Eli/Lilly, Incyte, Ipsen, Merck, and Roche: Consultancy; AstraZeneca, Beigene, Celgene/BMS, Incyte, Janssen, Roche: Research Funding.
See more of: Oral and Poster Abstracts