Hot spots and trends related to chemotherapy in nasopharyngeal carcinoma [2014–2024]: a bibliometric study

Introduction

Nasopharyngeal carcinoma (NPC) exhibits a distinctive geographic distribution, particularly prevalent in East and Southeast Asia, where NPC with Epstein-Barr virus (EBV), a herpesvirus linked to NPC pathogenesis, demonstrates high sensitivity to radiotherapy and platinum-based chemotherapy, whereas the squamous histologic subtype (which has been proposed to be related to human oncolytic virus) is much less radiosensitive and clinically more aggressive (1). Over the past decade, epidemiologic studies have revealed a gradual decrease in incidence and a significant reduction in mortality rates (2). This decline has been attributed to advancements in living standards and healthcare services in endemic regions, notably the clinical implementation of individualized chemotherapy and intensity-modulated radiotherapy (IMRT) (3). These findings may also reflect changes in lifestyle and environmental factors, a deeper understanding of pathogenesis and risk factors, population-based screening programs, advancements in imaging techniques, and the adoption of individualized integrated radiotherapy strategies (4). The therapeutic landscape of chemotherapy in NPC has evolved, transitioning from single-agent chemotherapy to combination chemotherapy, and ultimately to the integration of targeted therapy and immunotherapy. This evolution demonstrates the gradual progression and diversification of therapeutic approaches. Recent studies have showed that combination chemotherapy, especially when paired with immunotherapy, can markedly reduce the recurrence rate of NPC and enhance patient survival rates (5-7). Therefore, in this paper, we conducted a comprehensive search of articles related to chemotherapy in NPC in the Web of Science Core Collection (WoSCC). By employing bibliometric analysis, we summarized the key developments in this field over the past 10 years. Furthermore, we utilized knowledge mapping and visualization techniques to quantitatively present the development trends and comprehensively analyze the advancements and concerns within the field. We present this article in accordance with the BIBLIO reporting checklist (available at https://cco.amegroups.com/article/view/10.21037/cco-25-12/rc).

Methods

Bibliometrics

Bibliometrics is a field of study that examines the quantity, distribution, and developmental patterns of literature, particularly within the academic sphere. This discipline primarily employs quantitative analysis and statistical methodologies to investigate literature, thereby elucidating trends, influences, and the structural dynamics of academic research (8). As a subset of informatics, bibliometrics integrates components of statistics, library science, and computer science. Its applications are extensive, encompassing areas such as the assessment of academic research, the calculation of journal impact factors, the forecasting of scientific research trends, and the analysis of academic impact (9).

Visualization and analysis

Utilizing CiteSpace and VOSviewer to construct knowledge maps allows for the maximization of their distinct advantages and the attainment of complementary functionalities. CiteSpace employs data standardization grounded in set theory principles, which serves as the foundation for assessing the similarity of knowledge units (10). Its similarity algorithm facilitates the generation of Timezone and Timeline views across temporal segments, thereby elucidating the evolution of knowledge and the historical context of literature within specific clusters on the timeline. This feature aids in acquiring insights into the dynamics and trends within the field (11). In contrast, VOSviewer employs probabilistic data standardization to offer a diverse array of visualization formats, encompassing keywords, collaborative research institutions, co-authors, and other dimensions, including Network Visualization, Overlay Visualization, and Density Visualization (12). VOSviewer is particularly noted for its user-friendly interface and aesthetically pleasing visual outputs. In this study, a visualization analysis was conducted on 841 articles concerning subject headings, leading to the preliminary identification of gemcitabine and cisplatin-induced chemotherapy for NPC as a prominent contemporary research topic (13).

Search strategy

This research employed the WoSCC as the primary source for data collection, as it is a highly regarded digital literature database acknowledged by numerous scholars and is considered an optimal platform for conducting bibliometric analyses. To ensure the thoroughness and precision of the data obtained, the indices utilized in this study were Science Citation Index Expanded (SCI-EXPANDED) and Social Sciences Citation Index (SSCI). The search strategy implemented was “TI (nasopharyngeal carcinoma) AND (chemotherapy)”, covering a time frame from January 2014 to December 2024. A total of 870 articles were initially retrieved; however, following a process of screening and de-duplication (manually removing some publication types, such as correction, letter, early access, proceeding paper, and retracted publication, and some duplicate literatures), 846 valid papers were ultimately included in the analysis. The types and proportions of the literature are illustrated in Figure 1.

