Clinical Features and Outcomes of Primary Colorectal Diffuse Large B-Cell Lymphoma: A Multicenter Retrospective Study

Primary gastrointestinal (GI) diffuse large B-cell lymphoma (DLBCL) is a rare malignancy. Given its rarity, the nature of the disease, particularly those originating in the colorectum, remains poorly defined.

This multicenter retrospective study analyzed the clinical characteristics and treatment outcomes of primary GI DLBCL, with a focus on colorectal cases.

A total of 104 cases of primary GI DLBCL were retrospectively collected from three institutions (2010-2024) and classified into three groups based on the lymphoma's origin.

Among 104 patients, 57.7% had gastric, 18.3% small bowel, and 24.0% colorectal DLBCL. Approximately 60% presented with limited-stage disease (Stage I-II). All patients received front-line R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone), achieving a complete remission (CR) rate of 81.0%. The estimated 3-year overall survival (OS) and progression-free survival (PFS) were 91.7% and 91.9%, respectively. Outcomes varied by disease origin, with gastric DLBCL showing the most favorable prognosis and small bowel the poorest (3-year OS 93.9% vs. 69.3%).

In the colorectal subgroup (n = 25), 84.0% had disease in the ascending colon, and 70.0% had limited-stage disease. Obstructive symptoms were the most common initial presentation. The CR rate after R-CHOP was 80.0%, with estimated 3-year OS and PFS of 86.7% and 72.3%, respectively. While primary tumor resection improved local disease control, it did not confer an OS benefit. During follow-up, 13.5% of patients experienced relapse, most frequently more than 12 months after achieving CR. Relapsed or refractory primary GI DLBCL demonstrated better outcomes than conventional relapsed nodal DLBCL.

These findings confirm the efficacy of front-line R-CHOP in primary GI DLBCL and suggest that primary tumor resection may be a useful component of treatment for localized primary colorectal DLBCL.