ALK and anaplastic large cell lymphoma: However, considering only paediatric cases, overall survival (OS) rates are still higher for ALK-positive paediatric patients than for ALK-negative ones, with an event-free survival (EFS) of 65–75% for ALK-positive ALCL depending on the treatment regimen, compared to 15–46% for ALK-negative ALCL [12,13,14,15].