Treatment outcomes of stage IE intestinal extra-nodal marginal zone lymphoma: A National Cancer Database study.

e19530 Background: Extra-nodal marginal zone lymphoma is a rare, indolent non-Hodgkin lymphoma. Classically it involves the gastric mucosa and is associated with chronic infection, but it can also be found in the lower gastrointestinal (GI) tract. No standard therapy has been established for early stage disease in the small intestine, colon or rectum though multiple strategies have been employed. Little is known regarding the natural history and long-term outcomes of this disease when confined to the lower GI tract. We used the National Cancer Database (NCDB) to evaluate this patient population based upon treatment modality and disease site. Methods: Patients meeting the inclusion criteria were extracted from the 2017 Extra-Nodal Non-Hodgkin’s Lymphoma NCDB. Patients were grouped by primary treatment or observation status. Clinical and demographic factors were compared between the treatment groups via chi-square, Fisher’s exact and the Kruskal-Wallis tests. Comparison of Overall Survival (OS) between groups utilized either univariable log-rank comparison of the Kaplan-Meier estimator or multivariable Cox proportional hazards regression modelling, with patients censored at date of last contact. All analyses were performed with the SAS software suite, version 9.4. Results: 775 patients were identified with stage IE extra-nodal marginal zone lymphoma of the small intestine, colon or rectum with treatment and follow-up data. Prevalence increased over time. Median age at diagnosis was 65, with a ten-year overall survival for the entire cohort of 74.8% (69.8% - 79.0%). Location of disease was small intestine in 286 patients (36.9%), colon in 361 patients (46.6%) and rectum in 128 patients (16.5%). Ten-year overall survival was significantly worse for a small intestine primary site compared to colon and rectum primary sites (64.9% (55.6% - 72.6%) vs 81.5% (74.9% - 86.5%) and 80.9% (68.5% - 88.8%) respectively; p-value 0.013). Initial treatment was surgery in 361 patients (46.6%), radiation in 99 patients (12.8%), chemotherapy and/or immunotherapy in 120 patients (15.5%), and observation in 195 patients (25.1%). No significant differences in 5-year or 10-year survival were seen between treatment groups. Conclusions: Observation is a reasonable management strategy in patients with stage IE lower intestinal tract extra-nodal marginal zone lymphoma; survival is similar to those who received surgery, radiation or systemic therapy. Those with small intestine primary site had worse overall survival, irrespective of treatment modality, when compared to colon and rectum disease sites.