Background Patients with cancer are at risk of injury during treatment. Some injuries are preventable, but prevention requires knowledge about the hazards.

Aims To identify hazards and injuries relating to Danish patients with cancer (types and severity) and to test three different methods of identifying cancer-specific hazards.

Methods Adverse events in cancer care were identified through reports from healthcare staff to the Danish Patient Safety Database, a retrospective chart review using the Global Trigger Tool, and reports to the Danish Cancer Society from patients with cancer and their relatives. Events were typed using the draft International Classification for Patient Safety. Severity was assessed by Safety Assessment Coding, the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) and qualitative assessment.

Results 2429 cancer-related adverse event reports were found on the Danish Patient Safety Database, 260 adverse events were identified using the Global Trigger Tool, and 151 safety events were reported by patients and their relatives. Cancer-specific adverse events and general safety problems were identified. In most cases injury to patients was temporary but severe and permanent injury occurred with a relatively high frequency.

Conclusion Patients with cancer are at risk of injury from cancer treatment procedures and as a consequence of problems related to administrative processes and communication. Types of identified events varied according to the methods used, and each method added new information. Further research on patient safety in cancer care and safety-enhancing activities is needed.