Figure 1 Proportion of publications regarding chemotherapy in NPC over the past 10 years. NPC, nasopharyngeal carcinoma.

Results

Publication year analysis

A comprehensive screening and de-duplication process utilizing the aforementioned search methodologies yielded a total of 846 pertinent documents spanning the years 2014 to 2024. Specifically, 24 documents were identified in 2014, with a subsequent increase observed in the following years. Notably, the year 2021 marked the apex of document publication within the decade, with a total of 115 documents recorded. In the ensuing 3 years, a modest decline in the number of documents was noted (Figure 2).

Figure 2 Growth trends of publications on chemotherapy in NPC from 2014 to 2024. NPC, nasopharyngeal carcinoma.

Analysis of country and institutional collaboration

To analyze the significant contributions made by various countries in the domain of nasopharyngeal cancer chemotherapy, a co-occurrence analysis was performed utilizing VOSviewer for countries with five or more publications (refer to Figure 3). In this figure, the size of the circular nodes corresponds to the volume of publications from each country; larger nodes indicate a higher number of publications. The connecting lines between the nodes represent the strength of collaboration, with thicker lines denoting more frequent partnerships in publishing. The color of the nodes serves to differentiate between various clustering groups. An examination of Figure 3 reveals a markedly uneven distribution of publications within this research area, highlighting a pronounced concentration of contributions from a limited number of countries.

Figure 3 Country collaboration on chemotherapy of NPC. NPC, nasopharyngeal carcinoma.

A full analysis of the leading countries in this domain is presented in Table 1, which enumerates the top 5 nations based on the volume of published papers. The data indicate that Chinese researchers have made the most significant contributions, with a total of 742 publications, representing over half of the overall output in this field; however, the average citation count for these works is relatively low. The United States follows closely, having published 68 papers that garnered a total of 1,895 citations. Notably, France exhibits the highest average citation rate, with its 10 publications cited a cumulative 715 times, resulting in an average of 71.5 citations per paper. Furthermore, an analysis of institutional co-occurrence reveals that Sun Yat-sen University has made notable contributions to the study of NPC chemotherapy. Table 2 details the top 15 institutions ranked by publication volume, the majority of which are located in China.

Analysis of author

Based on an analysis conducted by VOSviewer on authors with five or more publications, Jun Ma emerges as the most prolific contributor within this cohort, having authored 63 publications that collectively garnered 2,386 citations from 2014 to 2024, resulting in an average citation rate of 37.87% per publication. He is closely followed by Ying Sun, who ranks second with 50 publications that have received a total of 1,632 citations, yielding an average citation rate of approximately 32.64% per publication (Table 3). It is noteworthy that Jun Ma and Ying Sun are affiliated with Shanghai Jiao Tong University and Sun Yat-sen University, respectively, and have engaged in several collaborative research efforts. Their published works predominantly concentrate on the integration of induction chemotherapy with concurrent radiotherapy (14). Additionally, Zhang and colleagues have made significant contributions to the field of induction chemotherapy utilizing gemcitabine and cisplatin for the treatment of NPC (15), with a particular emphasis on the effects of chemotherapy on the prognosis (16) and survival rates of patients diagnosed with advanced NPC (Figure 4).

Figure 4 Author collaboration on chemotherapy of NPC. NPC, nasopharyngeal carcinoma.

Analysis of journal

A statistical analysis of the journals in which relevant literature has been published indicates that, over the past decade, research papers in this domain have predominantly appeared in journals focused on oncology, radiotherapy, and chemotherapy. Table 4 provides a comprehensive overview of the top 20 journals ranked by the volume of published articles. Notably, the International Journal of Radiation Oncology Biology Physics, the Journal of Clinical Oncology, and Frontiers in Oncology lead the list with 88, 74, and 49 articles, respectively. Additionally, it is important to highlight that the Annals of Palliative Medicine and the Annals of Oncology are the two journals with the highest impact factors among the top 20 in terms of publication volume. A further examination of the citation metrics reveals that the European Journal of Cancer boasts the highest average citation rate at 42.41%, based on a total of 12 articles. Overall, the majority of the top 20 journals are centered on the fields of oncology and radiotherapy.

