Survival Outcomes of Histopathological Subtypes of Colorectal Adenocarcinoma in Ugandan Patients

Background: High grade mucinous adenocarcinomas have been found to be more common in younger patients and are associated with a poor prognosis in the West. In Uganda, survival outcomes of the different histopathologic subtypes of colorectal adenocarcinoma (CRC) and lymphovascular invasion (LVI) is unknown. We determined the survival outcome of the different histopathologic subtypes of CRC and LVI among Ugandan patients.

Methods: A retroprospective cohort study on patients diagnosed with CRC from 2008 to 2018 were identified from the Kampala Cancer Registry and hospital medical records. Retrieved data included date of diagnosis, demographics, stage, grade and location of CRC. Our outcome was survival, and the main predictor variables were the histopathologic subtype, stage, grade and LVI. We plotted Kaplan-Meier curves for survival, tested the equality of survival by log-rank tests and used multivariable Cox regression to determine factors associated with survival.

Results: 12.4% patients predominantly had mucinous adenocarcinoma/signet ring colorectal carcinoma (MAC/SRCC) and 87.6% patients had classical adenocarcinoma (AC). The median age (SD) at diagnosis of MAC/SRCC was 47.8 (16.6) years and 53.8 (15.9) years for AC. SRCC/MAC was significantly associated with more LVI than AC (p=0.002). In multivariate analysis, factors associated with increased mortality included stage III (aHR=2.56; p=0.009) and stage IV (aHR=6.64; p <0.001). After adjusting for lymph node involvement and metastasis, SRCC/MAC patients had a shorter survival than AC patients; however, this difference was not statistically significant (p=0.229).

Conclusions: In Uganda, the proportion of MAC is similar to that found in the Western world. SRCC/ MAC were associated with more LVI than AC. SRCC/MAC showed a tendency towards decreased overall survival. In Uganda, more patients present with advanced-stage CRC which was associated with poor survival hence national screening guidelines are necessary to improve survival.