Abbreviations: AITL, angioimmunoblastic T cell lymphoma; ALCL, anaplastic large cell lymphoma; ALK, anaplastic lymphoma kinase; EATL, enteropathy-associated T-cell lymphoma; ECOG, Eastern Cooperative Oncology Group; IPI, international prognostic index; LDH, lactate dehydrogenase; PIT, Prognostic Index for PTCL-U; PTCL-NOS, peripheral T-cell lymphoma-not otherwise specified; WHO, World Health Organization.