Adult T-cell leukemia/lymphoma (ATL) is a mostly incurable mature T-cell neoplasm caused by chronic infection of the human T-lymphotropic virus (HTLV) type 1 [1], [2], [3]. HTLV is endemic in regions such as Japan, the Caribbean, and South America [2–4], yet the burden of ATL in Latin America and the Western Hemisphere remains poorly characterized. Despite its strong association with HTLV-1, few efforts have been conducted to estimate the regional prevalence of ATL, largely due to the absence of population-based cancer registries [5]. Most estimates are from Western countries reporting a prevalence of 1–7 % [6], [7], [8], while some Asian countries have reported a broader range of 1–59 % [7], [9], [10]. Previous cohort studies describing the distribution of ATL among patients with mature T-cell lymphoma in Latin America have generally included a few countries, often those with lower HTLV-1 prevalence [11], [12], [13], [14], which may lead to an underestimation of the ATL burden in the region.

Although one cohort study provided survival estimates in the Latin American region [4], research gaps remain. It is unclear whether survival rates vary between countries and whether differences in HTLV-1 screening practices across settings may have affected patient outcomes. Because management of ATL remains unstructured in real-world settings, it is unknown if differences in clinical practices may affect survival rates across countries and demographic groups. The lack of population-based lymphoma registries in Latin America [15] further limits the reliability of survival estimates, making hospital data a valuable resource for understanding regional prevalence and survival patterns. This study estimates the hospital-based prevalence of ATL and overall survival (OS) rates, evaluating variations across Latin American countries. Additionally, we explore whether differences in HTLV-1 screening approaches may have influenced patient outcomes.