When measures are implemented to ensure that radiation protocols are followed, deviations decrease and overall survival improves in patients with cancer.

Deviating from a radiation therapy protocol in a clinical trial is widely accepted as being more than likely to result in adverse effects. Examples of deviation in radiation therapy include inadequate targeting of high-risk lymph nodes or incorrect dose calculation.

Significant quality assurance (QA) measures have been taken over the past several decades to minimize such effects. Though these measures have been shown to decrease deviation, no data had established the patient-outcome benefits of the measures. This study examined the effects of the QA measures on the risk of treatment failures and mortality.

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Researchers analyzed radiation therapy protocols, QA measures, and patient outcomes in eight large clinical trials. The analysis included two lung cancer trials, three trials for medulloblastoma, and trials for Ewings sarcoma, pancreatic cancer, and head and neck cancer. Overall, more than 2,000 patients were included. The researchers examined data on the number of patients included in QA analysis, the definition of radiation protocol deviation, and the number of patients with and without radiotherapy deviations. They sought to determine if deviations were associated with inferior clinical outcomes.

The researchers found that the frequency of radiation therapy deviations ranged from 8% to 71%. The deviations were associated with a significant decrease in overall survival and with an increase of about 75% in the risk of treatment failure and mortality.

“The magnitude of these effect sizes demonstrates that delivery of high-quality radiation therapy and having a rigorous QA program is critical for the successful execution of clinical trials and for the effective treatment of all cancer patients,” said Adam P. Dicker, MD, PhD, chair of the Department of Radiation Oncology at Thomas Jefferson University Hospital. “With such practices, deviations decrease and thus overall survival rates for cancer patients improve.”

This research was presented during a plenary session at the American Society for Radiation Oncology (ASTRO) 54th Annual Meeting in Boston.