Outcome of adult patients with T-lymphoblastic lymphoma treated according to protocols for acute lymphoblastic leukemia

We treated 45 adult patients with T-lymphoblastic lymphoma (T-LBL) (age range 15-61 years) with 2 protocols designed for adult acute lymphoblastic leukemia (ALL). An encouraging cure rate of 90% was recently reported for T-LBL in children treated with a similar approach. In our study, an 8-drug standard induction was administered over 8 weeks including prophylactic cranial (24 Gy) and mediastinal irradiation (24 Gy) followed by consolidation and reinduction therapy. At diagnosis, 91% of the 45 patients showed a mediastinal tumor and 40% had pleural/pericardial effusions; 73% of the patients had stage III/IV disease. Overall, 42 patients (93%) achieved a complete remission (CR), 2 patients (4%) achieved a partial remission, and 1 patient (2%) died during induction. In patients with stage I-III disease (n = 18) the CR rate was 100% compared with 89% in stage IV (n = 27). There were 15 patients who relapsed (36%) within 12 months. The majority of relapses (47%) occurred in the mediastinum (n = 7) despite mediastinal irradiation with 24 Gy in 6 out of 7 patients. The estimates for overall survival, continuous CR, and disease-free survival at 7 years are 51%, 65%, and 62%, respectively. Stage, age, lactate dehydrogenase, and all other parameters had no influence on achievement of CR or outcome. This study demonstrates in a large cohort of patients with adult T-LBL that a high CR rate and a favorable outcome can be achieved with an ALL-type regimen. Mediastinal recurrence was the major obstacle and further improvement by intensification of chemotherapy, increased dose of mediastinal irradiation (36 Gy), and extended indications for stem cell transplantation seem to be required.