The 100 most cited articles on lung cancer screening: a bibliometric analysis
Introduction
Lung cancer is the leading cause of cancer death worldwide, causing 24% of all cancer deaths in men and 23% in women (1,2). It is well known that if lung cancer can be treated surgically at an early stage, the prognosis will be significantly improved. However, early-stage lung cancer patients typically are asymptomatic, so that approximately 70% of patients have advanced disease at the time of diagnosis (2). Therefore, many medical and public health institutions have been committed to the early diagnosis and treatment of lung cancer through screening to ultimately thereby reduce deaths from lung cancer.
Since the first publication dedicated to lung cancer screening in 1955 (3), the body of relevant literature in this field has flourished. An evaluation of the most heavily influential or contributory literature will allow us to better understand the knowledge structure of lung cancer screening. A scientific way to recognize the significance of each article is needed since there are many publications and their quality varies substantially.
Bibliometric analysis is a mathematical and statistical method to estimate how much influence or impact a selected research article has on future research (4,5). The role of bibliometrics in academic medicine is increasing. Among all the bibliometric analyses (5-7), citation analysis is the most widely accepted method and measures the number of times an article has been cited by other articles (8-10). The number of citations of a particular article reflects the impact of that article in a specific scientific field. Therefore, a list of the most highly cited articles can help us to understand the important publishing advancements in one research field.
A very recent bibliometric study for research evaluation purposes was published on lung cancer diagnosis and treatment (11) and showed that significant progress had been achieved for molecular subgroup diagnoses and the matched target therapy in advanced lung cancer. However, to the best of our knowledge, no specific bibliographic analysis about lung cancer screening has been published. The aim of this study was to identify and analyze the characteristics of the 100 most cited articles related to lung cancer screening.
Methods
Ethics committee approval was exempted as this study was a retrospective bibliometric analysis of existing published classical studies.
Identification of the 100 most cited articles
We identified articles through the Web of Science (WOS) database, which is considered one of the most popular and well-established resources for clinical researchers interested in the field of citation analysis (12), in January 2020. Key words included “lung cancer screening”, “pulmonary cancer screening”, “lung carcinoma screening”, and “pulmonary carcinoma screening”, with no limitation on time, abstract availability, study type or research subjects. After an extensive search, all the retrieved articles were sorted according to the number of citations. The abstracts or full-texts of all these articles were screened by two reviewers (ML and LZ), and only articles strictly related to the field of lung cancer screening were selected. The articles focused on screening for cancer generally or screening for multiple cancers, including for lung cancer, were also excluded because the citations of these articles may not exactly reflect their influence on the lung cancer screening field.
Article analysis
These articles were analyzed by three reviewers (ML, QC and JWM) who extracted the relevant bibliometric and professional information. For each article, the citation count, language, publication year, journal name along with the latest 2018 journal impact factor (IF) released in 2019, authorship, country of origin, article type and research design of the original study, screening modality focused on by the research, and topic of interest were extracted.
Statistical analysis
The relationship between the IF of a journal and the number of published articles, the IF of a journal and the number of citations of each published article, were analyzed using Pearson correlation. Difference in the publication year of the different screening imaging modalities was compared using Mann-Whitney U test. All analyses were performed by using a statistical software package (SPSS version 21). P values less than 0.05 were considered significant.
Results
The 100 most cited articles regarding lung cancer screening are listed in https://cdn.amegroups.cn/static/application/817dcf099e2d3e0f820d53300b698036/atm-20-3199-1.pdf and are ranked by their number of citations.
Citations
The mean number of citations for the 100 most cited articles was 292.90 (ranging from 100 to 3,910) in total and 23.41 (ranging from 2.42 to 391) per year (https://cdn.amegroups.cn/static/application/817dcf099e2d3e0f820d53300b698036/atm-20-3199-1.pdf). The top 3 cited articles were “Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening” published in the New England Journal of Medicine (NEJM) in 2011, “Early Lung Cancer Action Project: overall design and findings from baseline screening” published in Lancet in 1999, and “Survival of patients with stage I lung cancer detected on CT screening” published in NEJM in 2006.
