Post‐ABVD biopsy results, and not post‐ABVD FDG‐PET results, predict outcome in early‐stage Hodgkin lymphoma

Abstract

We read with interest the recently published article by Milgrom et al (2017) entitled 'Early-stage Hodgkin lymphoma outcomes after combined modality therapy according to the post-chemotherapy 5-point score: can residual pet-positive disease be cured with radiotherapy alone?'. Their study included 174 patients with early-stage (I-II) Hodgkin lymphoma treated with ABVD (doxorubicin, bleomycin, vincristine; dacarbazine; median 4 cycles, range 2-6) followed by an 18 F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scan. Patients were treated with additional radiation therapy (RT) regardless of FDG-PET findings. The prognostic value of post-ABVD FDG-PET results according to the Deauville criteria and several quantitative FDG-PET biomarkers (table IV in Milgrom et al, 2017) was evaluated. After ABVD therapy, 5-year progression-free survival (PFS) was 100% (0 relapses/98 patients) in patients with Deauville scores of 1-2, 97% (2/65) for a Deauville score of 3, 83% (1/ 8) for a Deauville score of 4 and 67% (1/3) for a Deauville score of 5. Three of 11 (27Á3%) patients with positive FDG-PET results (i.e. Deauville score ≥4) underwent biopsy of residual FDG-avid lesions. FDG-PET results were false-positive in 2/3 (66%), with biopsy showing no lymphoma, whereas biopsy revealed residual lymphoma in 1/3 (33%) cases. This particular patient developed disease relapse during follow-up. On the other hand, none of the FDG-PET metrics was able to differentiate between relapsing and non-relapsing patients. The results were compared with a very selective group (inclusion criteria for this cohort not clearly described in the methods section) of 15 Hodgkin lymphoma patients treated with additional salvage chemotherapy and autologous stem cell transplantation (ASCT). Of these 15 patients, 13 had undergone post ABVD biopsy, with 13 of these biopsies (100%) showing residual lymphoma, highly contrasting the results of the other cohort, in which biopsy showed no lymphoma in the majority of cases. Despite intensive treatment with ASCT, 6/15 (40%) Hodgkin lymphoma patients developed disease relapse during follow-up. Comparison between these two cohorts revealed FDG-PET metrics to be more or less similar in both groups (table III in Milgrom et al, 2017), despite the clearly different prognosis of patients included in these two cohorts. Moreover, despite Milgrom et al.'s statement that the 15 patients treated with intensive therapies all suffered from stable or progressive disease, the reduction in FDG-PET metrics in this cohort was notable (Table III in Milgrom et al, 2017). On the other hand, a strong significant difference (P < 0Á001) between these two cohorts was the presence of a post-ABVD lymphoma-positive biopsy (table III in Milgrom et al, 2017). The authors concluded that a positive post-ABVD FDG-PET scan was associated with inferior PFS, but the majority of patients with positive FDG-PET results were considered to be curable with RT alone.However, we disagree with their interpretations. First, we believe the conclus...