Localized extranodal marginal zone B-cell lymphoma: clinical outcome with radiation therapy

Abstract

Purpose/Objective: Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a distinct lymphoma with unique clinical-pathologic features. However the etiology, sites of presentation, and biologic behavior remain variable and heterogeneous. Since our last report (70 patients, IJROBP 50:1258-64, 2001), we have now updated the clinical outcome of a series of patients with stage I/II MALT lymphoma treated with a policy of involved field radiation therapy (RT). Materials/Methods: 98 patients with stage IE (86) and IIE (12) disease were referred between 1989-2000. The data was collected prospectively since 1992 in a computerized datadase and clinical outcome updated regularly. Transformed MALTs (diffuse large B-cell lymphoma) were excluded. The median age was 59 yrs (range 22-83 yrs), M:F ratio 1:1.8. Presenting sites included: stomach 17, orbital adnexa 28, salivary glands 24, thyroid 13, other head and neck sites 4 (nasopharynx 2, sinus 1, larynx 1), lung 5, urinary bladder 3, skin 2, breast 1, and rectum 1. Staging included site-specific imaging, CT abdomen in 92% and bone marrow biopsy in 79%. Eighty-eight patients received RT: 80 RT alone, 8 chemotherapy and RT. Five patients had complete surgical excision alone, 2 patients with gastric lymphoma received antibiotics alone, and 3 other patients refused any treatment. The analysis focused on 88 patients who received RT; the median follow up was 4.3 yrs (range 1.0-9.8 yrs). Common RT prescriptions were 25Gy (39%, majority orbit), and 30Gy (44%), with median dose 30Gy (range 17.5-35Gy). Results: A complete response (CR/CRu) to RT was achieved in 87/88 patients, 1 patient had no response (orbit). To date, 3 patients have died (1 due to lymphoma, 2 from unrelated causes). The 5-yr disease-free survival (DFS) was 74%, and overall survival (OS) 97%. No relapses were observed in 26 patients with stomach or thyroid lymphoma, while 13/62 patients relapsed in the other sites. The 5-yr DFS for gastric and thyroid lymphoma was 93%, in contrast to 67% for other sites (p = 0.009), although OS was the same. Among 87 patients with CR, 13 relapsed (4 salivary, 5 orbit, 2 nasopharynx, 1 larynx, 1 breast). Relapse sites: the untreated contralateral paired-organ only, 4 patients (2 orbit, 2 parotid); distant sites, 7 patients; and both local (both parotid) and distant sites, 2 patients. The overall local control rate with RT was 97% (85/88 patients). All 4 patients with paired-organ relapse were radiated with complete response. Two of the relapsed patients had transformed lymphoma (diffuse large B-cell) at relapse (both at distant sites). The locations of distant relapse were commonly in MALT sites rather than lymph nodes. Conclusions: Moderate-dose RT achieved excellent local control in localized MALT lymphomas and appears to have curative potential for three-quarters of the patients. Relapses were observed in non-irradiated paired-organs or distant sites. Gastric and thyroid MALT lymphomas had better outcome, as compared to the other sites where distant failures were more common. Patients with relapse of lymphoma generally maintained an indolent course of disease with prolonged survival despite multiple relapses.