Primary tumors arising from different regions of the colon are biologically distinct; thus location is associated with different features such as microbiota and molecular alterations. Recently, retrospective analysis of phase III trials have shown better prognosis and a significant benefit of anti-EGFR antibodies in left sided RAS wild-type metastatic colon cancer patients. Epidemiological analysis of colon cancer patients from the neighbouring Cancer Registries of Salzburg, Tyrol and Vorarlberg, St. Gallen, Graubünden, and Liechtenstein was to support different prognostic value of left-and right-sided colon cancer.
7626 patients with pathologically confirmed colon cancer diagnosed between 2005 and 2015 were identified from the database of the population-based cancer registries of Western Austria, Eastern Switzerland and Liechtenstein. Patients were categorized in two groups: Right-sided colon cancer (RCC) including tumors of the colon transversum and left-sided colon cancer (LCC). Analysis was conducted separately for UICC stages III and IV. Survival curves were estimated applying the Kaplan-Meier method; for comparison of RCC and LCC cohorts the Logrank test was applied. Tumor stage and localisation are shown in the following table.Table:
|I||626 (16.7%)||918 (23.6%)||1544 (20.2%)|
|II||1091 (29.2%)||979 (25.2%)||2070 (27.1%)|
|III||995 (26.6%)||1016 (26.1%)||2011 (26.4%)|
|IV||863 (23.1%)||807 (20.8%)||1670 (21.9%)|
|X/nos||164 (4.4%)||167 (4.3%)||331 (4.3%)|
|Total||3739 (100.0%)||3887 (100.0%)||7626 (100.0%)|
Tumor location per se in stage III and IV colon cancer in the current retrospectively, epidemiological study, revealed a significantly better overall survival for LCC than for RCC in stage III and IV in a univariate analysis. After stratification by age, hazard ratio was 0.91 (95% Confidence interval 0.78-1.07) in stage III and 0.75 (95% confidence interval 0.66-0.84) in stage IV, thereby confirming recent, retrospective data from large phase III clinical trials (FIRE-3, CHRYSTAL; PEAK and PRIME).
Real life registry data of a well- defined colon cancer population confirm retrospective clinical trial data that LCC in stage III and IV carry a more favourable outcome than RCC, even in the era of modern chemo-immunotherapy.
Clinical trial identification
Legal entity responsible for the study
Alois H. Lang
All authors have declared no conflicts of interest.