Characterization of peripheral T-cell lymphomas in a single North American institution by the WHO classification

All peripheral T-cell lymphomas (PTCLs) diagnosed at a single institution were evaluated to determine the unique clinical features and outcome of specific entities and test the predictive validity of the International Prognostic Index (IPI).

Cases of PTCL seen at the British Columbia Cancer Agency between 1981 and 2000 were identified. Pathologic material was re-assessed and classified according to the WHO classification, and patients were staged and treated uniformly according to era-specific guidelines. In total, there were 199 patients with PTCL and the most common subtypes were peripheral T-cell lymphoma unspecified (PTCL-US) (59%), anaplastic large-cell lymphoma, systemic type (ALCL) (17%) and extranodal NK/T-cell lymphoma, nasal and nasal-type (NASAL) (9%). Most patients were treated with CHOP-type chemotherapy.

Three distinct prognostic subgroups were notable on survival analysis: favorable (cutaneous ALCL), 5-year overall survival (OS) 78%; intermediate [PTCL, ALCL and angioimmunoblastic lymphoma (AILT)], 5-year OS 35-43%; unfavorable [NASAL and enteropathy-type T-cell lymphoma (ETTL)], 5-year OS 22-24%. Furthermore, in PTCL-US and ALCL clinical separation of patients into good risk (IPI 0,1) and poor risk (IPI > or =2) subsets was demonstrated.

A large proportion of PTCL patients have poor risk disease and/or a histologically aggressive subtype with frequent relapse and unfavorable outcome. For these patients, treatment with CHOP chemotherapy is only minimally effective and new strategies need to be developed, an effort that will require a multi-institution international collaboration due to the rarity of most subtypes.