# Clinical Characteristics and Long-Term Prognosis of Colorectal Mucosa-Associated Lymphoid Tissue Lymphoma According to the Endoscopic Classification and Treatment Modality: A Multicenter Study

## TL;DR

This study examines the clinical features and outcomes of colorectal MALT lymphoma, finding it has a generally good prognosis regardless of treatment or disease stage.

## Contribution

The study provides new insights into the indolent nature of colorectal MALT lymphoma and suggests that treatment may not always be necessary.

## Key findings

- Colorectal MALT lymphoma typically has an excellent prognosis with high survival rates.
- Observation without treatment did not lead to disease progression in patients.
- Treatment modality was not associated with differences in disease progression.

## Abstract

Colorectal mucosa-associated lymphoid tissue (MALT) lymphoma is a rare subtype of non-Hodgkin’s lymphoma. Unlike gastric MALT lymphoma, which has a standardized treatment approach, colorectal MALT lymphoma lacks an established therapeutic approach. This study analyzed the clinical characteristics and long-term outcomes of 51 patients diagnosed with colorectal MALT lymphoma across six hospitals in Korea’s Busan–Ulsan–Gyeongnam area. The findings revealed that the disease was typically detected at an early stage, progressed slowly, and had an excellent prognosis with high survival rates. Treatment methods were not associated with disease progression rates. All disease progression occurred at stage I, showing that advanced stages were not necessarily related to poor prognosis. Additionally, none of the nine patients who underwent observation without treatment experienced disease progression. These results underscore the indolent nature of colorectal MALT lymphoma and provide valuable insights to guide individualized management strategies.

Background/Objectives: The clinical characteristics of colorectal mucosa-associated lymphoid tissue (MALT) lymphoma remain poorly defined, and there is no standardized treatment for the disease. Therefore, we investigated the clinical characteristics of colorectal MALT lymphoma and its prognosis based on different treatment modalities. Methods: A retrospective analysis was performed on patients diagnosed with colorectal MALT lymphoma from 2003 to 2021 across six hospitals in Korea’s Busan–Ulsan–Gyeongnam area. Macroscopic findings classified all cases into polyposis type, mass-forming type, subepithelial lesion type, and inflammatory type. Results: Fifty-one patients were enrolled. The median age was 59 years, and 27 patients (52.9%) were male. Five patients (9.8%) were stage IV at initial diagnosis. As for the endoscopic type, the polyposis type was the most common (39.2%). There was no statistically significant difference in disease progression according to the endoscopic type (p = 0.813). Three cases of disease progression were confirmed in stage I after treatment, and one of them died due to disease progression. No disease progression was identified in other stages. According to the treatment modality, disease progression was identified in 1 of 16 patients who underwent endoscopic resection and 2 of 16 patients who underwent chemotherapy. There was no disease progression in the observation group. However, there was no statistically significant difference in disease progression according to treatment modality (p = 0.889). Conclusions: Colorectal MALT lymphoma showed good prognosis regardless of the initial stage, endoscopic type, or treatment modality.