The prognostic impact of lipid biosynthesis-associated markers, HSD17B2 and HMGCS2, in rectal cancer treated with neoadjuvant concurrent chemoradiotherapy

Neoadjuvant concurrent chemoradiotherapy has been widely used for rectal cancer to improve local tumor control. The varied response of individual tumors encouraged us to search for useful biomarkers to predict the therapeutic response. The study was aimed to evaluate the prognostic impact of lipid biosynthesis-associated biomarkers in rectal cancer patients treated with preoperative chemoradiotherapy. Through analysis of the previously published gene expression profiling database focusing on genes associated with lipid biosynthesis, we found that HSD17B2 and HMGCS2 were the top two significantly upregulated genes in the non-responders. We further evaluated their expression by immunohistochemistry in the pre-treatment tumor specimens from 172 patients with rectal cancer and statistically analyzed the associations between their expression and various clinicopathological factors, as well as survival. High expression of HMGCS2 or HSD17B2 was significantly associated with advanced pre- and post-treatment tumor or nodal status (P < 0.001) and lower tumor regression grade (P < 0.001). More importantly, high expression of either HMGCS2 or HSD17B2 was of prognostic significance, with HMGCS2 overexpression indicating poor prognosis for disease-free survival (P = 0.0003), local recurrence-free survival (P = 0.0115), and metastasis-free survival (P = 0.0119), while HSD17B2 overexpression was associated with poor prognosis for disease-free survival (P <0.0001), local recurrence-free survival (P = 0.0009), and metastasis-free survival (P < 0.0001). In multivariate analysis, only HSD17B2 overexpression remained as an independent prognosticator for shorter disease-free survival (P < 0.001) and metastasis-free survival (P = 0.008). In conclusion, high expression of either HSD17B2 or HMGCS2 predicted poor susceptibility of rectal cancer to preoperative chemoradiotherapy. Both acted as promising prognostic factors, particularly HSD17B2.