In peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), alterations in TP53, PRDM1, PTEN, CDKN2A/B, STAT3, and MYC are associated with the more aggressive PTCL-GATA3 subtype. This evidence concerns the gene STAT3 and mature T-cell and NK-cell non-Hodgkin lymphoma.