Genetic analysis of cell-free DNA in follicular lymphoma in comparison with tissue-derived DNA

Early disease progression, including histological transformation, can occur in follicular lymphoma, but tumor heterogeneity makes comparison difficult. We analyzed cell-free DNA from 30 patients with follicular lymphoma to assess cell-free DNA concentration and gene mutations. Mutational profiles were also examined in 16 cases using DNA from formalin-fixed, paraffin-embedded tissue samples. Cell-free DNA concentrations were higher in cases with histological transformation. Both the number of mutations per patient and the number of mutated genes were greater in cell-free DNA than in formalin-fixed, paraffin-embedded tissue-derived DNA. Notably, TP53 mutations were more frequently detected in cell-free DNA. CIITA mutations were more commonly observed in cases with a low frequency of somatic hypermutation in VH genes. Cell-free DNA analysis in follicular lymphoma may become a complementary approach, overcoming the limitations of assessing disease status from single biopsy sites. Further studies will examine the usefulness of cell-free DNA in predicting disease progression in follicular lymphoma.