Exploration Of Clinical Target Area For Postoperative Radiotherapy Of Thoracic Esophageal Squamous Cell Carcinoma Based On Recurrence Pattern

Objective:The recurrence rate of esophageal squamous cell carcinoma(ESCC)after radical resection is as high as 40%-50%[1],and local-regional recurrence(LRR)is the main cause of treatment failure.postoperative radiotherapy(PORT)can reduce the local regional recurrence rate and improve the overall survival and disease-free survival of patients with esophageal squamous cell carcinoma[2],which has been used for the treatment of esophageal carcinoma for many years.At present,the specific clinical target volume(CTV),especially the target volume of lymph nodes(LN),is still controversial.Therefore,in order to determine the CTV that should be included in postoperative radiotherapy(RT)to achieve more accurate target coverage,we studied the recurrence pattern of thoracic esophageal squamous cell carcinoma(TESCC)after radical resection,especially the pattern of lymph node recurrence(LNR),in order to provide reference for the clinical target design of postoperative radiotherapy for TESCC,and further analyze the feasibility and prognosis of postoperative radiotherapy for T-shaped field after radical resection of thoracic esophageal squamous cell carcinoma.Research methods:1.The clinical data of 1455 patients who underwent TESCC root treatment in the First Affiliated Hospital of Soochow University from June 2013 to January 2022 were collected,of which 358 patients met the inclusion criteria,and were retrospectively analyzed.According to the United States Joint Committee on Cancer(AJCC)8th edition of esophageal cancer TNM staging standards and lymph node atlas for zoning,staging[3].Localregional recurrence(LRR)was defined as lymph node recurrence(including regional lymph node recurrence and supraclavicular lymph node recurrence)and anastomotic recurrence(AR),with a 10%cut-off value to distinguish between high-risk and low-risk recurrence areas.PS software was used to draw the high risk recurrence area.Chi-square test was used for univariate analysis,and Logistic regression analysis was used for multivariate analysis.2.The clinical data of 58 patients with thoracic esophageal squamous cell carcinoma treated with T-field postoperative radiotherapy in the First Affiliated Hospital of Soochow University from January 2016 to January 2021 were retrospectively analyzed.Cumulative survival was calculated using the Kaplan-Meier method and survival curves were plotted.COX regression analysis was used to analyze the influencing factors of overall survival(OS).α=0.05,that is,P<0.05,was considered statistically significant.Research results:1.We included 358 eligible patients in the entire study cohort.Among them,288 cases were male(80.45%)and 70 cases were female(19.55%).The median age was 64.39 years.35 cases(9.78%)in the upper thoracic segment,204 cases(56.98%)in the middle thoracic segment and 119 cases(33.24%)in the lower thoracic segment.212 patients(59.22%)in stage Ⅱ,130 patients(36.31%)in stage Ⅲ;257 cases(71.79%)recurred within 24 months.There were 269 cases(75.14%)with local-regional recurrence(LRR)and 120 cases(33.52%)with LNR only.In the patients with LRR only,14 cases(11.67%)had lymph node recurrence and anastomotic recurrence(LNR+AR),63 cases(52.50%)had LNR only,and 43 cases(35.83%)had AR only.In patients with LNR,1R,2R,4R,7,8M lymph nodes were high risk areas for recurrence,with recurrence rates of 15.12%,13.51%,13.91%,11.49%and 10.28%,respectively.The recurrence rates of supraclavicular/infraclavicular neck and superior mediastinal lymph nodes were 23.39%and 67.34%,respectively.pN stage and tumor thrombus were independent risk factors of LNR(P<0.05),pN stage and tumor thrombus were independent risk factors of distant metastasis(DM),(P<0.05).2.The rates of local regional recurrence and distant metastasis were 18.97%and 24.14%respectively.At the end of follow-up,the 1-year overall survival rate was 95.9%,the 2-year overall survival rate was 81.4%.The 1-year and 2-year local recurrence-free survival rates were 93.9%and 75.3%respectively.The 1-year and 2-year disease-free survival rates were 85.0%and 56.4%respectively.The 1-year and 2-year DFS rates were 90.6%and 72.4%respectively.The mean dose(Dmean)to both lungs was 11.16±1.68Gy,the volume fraction of both lungs irradiated>20Gy(V20)was 19.86±3.81%.and the volume fraction of both lungs irradiated>5Gy(V5)was 47.67±9.29%.No patient had≥Grade 3 radiation esophagitis and radiation pneumonitis,22.41%of patients had Grade 2 radiation esophagitis,and 24.14%of patients had Grade 2 radiation pneumonitis.Research conclusion:1.The recurrence pattern of patients with TESCC after radical operation was mainly LRR,and LNR was the main recurrence pattern in LRR.The lymph nodes in 1,2,4,7 and 8M regions were the high-risk recurrence areas(accounting for 23.39%,18.35%,21.57%,11.49%and 10.28%respectively),namely supraclavicular/inferior neck and upper middle mediastinum.The recurrence rate of lymph nodes in the abdominal region is low and does not exceed 10%.Postoperative adjuvant radiotherapy should cover the above high risk areas to reduce the local recurrence rate.2.For patients with locally advanced thoracic esophageal squamous cell carcinoma,postoperative T-field radiotherapy,the common high-risk recurrence areas of esophageal cancer into the field range(bilateral supraclavicular and upper mediastinum),tend to improve OS and reduce local recurrence rate,prolong local recurrence-free survival,and toxicity is within the controllable range,T-field may be used as a reference field for postoperative radiotherapy.