Language and Year of publication
The top 100 articles were all English and published between 1973 and 2017. Figure 1 shows a graphical representation of the distribution of the 100 most cited articles by decade of publication. The vast majority (n=81) of articles were published after 2000.
Authorship and countries of origin
The total number of authors for the 100 most cited works was 627. Twenty-three prolific authors contributed more than 5 to 9 articles (Table 1). The first authors were from 10 countries with the United States being the most frequent (n=60) (Table 2).
Full table
Full table
Journals
A total of 32 journals published the 100 most cited articles, with 17 journals publishing two or more articles (Table 3). The journal with the highest number of articles was Radiology (n=13), followed by Chest (n=10) and Lung Cancer (n=8). The IF of the 32 journals ranged from 1.301 to 223.679. Statistical analysis showed that there was no significant association between journal IF and the number of published articles (r=0.023, P=0.903). There were significant, but weak positive associations between journal IF and total citations of the published article (r=0.238, P=0.018) and citations per year (r=0.288, P=0.004).
Full table
Lung cancer screening modality
The most common screening modality studied in these 100 most cited articles was low-dose computed tomography (LDCT) (n=78), and all of these studies were published after 1996. LDCT was followed by chest X-ray radiography (CXR) plus sputum cytology (n=11) or only CXR (n=8), with all of these studies being published before 2011 (Table 4) (Figure 2). The publication year of the two-imaging modality (LDCT and CXR) was significantly different (P=0.000).
Full table
Article type, design and topic
Table 5 summarizes the types of article and study designs of the original studies within the 100 most cited articles. The main topics covered in each article are grouped and outlined in Table 6.
Full table
Full table
Discussion
This study is an interdisciplinary study in bibliometrics and medicine. In order to recognize the key contributions and their influence on lung cancer screening, we presented an accessible list of the 100 landmark articles and offered a comprehensive bibliometric and professional analysis.
This bibliometric analysis on publication time showed that the majority (n=80) of the 100 most cited articles were published in this century after 2000, with the earliest article published in 1973. This differs with the bibliometrics published for the whole field of radiology, where the peak time period for the most cited articles was 1990 to 1999 (13-15). However, some subdisciplines depending on advanced radiological techniques, such as CT colonography, oral cone-beam CT and cardiology imaging, show similar peaks after 2000 (16-19). This result suggests that lung cancer screening is still a relatively new field that is evolving rapidly. Our study also showed that 627 authors wrote the 100 most cited articles, and the first authors of 60% of the articles came from institutions in the United States (Table 2). This finding reflects the overwhelming influence of the United States on lung cancer screening research.
In the bibliometric analysis of the published journal, the 100 most cited articles were published among 17 different journals, with the top 3 journals being Radiology, Chest and Lung Cancer. The reason why Radiology garnered the most publications may be due to the critical role of imaging in lung cancer screening. Although most of these articles are related to imaging, such as CXR and LDCT (n=97), we observed that the top 6 cited lung cancer screening articles were all published in top-tier general medicine journals, such as NEJM and Lancet. This might be because top-tier general medical journals usually have higher IFs than specialized radiology journals and also have a more influential and broader readership. Furthermore, lung cancer screening is a multidisciplinary topic and therefore is of interest to a general medical audience.
Analysis of the IF was first proposed in 1955 (20) as IF is probably the most widely used indicator for evaluating the influence of journals in various scientific fields as it reflects the average number of citations to recent articles published in that journal. By convention, IF is based on the previous 2 years. Our study showed that journal IF and number of citations had a significant relationship. Overall, this result of lung cancer screening also seems to follow Bradford’s law which states that most researchers obtain their citations from a few specific core journals (21). However, the relationship between the number of times cited and journal IF was weak (r=0.238), which may be because the journals that published the 100 most cited articles included articles a wide scope of disciplines including radiology, cancer, chest surgery, respiratory or internal medicine, and general medicine. Also, IF widely differs across different disciplines.
