Potential Pathogenetic Role of Achromobacter (Alcaligenes) Xylosoxidans in Primary Extranodal Marginal Zone Lymphoma of the Lung (BALT-Lymphoma): Update of the Results of a Retrospective Analysis on Behalf of IELSG

Abstract 880

Pulmonary marginal zone lymphoma is a distinct subgroup of B-cell non-Hodgkin's lymphomas originating from the bronchial-associated lymphoid tissue (BALT) and characterized by an indolent clinical course. Here we present the data of the IELSG-28 study of the International Extranodal Lymphoma Study Group (IELSG) on primary pulmonary lymphoma patients. Clinical records and histological material of 186 patients diagnosed with pulmonary marginal zone lymphoma from December 1986 to June 2009 were collected. The pathology was reviewed centrally and the diagnosis was confirmed in 180 (96%) patients. The median age at diagnosis was 62 (30 – 88). The majority of the patients (149/180) had localized disease at diagnosis with a good performance status (0–1) and low prognostic index (IPI 0–2). Eighty-one patients (45%) received local treatment, including surgery (74%) or radiotherapy (4%). Ninety-nine patients with advanced stage disease or incomplete surgical resection received an additional systemic treatment. Most of these patients (66; 66%) received an alkylating containing regimen, 22 (22%) patients were treated with an anthracycline containing regimen and 29 (29%) received the anti-CD20 monoclonal antibody in combination with chemotherapy. With a median follow up of 67 (range 1–256) months, 47/180 patients (26%) experienced disease progression. (median time to progression 30 months, range 0–109). Progression free survival analysis showed a trend in favour of patients treated with immuno-chemotherapy versus those receiving chemotherapy alone (HR 0.53–95%CI: 0.21, 1.33), while no difference in terms of OS and PFS was observed between patients receiving systemic anthracycline or alkylating containing regimens. In twenty five cases a specific PCR-assay was carried out for detecting the presence of Achromobacter (Alcaligenes) xylosoxidans. The presence of Achromobacter was detected in 50% of patients.

Our results confirm that local therapy (surgery or radiotherapy) is the treatment of choice for patients with localized disease. Chemotherapy has to be considered in case of relapse, incomplete surgical excision or advanced disease. In this setting, alkylating containing regimens plus rituximab is the most effective option. Further studies are ongoing to confirm the relevance of infection/colonization with Achromobacter (Alcaligenes) xylosoxidans for pathogenesis of BALT lymphoma.