Can an IL13 -1112 C/T (rs1800925) polymorphism predict responsiveness to neoadjuvant chemoradiotherapy and survival of Chinese Han patients with locally advanced rectal cancer?

We sought to determine whether a polymorphism in the Interleukin 13 gene (IL13), 1112 C/T (rs1800925) predicts responsiveness to neoadjuvant chemoradiotherapy (neoCRT) and prognosis in Chinese Han patients with locally advanced rectal cancer (LARC). Pre-treatment biopsies of primary rectal lesion and surgical specimens were collected from 58 patients with LARC, who were treated with neoCRT and surgery. Tumor DNA was extracted from these biopsies and sequenced to analyze the rs1800925 polymorphism. The tumor response to neoCRT was categorized using a tumor regression grade (TRG, 0-2 were poor responders; 3-4 were good responders). Analyses of progression free survival (PFS) and overall survival (OS) were carried out using the Kaplan-Meier method. Of the forty-six patients for whom tumor DNA was successfully sequenced, 23 were good responders to neoCRT (11 patients with a pathological complete response, i.e. pCR) and the other 23 were poor responders. Good and poor responders were equally likely to have a C/C genotype at rs1800925 (73.9%) as a T/T or C/T genotype (26.1%). There were no differences between the C/C and T/T+C/T genotypes with respect to the ypT0-2 ratio (38.2% vs. 41.7%, P = 1.0), ypN0 nodal status (67.6% vs. 50.0%, P= 0.314), 6-year PFS (67.6% vs. 50%, P=0.274), or 6-year OS (76.5% vs. 66.7%, P=0.441). Thus, the IL13-1112 C/T (rs1800925) polymorphism does not predict responsiveness to neoCRT or prognosis of Chinese Han patients with LARC.