Survival Analysis And Pattern Of Local Recurrence For R0Resected Stage Ⅲ-pN2 Non-Small Cell Lung Cancer

Objective: For resectable non-small cell lung cancer(NSCLC)of stage III-pN2,the prognosis of patients with different resectable states and pathological stage of mediastinal lymph node is significantly different,individualized treatments like surgery combined with chemoradiotherapy are required.The value of PORT in stage III-pN2 was unknown,studies have shown that a new radiotherapy technology can significantly reduce local recurrence and survival benefit.Defined postoperative recurrence pattern and high-risk of local recurrence group can improve the accuracy and pertinence of postoperative radiotherapy.This study aimed to verify the efficacy of PORT and find patients with high postoperative local recurrence risk and explore the locoregional relapse(LR)patterns to provide a reference for PORT CTV delineation in patients with R0 resected stage III-pN2 NSCLC.Methods: 183 patients with resected stage III-pN2 NSCLC from Hunan Cancer Hospital between 2013 and 2016 were divided into two groups for postoperative chemotherapy(POCT)(n=105)or combination chemotherapy and radiotherapy(POCRT)(n=78).The LRFS and OS were compared,the factors affecting local recurrence were illustrated,the sites of local recurrence based on the lobe of primary tumor and region of positive lymph node were described.Result: PORT leads to a strikingly lower risk for local recurrence(29m vs.17 m,P< 0.001)and brought superior OS benefit(34m vs.29 m,P=0.008).After PSM,PORT still increased the median LRFS(28m vs.18 m,P=0.013)and Translate into a survival benefit trend(34m vs.29 m,P=0.080).For different pN2 Subclassification,Patients with multiple-station pN2±pN1 disease had the worst LRFS(11 months)and single-station pN2+multiple station pN1 disease had a relatively short LRFS(24 months),in group POCT,PORT significantly prolonged LRFS of multi-station pN2(27m vs.11 m,P < 0.001).Short LRFS is correlated with non-PORT(P< 0.001),multiple-station pN2(P=0.003),older age(Y>55)(P=0.028),patients with a high positive LN ratio>1/3(P=0.029)and a poor tumor histological differentiation degree(P=0.001).In group POCT,Local recurrence(first or cumulative)occurred in 50 patients,the most frequent failure site occurs at the ipsilateral hilum(21.0%),the bronchial stump(20.0%),followed by LNs4R(19.0%),LNs4L(18.1%),LNs7(15.2%),most of left-sided tumors more frequently involved the contralateral mediastinum,whereas the ipsilateral recurrences dominated for right-sided tumors,especially for LNs4 R.In group POCRT,Local recurrence(first or cumulative)occurred in 17 patients,the highest failure site was the bronchial stump(11.5%),followed by LNs4L(8.97%),LNs1(7.69%),the ipsilateral hilum(6.41%)and LNs4R(6.41%).Conclusion: PORT remarkably reduced local recurrence and a tendency to improved OS in stage III-pN2 NSCLC.The definition of CTV might according to the lung lobe in which the tumor is located.Except the bronchial stump,the ipsilateral hilum and positive lymph node regions,LNs4,LNs7,LNs5 and LNs6 may be considered within CTV for left-side lung,LNs4 R and LNs7 should be considered within CTV for right-side lung.