Frequencies of ALK rearrangements in lung adenocarcinoma subtypes: a study of 2299 Chinese cases

Yu et al. SpringerPlus (2016) 5:894 DOI 10.1186/s40064-016-2607-5 Open Access RESEARCH Frequencies of ALK rearrangements in lung adenocarcinoma subtypes: a study of 2299 Chinese cases Yongfeng Yu1†, Zhengping Ding1†, Lei Zhu2, Haohua Teng2 and Shun Lu1* Abstract Purpose: This study aimed to determine the relationship between ALK status and lung adenocarcinoma subtypes, according to the IALSC/ATS/ERS classification in Chinese patients. Methods: A reclassification of 2299 surgically resected lung adenocarcinomas was performed, and ALK status was detected by immunohistochemistry (Ventana Medical Systems) in Shanghai Chest Hospital. Results: ALK rearrangements were identified in 93 of 2299 tumors (4.0 %). The ALK rearrangements frequencies were: 14.8 % (16/108), 10.3 % (20/195), 7.6 % (13/170), 2.8 % (29/1035), 2.5 % (3/119), 2.0 % (11/539), 0.9 % (1/114), and 0 % (0/19) for variants of invasive adenocarcinoma, solid predominant, micropapillary predominant, acinar predominant, minimally invasive adenocarcinoma, papillary predominant, lepidic predominant, and adenocarcinoma in situ, respectively. Conclusions: We reported significant discrepancies of ALK status in lung adenocarcinoma subtypes in Chinese patients. Keywords: Lung adenocarcinoma, Histologic classification, ALK status Background Lung cancer is the leading cause of cancer related mortality in both men and women worldwide (Jemal et al. 2011). Adenocarcinoma has become the most common histologic type of non–small cell lung cancer (NSCLC), accounting for nearly 40 % of all lung cancer cases, and it is a heterogeneous tumor. In 2011, the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) proposed a new classification system for lung adenocarcinoma (Travis et al. 2011). The 2015 WHO classification of lung adenocarcinoma is consistent with the IALSC/ATS/ERS classification in resection specimens (Travis et al. 2015). *Correspondence: † Yongfeng Yu and Zhengping Ding contributed equally to this work 1 Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Xuhui District, Shanghai 200030, China Full list of author information is available at the end of the article ALK rearrangements in NSCLC were first described in lung adenocarcinomas. Approximately 3–6 % of lung adenocarcinoma were shown to harbor rearrangements of the ALK gene, which has been demonstrated to be a potent oncogenic driver and a promising therapeutic target (Paik et al. 2011). The US Food and Drug Administration (FDA) has approved crizotinib to treat locally advanced or metastatic ALK rearrangements lung adenocarcinomas (Shaw et al. 2013). Detecting ALK rearrangement is emerging as an important component of the pathologic analysis of lung adenocarcinomas. However, whether ALK status in lung adenocarcinomas correlates with histologic subtypes remains unclear. The aim of this study was to evaluate whether or not the proposed IASLC/ATS/ERS classification correlates with ALK status in Chinese patients. © 2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Yu et al. SpringerPlus (2016) 5:894 Methods Patients and eligibility All patients had received curative surgery with pathologic stage I to stage III lung adenocarcinomas at Shanghai Chest Hospital between July 2013 and December 2014. These patients did not receive previous chemotherapy or radiotherapy before surgery. Histological typing confirmed the lung adenocarcinoma according to the 2004 World Health Organization classification criteria. Lung cancer staging was performed for all the patients according to the seventh TNM classification. For all patients, medical records were reviewed to extract data on clinicopathologic characteristics. This study was approved by Shanghai Chest Hospital Ethics Committee. Histological evaluation All these tumor samples were fixed in 10 % neutral buffered formalin, embedded in paraffin and stained with hematoxylin and eosin in the routine manner. Each of the slides was reviewed by two pathologists independently. Any discrepancies between the pathologists during determination of predominant subtypes were resolved via consensus by using a multiple-headed microscope. The average number of slides from each case reviewed in the this study was 8 (range 4–26). According to the IASLC/ATS/ERS classification scheme, each tumor was examined using comprehensive histologic subtyping, recording the percentage in 5 % increments for each histologic component. Tumors were classified as adenocarcinomas in situ, minimally invasive adenocarcinomas, and invasive adenocarcinomas, which were divided into lepidic predominant, papillary predominant, acinar predominant, micropapillary predominant and solid predominant. Variants of invasive adenocarcinoma included invasive mucinous adenocarcinoma and others. The predominant pattern was defined as the pattern with the greatest percentage. ALK immunohistochemistry IHC was performed for all cases on 5-μm thick FFPE sections with the D5F3 rabbit anti-human monoclonal antibody (Cell Signaling Technologies) in a Bechmark XT staining module (Ventana Medical Systems, Illkirch Graffenstaden, France). The slides were dried at 60 °C for 1 h, deparaffinized using EZ Prep at 75 °C for 4 min, and incubated with the primary mAb at a dilution of 1:100 for 1 h at 37 °C for all samples. Detection was performed with the OptiView DAB IHC Detection Kit with signal amplification (Ventana Medical Systems). A positive external control consisting of a slide of a previously FISH-validated ALK-rearranged and IHC-positive sample was included. Negative controls consisted of the omission of the primary antibody and incubation with Page 2 of 6 immunoglobulins of the same species. All sections were independently evaluated by two pathologists using a semi-quantitative system based on the H-index: 3× percentage of strongly staining cells + 2× percentage of moderately staining cells + percentage of weakly staining cells, giving “composite scores” that ranged from 0 to 300. Cases with the scores of 0 to 100 were interpreted as negative, 101 to 300 as positive. EGFR mutation analysis Tumor samples were obtained from resected lesions. Tumor DNA was extracted using the QIAamp DNA FFPE tissue kit (Qiagen, Crawley, UK), and EGFR mutation was analyzed using the amplification refractory mutation system (ARMS)-based EGFR mutation detection kit (EGFR RGQ PCR kit, Qiagen, Crawley, UK) as instructed by the manufacturer. The commercial kit allows detection of 29 mutations in the EGFR (...truncated)