ATM and cancer: Treatment-naïve cancer patients showed significantly elevated rates: 20.1% for ANA (P = 0.003), 11.5% for aPL (P = 0.006), 1.7% for ANCA (P = 1.0), and 17.3% for ATA (P = 0.012), suggesting tumor-associated B-cell activation or autoimmune dysregulation.