An August 2025 ransomware attack on the University of Hawaii Cancer Center’s research study data systems was disclosed in early 2026 as affecting approximately 1.2 million individuals who had participated in cancer research studies. Research participants had provided personal and medical information for oncology research trials. The exposure of cancer research participant data is particularly sensitive as it may reveal health diagnoses, genetic information, and treatment history. The University of Hawaii Cancer Center conducts population-based cancer research serving Hawaii’s diverse population. HHS OCR and the University of Hawaii system were notified. See also the primary University of Hawaii Cancer Center ransomware record.