Effects of Hypomagnetic Field Environment on Tumor Progression and Gut Microbiota in LLC Tumor-Bearing Mice

The tumor microenvironment interacts bidirectionally with systemic host factors, including the gut microbiota. However, it remains unclear whether physical environmental stimuli, such as a hypomagnetic field (HMF), can modulate tumor progression and associated microbial features. In this study, C57BL/6 mice bearing subcutaneous Lewis lung carcinoma (LLC) were maintained under geomagnetic field (GMF) or HMF conditions. We evaluated tumor growth and systemic toxicity, and analyzed fecal samples using 16S rRNA sequencing and short-chain fatty acid (SCFA) profiling. Compared with the GMF control, HMF exposure significantly reduced tumor growth, with an approximately 40% decrease in endpoint tumor volume. No obvious systemic toxicity was detected by monitoring body weight, serum biochemical parameters, and organ histology. HMF exposure altered gut microbial diversity and community composition, with enrichment of several Clostridia-related lineages. Fecal SCFA analysis revealed increased butyrate levels in the HMF group (p = 0.013). Overall, these findings indicate that HMF exposure is linked to reduced LLC tumor growth and changes in gut microbial composition and metabolites. Further studies are needed to clarify the mechanisms underlying these interactions.