Approximately 700 people are diagnosed with diffuse large B-cell lymphoma (DLBCL) in Finland each year. It is the most common cancer that originates from lymphocytes, immune system cells. Although the disease is treated with the goal of achieving complete remission and preventing recurrence, a third of the patients experience progression and have a dismal prognosis. One of the challenges in treatment is that DLBCL is a heterogeneous disease, and better tools are needed for grouping the patients for adequate treatment.