Medical errors in radiation oncology (RO) practice have received significant national attention over the last decade. Medical errors can lead to malpractice cases. Better characterizing these events can educate providers with the goal of improving patient care.

The Controlled Risk Insurance Company Strategies' Comparative Benchmarking System (CBS) represents approximately 30% of all closed US malpractice cases and includes the experience of more than 30 academic hospitals. Registered nurses trained as clinical taxonomy specialists code each case, and individual case-level details are available. Practicing radiation oncologists extracted all closed RO cases from years 2005 to 2014 and subgrouped them by patient allegation category, clinical injury severity, care setting and academic affiliation, disease site and natural history, treatment modality, and contributing factor. Within categories, χ tests were used to test for the variables' association with an indemnity payment.

RO was the primary service in 102 closed cases (0.2% of all cases in the CBS), accounting for $13,323,578 in indemnity payments (0.1% of all payments in the CBS). The median indemnity payment was $100,000. Head-and-neck and central nervous system tumors accounted for 23.9% and 10.9% of all RO cases, respectively, and 41.3% and 31.4% of all indemnity payments, respectively. Benign diseases and brachytherapy were involved in 12.0% and 15.2% of cases, respectively. Cases involving benign disease (P = .009), treatment of the wrong site (P = .001), or treatment using the wrong dose (P < .001) were all associated with indemnity payments. The top 5 most expensive cases accounted for nearly 80% of all indemnity payments, and all involved head-and-neck, central nervous system, benign, or brachytherapy cases.

We found that although closed malpractice cases involving RO are rare events, certain populations may be overrepresented in closed claims. These data can help inform providers and systems with the goal of ultimately improving patient safety.