OBJECTIVETo explore the associations between the genetic variations in the SDC2 gene and overall survival and risk of radiation esophagitis in patients with esophageal squamous cell carcinoma (ESCC).

METHODSEleven functional haplotype-tagging single nucleotide polymorphisms (htSNPs) of SDC2 were genotyped in 296 ESCC patients who received radiotherapy alone, and had different response and esophagitis. The associations between genotypes and risk of esophagitis were measured by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, age, tumor location, staging, radiotherapy mode and total radiation dose. The hazard ratios (HRs) were estimated using Cox proportional hazards regression model.

RESULTSThe median survival time (MST) of these patients was 14 months. Of them, 260 (87.8%) had died until the last date of follow-up of 30 June, 2014. Clinical stage (stage IV vs. stage II) and total radiation dose (≥ 60 Gy vs. < 60 Gy) influence the overall survival time of the patient significantly. Cox proportional hazards regression model analysis showed that the subjects with rs61599409 T allele had an decreased hazard ratio as compared with those with C allele (adjusted HR = 0.82, 95% CI, 0.66-1.02), but the difference was not statistically significant (P = 0.071). The rest 10 htSNPs were not associated with the overall survival of ESCC patients treated with radiotherapy. Among this set of patients, 160 (54.1%) suffered from radiation esophagitis. We found that rs17788084 A > T SNP in the 3'-untranslational region of SDC2 was associated with esophagitis risk, with the OR being 0.48 (95% CI = 0.28-0.85, P = 0.011) for the TA or TT genotype compared with the AA genotype.

CONCLUSIONSThese results suggest that rs17788084 genetic variation in SDC2 is associated with risk of radiation esophagitis and might serve as a potential biomarker for personalized radiotherapy of ESCC.