A suitable screening test that can accurately detect lung cancer in earlier stages before a person has any symptoms has been sought after for a long time. Through the top 100 most cited articles, we can see that screening tests for lung cancer include CXR, sputum cytology, blood tests, and LDCT. We demonstrated that the large majority of the top 100 most cited articles focused on LDCT, followed by CXR with sputum cytology, as the screening modality. The CXR and sputum studies which included several famous randomized controlled trials (RCTs) sponsored by the National Cancer Institute (NCI) (22-24), showed that these screening modalities did not reduce mortality from lung cancer, even in high-risk smokers (25-28). After 1996, LDCT, a more sensitive radiographic modality, has been studied widely, as 91.8% articles (78/85) investigated LDCT which reflects that LDCT is currently the only widely recognized test for lung cancer screening. New potential practical screening modalities other than LDCT are still exploratory, including biomarkers from plasma or serum with advances in molecular diagnostics and genomics. These, however, have not been used in clinical practice (29). In our study, only 3 articles were relevant to these screening modalities.
Our analysis revealed that the most cited article on lung cancer screening was the 2011 paper “Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening” published in NEJM. This article has been cited 3,910 times. This milestone research from the National Lung Screening Trial (NLST) is the first trial to date that has shown that screening with LDCT reduces lung cancer mortality. The NLST provided confirmatory evidence to support lung cancer screening with LDCT instead of CXR. To date, three screening tests have been studied to determine whether they decrease the risk of dying from lung cancer, and LDCT is the only screening test shown to lower the chance of dying from lung cancer. The results from the NLST and other key studies resulted in the United States Preventative Services Task Force Grade B recommendation to use screening with LDCT for early detection of lung cancer and generated much excitement in the lung cancer community (30).
The bibliometric analysis on article type showed that these 100 most cited articles contained 79 original research articles (including 1 research letter), 10 guideline/consensus/statement, 9 reviews and 2 commentaries. Among the original research articles, there was a higher proportion of RCTs (37.9%) than in other similar bibliographic analyses (Table 5) (17,31,32). These articles covered 10 topics related to lung cancer screening, with screening test effectiveness being the most frequent topic. Lung cancer screening articles cover contains wide range of topics, including high-risk population selection, screening design and protocol, test modality and effectiveness, nodule diagnosis and management, and modality reduction, which require multidisciplinary cooperation and collaboration. Beyond the benefits of mortality reduction and smoking cessation, lung cancer screening can also generate potential harms such as false-positive results, overdiagnosis, radiation risk, and added cost. The potential benefits and risks for each candidate need to be evaluated and balanced, especially by high-level evidenced studies such as RCTs. Moreover, LDCT provides a large number of images, which in the future need to be analyzed by a new computer-assisted system or artificial intelligence (33). These features of lung cancer screening may have resulted in the diverse distribution of article types and topics in our study.
Several limitations to our study should be considered. First, citation analysis maybe not a perfect measure of the impact an article has on its field. Articles published more recently are at a disadvantage because less time has elapsed from the date of publication to allow for citations. Therefore, a potential milestone article published in 2020 was not included in this research (34). However, the number of citations is currently still the best and simplest measurement for studies, and old articles can show the historical development in this field. Second, the impact of self-citations was also not considered. Self-citation has not been shown to have a major impact on bibliometric measures, especially over a long duration (35). Third, the h-index is a new author-level metric that attempts to measure both the productivity and citation impact of the publications and it is considered to be a more comprehensive quantitative measurement of a scholar (10,36,37). However, our study was focus on the article instead of author, so the h-index was not introduced in this study.
In conclusion, this study demonstrates the bibliometric and professional characteristics of lung cancer screening. The results may also provide an important framework to understanding the historical advancements and trends of lung cancer screening as well as the potential future research opportunities for researchers.
Acknowledgments
Funding: None.
