ecDNA was detected in 54.9% of liposarcomas (n = 82, 95% confidence interval (CI) 44.7–65.8%), 49.1% of glioblastoma (n = 291, 95% CI 43.3–55.0%), 46.4% of HER2+ breast cancer (HER2+ BRCA, n = 196, 95% CI 39.3–53.7%; examples of which we were able to identify through FISH in an independent cohort; Extended Data Fig. 4), 37.9% of upper gastrointestinal adenocarcinomas and 22.4% of lung squamous cell carcinomas, 24.6% of bladder cancers and 20.4% of ovarian cancers, among others (Fig. 1d). Here, ERBB2 is linked to urinary bladder cancer.