Cell-free circulating DNA in Hodgkin's and non-Hodgkin's lymphomas

Patients and methods: Cell-free DNA levels in the plasma samples of 142 patients with lymphomas [45 with Hodgkin's lymphoma (HL), 63 with diffuse large B-cell non-Hodgkin's lymphoma (DLBCL), 24 with follicular, and 10 with mantle cell non-Hodgkin's lymphoma (NHL)] at diagnosis and of 41 healthy individuals were determined using a quantitative PCR for the beta-globin gene. Results: Levels of circulating DNA in patients with HL, DLBCL, and mantle cell NHL were significantly higher than in controls (P < 0.01 for all). Increased levels of plasma DNA were associated with advanced stage disease, presence of B-symptoms, elevated lactate dehydrogenase levels, and age > 60 years (P = 0.009; < 0.0001; < 0.0001; 0.04, respectively). In HL, histological signs of necrosis and grade 2 type of nodular sclerosis were associated with increased plasma DNA. Elevated plasma DNA levels were associated with an inferior failure-free survival in patients with HL (P = 0.01) and DLBCL (P = 0.03). Conclusion: Quantification of circulating DNA by real-time PCR at diagnosis can identify patients with elevated levels that are associated with disease characteristics indicating aggressive disease and poor prognosis.