A prospective, multi-institutional clinical study supported by the French National Cancer Institute (INCa: Institut National du Cancer) demonstrated that patients with head and neck cancer treated with intensity-modulated radiation therapy (IMRT) showed a significantly better local control rate, cancer-specific survival rate and post-treatment salivary function when treated with Helical TomoTherapy (Accuray’s TomoHelical™) compared to volumetric modulated arc therapy (Varian’s RapidArc).
The study, the first to prospectively compare clinical outcomes across radiation therapy platforms, was published online on June 26, 2017 in the peer-reviewed International Journal of Radiation Oncology – Biology – Physics. It was part of a voluntary evaluation of IMRT platforms by French centers following a rigorous methodology.
* Weighted analysis (Inverse probability of treatment weighting)
Randomization was not possible as participating centers offered only one of the delivery techniques. Inverse probability of treatment weighting (IPTW) using the propensity score analysis was undertaken to adjust for potential bias due to
non-randomization. The propensity score is the conditional probability of a patient being treated with TomoHelical given other observed characteristics. Even before the adjustment the TomoHelical results were better than RapidArc as measured by local control, cancer-specific survival and acute salivary function, even though significant differences in several
pre-treatment characteristics may have placed the TomoHelical group at a disadvantage.
The TomoTherapy System was designed specifically for image-guided radiotherapy and IMRT delivery. Its unique helical delivery mode (TomoHelical™) provides continuous delivery of intensity modulated radiation beamlets from 360 degrees around the patient. It offers optimal dose sculpting capability enabling highly conformal and homogeneous dose distribution.
The study suggests that TomoHelical contributes to better cancer-specific survival rate (97.2% vs 85.5%) and local control rate (83.3% vs 72.7%) compared to RapidArc. Further analysis suggests an even greater benefit in the local control of larger tumors and those that have spread to more lymph nodes.
The study also suggests that reduced dose outside the tumor carved by TomoHelical leads to better acute salivary function than with RapidArc. Mouth dryness was worse and salivary disorders were more frequent in the RapidArc patient group (20.4% vs 7.5%). Less toxic treatments may lead to lower overall healthcare provider and system costs when treating patients with head and neck cancers.
TomoHelical enables the treatment of the entire spectrum of head and neck cancers, regardless of shape or size or nodal involvement. The results from this study are expected to also apply to other clinical indications benefiting from highly conformal and homogeneous dose distribution.
Radixact™ SystemThis landmark study demonstrates that the technique used to deliver IMRT can have a major impact on patient outcomes. The better local control, cancer-specific survival, and acute salivary function rates reinforce the TomoTherapy System’s superiority in managing head and neck tumors. The same results are expected with the Radixact™ System, the next-generation TomoTherapy platform, delivering the same highly conformal and homogeneous dose distribution faster with 18% higher dose rates and 66% faster imaging times.
Accuray Precision™ Treatment Planing and iDMS™ Data Management Systems
The additional functionalities provided with the recently
released treatment planning and data management systems (Accuray Precision and iDMS) are expected to further improve clinical outcomes and treatment efficiency. The fully integrated and automated PreciseART™ Adaptive Radiation
Therapy option makes plan monitoring and replanning practical for every patient and every clinic. The automatic contouring option (Head & Neck AutoSegmentation™) enables consistent and efficient treatment planning.