Analysis Of The First Local Recurrence Patterns And Related Factors Of Stage ⅢA-N2 Non-small Cell Lung Cancer Cases Without Postoperative Radiotherapy

Background and ObjectivePostoperative radiotherapy is an important treatment for completely resected stage IIIA-N2 non-small cell lung cancer(NSCLC),but there is no consensus on the scope of irradiation.To analyze the first local recurrence patterns and related factors of stage ⅢA-N2 NSCLC cases without postoperative radiotherapy,and provide a basis for delineation of the radiation range in the high-risk lymphatic drainage area.Material and MethodA retrospective analysis was performed in 75 patients with stage ⅢA-N2 NSCLC who were newly treated in our hospital from 2012 to 2016 and had complete clinical data.Inclusion criteria are as follows: receiving radical resection,histologically proven stageⅢA-N2 NSCLC,not receiving adjuvant therapy or postoperative radiotherapy,receiving postoperative adjuvant chemotherapy,the first recurrence involves a local area with available first recurrence imaging data.Sites of intrathoracic disease recurrence were documented.Diagrams were construced that illustrated sites of failure on the basis of lobe of primary tumor.Failure rates were compared by Chi-square test.ResultThe median time to recurrence was 11 months(3-45 months).Thirty-seven(49.3%)patients had distant metastasis.The most common site of local failure was 4R(44%),followed by 7(43%)and stump(27%).Sites with ≥ 10% failure rate in all subgroups based on location of the primary lesions included 4R,7,the ipsilateral hilum and the stump.Additional sites with ≥ 10% failure rate included 2R,2L,4L and 5 for lesions in the left upper lobe;4L and 5 for lesions in the left lower lobe;and 2R and 3P for lesions in the right upper-middle lobe.The stump failure rate of squamous cell carcinoma was higher than that of adenocarcinoma(56.3% vs 18.0%,p=0.003).The stump failure rate of the patients with tumor diameter ≥5cm was higher than that of the patients with tumor diameter < 5cm(44.0% vs 18.0%,p=0.016).Compared with the patients of nonskip N2 metastasis,the patients with skip N2 metastasis had lower failure rate in ipsilateral hilum(7.5% vs 31.4%,p=0.008).ConclusionFor stage ⅢA-N2 NSCLC patients without postoperative radiotherapy,different lobe had different high-risk recurrence sites,and a ipsilateral recurrences dominated for right-sided tumors,whereas left-sided tumors more frequently involved the bilateral mediastinum,and the local recurrence patterns were influenced by pathological type,tumor size and skip N2 metastasis.This information should be considered in target volume delineation for postoperative radiotherapy.