Keyword analysis

A visual analysis of the chemotherapy domain pertaining to nasopharyngeal cancer was conducted using VOSviewer. Figure 5 illustrates both the network view and density view for keywords that appeared 15 or more times, where each point signifies a keyword, and the connecting lines between points indicate the co-occurrence relationships among these keywords. The diameter size of the dots visualized the frequency of keyword occurrence, and all keywords were categorized into five clusters. The network view (Figure 5A) highlights a green cluster centered around the term “nasopharyngeal carcinoma”, with closely associated keywords such as “cancer”, “chemotherapy”, “adjuvant chemotherapy”, and “cisplatin”. Variations in frequency are depicted in the density view provided by VOSviewer (Figure 5B). A more detailed understanding of the keywords within each cluster can be obtained from Table 5. By integrating this analysis with the timeline spectrum analysis of keywords presented in Figure 6, alongside relevant literature, it becomes evident that recent research has predominantly focused on the prognosis and survival outcomes associated with NPC chemotherapy, adjuvant chemotherapy, and induction chemotherapy (17). Furthermore, multicenter randomized controlled trials involving various chemotherapeutic agents have demonstrated that synchronous chemotherapy and adjuvant chemotherapy (18) significantly enhance the overall survival rates of patients diagnosed with regionally advanced NPC (19).

Figure 5 The mapping of keywords in chemotherapy of NPC studies. (A) Network visualization; (B) density visualization. NPC, nasopharyngeal carcinoma.

Table 5

Cluster of keywords in the field of chemotherapy of NPC

Cluster	Color	Keywords
1		Cisplatin, chemotherapy, head, multicenter, radiation, therapy, 5-fluorouracil, neck, cetuximab, antitumor-activity, combination, gemcitabine, nimotuzumab, recurrent, phase-II trial, express
2		Nasopharyngeal carcinoma, DNA, concurrent chemoradiotherapy, radiotherapy, Barr-virus DNA, impact, induction chemotherapy, neoadjuvant chemotherapy, prognostic value, nomogram, radiomics, staging system, survival, tumor response
3		Comparing neoadjuvant, Epstein-Barr-virus, cisplatin-radiotherapy, long-term survival, neck-cancer, phase-III, therapeutic gain, progression-free survival, modulated radiation-therapy
4		Cancer, chemoradiation, conventional 2-dimensional rad, experience, intensity-modulated radiotherapy, neoadjuvant, outcomes, patterns, prognosis, concurrent chemotherapy, toxicity
5		Docetaxel, 5-fluorauracil, meta-analysis

NPC, nasopharyngeal carcinoma.

Figure 6 A timeline spectrum of keywords in the field of chemotherapy of NPC based on CiteSpace. NPC, nasopharyngeal carcinoma.

Discussion

Bibliometrics originated at the beginning of the 20^th century and evolved into a distinct academic discipline by 1969 (20). Since then, it has been extensively utilized in the domain of document analysis (21). This discipline provides bibliometric analytical methods that facilitate a quantitative assessment (22) of the existing literature within specific academic fields (23). Through bibliometric analysis, researchers can extract a variety of detailed data, including information on authors, keywords, journals, countries, research institutions, and references. Co-citation analysis is frequently employed within bibliometrics; it identifies correlations when two papers are cited together by one or more other papers, making it particularly suitable for visual representation. A study conducted in 1992 underscored the significance of visualization techniques in co-citation analysis, asserting that such methods enhance the comprehensiveness of analytical outcomes. It is important to note that various elements of a publication—such as authors, keywords, research institutions, and countries—can be subjected to this analytical approach. Visualization aids in uncovering potential relationships among these elements, including shared research themes among different authors, the scientific priorities of various institutions, and the emergence of new theories from established entities.

This study conducts a bibliometric analysis of scholarly articles pertaining to chemotherapy in NPC over the past decade. A substantial portion of the literature examined is considered seminal within this domain, with the objective of updating readers on the latest advancements and prospective research trajectories. Furthermore, we identify key journals, institutions, and authors that serve as reliable sources of information on this subject. Notably, while The Lancet and Annals of Oncology are recognized as high-impact journals and are at the forefront of the field, there are also several articles published in lower-impact journals that demonstrate significant productivity.

