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SUMMARY
The mature T-cell and natural killer (NK)-cell lymphomas represent 10 to 15 percent of the non-Hodgkin lymphomas by incidence and comprise 23 clinicopathologic entities in the most recent classification. They include cutaneous T-cell lymphomas, discussed in Chap. 103, and systemic T-cells lymphomas, which are discussed here. The systemic T-cell lymphomas have highly variable courses and are typically aggressive and frequently less responsive to conventional chemotherapy than their B-cell counterparts. The most common systemic T-cell and NK-cell lymphomas worldwide include peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) and angioimmunoblastic T-cell lymphoma (AITL), representing 26 percent and 19 percent of systemic T-cell and NK-cell lymphomas, respectively. There is considerable geographic variation in the incidence of certain entities, such as adult T-cell leukemia/lymphoma (ATL) and extranodal NK/T-cell lymphoma (ENKTL). In view of the rarity of systemic T-cell and NK-cell disorders, large randomized trials are lacking to guide therapies. Treatment strategies are generally based upon the best data available, which includes prospective phase II studies and retrospective analyses. The most frequently used regimens for the more common entities, PTCL-NOS, AITL, and anaplastic large cell lymphoma (ALCL) are cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP)-based, although long-term outcomes are often unsatisfactory. Therefore, ongoing clinical trials are aimed at improving upon CHOP by adding novel agents or using alternate regimens. Although controversial, patients are often considered for consolidation with autologous stem cell transplant in first remission to improve remission durations. Recently, targeted agents specific for particular T-cell and NK-cell lymphomas, such as brentuximab vedotin for ALCL and crizotinib for anaplastic lymphoma kinase (ALK)-positive ALCL, are now allowing the investigation of more individualized therapy for these entities. Furthermore, for a considerable number of the T-cell and NK-cell lymphoma entities, including ENKTL and ATL, CHOP-based therapy is ineffective, and treatment strategies are disease-specific. There is still much to learn about the biology and potential drug targets for these diseases and ongoing studies using gene expression profiling and genomics may help answer some of these questions. In addition, ongoing clinical trials evaluating disease-specific treatment approaches and employing novel and often targeted agents will hopefully lead to improved outcomes for patients with these diseases.
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Acronyms and Abbreviations
AITL, angioimmunoblastic T-cell lymphoma; ALCL, anaplastic large cell lymphoma; ALK, anaplastic lymphoma kinase; ASCT, autologous stem cell transplantation; ATL, adult T-cell leukemia/lymphoma; BCCA, British Columbia Cancer Agency; CHOEP, cyclophosphamide, doxorubicin, vincristine, etoposide, prednisone; CHOP, cyclophosphamide, hydroxydaunorubicin (doxorubicin), vincristine (Oncovin), prednisone; CR, complete response; CT, computed tomography; DHAP, dexamethasone, cytarabine, cisplatinum; DSHNHL, German High-Grade Non-Hodgkin Lymphoma Study Group; EBV, Epstein-Barr virus; EFS, event-free survival; ENKTL, extranodal NK/T-cell lymphoma; FFS, failure-free survival; HTLV, human T-lymphotrophic virus; hyper-CVAD, cyclophosphamide, vincristine, doxorubicin, methotrexate, cytarabine; ICE, ifosfamide, carboplatin, etoposide; IVAC, ifosfamide, etoposide, cytarabine; IPI, International Prognostic Index; IPTCLP, International Peripheral T-Cell Lymphoma Project; LDH, lactate dehydrogenase; MACOP-B, high-dose methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin; NK, natural killer; ORR, overall response rate; OS, overall survival; PCR, polymerase chain reaction; PET, positron emission tomography; PFS, progression-free survival; PIT, ...