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In this article, we broadly review the application of cfDNA analysis to the diagnosis and management of lymphoma. We introduce the advantages of cfDNA measurement over conventional tissue biopsy and describe how cfDNA may be utilized for both genotyping and detection of minimal residual disease. First, we discuss genotyping, beginning with differences in identifying mutations from the blood plasma vs. from circulating cells. We review the technical distinctions between PCR- and NGS-based assays and describe two important applications of NGS-based cfDNA tests, namely the identification of resistance mutations and classification of disease subtype. We discuss difficulties in genotyping diseases with low burden of tumor cells and the application of cfDNA assays in these contexts. Second, we describe the utility of ctDNA measurement in assessing MRD. We cover recent advances in the assessment of pre-treatment disease burden as a prognostic biomarker, detection of molecular response to therapy, and early detection of relapsing disease. Third, we explore select emerging areas of research in ctDNA technologies that show promise in boosting the performance of existing ctDNA-based assays. These include cell-free DNA fragment structure analysis or 'fragmentomics', epigenetic modifications, and novel circulating analytes such as tumor-educated platelets and extracellular vesicular DNA. We also discuss alternative analytes to blood plasma for tumor detection, such as urine, saliva, and stool. Finally, we present a case that highlights potential applications of ctDNA approaches to the management of patients with lymphoma, while also defining important prerequisite advances before this can be fully realized. We close with a look to the future of cfDNA applications, outlining one potential timeline and path forward towards routine clinical application., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Summary: Hodgkin Lymphoma (HL) is an unusual B‐cell lymphoma because the malignant cells exist as a minority population in a densely cellular microenvironment. The microenvironment is comprised predominately of inflammatory and immune cells with fibrosis in some cases. There are multiple dysregulated signalling pathways that sustain HL within this microenvironment, such as the Nuclear factor‐κB and Janus kinase/signal transducers and activators of transcription pathways. Advances in genomic medicine have enabled a better characterisation of the rare tumour cells and improved our understanding of the signalling mechanisms that exist between the malignant cell and its microenvironment. Current therapy for HL produces excellent clinical outcomes in most younger patients. However, problems with current treatment approaches include poorer outcomes in the elderly, toxicity of highly‐effective combination chemotherapy regimens and relapse in high‐risk patients. Better understanding of disease biology aids in upfront prognostication of patients, defines new methods for treatment monitoring and assists in the recognition of novel targets for therapy. Biology‐driven therapies, including anti‐CD30 antibody conjugates, cellular immunotherapies and immune modulation, particularly with checkpoint inhibitors, have changed treatment algorithms for relapsed/refractory patients. Future challenges exist in incorporating immune‐based therapies earlier in treatment algorithms to reduce toxicity and prevent relapse for patients with HL. [ABSTRACT FROM AUTHOR]