As a core producing country (742 articles), China has formed a “high-yield” research cluster through institutions such as Sun Yat-sen University and Shanghai Jiao Tong University, but mainly published in midstream journals such as Frontiers in Oncology (with low citation rates), reflecting that its scale advantage has not yet been fully transformed into influence. France (10 articles), relying on the European Cancer Research Network, has published their results in the European Journal of Cancer (42 times per article), forming a “refined” transmission path, while the United States is in between the two. The collaboration between Jun Ma’s team from Sun Yat-sen University (63 articles) and Ying Sun’s team from Shanghai Jiao Tong University (50 articles) has not only promoted the growth of research volume in China, but also transformed the “induction chemotherapy + radiotherapy” scheme into a field consensus through professional journals such as the International Journal of Radiation Oncology, reflecting the high matching of institutional research direction and journal positioning.

In recent years, many scholars have devoted themselves to the study of combination chemotherapy, induction chemotherapy, and adjuvant chemotherapy in the treatment of NPC. For instance, the combination of gemcitabine and cisplatin has been shown to elicit a B cell-centered effector T cell response, indicating that chemotherapy may serve as an effective adjunct to immune checkpoint inhibitors (ICIs). This effect is achieved through the upregulation of major histocompatibility complex (MHC) class I expression, which directly influences tumor immunogenicity, while simultaneously enhancing the efficacy and proliferation of CD8 T cells via improved interactions between innate-like B cells (ILB) and effector T cells (24). The chemotherapy-induced remodulation of the tumor immune microenvironment (TIME) underscores the potential for synergistic therapies involving ICIs. Additionally, the use of terazepril or placebo in conjunction with chemotherapeutic agents has been explored, with these induction chemotherapies demonstrating a survival advantage for patients with locally advanced NPC, thereby contributing to the existing body of knowledge (25). Pembrolizumab has recently exhibited antitumor efficacy and a favorable safety profile across various tumor types, leading to its approval in over 60 countries for the treatment of multiple advanced malignancies (26). In the context of intensity-modulated radiochemotherapy, neoadjuvant chemotherapy should be considered, particularly for patients with high-risk disease, including those with advanced lymph node involvement (27). Furthermore, there is a growing interest in investigating novel applications of ICIs in adjuvant therapy (28). Consequently, the future management of locally advanced NPC may increasingly involve a combination of radiotherapy and immunotherapy, reflecting an emerging trend in treatment strategies (29).

Extensive research conducted by numerous scholars on the pathogenesis of NPC has led to significant advancements in treatment modalities, particularly the combination of chemotherapy and immunotherapy, with a focus on ICIs such as programmed cell death-protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors. The customization of chemotherapy regimens has emerged as a prominent area of investigation. Through genetic testing and other methodologies, specific genetic variants in patients can be identified, enabling the formulation of targeted chemotherapy regimens aimed at enhancing therapeutic efficacy while minimizing adverse effects. Additionally, the continuous emergence of novel pharmacological agents, including targeted therapies and cellular immunotherapy, offers promising new treatment avenues for patients diagnosed with NPC. The development and implementation of these innovative drugs contribute to expanding the therapeutic options available for this patient population.

Limitation

The database selected for this study is the WoSCC. While it is recognized as one of the most widely employed and effective databases, it is essential to note that it may overlook a limited number of articles. Additionally, the WoSCC is predominantly comprised of journals published in English (30), which has been established as the lingua franca of scientific discourse. This may result in a potential bias against non-English literature. Furthermore, the Matthew effect (31) suggests that citation counts, often used as a metric for assessing scientific quality, may be skewed. Lastly, the rapid proliferation of relevant publications in the field may lead to discrepancies between the bibliometric data analyzed and the actual advancements in research.

Conclusions

In summary, high output journals form a close mutual relationship with core authors. The research of these authors is mostly published in professional journals of tumor radiotherapy, chemotherapy and radiotherapy, and the journals further consolidate their academic influence by publishing their high-quality achievements, forming a targeted matching of "research topic publication platform". This paper further elucidates the key areas of focus and prospective directions for future inquiry within this domain.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the BIBLIO reporting checklist. Available at https://cco.amegroups.com/article/view/10.21037/cco-25-12/rc

Peer Review File: Available at https://cco.amegroups.com/article/view/10.21037/cco-25-12/prf

Funding: This article was supported by the Research Project of Nantong Municipal Health Commission (No. MS2023005) and the Nantong Science and Technology Project (No. MS2024030).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://cco.amegroups.com/article/view/10.21037/cco-25-12/coif). The 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.

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/.

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