Research–evidence gap analysis of hypofractionated radiotherapy for breast cancer: a bibliometric knowledge graph study

Background: Hypofractionated radiotherapy (HFRT) has become a standard option for early-stage breast cancer, supported by multiple randomized controlled trials and endorsed by major guidelines. However, whether research production, high-level evidence, and clinical guideline adoption are fully aligned remains unclear. Methods: Publications on HFRT for breast cancer (2014-2024) were retrieved from the Web of Science Core Collection. Bibliometric analyses were performed using CiteSpace (6.4.R1) and VOSviewer (1.6.20) to assess publication trends, collaboration networks, keyword clustering, and highly cited references. In parallel, clinical trials from PubMed were reviewed to evaluate the evolution of clinical evidence. A knowledge-mapping framework was applied to identify research evidence gaps. Results: A three-phase developmental pattern was identified: slow growth (2014-2019), rapid expansion (2019-2021), and stabilization (2021-2024). Italy, the United States, and China accounted for more than 60% of global publications. Research hotspots shifted from efficacy validation to toxicity, dose optimization, and patient-centered outcomes. Although efficacy evidence is well established, significant gaps persist, including (i) limited long-term cardiac and pulmonary toxicity data, (ii) inconsistent cosmetic and quality-of-life reporting-especially among younger patients, and (iii) insufficient evidence for locally advanced disease or post-reconstruction irradiation. Conclusions: HFRT research has matured substantially and strongly supports its use in early-stage breast cancer. However, long-term safety, patient-reported outcomes, and complex clinical scenarios remain underexplored. Future work should prioritize multicenter prospective studies, integration of radiomics and AI-driven analyses, and standardized reporting to better align research output with guideline development and patient needs. Systematic review registration: [website], identifier registration number.