Management and Outcomes of Primary Colorectal Lymphomas in Queensland: A Retrospective Study.

AIM: Primary colorectal lymphoma (PCL) is a rare gastrointestinal malignancy with heterogeneous pathology and limited evidence to guide management, particularly in the Australian setting. This study aimed to describe the epidemiology, treatment patterns and short- to medium-term outcomes of patients with PCL in Queensland. METHOD: A retrospective population-based cohort study was performed using the Queensland Oncology Repository. Patients with histologically confirmed primary colorectal lymphoma diagnosed between January 2000 and July 2017 were included, excluding those with prior or synchronous extra-colorectal lymphoma. Demographic, clinicopathological, treatment and outcome data were analysed. Disease-specific survival was assessed to 3 years using Kaplan-Meier methods, with Gehan's test applied. RESULTS: A total of 173 patients were identified. Diffuse large B-cell lymphoma was the most common histological subtype (60.1%), and the right colon was the most frequently involved site (60.7%). Combined chemotherapy and surgery were the most frequently employed treatments (43.9%). Three-year disease-specific survival was 83%. Treatment modality was the strongest determinant of survival (p < 0.001), with chemotherapy-based regimens associated with superior outcomes. Surgery alone was associated with poor disease-specific survival, with a 45% disease-related mortality. Increasing age (≥ 65 years) was independently associated with inferior disease survival (p = 0.006). CONCLUSION: This population-based study represents the largest Australian cohort of primary colorectal lymphoma reported to date. PCL predominantly affects older males and is most commonly treated with chemotherapy-based regimens, which are associated with favourable survival. Surgery alone should not be considered definitive therapy except in selected clinical circumstances.