Radiotherapy is a safe and effective form of treatment for many types of cancer.
Radiation necessarily hits normal tissues when targeting tumor volumes.
This requires balancing the pursuit of tumorcidal dose to the target with sparing of normal tissues.
Technology adoption, practice patterns, and standards of care differ across geographies and clinics.
The result is large variability in the radiation dose received by study subjects.
This variability has significant implications for both patient response and study endpoints, and is critical to understand and document.
Radiation therapy is a cornerstone treatment for cancer and is frequently employed in clinical trials to explore novel systemic therapy agents in both curative and non-curative settings. The sophistication of RT provides patients with access to treatments with high levels of accuracy and precision as well as reduced toxicity, if employed correctly. However, the inherent complexity of RT planning and delivery requires rigorous quality assurance to reduce practice variability, minimize suboptimal treatments, and ensure safe and effective patient care.
Clinical trials use highly prescriptive treatment guidelines to standardize practice, isolate treatment effects, and minimize sources of variability that could impact patient response and potentially confound study results. Like other therapies, the impact of RT is often significantly modulated by investigator-related, patient-specific, and technological factors that influence the course of treatment. This introduces variability that can have direct consequences on overall treatment outcomes and trial endpoints.
Extensive research has demonstrated the importance of radiation therapy quality assurance (RT QA) on primary study outcomes in clinical trials. A meta-analysis of prospective clinical trials found that 32% of patients had RT treatment plans that were not-per-protocol and those subjects were associated with an almost two-fold increase in risk of tumor recurrence and mortality compared to per-protocol plans. Due to this potential interaction, RT quality must be rigorously controlled as any other study variable to ensure the integrity of trial results.