Prognosis in stage II colorectal cancer: the effect of the primary tumor location and biomarkers-a retrospective cohort study.

BACKGROUND

The prognostic impact of primary tumor location (right- vs left-sided) is well-established in stage III/IV colorectal cancer (CRC), with right-sided tumors associated with poorer outcomes. However, its prognostic role in stage II CRC remains unclear. This study investigates whether the worse outcomes observed in advanced right-sided cancers also apply to early-stage CRC, or if they may be influenced by other factors such as patient demographics and molecular biomarkers. Clarifying this could help improve risk stratification in clinical practice.

METHODOLOGY: For this study, we analyzed data of all Belgian patients diagnosed with stage II CRC in 2015-2016 (n = 3.278, data obtained from the Belgian Cancer Registry). Information on primary tumor location, demographics, pathologic T-category, molecular biomarkers (including microsatellite instability [MSI], BRAF, and KRAS status), and overall survival (OS) was collected.

RESULTS

In the univariable analysis, patients with stage II right-sided colon cancer had a significantly worse OS than left-sided colon cancer. Furthermore, advanced age and pT4 were also associated with worse OS. However, in the multivariable analysis, only gender, age, and pathologic T-category significantly affected OS. Primary tumor location was not significantly associated with OS in the multivariable analysis. Furthermore, the molecular biomarkers did not show a significant effect in either analysis. However, due to the limited size of the multivariable cohort, these results should be interpreted with caution.

CONCLUSION

The primary tumor location is not an independent prognostic factor in stage II CRC with a confounding effect of age. Notably, -molecular biomarkers did not affect the prognosis in either uni- or multivariable analysis.