Abstract
PURPOSE: For locally advanced rectal cancer, neoadjuvant concurrent chemoradiotherapy (CCRT) allows tumor downstaging and makes curative radical proctectomy possible. However, we lack a genetic biomarker to predict cancer prognosis or treatment response. We investigated the association between ubiquitin D (UBD) expression and clinical outcomes in rectal cancer patients receiving CCRT. PATIENTS AND METHODS: We analyzed the genes associated with the protein modification process (GO:0036211) and identified the UBD gene as the most relevant among the top 7 differentially expressed genes associated with CCRT resistance. We collected tissue specimens from 172 rectal cancer patients who had received CCRT followed by a curative proctectomy. We examine the relationship between UBD expression and patient characteristics, pathological findings, and patient survival, such as metastasis-free survival (MeFS) and disease-specific survival. RESULTS: Upregulated UBD expression was associated with lower pre-CCRT tumor T stage (P = 0.009), lower post-CCRT tumor T stage (P < 0.001), lower post-CCRT nodal stage (P < 0.001), less vascular invasion (P = 0.015), and better tumor regression (P < 0.001). Using univariate analysis, we found that high UBD expression was correlated with better disease-free survival (DFS) (P < 0.0001), local recurrence-free survival (LRFS) (P < 0.0001) and MeFS (P < 0.0001). Moreover, multivariate analysis demonstrated that high UBD expression was associated with superior DFS (P < 0.001), LRFS (P = 0.01), and MeFS (P = 0.004). CONCLUSION: UBD upregulation was linked to better clinical prognosis, favorable pathological features, and good treatment response in rectal cancer patients undergoing CCRT. These results suggest UBD is a biomarker for rectal cancer.