Primary colorectal diffuse large B-cell lymphoma: A report of eighteen cases in a tertiary care center.

Primary colorectal diffuse large B-cell lymphoma (DLBCL) is very rare colon malignancy. It is important to know the main demographic and clinical characteristics of these patients. We conducted a retrospective analysis of 18 patients diagnosed with primary colorectal DLBCL during a 17-year period at the National Cancer Institute of Brazil (INCA) between 2000 and 2018. Demographic characteristics, tumor localization, HIV status, lactate dehydrogenase (LDH) levels, treatment modality and follow-up status were obtained from medical records. Survival was estimated from the date of diagnosis until death. There were 11 male and seven female patients in our cohort, the median age at diagnosis was 59.5 years and four patients were HIV positive. Tumor was mainly localized in the right colon. Patients were treated with chemotherapy (CT) and/or surgical resection. Eleven patients died during a median follow-up of 59 months and the median survival time was 10 months. Six or more cycles of CT (HR=0.19; CI 95% 0.054-0.660, p = 0.009), LDH levels below 350 U/L (HR=0.229; CI 95% 0.060-0.876, p = 0.031) and surgical resection (HR=0.23; CI 95% 0.065-0.828, p = 0.030) were associated with reduced risk of death in univariate analysis. Patient's age and DLBCL right colon localization should be considered at diagnosis to distinguish between DLBCL and other diseases for differential diagnosis. Six cycles of CT, LDH levels below 350 U/L and surgical resection were associated with better survival. Our results are consistent with previous publications and address the importance of correct colorectal DLBCL diagnosis and treatment.