Patterns of Local-Regional Failure in Completely Resectable IIIA-N2 Non-Small Cell Lung Cancer: Implications for Postoperative Radiation Target Volumes Design

Abstract

This study aimed to analyze patterns of local-regional failure (LRF) in completely resected pIIIA-N2 non-small cell lung cancer (NSCLC) to guide the design of target volumes for postoperative radiotherapy (PORT). From Jan. 2003 to Jan. 2015, consecutive patients with pIIIA-N2 NSCLC who had undergone complete resection with or without adjuvant chemotherapy in our hospital were retrospectively reviewed. Those who had received no PORT, with margin-negative resection and exact failure patterns were included in this study. Patterns were constructed to illustrate sites of first failure on the basis of the location of primary tumor. The clinicopathological factors related to LRF were assessed. With a median follow-up of 27 months, 554 of 1024 patients (54.1%) experienced treatment failure. Of the 233 patients with LRF as the first event, the most frequent site of LRF was the ipsilateral lymph node station 4 (16.3%), followed by lymph node station 7 (10.8%), ipsilateral lymph node station 2 (10.7%) and bronchial stump (9.5%). For left-sided lung cancer, the most common LRF site was 4L (13.8%), followed by 4R (12.2%), bronchial stump (11.4%), 7 (10.3%) and 6 (9.4%). For right-sided lung cancer, the most common site was 4R (18.2%), followed by 2R (15.3%), 7 (11.0%), right supraclavicular fossa (10.1%) and bronchial stump (8.1%). Patients with squamous cell carcinoma were more likely to experience bronchial stump recurrence than those with non-squamous cell carcinoma (35.5% vs. 19.1%, p=0.006). While, the patterns of failure in the hilum, mediastinum and supraclavicular fossa did not differ significantly between squamous cell carcinoma and non-squamous cell carcinoma. Patients with preoperative cN2 were more likely to have recurrence of the contralateral hilum than those with cN0-1 (7.4% vs. 1.0%, p=0.03). No difference in patterns of LRF was observed among T1, T2 and T3. Adjuvant chemotherapy had no significant impact on patterns of LRF. For patients with completely resected pIIIA-N2 NSCLC, the ipsilateral lymph node station 4, 7, 2 and bronchial stump are the most common LRF sites. Besides, LRF of 4R and 6 for left-lung cancer and contralateral hilum for cN2 disease is more common, which should also be included in PORT.