Clinical factors and outcome in T-cell lymphoma: a population-based perspective

Sammanfattning: The heterogeneous group of T-cell lymphomas consist mostly of aggressive diseasess, with generally unfavourable outcome compared to aggressive B-cell lymphomas following similar therapy. This thesis focus on outcome and risk factors for inferior survival, in an unselected population-based cohort of T-cell lymphoma patients. In the first study, outcome of the precursor malignancy T-cell Lymphoblastic Lymphoma was investigated. This lymphoma has many similarities to T-cell Acute Lymphoblastic Leukemia, and intensive chemotherpay developed for leukemia is known to result in better outcome, than standard lymphoma therapies. The study confirms the superior survival after intensive therapy also in a population-based setting. Intensive as opposed to non-intensive treatment was the main prognostic factor for survival, while age was not associated with an inferior outcome among intensively treated patients. The other three studies focus on outcome in peripheral T-cell lymphomas (PTCL). The second study investigates outcome according to treatment and standard clinical factors at diagnosis. Male gender was found to be associated with inferior survival. Intensification of first-line treatment with up-front autologous stem cell transplantation (auto SCT) consolidation was found to be associated with a favourable outcome in patients younger than 70 years. Relapsing patients had a dismal outcome, with a median post relapse survival of 6 months. Study number three focused on the occurance of central nervous system (CNS) relapse in PTCL. In all, 28 patients (4.5%) experienced CNS relapse, most commonly with leptomeningeal involvement. Extensive extranodal involvement, skin or gastrointestinal involvement was associated with a higher risk for secondary CNS spread. At relapse patients had a very poor survival, irrespective of CNS involvement or not, with no survival difference between the groups. The last study investigates the impact of comorbidity in PTCL. Using the Charlson Comorbidity Index (CCI), presence of concomittant disease was found to be independently associated with inferior survival. CCI was the only factor at diagnosis that showed an association with survival after first-line auto SCT. The association with favourable outcome in patients treated with auto SCT found in the second study, was still significant when adjusting for CCI. In patients ≥75 years, a similar survival in patients treated with curative and low-intensity chemotherapy was found. This was not changed when adjusting for the CCI. In summary, the studies included in this thesis provides information on risk factors and population-based outcomes in T-cell lymphomas. Associations between treatment intensification and better outcome suggests a beneficial effect of these strategies in younger patients. The thesis also provides information on previously poorly documented disease, and patient-related, factors in PTCL, and will possibly serve as comparative data for future population-based studies.