Prognostic Assessment of the PET-CT Role in Primary Patients with Hodgkin Lymphoma: Do We Still Need More Data?

Introduction.PET-CT is the new imaging modality for staging of patients with Hodgkin Lymphoma (HL) with its excellent results in prognostic role for survival rate. Despite this fact, there are still patients in different risk groups who need intensification in treatment or dose de-escalation. In recent years several studies have been activated and published data about baseline, interim (iPET) and end-of-treatment (PET3) PET-CT prognostic role. But somewhere, there are still a lot of controversies. Here we report the results of a multicenter prospective study of iPET and PET3 in HL.

Methods.113 patients with the primary HL were evaluated in the study. Between 113 patients 67.2% (76) were females and 32.8% (37) - males, with median age 42.5 years (range - 18 to 67years ). Patients received standart chemotherapy protocols based on risk group - ABVD or BEACOPP-14/esc. Metabolic PET-CT imaging was performed at participating PET centers according to routine protocols. iPET and PET3 with 1-3 and 4-5 scores by Deauville were considered as astatus-negative and status-positive result, respectively.The primary endpoints of the study were evaluated predicting treatment outcome and event free survival (EFS).

Results.40.7% (46/113) with early stages were treated by ABVD and 59.3% (67/113) patients with advance stages received BEACOPP-esc/14 and ABVD, respectively (p<0.05).

The ORR of 96 patients (CR, PR) was 92%. The maximum follow-up period in this group of patients was 62 months (median 17 months). 98% (111/113) patientsare still followed up.

89% (89/100) and 11% (11/100) of patients had 1-3 and 4-5 scores of iPET by Deauville 5-PS scale, respectively (p < 0.05). In total, disease progression was documented in 27.2% (3/11) of iPET-positive patients and 12.3% (11/89) of iPET-negative patients (p<0.05). There was one death from refractory disease.

We did not find anysignificantprognostic roleof iPETanddepends on type of regimen in patients from that group to predict the EFS. Thus, 3-year EFS of patients with iPET-positive versus iPET-negative was 57% and 85%, respectively (Log-rank test, p=0.3).

95.5% (108/113) and 4.5% (5/113) patients in our cohort had PET3- negative (PET3-) and positive (PET3+) status, respectively (p<0.05). The 2-year EFS rates were 90% and 15% for patients whose PET3 was negative and positive, respectively (Log-rank test, p<0.0001).

2-year EFS for pts PET3+ with I-IIA was higher compared in cases with IIB-IVB stages (50% vs 15%,respectively; Log-rank test, p<0.0001). But EFS ratein patients with PET3- depends on stage of disease was similar: 95 % vs 90% in patients with I-IIA vs IIB-IVB, respectively.

Conclusion. While performed iPET provides valuable information about the quality of the treatment response, there is still a need for its prospective confirmation as a prognostic factor. Clinical trials are designed to improve upon the current 1st-line therapy, may be more informative, if focused on PET-positive patients after treatment.