PROGNOSTIC ROLE OF LESION DISSEMINATION FEATURE (DMAX) CALCULATED ON BASELINE PET/CT IN HODGKIN LYMPHOMA

Abstract

Aim/Introduction: A non negligible number of patients with Hodgkin Lymphoma (cHL) experience disease relapse requiring salvage therapies. Identifying these relapsing or refractory patients is very important to improve risk stratification and individualize treatment. Recently, the largest distance between two lesions (Dmax) measured from FDG PET scans and reflecting lesions dissemination, has been identified as a new prognostic factor in diffuse large B cell lymphoma. The aim of this study was to investigate the prognostic value of Dmax in newly diagnosed cHL patients and to define interaction of Dmax with other available prognostic factors. Materials and Methods: We selected a retrospective cohort of patients treated between 2007-2020. Available baseline FDG-PET scan for review and clinical data were required for inclusion. From the baseline PET images all lesions were semiautomatically segmented. The centroid of each lesion was automatically obtained and considered as the lesion location. The distances between all pairs of lesions were calculated and Dmax was obtained for each patient. Dmax was dichotomized according to the median value within our cohort. Early metabolic response (iPET) was also reviewed when possible and reported according to the five-point Deauville scale (DS). Main study endpoint was Progression Free Survival (PFS). Results: We identified a study population of 215 cHL patients. Median age was 39 (15-88), 43% were younger that 45 years and 45% had stage III-IV. Dmax was calculated in 184/215 patients, median value was 21cm (range 2.6-78). iPET was available in 187/215 patients and was positive in 34 cases (DS4-5; 18%). 42% had a IPS score more than 2. Higher DMAX values were observed for males, for patients with low serum albumin, low LDH, elevated ESR, and high MTV. Median follow up was 38 months and 5year PFS was 77% (95% CI 70-82%). In univariate analysis, IPS>2 (HR 2.20 CI 1.26-3.87, p = 0.006), iPET+ (HR 3.32 CI 1.73-6.39, p < 0.001) and Dmax>20 (HR 2.42 CI 1.31-4.47, p = 0.005): were associated with shorter PFS. Combining DMAX with iPET we were able to show a meaningful role of DMAX in the identification of patients at different risk of progression among iPET- cases. Using iPET- and DMAX < 20cm as reference groups the iPET- and Dmax >20 had a HR of 4.16 (95% CI 1.54-11.2), and iPET+ had a HR of 6.13 (95% IC 2.18-17.2 ) (Figure 1) Conclusion: Dmax, a PET feature reflecting the spread of the disease, is a promising prognostic factor in cHL. Combining Dmax and iPET further improves risk stratification of patients with HL and might improve tailored therapy approach.