Room for improvement
“MRI-guided adaptive brachytherapy in locally advanced cervical cancer works in multicenter clinical practice, within such a study, with adaptation of the target and application technique, and multiparametric treatment planning and dose prescription,” Dr. Pötter summarized.
However, “the mature clinical outcomes appear challenging,” he added. Specifically, although the rate of local control was high, the rate of nodal control left room for improvement in node-positive patients, and the rates of systemic control and overall survival left room for improvement in high-risk patients.
In addition, “the grade 3-5 morbidity was limited per organ and per endpoint, but was considerable overall, and this asks for a reduction,” Dr. Pötter said.
Two of the areas needing improvement are being addressed in ongoing and planned research, according to Dr. Pötter. “The nodal part is already being addressed in EMBRACE II, intensifying treatment for node-positive patients through a simultaneous integrated boost and a very sophisticated probability planning concept, and also including more patients for paraaortic radiotherapy,” he elaborated. “For the systemic part, we have thought about [a study testing an] additional drug ... and there are thoughts for EMBRACE III to investigate such effect.”
A benchmark for brachytherapy
“This is the largest prospective cohort of patients treated with image-guided brachytherapy. The high rates of local control with long-term follow-up are impressive and speak to the clear value of high-quality brachytherapy,” commented Ann H. Klopp, MD, PhD, of the University of Texas MD Anderson Cancer Center, Houston, who was not involved in this study.
With its consistent reporting of detailed dose and toxicity data, the study establishes a benchmark for brachytherapy worldwide, Dr. Klopp said. It also better informs treatment decision-making in cases where replacing brachytherapy with external beam techniques is being considered.
Although MRI guidance is increasingly being used in brachytherapy, the latest studies on patterns of care suggest that overall use is still low, according to Dr. Klopp.
“The challenges are primarily logistical,” she elaborated. “MRI-compatible applicators must be placed, and patients need to wait for the scans to be performed, which can take an hour or more. In addition, the times that patients get scanned can be unpredictable based on procedure times, which can create practical challenges for scheduling. In some cases, cost may also be a deterrent.
“The bar is high for brachytherapy. It’s an excellent treatment modality that provides very high rates of local control with very low toxicity when done optimally,” Dr. Klopp concluded. “I do think that this experience provides very convincing evidence that the best brachytherapy is image-guided and requires care to monitor normal tissue doses in order to reduce the risk of long-term toxicity.”
The study was supported by unrestricted grants from Elekta and Varian. Dr. Pötter and Dr. Klopp disclosed no conflicts of interest.
SOURCE: Pötter R et al. ESTRO 2020, Abstract OC-0437.