Identification Of Risk Factors And The Pattern Of Lower Cervical Lymph Node Metastasis In Esophageal Cancer: Implications For Radiotherapy Target Delineation

Background Radiotherapy remains the important therapeutic strategies for patients with esophageal cancer(EC).In thoracic esophageal squamous cell carcinoma,a great number of data suggested that IFRT is feasible in EC patients.However,Based on our observation,there has recent reports suggesting higher than expected nodal recurrence in the supraclavicular region after IFRT.Thus,for patients with high risk of lower cervical lymph nodes failure,prophylactic irradiation of supraclavicular areas may be necessary.At present,there is no uniform opinion or standard care on the range of radiotherapy in the treatment of esophageal cancer.This study aimed to investigate the risk factors associated with lower cervical lymph node metastasis(LNM)and to explore the distribution pattern of lower cervical metastaitc lymph nodes.It could provide useful information regarding accurate target volume delineation for EC.Methods Clinical characteristics of ESCC patients who were initial diagnosis in our hospital from January 2010 to July 2015 were reviewed.The lower cervical area was further divided into four subgroups areas.Subgroup?(No.100 Superficial lymph nodes of the lower neck);subgroup?(No.101 Cervical paraesophageal lymph nodes);subgroup ?(No.104 Lower cervical lymph nodes):;subgroup ?(Posterior cervical lymph nodes level).The clinicopathological factors related to LNM were analyzed and the nodes were considered to be clinical metastatic in the lower cervical region for all patients were registered by hand drawings from the original CT image onto the template CT image.The volumetric center of each lymph node was identified and used for mapped on the template images to the best of our ability,and then a volume probability atlas of those nodes was generated.Results 1.The univariate analysis showed that tumor localization,tumor invasion depth,mediastinal level 1-2 LNM,mediastinal level 4 LNM,mediastinal level 5 LNM and the number of LNM were the significant risk factors for metastasis in the lower cervical area.The multivariate logistic regression analysis demonstrated that tumor invasion depth,mediastinal level 1-2 LNM,mediastinal level 4 LNM and the number of LNM were independent risk factors for lower cervical lymph nodes metastasis.2.Our study demonstrated that the rate of lower cervical LNM was 37.2 %(89 of 239).Among those patients,lower cervical subgroup III LNM were affirmed in 67 of 89 patients(75.3 %),followed by the sequence of subgroup II lymph nodes 69.7%(62 of 89 patients),subgroup I lymph nodes 4.5%(4 of 89 patients),and subgroup IV lymph nodes 1.1%(1 of 89 patients),respectively.According to our results,94.4 % had subgroup II and/or subgroup ? regions LNM,while only 5.6% had subgroup?and subgroup IV region LNM.In addition,we analyzed the distribution pattern of lower cervical LNM in these patients.In the entire cohort,151 nodes were considered to be metastatic in the lower cervical region of those patients.The median number of positive nodes was 2(ranged,1-5).The anatomic distribution of metastatic nodes was 4 of 151(2.6%)in group,I,68 of 151(45%)in group?,77 of 151 nodes(51%)in group III,and 2 of 151(1.4%)in group IV,respectively.Conclusions Based on our study,prophylactic irradiating to lower cervical areas is recommended for patients with deeper tumor invasion,the mediastinal level 1,2,and 4 station LNM and the more number of LNM.The atlas showed that,for the lower cervical area,the subgroup?and ? region should be precisely covered in the target volume and the subgroup I and IV may be spared for minimizing the toxicity.Background At present,delineating the supraclavicular region lymph nodal clinical target volume(CTVn)for esophageal carcinoma remains a challenging task.We describe the distribution of supraclavicular lymph nodes metastasis for esophageal carcinoma patient after surgery according to computed tomography imaging in our institution.Then analyzed the anatomic distribution of supraclavicular region lymph nodes to outline the spatial and probabilistic distributions of lymph nodes,and to provide data for an evidence-based approach to supraclavicular region radiation therapy field design.Methods A total of 103 thoracic esophageal carcinoma patients after surgery experienced supraclavicular lymph nodes metastasis were retrospectively examined.The supraclavicular region is further divided into four subgroups.Using hand drawings registration,nodes were mapped to a template computed tomogram to provide a visual impression of nodal frequencies and anatomic distribution.Results In all,158 nodes were considered to be clinical metastatic in the supraclavicular region in the 101 patients,74 on the left and 84 on the right.7 of 158(4.4%)positive lymph nodes were located in group I,78 of 158(49.37%)were located in group?,72 of 158 nodes(45.6%)were located in group ?,1 of 158(0.63%)located in group ?.Conclusions According to our results,the supraclavicular group ? and group III are considered to be the high risk regions of ESCC lymph node metastasis,which were defined as elective nodal irradiation areas.