High Expression of RAR β Is a Favorable Factor in Colorectal Cancer.

RAR plays a critical role in cancer progression and is associated with several types of human cancer. It remains unclear, however, whether it is linked to the clinicopathological parameters of colorectal cancer (CRC). We therefore determined the expression of RAR protein in patients with primary CRC and examined its relationship with clinical outcomes. RAR expression in 234 samples of CRC patients and matched benign noncancerous tumors was detected by immunohistochemistry. RAR mRNA expression was confirmed using the TCGA and Oncomine databases. COX regression analysis and Kaplan-Meier survival analysis were performed to determine the relationship between RAR expression and CRC prognosis. Our results show that high expression of RAR correlated with better prognosis in CRC patients. RAR expression in CRC specimens was clearly lower than in peritumoral specimens (30.8% vs 58.8%, p<0.001) and significantly correlated with gender (2=3.926, p=0.048), tumor differentiation (2=5.978, p=0.014), and tumor stage (2=6.642, p=0.036). Multivariate analyses further revealed that low RAR expression (p=0.001), distant metastasis (p=0.001), tissue differentiation (p=0.006), and tumor stage (p=0.002) were associated with overall survival in CRC patients. In addition, Kaplan-Meier analysis indicated that increased RAR expression in cytoplasm (p=0.001) and early tumor TNM stage (p=0.030) was associated with a more favorable outcome in patients with CRC. In conclusion, RAR expression was strongly correlated with several clinicopathological factors of CRC and may represent a favorable prognostic marker in patients with CRC.