Treatment Outcome and Prognostic Factors in Patients with Precursor B and T Lymphoblastic Lymphoma

Introduction: Lymphoblastic lymphoma is an uncommom subtype of non-Hodgkin’s lymphoma. Lymphoblastic lymphoma represents a distinctive lymphoma entity with cytological and histological features similar to those of acut lymphoblastic leukemia (ALL). Thus, World Health Organization (WHO) classification classifies this disease entity as precursor B and T lymphoblastic lymphoma/leukemia. At present, precursor B and T lymphoblastic lymphoma has been treated with intensive chemotherapy similar to acute lymphoblastic leukemia. However, there is few study about the treatment outcome and prognostic factors in precursor B and T lymphoblastic lymphoma presenting as lymphoma not leukemia. Thus. the purpose of this retrospective study was to investigate clinical features and treatment outcomes of lymphoblastic lymphoma.

Patients and methods: We analyzed 62 patients newly diagnosed with precursor B and T lymhpoblastic lymphoma. All patients were histologically confirmed by pathologists between October 1996 and November 2007, who met the following criteria were included in this retrospective evaluation: age over 15 years, presence of an extramedullary primary and ≤20% blasts in bone marrow, the presence of lymphoblastic histology, the immunophenotype of the malignant cells.

Results: The patients were male predominent (77%), with 77% (48) of patients having a T-cell immunophenotype. The median age at time of presentation was 28.5 years (16–69). The presenting sites of primary disease included mediastinal mass in twenty-eight cases. The bone marrow was involved in 22.6% (14) patients. Extranodal involvements were found in 40 patients. Four major chemotherapeutic regimens including vincristine, prednisone, daunorubicin, L-asparginase (VPDL), CALGB 19802, Standford/NCOG, CHOP were used to treat 25,12,9 and 5 patients, respectively. Eleven other patients were treated with five different chemotherapeutic regimens, respectively. Two patients in relapse received allogeneic stem cell transplantation, and the other two received autologous stem cell transplantation. In 19 patients with first complete response, they were treated with autologous stem cell transplantation. When we compared precursor T lymphoblastic lymphoma with precursor B lymphoblastic lymphoma, precursor T lymphoblastic lymphoma showed older age (40≤ p=0.031), more mediastinal involvement (p=0.002), and male predominenance (p=0.005). Overall response rate of patients treated with initial chemotherapy was 83.9% (50% of CR, 33.9% of PR). Event-free survival (EFS) and overall survival (OS) rate at 30 months were estimated to be 53%±6 and 59%±6, respectively, with a median follow-up of 31 months. Twenty-six of 52 relapses occurred. ALL-type chemotherapy is not superior to conventional chemotherapy used for non-Hodgkin’s lymphoma (p=0.531). The survival differences was observed between stage I to III patients and IV patients (p=0.007), and patients with and without two or more extranodal sites of disease(p=0.038). There is no difference between precursor B lymphoblastic lymphoma and precursor B lymphoblastic lymphoma. Therefore, stage IV and two or more than two of extranodal involvements were found to be as prognostic factor in precursor B and T lymphoblastic lymphoma.

Conclusion: Overall prognosis of precursor B and T lymphoblastic lymphoma was poor although they showed a good response to chemotherapy because of their high relpase rate. And stage and the number of extranodal involvement are two pretreatment prognostic factors for adult lymphoblastic lymphoma. Thus, newer treatment strategy adapted on the poor prognostic factors should be warranted.