Footnote
Data Sharing Statement: Available at http://dx.doi.org/10.21037/atm-20-3199
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/atm-20-3199). ML served as the unpaid Section Editor of Annals of Translational Medicine from Jan 2020 to Dec 2020. Dr. CIH is a named inventor on a number of patents and patent applications relating to the evaluation of pulmonary nodules on CT scans of the chest which are owned by Cornell Research Foundation (CRF). Since 2009, Dr. CIH does not accept any financial benefit from these patents including royalties and any other proceeds related to the patents or patent applications owned by CRF. Dr. CIH is the President and serve on the board of the Early Diagnosis and Treatment Research Foundation. I receive no compensation from the Foundation. The Foundation is established to provide grants for projects, conferences, and public databases for research on early diagnosis and treatment of diseases. Recipients include, I-ELCAP, among others. The funding comes from a variety of sources including philanthropic donations, grants and contracts with agencies (federal and non-federal), imaging and pharmaceutical companies relating to image processing assessments. The various sources of funding exclude any funding from tobacco companies or tobacco-related sources. The other authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Ethics committee approval was exempted as this study was a retrospective bibliometric analysis of existing published classical studies.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
References
- Chen W, Zheng R, Baade PD, et al. Cancer statistics in China, 2015. CA Cancer J Clin 2016;66:115-32. [Crossref] [PubMed]
- Siegel RL, Miller KD, Jemal A. Cancer statistics, 2019. CA Cancer J Clin 2019;69:7-34. [Crossref] [PubMed]
- Guiss LW. Mass roentgenographic screening as a lung-cancer-control measure. Cancer 1955;8:219-36. [Crossref] [PubMed]
- Cooper ID. Bibliometrics basics. J Med Libr Assoc 2015;103:217-8. [Crossref] [PubMed]
- Durieux V, Gevenois PA. Bibliometric indicators: quality measurements of scientific publication. Radiology 2010;255:342-51. [Crossref] [PubMed]
- Garner RM, Hirsch JA, Albuquerque FC, et al. Bibliometric indices: defining academic productivity and citation rates of researchers, departments and journals. J Neurointerv Surg 2018;10:102-6. [Crossref] [PubMed]
- Cabezas-Clavijo A, Robinson-Garcia N, Escabias M, et al. Reviewers' ratings and bibliometric indicators: hand in hand when assessing over research proposals? PLoS One 2013;8:e68258 [Crossref] [PubMed]
- Garfield E. Citation analysis as a tool in journal evaluation. Science 1972;178:471-9. [Crossref] [PubMed]
- Moed HF. New developments in the use of citation analysis in research evaluation. Arch Immunol Ther Exp (Warsz) 2009;57:13-8. [Crossref] [PubMed]
- Choudhri AF, Siddiqui A, Khan NR, et al. Understanding bibliometric parameters and analysis. Radiographics 2015;35:736-46. [Crossref] [PubMed]
- Samanci NS, Celik E. The top 100 cited articles in lung cancer - a bibliometric analysis. Contemp Oncol (Pozn) 2020;24:17-28. [Crossref] [PubMed]
- Kulkarni AV, Aziz B, Shams I, et al. Comparisons of citations in Web of Science, Scopus, and Google Scholar for articles published in general medical journals. JAMA 2009;302:1092-6. [Crossref] [PubMed]
- Yoon DY, Yun EJ, Ku YJ, et al. Citation classics in radiology journals: the 100 top-cited articles, 1945-2012. AJR Am J Roentgenol 2013;201:471-81. [Crossref] [PubMed]
- Brinjikji W, Klunder A, Kallmes DF. The 100 most-cited articles in the imaging literature. Radiology 2013;269:272-6. [Crossref] [PubMed]
- Yoon SJ, Yoon DY, Ja Lim K, et al. The 100 top-cited articles focused on magnetic resonance: a bibliometric analysis. Acta Radiol 2019;60:710-5. [Crossref] [PubMed]
