Treatments and Outcomes in Stage I Extranodal Marginal Zone Lymphoma in the United States.

A considerable number of patients with extranodal marginal zone lymphoma (EMZL) are diagnosed with stage I disease. Information on treatments and survival by primary location remains limited. We extracted data from the Surveillance, Epidemiology, and End Results (SEER) database to assess treatment, primary location, and survival of patients with stage I EMZL. Results show that 7961 patients met inclusion criteria. Observation (no treatment) was the most common approach (31%) followed by radiation therapy (RT, 23%). The median overall survival (OS) was 17.3 years (95%CI 16.3 to 18.3). Shorter survival was observed in patients with stage I EMZL compared to expected survival in a cohort derived from the general U.S. population matched by sex, age, and calendar year at diagnosis. However, similar survival was observed in RT-treated patients. We identified age ≥ 60 years (SHR = 4.00, 95%CI 3.10-5.15; < 0.001), higher grade transformation (SHR = 4.63, 95%CI 3.29-6.52; < 0.001), and primary lung EMZL (SHR = 1.44, 95%CI 1.05-1.96; = 0.022) as factors associated with shorter lymphoma-specific survival (LSS). Conversely, primary skin location (SHR = 0.50, 95%CI 0.33-0.77; = 0.002) was associated with longer LSS. Our results support the use of RT as the preferred approach in localized EMZL.