Clinical target volume (CTV) in postoperation radiotherapy of esophageal squamous cell carcinoma could benefit from the detection of telomere length in lymph node

Background: This study evaluated the relation between telomere length in lymph node (LN) and prognosis of esophageal squamous cell carcinoma (ESCC).  Materials and Methods: LNs collected from 50 patients were assessed by pathological examination and quantitative reverse transcription polymerase chain reaction (qRT-PCR), which was used for detecting telomere length. The relation between clinical factors and the number of lymph node metastasis (LNM) identified were analyzed by the χ2 test. The comparison of the pattern of LNM identified by pathological examination and detection of telomere length was assessed by Wilcoxon signed-rank test. Overall survival was assessed using the Kaplan-Meier method, and Cox proportional hazard regression analysis was used to evaluate the relationship between survival and the number of LNM.  Results: The best threshold values, which could define the positive metastasis by detecting the telomere length, were 1.50, using the critical value method of statistic. Length of tumor, depth of tumor invasion and differentiation of tumor correlated closely with LNM were identified by detecting telomere length. The rates of LNM identified by detecting telomere length were 34.4%, 22.4%, 22.9%, 5.0% in 108, 107, 7, and 3 LN station, respectively. The number of LNM identified by detecting telomere length was more closely related to the prognosis of ESCC than that of pathological examination (HR: 1.23 VERSUS 1.04). Conclusion: The change of telomere length in LN was closely related to the prognosis of ESCC. Delineation of clinical target volume (CTV) may benefit from the detection of telomere length in regional LN.