End-of-treatment and serial PET imaging has prognostic value and clinical utility in primary mediastinal B-cell lymphoma following dose-adjusted EPOCH-R - Response to Adams et al.
Year: 2018
Type: article
Abstract: End-of-treatment and serial PET imaging has prognostic value and clinical utility in primary mediastinal B-cell lymphoma following dose-adjusted EPOCH-R -Response to Adams et al.We recently published additional and extended followup results from our prospective phase 2 study and independent series of DA-EPOCH-R in the front-line treatment of primary mediastinal B-cell lymphoma (PMBCL). 1 In this study, analyses of singular and serial end-of-treatment (EOT) FDG-PET imaging was included in an attempt to better define the predictive ability of such imaging in PMBCL patients following DA-EPOCH-R.In response to our paper, Adams and Kwee noted several limitations to our study and call into question the value of EOT and serial FDG-PET imaging given the overall favorable prognosis and low incidence of relapse in PMBCL and the unproven survival benefit with such imaging.Although we recognize these limitations, we disagree with their conclusions and believe that EOT serial FDG-PET imaging does indeed have clinical utility in PMBCL patients following DA-EPOCH-R.One of the main benefits of dose-intensive therapy, such as DA-EPOCH-R, is its ability to obviate the need for radiotherapy in most patients with PMBCL. 2 A recent retrospective, multicenter study claimed comparability of R-CHOP to DA-EPOCH-R in the up-front treatment of PMBCL based on a similar 2-year rate of progression-free (PFS) and overall survival (OS), however, this "comparability" was at the expense of significantly greater radiotherapy use in R-CHOP treated patients (59% vs. 13%, P<0.001).3 Given the young median age in PMBCL and the significant long-term toxicity associated with routine radiotherapy use, accurate discrimination of patients who are cured following immuno-chemotherapy alone is critically important in order to spare these patients from the harmful effects of additional radiotherapy.EOT FDG-PET is one such technique that is frequently used in clinical practice for this purpose.Of the 80 PMBCL patients with evaluable EOT FDG-PET scans in our study, 55 (69%) patients had negative (i.e., Deauville 1-3) scans with only 1 patient experiencing treatment failure (negative predictive value (NPV) of 98.2%). 1 The high NPV of EOT FDG-PET as well as the favorable outcome in those with negative EOT scans is in line with other retrospective studies in PMBCL following DA-EPOCH-R 4 as well as the prospective IELSG-26 study which utilized combined-modality therapy.5 The low rate of treatment failure seen in our study is not appreciably different from other retrospective studies using DA-EPOCH-R alone in PMBCL, 4 and cannot be directly compared to studies utilizing alternative up-front treatment regimens such as R-CHOP.Despite the small number of treatment failures in our study, EOT FDG-PET did indeed have prognostic value with a lower rate of treatment failure (2% vs. 20%) and a significant improvement in PFS and OS in those PMBCL patients with a negative EOT scan following DA-EPOCH-R. 1 More important are the results obtained from the patients in our study with positive EOT FDG-PET scans.Of the 25 patients with positive (i.e., Deauville 4-5) EOT FDG-PET scans, 20 (80%) remained progression-free after long-term follow up, highlighting the poor positive predictive value (PPV) and high false-positive rate seen with EOT FDG-PET imaging in this patient population. 1 Common clinical practice in PMBCL, however, is to consider a positive EOT FDG-PET scan indicative of active residual disease and need of further radiotherapy.
Source: Haematologica
Language: English
Subfield: Pathology and Forensic Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,157
OpenAlex ID: W2885567728