Bibliometric Analysis of Theses Published in the Field of Radiation Oncology Specialization in Türkiye

Medical oncology and radiation oncology are rapidly developing and technology-related specialties. For example, in a study where bibliometric analyses of research trends in targeted therapy for breast cancer were conducted from 2003 to 2022, it was found that the number of publications has been increasing over the years and that the most productive country in this regard is the USA.[] Similarly, global research trends in the field of radiotherapy are also noteworthy in the literature. In a study that conducted a bibliometric analysis of 62,550 articles published in the Web of Science database between 2001 and 2015, it was emphasized that despite radiotherapy developing rapidly in terms of technical aspects, it has become the focus of less research compared to other areas of cancer treatment. In the analysis, 32.3% of the publications came from the USA, 8% from Japan, and 7.7% from Germany. While approximately half of the studies focused on application-oriented issues, critical topics such as health services research, palliative care, and quality of life were represented at very low rates. In addition, significant differences in research types were observed across countries, and a striking discrepancy was found between the number of publications and citation impact. This draws attention to radiotherapy research as an area that needs to be supported more, especially in low- and middle-income countries, and suggests that it should guide future national strategies.[]

For the application to associate professorship in the basic field of Health Sciences; the declared works and academic activities are required to be published from postgraduate theses in the application. This indicates that this rate will increase in the future.

Our analysis showed that there were 202 theses published in the national database between 1988?2024. This may be because collecting sufficient data requires cooperation and usually takes several years. In addition, there may be a limited number of positions opened for Radiation Oncology specialist students.

According to the research results, it was seen that the most preferred research method in the examined articles was quantitative research, and the most preferred research design was retrospective descriptive research. It was determined that the statistically significant difference between the study design and the publication status of the theses was between the experimental research-retrospective descriptive and prospective- retrospective descriptive study types.

In our dataset, a statistically significant difference was found between thesis years and the status of publication as an article between the groups 2011-2020 and 2000 and before. As in all WoS-based bibliometric studies, it is not possible to evaluate journals that have ended their publication life before 2013. In addition, this study may not show the absolute scientific activity of the authors and institutions. An evaluation made by considering articles published in SciVerse, Scopus, Pubmed or other search engines, in journals outside the study and within the country may provide better information. The publication numbers of institutions and authors may differ due to the fact that they do not use standard names or abbreviations during publication submission. In this study, all institution and author names in the literature were examined and analyzed to prevent this. Bibliometric analyses provide objective data in showing the scientific activities of countries in that branch of science or any subject and in comparing them with other countries.[] The most important counterpart of the validity and scientific value of the publications is the scientific citations made to the publication. A strong and positive correlation was found between the number of articles published by journals and the number of articles cited. It was thought that the high number of publications in journals caused them to be viewed more in search engines and that this may be due to the increased recognition among authors due to the high number of accepted articles.[,] When the number of citations received by the theses published in our study was calculated per year, it was seen that the median value was 0.2 (Q1: 0.0- Q4: 5.5).

The findings of this study indicate that approximately one-third of radiation oncology residency theses in Türkiye have been published in internationally indexed journals. When compared with similar studies conducted at the international level, this proportion appears relatively low. For example, in a study conducted by Verma et al.[] on 334 radiation oncology residents who graduated in the United States between 2014 and 2015, a total of 659 first-author publications were identified, corresponding to an average of 2.0 publications per resident. In that study, 66% of residents had published at least one article, while 45% had published at least two. Notably, 75% of these publications were original research articles.

Similarly, in a study by Rowley et al.[] including 909 residents who graduated from 89 different training programs in the U.S. between 2015 and 2019, the average number of publications per resident was found to be 2.90. During this period, a 44% increase in publication output was observed. Among the identified publications, 69.7% were original research articles. The only statistically significant factor associated with higher publication productivity in that study was training in a residency program with a larger number of residents.

In another study conducted in Canada by Mutsaers et al.,[] the research productivity of Canadian radiation oncology residents was evaluated over a 12-year period (2005-2016). A total of 363 publications were identified during this interval. Notably, 82% of the publications occurred during the fourth year of residency or later, indicating a concentration of research output in the latter stages of training. Furthermore, larger institutions-defined as those graduating more than three residents per year-were associated with higher publication rates.

These findings suggest that research productivity among radiation oncology residents is higher in the United States and Canada, which may be attributed to systemic factors such as strong academic mentorship, statistical support, publication incentives, and a robust institutional research culture. In this study, experimental and prospective research projects were more likely to be published than retrospective studies, indicating that journals may favor certain methodological designs. These study types typically require greater resources and time investment, which may reflect the presence of stronger research infrastructure and academic mentoring in the institutions where they are conducted. In Türkiye, some institutions may benefit from factors such as adequate laboratory access, availability of clinical data, and supervisors with publication experience, which may facilitate publication. Conversely, challenges such as limited supervisor availability, language barriers, and underdeveloped incentive structures may hinder the transformation of theses into publishable manuscripts. These findings highlight that not only individual motivation but also institutional and systemic conditions play a critical role in promoting research dissemination.

Limitations
There are some limitations to the study. Firstly, our analysis focused primarily on quantitative aspects such as the number of publications, citation impact, and collaboration networks. Qualitative aspects such as specific research questions, methodological quality, and clinical implications of individual studies were not investigated in depth. Secondarily, theses included in the National Thesis Center database in Türkiye were included. Therefore, it may be wrong to generalize the results to all theses. In addition, we could not detect the change in thesis title to an article and we could not detect that some other theses may have reached publication or may be currently in the peer-review process or in press. Another limitation is that we focused on published articles and did not conduct a search for oral or poster presentations at a medical congress.