Role of Postoperative Radiotherapy in Advanced Stage Non–small Cell Lung Cancer

Abstract

To evaluate outcomes and prognostic factors of postoperative radiotherapy (PORT) for patients with advanced stage non–small-cell lung cancer (NSCLC) at single academic institution. From 2000 to 2007, 88 patients had PORT after curative operation for pathologic Stage III NSCLC at our institution. At diagnosis, median age was 59 years (range, 31–81). Surgical types included pneumonectomy (n = 14), bilobectomy (n = 14), or lobectomy (n = 60) with mediastinal lymph node dissection (MLND) (n = 73) or multi-level mediastinal lymph node sampling (n = 15). Four patients had resection margin involved by tumor. There were 80 patients in Stage IIIA and 8 patients in Stage IIIB. Majority of patients (n = 83) had postoperative N2 disease. Preoperative nodal stage was as follows: 45 patients in N0, 8 patients in N1, and 35 patients in N2. Among 35 preoperative N2 diseases, 30 (85%) patients had single or two station mediastinal lymph node metastasis. Seventy six patients had received radiotherapy using conventional technique. Initially 23.4–56 Gy (median 45 Gy) was delivered to mediastinum and bronchial stump area using opposed AP-PA field arrangement. And then tumor bed received additional 3.6–23.4 Gy (median 9 Gy). 3D-conformal radiotherapy was administered in 12 patients from 2005. Thirty six patients had received chemotherapy; 17 patients with adjuvant chemotherapy, 5 patients with neoadjuvant chemotherapy and 14 patients with both. Median survival was 54 months. Five-year overall survival (OS) and disease free survival (DFS) rates were 45% and 38%, respectively. MLND, total radiation dose greater than 54 Gy and adjuvant chemotherapy did not affect OS (p value = 0.9525, 0.4160, and 0.8956, respectively). Five-year loco-regional recurrence free survival (LRFS) and distant-metastasis free survival (DMFS) rates were 86% and 48%, respectively. Fifty-one relapses occurred at following site: 10 (19%) loco-regional, 41 (81%) distant metastasis. Of 10 loco-regional relapse, 6 relapses occurred in radiation field. Total radiation dose greater than 54 Gy did not reduce loco-regional recurrence (p value = 0.6376). Distribution of distant metastasis was as follows: 11 in lung, 11 in bone, 10 in brain, 4 in kidney, adrenal gland, 3 in non-regional lymph node, and 2 in liver. Administration of adjuvant chemotherapy had no significant effect on distant metastasis (p value = 0.5583). PORT after curative operation for resectable advanced stage NSCLC may reduce loco-regional recurrence and increase overall survival. However, criteria for resectability of Stage III disease should be further defined because of heterogeneous presentation of advanced stage NSCLC. Further efforts are necessary to reduce distant metastasis.