Recurrence Pattern Of Squamous Cell Carcinoma In The Midthoracic Esophagus:Implications For The Clinical Target Volume Design Of Postoperative Radiotherapy Carcinoma

ObjectivePostoperative radiotherapy has shown positive efficacy in lowering the recurrence rate and improving the survival rate for patients with esophageal squamous cell carcinoma(ESCC).However,controversies still exist about the postoperative prophylactic radiation target volume.This study was designed to analyze the patterns of recurrence and to provide a reference for determination of the postoperative radiotherapy target volume for patients with midthoracic ESCC.Materials and MethodsPatients with midthoracic ESCC who were admitted to our hospital from January 2008 to December 2013 were enrolled as subjects.All patients were diagnosed with recurrence or metastasis by imaging after R0 radical surgery.The exact regions of mediastinum lymph node metastasis were classified according to the 7th edition of American Joint Committee on Cancer(AJCC),and the abdominal lymph nodes were grouped according to the gastric cancer lymph node grouping criteria established by the Japan Association of gastric cancer.A total of 338 patients with recurrent or metastatic midthoracic ESCC after radical surgery were retrospectively examined.ResultIn the entire cohort,the most common site of recurrence for patients with midthoracic ESCC was locoregional recurrence(88.4%)followed by distant metastasis(11.6%)and combined locoregional recurrence with distant metastasis(7.1%).The sites of locoregional from high to low were mediastinal LNs(83.1%),supraclavicular LNs(28.4%)and celiac LNs(19.5%),respectively.The most common sites in the mediastinum were stations 2,4,5,and 7 LNs,and the overall rate of the LNs mentioned above is 92.3%.The most common sites of celiac lymph nodes were stations 16a2,16a1,9,13 and 8 LNs,and the overall rate of the LNs mentioned above is 89.3%.The recurrence rate in the other parts of the upper abdominal LNs was less than 10%.Univariate and multivariate analysis revealed that the rate of abdominal LN metastasis was signifcantly higher in patients with histological node-positive than that in patients with histological node-negative(p = 0.033).Further analysis in patients with three or more positive nodes are more prone to abdominal LN metastasis,compared with patients with one or two positive nodes(χ2 =4.367,P=0.037).The length of tumor and histological differentiation were also the high-risk factors for abdominal LN metastasis.Multivariate analysis also showed that p N staging(P=0.028),the length of the tumor(P=0.01),and the degree of differentiation(P=0.041,P=0.029)were independent factors affecting the occurrence of postoperative abdominal esophageal carcinoma.ConclusionLocoregional recurrence was the most common and potentially preventable type of initial treatment failure after curative surgery among patients with midthoracic ESCC.For midthoracic ESCC with histological node-negative,or one or two positive nodes,the supraclavicular and stations 2,4,5,and 7 LNs should be delineated as clinical target volume of postoperative prophylactic irradiation,and upper abdominal LNs should be excluded.While for midthoracic ESCC with three or more positive nodes,upper abdominal LNs should also be included.The length of tumor and histological differentiation should be considered comprehensively to design the clinical target volume for radiotherapy.