- Khan MS, Ullah W, Riaz IB, et al. Top 100 cited articles in cardiovascular magnetic resonance: a bibliometric analysis. J Cardiovasc Magn Reson 2016;18:87. [Crossref] [PubMed]
- O'Keeffe ME, Hanna TN, Holmes D, et al. The 100 most-cited original articles in cardiac computed tomography: A bibliometric analysis. J Cardiovasc Comput Tomogr 2016;10:414-23. [Crossref] [PubMed]
- Mohammed MF, Chahal T, Gong B, et al. Trends in CT colonography: bibliometric analysis of the 100 most-cited articles. Br J Radiol 2017;90:20160755 [Crossref] [PubMed]
- Wu Y, Tiwana H, Durrani M, et al. Hallmark of success: top 50 classics in oral and maxillofacial cone-beam computed tomography. Pol J Radiol 2018;83:e11-8. [Crossref] [PubMed]
- Garfield E. Citation indexes for science; a new dimension in documentation through association of ideas. Science 1955;122:108-11. [Crossref] [PubMed]
- Brookes BC. Bradford's law and the bibliography of science. Nature 1969;224:953-6. [Crossref] [PubMed]
- Fontana RS, Sanderson DR, Woolner LB, et al. Lung cancer screening: the Mayo program. J Occup Med 1986;28:746-50. [Crossref] [PubMed]
- Melamed MR, Flehinger BJ, Zaman MB, et al. Screening for early lung cancer. Results of the Memorial Sloan-Kettering study in New York. Chest 1984;86:44-53. [Crossref] [PubMed]
- Frost JK, Ball WC Jr, Levin ML, et al. Early lung cancer detection: results of the initial (prevalence) radiologic and cytologic screening in the Johns Hopkins study. Am Rev Respir Dis 1984;130:549-54. [PubMed]
- Oken MM, Hocking WG, Kvale PA, et al. Screening by chest radiograph and lung cancer mortality: the Prostate, Lung, Colorectal, and Ovarian (PLCO) randomized trial. JAMA 2011;306:1865-73. [Crossref] [PubMed]
- Strauss GM, Gleason RE, Sugarbaker DJ. Screening for lung cancer. Another look; a different view. Chest 1997;111:754-68. [Crossref] [PubMed]
- Kubik A, Parkin DM, Khlat M, et al. Lack of benefit from semi-annual screening for cancer of the lung: follow-up report of a randomized controlled trial on a population of high-risk males in Czechoslovakia. Int J Cancer 1990;45:26-33. [Crossref] [PubMed]
- Eddy DM. Screening for lung cancer. Ann Intern Med 1989;111:232-7. [Crossref] [PubMed]
- Sozzi G, Boeri M, Rossi M, et al. Clinical utility of a plasma-based miRNA signature classifier within computed tomography lung cancer screening: a correlative MILD trial study. J Clin Oncol 2014;32:768-73. [Crossref] [PubMed]
- Moyer VA, Force USPST. Screening for lung cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2014;160:330-8. [Crossref] [PubMed]
- Jin K, Hu Q, Xu J, et al. The 100 most cited articles on thoracic surgery management of lung cancer. J Thorac Dis 2019;11:4886-903. [Crossref] [PubMed]
- Mohammed MF, Marais O, Qureshi AI, et al. The Top 100 Most-Cited Articles in Stroke Imaging: A Bibliometric Analysis. Curr Probl Diagn Radiol 2018;47:161-7. [Crossref] [PubMed]
- Arimura H, Katsuragawa S, Suzuki K, et al. Computerized scheme for automated detection of lung nodules in low-dose computed tomography images for lung cancer screening. Acad Radiol 2004;11:617-29. [Crossref] [PubMed]
- de Koning HJ, van der Aalst CM, de Jong PA, et al. Reduced Lung-Cancer Mortality with Volume CT Screening in a Randomized Trial. N Engl J Med 2020;382:503-13. [Crossref] [PubMed]
- Swanson EW, Miller DT, Susarla SM, et al. What Effect Does Self-Citation Have on Bibliometric Measures in Academic Plastic Surgery? Ann Plast Surg 2016;77:350-3. [Crossref] [PubMed]
- Hicks D, Wouters P, Waltman L, et al. Bibliometrics: The Leiden Manifesto for research metrics. Nature 2015;520:429-31. [Crossref] [PubMed]
- Hirsch JE. An index to quantify an individual's scientific research output. Proc Natl Acad Sci U S A 2005;102:16569-72. [Crossref] [PubMed]