[Treatment of primary mediastinal large B-cell lymphomas]

Abstract

Introduction: Primary mediastinal large B-cell non-Hodgkin's lymphoma is a relatively rare disease with specific clinical symptoms. This tumour originates from a subset of B-cells of the thymus and at the time of the diagnosis the disease is predominantly localised in the mediastinum. The tumor grows rapidly and frequently involves other thoracic structures. The majority of the patients are young females. There are no histologic features that reliably distinguish these tumors from other diffuse large B-cell lymphomas. This is the only lymphoma subtype which can only be defined by the combination of clinical and pathologic features. Analysis with DNA microarrays verified that primary mediastinal and diffuse large B-cell lymphomas are different diseases.

Aims: Comparing the effectiveness of two types of anthracycline-based standard chemotherapy regimens and the evaluation of the prognostic markers which are applied in large B-cell lymphomas.

Methods: 27 patients with primary mediastinal lymphoma were treated by the authors with anthracycline-based polychemotherapy with complementary radiotherapy from January 1995 to December 2002.

Results: Complete remission was obtained in 15 patients (56%) and no relapse was observed in this group. 9 additional patients (33%) achieved partial remission, while in 3 cases (11%) the treatment was ineffective. The patients who failed to achieve complete remission were subsequently treated with more intensive chemotherapy. Afterwards, those patients who were chemosensitive, underwent high-dose chemotherapy with autologous peripheral blood stem-cell transplantation. The chemoresistant patients received palliative chemotherapy. The 5-year overall survival rate of the 27 patients was 62.11%.

Conclusion: The authors found that the procarbazine, prednisolone, adriamycin, cyclophosphamide, etoposide, cytosine-arabinoside, bleomycin, vincristine, methotrexate treatment was more effective than the cyclophosphamide, adriamycin, vincristine, prednisolone combination. The expected 5-year overall survival rates were 83.57% vs. 33.33%, respectively. This difference was significant (p = 0.017). No prognostic value of age adjusted international prognostic index, LDH- and b2-microglobulin levels were found. The results with the new standard of combined immuno-chemotherapy (rituximab--cyclophosphamide, adriamycin, vincristine, prednisolone) seem to be hopeful and more effective than earlier treatments.