Bibliometric analysis of immunotherapy for bladder cancer: A correspondence

To the Editor

We have recently engaged in a thorough examination of the erudite work authored by Lv et al., titled “Knowledge-map analysis of bladder cancer immunotherapy¹.” The study aimed to conduct a bibliometric analysis of the field related to bladder cancer (BC) immunotherapy, discussing research trends, hotspots, and frontiers from 2000 to 2022. These findings can help readers to quickly understand the current status of the field as well as the hot research directions. Hinpetch Daungsupawong and others have commented on the manuscript,² stating that it only focuses on bibliometric analysis without delving into the relevant results or providing insights on effectiveness or impact. They believe that a systematic review or meta-analysis could be the future direction of this study. We agree with this opinion. However, the purpose of this manuscript is to analyze the current research status and future directions of bladder cancer immunotherapy from a bibliometric perspective. Including a relevant meta-analysis would be an additional benefit rather than a necessity. Nevertheless, we found some defects in the retrieval strategy in the manuscript and put forward our reasonable suggestions for reference.

In the field of bibliometric analyses, it is important to develop precise search methods. The original authors mentioned that the raw data came from the Web of Science Core Collection (WoSCC), which is a comprehensive database consisting of many sub-databases, including Science Citation Index Expanded (SCI-Expanded), Emerging Sources Citation Index, and more. We believe that it may not be rigorous to select all these sub-databases when searching for articles that meet the screening criteria. According to previous studies, not all sub-databases are suitable for bibliometric analyses.³ In contrast, SCI-Expanded is currently the most widely accepted, widely used, and most suitable one. Therefore, we suggest that authors should specify which database has been used to ensure the reproducibility of the data retrieval process.

In addition, some researchers believe that Topic Search (TS) is not well suited for bibliometric analyses.⁴ The “Keywords Plus” are generated by WoSCC’s automated computer algorithm, not by the authors. Based on some articles we have previously read, using “TI,” “AB,” and “AK” might be a better approach as screening criteria.^5,6 At the same time, assuming that the search formula is relatively simple and ignores some of the relevant keywords, perhaps some of the relevant publications are missed. In the manuscript, the author uses “TS = ((“bladder cancer” OR “bladder carcinoma”) AND (“immunotherapy” OR “immunotherapeutic”))” as the retrieval strategy. We believe that such a filter is not sufficient to cover all relevant articles. We suggest authors to use wildcards (e.g. “*”) to enhance the search strategy. The wildcard character “*” can be substituted for any other character for variable keyword endings. For example, “neoplasm*” will return both “neoplasm” and “neoplasms.” Our proposed retrieval formula is summarized in Table S1.

Using the optimized retrieval method, we searched a total of 3221 related articles from January 1, 2000 to December 31, 2022. After excluding non-English articles and non-articles, 2079 articles were included in the study after data filtering, which decreased by 53 compared with the original manuscript Lv et al. However, the literature selected by us is more in line with the research conditions and more representative. Figure 1a provides a comprehensive overview of all these publications. It can be seen that there is a significant upward trend in the research literature related to immunotherapy for bladder cancer, especially after 2019 Figure 1b.

Figure 1.

A bibliometric analysis of bladder cancer immunotherapy. (a) the overview of bladder cancer immunotherapy in WOSCC SCI-EXPANDED by ‘bibiometrix’ package. (b) Annual scientific output on bladder cancer immunotherapy during the period from 2002 to 2022. (c) A three-field plot of bladder cancer immunotherapy. AU: authors. AU _CO: countries. DE: keywords (d) the networks of cooperation between different countries. (e) The top 10 most relevant resources on immune therapy for bladder cancer. (f) The top ten most relevant resources on immune therapy for bladder cancer. (g) Authors’’ production over time of bladder cancer immunotherapy. (h) Trend topics of bladder cancer immunotherapy.

In terms of the number of publication citations, the United States ranks first with 20,317 articles, which is the only country worldwide that exceeds 10,000, followed by China and the United Kingdom. The research of Lv et al. is slightly different. In Figure 1c-d, we provide Three-Field Plot of chart countries, corresponding authors and main keywords, and we show countries and inter-country cooperation network diagrams. It is worth noting that, after optimizing the search, we found that the journal with the most published related literature is UROLOGIC ONCOLOGY-SEMINARS AND ORIGINAL INVESTIGATIONS, followed by the JOURNAL OF UROLOGY. This differs from Lv et al.‘s research Figure 1e-f. Not only that, we longitudinally display the research results of the relevant authors from 2000 to 2022 on the basis of LV et al., interestingly, we find that O’DONNELLMA has been published for 20 years Figure 1g. In addition, through the analysis of related research trends, the hot topics in this field in the past three years are randomized trial, cytolytic t-lymphocytes and stage stages Figure 1h.

Compared to the findings proposed by Lv et al., our investigation revealed a more rigorous literature database in the field of bladder cancer immunotherapy. It must be emphasized that significant fluctuations in publishing can have a significant impact on various quantitative indicators, including publication count, citations, major countries, institutions, authors, journals, keywords, and references. This highlights the crucial importance of systematically formulating appropriate search formulas as the foundation of objective bibliometric analysis. In conclusion, we congratulate Lv et al. on their work; however, we think our suggestions have the potential to improve the accuracy and precision of data analysis regarding research trends in bladder cancer immunotherapy over the past 20 years.

Funding Statement

The work was supported by the Shandong Province Medical and Health Science and Technology Development Plan Project [NO. 202209030830]; Scientific and Technological Innovation Plan Project for Medical System Staff in Shandong Province [SDYWZGKCJHLH2023031].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data statement

The datasets used during the present study are available from the corresponding authors upon reasonable request.

Author contributions

Yandong Miao and Jiangtao Wang organized and designed the manuscript. Baifeng Lia and Kai Chenga organized and edited the retrieval formula. Ruochen Bao and Hongtao Qu wrote the manuscripts

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2313287.