BACKGROUND: Peripheral T-cell lymphomas represent a rare and heterogeneous group of mature T-cell neoplasms characterised by aggressive behavior. Previous studies evaluating peripheral T-cell lymphoma epidemiology across Latin America have been restricted in their representation of most countries in the region. In this study, we aimed to describe peripheral T-cell lymphoma epidemiology across Latin America.

METHODS: We did an international, retrospective, cohort study of patients (aged ≥18 years) with newly diagnosed peripheral T-cell lymphoma across 11 countries in Latin America (Argentina, Brazil, Chile, Colombia, Cuba, Guatemala, Mexico, Paraguay, Peru, Uruguay, and Venezuela). We used the hospital-based registries of the Grupo de Estudio Latinoamericano de Linfoproliferativos (retrospective registry; Jan 1, 2000, to June 30, 2023), the Brazilian T-cell Project (retrospective from Jan 1, 2015, to June 30, 2017 and prospective from July 1, 2017, to June 30, 2023), and the International T-cell Lymphoma Project (prospective registry). The main outcomes were prevalence of peripheral T-cell lymphoma subtypes, overall survival, estimated using the Kaplan-Meier method, and objective response rate. Survival probabilities were estimated using the Kaplan-Meier method and compared with the log-rank test. Overall response rate was calculated by summing complete and partial responses, with 95% CIs estimated using the Clopper-Pearson method.

FINDINGS: 1979 patients diagnosed with peripheral T-cell lymphoma by pathology, between 2000 and 2023, met our inclusion criteria for the distribution analysis and 1349 were included in the treatment patterns and outcome analysis. Median age at diagnosis was 54 years (IQR 41-67), 733 (41%) of 1794 patients were female, and 1061 (59%) patients were male. The most common subtype was peripheral T-cell lymphoma, not otherwise specified (688 [35%] of 1979 patients); the second and third most frequent subtypes were adult T-cell leukaemia or lymphoma (333 [17%] of 1979 patients) and extranodal natural killer T-cell lymphoma (291 [15%] of 1979 patients). The next most common subtypes were ALK-negative anaplastic large T-cell lymphoma (186 [9%] of 1979 patients), mature T-cell lymphoma, not otherwise specified (163 [8%] of 1979), angioimmunoblastic T-cell lymphoma (123 [6%] of 1979 patients), and ALK-positive anaplastic large T-cell lymphoma (73 [4%] of 1979 patients). The observed proportion of people with adult T-cell leukaemia or lymphoma was higher in Peru (158 [39%] of 414 patients; p<0·0001) and Colombia (17 [29%] of 58 patients; p=0·011), whereas the percentage for extranodal natural killer T-cell lymphoma was higher in Central America and the Caribbean (105 [41%] of 255 patients; p<0·0001) and Mexico (22 [31%] of 70 patients; p<0·0001). With a median follow-up of 36 months (IQR 12-60) in the analytical cohort, we observed 674 deaths, and 3-year overall survival was 40% (95% CI 38-44). ALK-positive anaplastic large T-cell lymphoma had the highest survival outcomes, with 11 deaths and a 3-year overall survival of 77% (95% CI 66-90), followed by ALK-negative anaplastic large T-cell lymphoma (52 deaths and 3-year overall survival of 55%, 95% CI 46-65) and extranodal natural killer T-cell lymphoma (108 deaths and 3-year overall survival of 48%, 95% CI 42-56). The use of CHOEP (cyclophosphamide, doxorubicin, etoposide, vincristine, and prednisone) or EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) was associated with superior 3-year overall survival compared with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) among patients with ALK-negative anaplastic large T-cell lymphoma (20 deaths; 67%, 95% CI 56-81 vs 16 deaths; 41%, 26-65; p=0·018) and adult T-cell leukaemia or lymphoma (45 deaths; 20%, 11-38 vs 100 deaths; 18%, 12-27; p=0·0087), but not for all other subtypes.

INTERPRETATION: Our study underscores the unique epidemiological profile of peripheral T-cell lymphoma in Latin America, with a high prevalence of adult T-cell leukaemia or lymphoma and extranodal natural killer T-cell lymphoma. These findings present a crucial opportunity to prioritise clinical trials on these rare subtypes of peripheral T-cell lymphoma by integrating Latin American countries into global research. However, our findings require further validation in robust epidemiological studies.

FUNDING: American Society of Hematology Harold Amos Medical Faculty Development Program Award and the Robert A Winn Diversity in Clinical Trials Program Award.

TRANSLATIONS: For the Portuguese and Spanish translations of the abstract see Supplementary Materials section.