Association of radiotherapy with atrial fibrillation-related gene expression in breast cancer patients: a study based on the TCGA-BRCA database

Radiotherapy (RT) for breast cancer may increase atrial fibrillation (AF) risk. This study explored the association between RT and expression of AF-related genes in breast tumor tissues. A total of 1094 breast cancer patients (RT group: 1020; non-RT group: 74) were included based on inclusion criteria. Clinical data and RNA-seq profiles (TPM) were retrieved. Six AF-related genes (MYBPC3, LMNA, PKP2, FAM189A2, KDM5B, MYL4) were analyzed. Gene expression was compared using Wilcoxon rank-sum test after Log2(TPM + 1) transformation. Subgroup analyses were conducted by AJCC stage (I–III), laterality (left/right), age (< 65/≥65 years), clinical subtype (Luminal, HER2-positive, Triple-negative), and PAM50 molecular subtype (Basal, Her2, LumA, LumB, Normal). Multivariate linear regression was applied to evaluate RT’s independent effect on gene expression. In tumor tissues, expression levels of MYBPC3, LMNA, and MYL4 were significantly higher in the RT group compared to the non-RT group.Subgroup analysis revealed higher MYBPC3 expression in the RT group specifically in Stage III tumors, but lower expression in left-sided tumors and in patients < 65 years old. LMNA expression was higher in the RT group in Stage III tumors. MYL4 expression was higher in the RT group in Stage II tumors, in both left and right-sided tumors, and in both age groups (< 65 and ≥ 65 years). No significant differences were found across clinical or molecular subtypes for any gene.Multivariate regression confirmed RT as an independent predictor of increased MYL4 expression (β = 0.204), but not for MYBPC3 or LMNA expression. Sensitivity analysis in the 45–65 age subgroup supports the above findings. Based on tumor tissue analysis, breast cancer radiotherapy is associated with altered expression of AF-related genes (particularly MYL4) in tumor tissues, suggesting a potential molecular link worthy of further exploration in relation to atrial fibrillation. These findings warrant future validation in cardiac or circulatory tissues.