Research on radiotherapy safety is invaluable for identifying potential vulnerabilities in the treatment process. Such work should focus on analyses of safety-related incidents, as well as reporting of near-misses, which has been identified as a valuable tool for preventing serious incidents in the non-medical domain.2 It's likely, however, that many radiotherapy-related adverse events have either not been recognized, not reported to regulatory authorities or not published in the literature.
To address the scarcity of literature on publicly recognized events, we have collated and synthesized evidence on radiotherapy errors and recommended safety measures. Our study - commissioned by the World Health Organization (WHO) World Alliance for Patient Safety and published in the Green Journal - includes reviews of published articles as well as unpublished "grey literature" (Radiother. Oncol. 92 15).
We gathered our data via rigorous searches of web-based sources, including working papers, organizational reports and conference proceedings, as well as acquiring information through personal communication (peer review reports) and via analysis of radiotherapy incident data from individual departments that have not been made available publicly. Our goal was to develop radiotherapy safety guidelines with targeted interventions that would be applicable in many different countries. The initiative is complementary to guidelines developed by the International Atomic Energy Agency (IAEA) and other international safety organizations.
Key findings
The study identified nearly eight thousand (N=7741) radiotherapy-related incidents and near misses during the last three decades (1976-2007). About three thousand (N=3125) incidents resulted in recognizable patient harm. This included radiotherapy underdose leading to risk of recurrence, radiotherapy overdose with signs and symptoms of radiation toxicity, and patient death in 1.4% of reported incidents.
Of 4616 near misses without any known adverse outcome to patients, 9% were related to the planning stage, 38% were related to the treatment information transfer stage and 18% to the treatment delivery stage. The remaining 35% of these incidents occurred within a combination of stages.
Our research also revealed the following points:
• Radiotherapy errors leading to serious incidents are rare, occurring only about 50 to 100 times per million courses of treatment, compared to other medical errors with adverse consequences.3
• Misinformation or errors in data transfer constitute the greatest bulk of radiotherapy-related incidents in the modern radiotherapy services.
• More system- or equipment-related errors documented by medical physicists are reported, as compared to errors that occur during initial choice of treatment, dose prescription and other random errors unrelated to equipment or system faults.
Because of the variability in the nature of data sources and lack of a uniform grading system for description of radiotherapy errors, it was not possible for us to compare severity between incidents except when the incident resulted in death.
Emerging remedies
Based on our work, an expert group facilitated by the WHO World Alliance for Patient Safety has recently published a "risk profile" for radiotherapy incidents.4 We have identified factors that are prone to radiotherapy safety failures in different stages of radiotherapy, plus those that pose a risk in all stages of the procedure and require priority action.
The WHO document recommends several interventions that are likely to be effective in reducing risks at multiple stages in the radiotherapy treatment process. Specific competency certification could address 11 identified risks, planning protocol checklists are relevant to 20 risks, while independent checking could minimize 12 risks (see table below).
Despite the lack of systematic evidence with which to quantify and prioritize the risk areas, the clear message from the data is that each radiotherapy service should individually and repeatedly examine its risk profile - including patient issues, equipment and/or system issues, and staff issues related to radiotherapy. Another pressing point is that these facilities should ensure that there's a system in place for prospectively collecting, measuring and categorizing radiotherapy incidents and near misses.