ObjectiveTo systematically evaluate the composition spectrum of oral microbiota diversity in patients with head and neck tumors undergoing radiotherapy. MethodsComputer searches were conducted on CNKI, CBM, WanFang Data, PubMed, Embase, and Web of Science databases to collect cohort and control studies on changes in oral microbiota in patients with head and neck tumors after radiotherapy. The search period was from January 1, 2015 to June 1, 2025. Two researchers screened and evaluated literature, extracted data, and conducted meta-analysis using RevMan 5.4 software. ResultsA total of 25 studies were included, including 731 patients with head and neck tumors and 275 healthy controls. The meta-analysis results indicated that compared with the control group not exposed to radiotherapy, the detection rates of major oral opportunistic pathogens such as Candida albicans and Streptococcus mutans had significantly increased (OR=3.62, 95%CI 2.23 to 5.89, P<0.01). The Shannon index and Chao1 index for oral alpha diversity had decreased after radiotherapy (SMD=?0.78, 95%CI ?1.23 to 0.34, P<0.01; SMD=?0.64, 95%CI ?1.14 to ?0.15, P<0.001), and the differences were statistically significant. Qualitative analysis showed that after radiotherapy, the relative abundance of Firmicutes, Streptococcus, Lactobacillus, etc. in patients increased, while the relative abundance of Clostridium, Neisseria, etc. decreased. ConclusionThere are changes in the oral microbiota of patients with head and neck tumors after radiotherapy, mainly manifested as an increase in the detection rate of opportunistic pathogens, a decrease in alpha diversity, and an imbalance in the relative abundance of some bacterial phyla. This suggests that oral care should be taken seriously for radiotherapy patients.
Radiation-induced optic neuropathy (RION) is a severe complication of radiotherapy for head and neck tumors, characterized by painless, often irreversible visual decline after a long and highly variable latent period. Its incidence correlates with radiotherapy techniques and tumor types, with radiation dose constituting the principal risk factor. Advanced age and pre-existing vascular conditions can further elevate the risk of RION. The underlying pathology is thought to involve vascular injury, dysregulated molecular signaling, and impaired axoplasmic transport, although these mechanisms are not fully understood. Diagnosis in clinical practice remains largely exclusionary, based on patient history, imaging, and visual function testing. No specific cure exists, so management focuses on symptomatic relief and vision stabilization. Adherence to established safe radiation dose thresholds is the most effective strategy for reducing RION incidence. This review synthesizes clinical insights to summarize the epidemiology, risk factors, pathophysiology, diagnosis, and management of RION, discusses ongoing challenges in its prevention and treatment, and aims to inform more precise prevention and personalized therapeutic strategies.
