Introduction
Diffuse large B-cell lymphoma (DLBCL) is the single most common type of lymphoma worldwide. (1) It is a clinically aggressive cancer that rapidly grows and usually metastasizes throughout the body at early stages yet it's potentially curable; therefore, it requires early diagnosis, urgent treatment and close monitoring. In DLBCL, the diagnosis, prognosis and monitoring of the disease are currently based on clinical assessment, invasive biopsies, CT scans and PET scans. Those methods are highly valuable; however, there's an urgent need for a simpler tool to assess prognosis, closely monitor the patient's response to treatment and allow earlier detection of relapse. Circulating cell free DNA (ccfDNA) is this promising biomarker; the liquid gold that must be further studied to obtain such a simple accessible biomarker that can reflect so much information about the underlying malignant clone. Circulating cfDNA is mainly composed of double stranded DNA fragments circulating in the bloodstream of both healthy and diseased individuals. Normally, ccfDNA is present in low concentrations; however, ccfDNA levels are increased in certain conditions like pregnancy, malignant diseases and non-malignant diseases such as inflammatory conditions, autoimmune diseases, trauma, myocardial infarction stroke, sepsis and allograft transplant rejection. It has been found that circulating cfDNA in cancer patients show a different fragmentation profile from cfDNA in healthy individuals; therefore, the integrity of cfDNA has been investigated as a potential diagnostic and prognostic marker in several cancers.