EP145 - Primary Colorectal Lymphoma: A Systematic Review of Population-Based and Cohort Studies

Purpose/Background: Primary colorectal lymphoma (PCL) is a rare extranodal malignancy of the gastrointestinal tract, accounting for only 0.2% to 1.2% of all primary colorectal cancers. This systematic review aims to synthesize the available evidence on PCL by evaluating patient demographics, clinical presentation, histological subtypes, treatment patterns, and survival outcomes. We sought to clarify prognostic factors and inform potential management strategies given the paucity of standardized treatment protocols.

Methods/Interventions: A comprehensive literature search of Embase and MEDLINE was conducted, spanning 1962 to 2025, identifying 5,603 abstracts. Following PRISMA guidelines, duplicates and irrelevant studies were removed, and 5,460 titles and abstracts were screened. Full texts of 47 articles were assessed for eligibility. Inclusion criteria comprised studies strictly focused on primary colorectal or large-bowel lymphoma, observational in design, and reporting demographics, histology, treatment, or survival. Studies including secondary lymphoma, small bowel or gastric lymphoma, Hodgkin lymphoma, or unaggregated case reports were excluded. Ultimately, 14 studies met inclusion criteria and were included in the qualitative synthesis. Extracted data included study design, population, interventions, outcomes, follow-up, and methodological rigor, including staging and adherence to Dawson criteria.

Results/Outcomes: This systematic review included 14 studies with 2,093 patients with primary colorectal lymphoma (PCL), ranging from small series (n=7-95) to the SEER cohort (n=1,721). Median age ranged 44-76 years, with male predominance (1.9:1-13:1). Common symptoms included abdominal pain (49-100%), hematochezia (up to 49%), weight loss, and altered bowel habits. Urgent surgery occurred in 56-71% for obstruction, bleeding, or perforation. Tumors were most often in the cecum/ileocecal region (47-81%). Histology was mainly B-cell, especially DLBCL (45-92.9%); T-cell lymphomas (17.9-42%) were associated with younger age (P=0.016), diffuse involvement (P < 0.001), perforation (23.5% vs 3.8%, P=0.005), and worse OS (P=0.002). Treatments included surgery (60-78%), chemotherapy (CHOP/R-CHOP), and multimodal therapy. Surgery plus chemotherapy improved 5-year OS versus chemotherapy alone (62.1% vs 14.3%, P=0.035), with DFS benefit (P=0.001). SEER data confirmed OS advantage for surgery plus chemotherapy (HR 0.76) and worse outcomes with surgery alone (HR 1.53) or no treatment (HR 1.93). Negative prognostic factors included age ≥65 (P=0.004), T-cell histology (P=0.002), perforation (P < 0.001), Black race, and lack of treatment (P < 0.001). PCL is rare, often presenting with nonspecific symptoms, most commonly in the cecum, predominantly B-cell, and frequently requiring urgent intervention. Multimodal therapy improves survival.

Conclusion/Discussion: PCL is a rare, aggressive malignancy frequently diagnosed at an advanced stage or following emergent complications. Retrospective evidence supports a multidisciplinary approach integrating surgical resection for local control or complications with systemic chemotherapy. Prognosis is influenced by age, race, stage, histology, and emergency presentations. High-quality, multicenter prospective studies are needed to standardize treatment protocols and improve survival outcomes in this uncommon malignancy.

Treatment Modalities and Patterns of Care as well as Prognostic Factors and Survival Outcomes