• Gouji Toyokawa, Kazuki Takada, Tatsuro Okamoto, Satoshi Kawanami, Yuka Kozuma, Taichi Matsubara, Naoki Haratake, Shinkichi Takamori, Takaki Akamine, Masakazu Katsura, Yuichi Yamada, Fumihiro Shoji, Shingo Baba, Takeshi Kamitani, Yoshinao Oda, Hiroshi Honda, and Yoshihiko Maehara.
• Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: gouji104kawa@gmail.com.
• Ann. Thorac. Surg. 2017 Jun 1; 103 (6): 1750-1757.

BackgroundProgrammed death ligand 1 (PD-L1) was reported to predict the response of immunotherapy; however, the association between PD-L1 expression and radiologic and pathologic features has yet to be elucidated.MethodsIn all, 292 patients with resected pathologic stage I adenocarcinoma were analyzed for PD-L1 expression by immunohistochemistry and evaluated to determine the association between PD-L1 expression and the radiologic/pathologic invasiveness. Specifically, the radiologic invasiveness and noninvasiveness were determined based on the consolidation/tumor ratio, with a cutoff value of 0.25 by thin-section computed tomography.ResultsAmong 292 patients, 47 (16.1%) were positive for PD-L1 expression; the remaining 245 patients (83.9%) were negative for PD-L1 expression. Fisher's exact test demonstrated that PD-L1 expression was significantly associated with a higher consolidation/tumor ratio (p = 0.029) and higher maximum standardized uptake value (p = 0.004). The mean values of consolidation/tumor ratio and maximum standardized uptake in patients with and without PD-L1 expression were 0.845 ± 0.052 and 7.241 ± 0.795, and 0.607 ± 0.023 and 3.60 ± 0.364, respectively (p < 0.001 and p < 0.001, respectively). Among 47 adenocarcinomas harboring PD-L1 expression, the frequencies of PD-L1 expression for consolidation/tumor ratios of 0, 0.1 to 0.25, 0.26 to 0.5, and 0.51 or more were 6.4%, 2.1%, 4.3%, and 87.2%, respectively (p = 0.007). Pathologically, PD-L1 was identified exclusively only in more invasive subtypes, not in less invasive ones, such as atypical adenomatous hyperplasia, adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic predominant ones (p < 0.001).ConclusionsExpression of PD-L1 was significantly associated with radiologic/pathologic invasive adenocarcinomas. This study provides the first evidence of the radiologic and pathologic invasiveness in resected pathologic stage I adenocarcinoma with PD-L1 expression.Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

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