Last updated on June 2019

Phase II Multi-center Trial Evaluating 5 Fraction Stereotactic Partial Breast Irradiation Using Gammapod

Brief description of study

Stereotactic radiation has been implemented more than 3 decades ago, initially to radiate benign and later malignant tumors within the brain. Doses up to 24 Gy in one session have been used. Hundreds of thousands of patients have been treated worldwide with very good outcomes . Over the last decade, the stereotactic radiation techniques have been implemented to treat extra-cranial tumors. The challenges of extra cranial tumors were in part target motion during the radiation session, but also accurate re positioning of the patient and of the target volume at time of radiation treatment. Specific immobilization devices are now available to improve accuracy of target localization. Stereotactic radiation therapy is widely available, non-invasive for the patient and less operator dependent as the planning process (from target volume to dose calculation) can be done and verified by different operators through a quality assessment procedure. Stereotactic radiation is a complex type of 3D CRT that is a very attractive technique making the 3D CRT more conformal and more accurate delivery of the prescription dose within the target volume with a very good sparing of surrounding normal tissue. The principles of stereotactic radiation are the following: precise image definition of target volume and OARs, very conformal radiation treatment.

Detailed Study Description

The GammaPod is a new external beam radiotherapy device dedicated for stereotactic radiotherapy of breast cancer (Xcision Medical Systems, LLC, Columbia, Maryland). The design goal of the GammaPod has been the ability to deliver ablative doses with sharp gradients under stereotactic image guidance. Highly focused radiation is achieved at the isocenter due to the cross-firing from 36 radiation arcs generated by rotating 36 individual Cobalt-60 beams.In order to immobilize the breast during imaging and treatment and in order to get a stereotactic localization of the breast target volume, a vacuum-assisted breast immobilization cup with built-in stereotactic frame is used. The patient can be imaged on a CT or MRI wearing the vacuum-assisted breast cup and then be transferred to the GammaPod for treatment. Then, the planner is required to delineate the gross tumor volume (GTV) and its subclinical extensions. Multiple targets within a breast are allowed.Different doses can be prescribed to different targets.One benefit of using the GammaPod over the cyberknife for breast SBRT, is elimination of the need for internal gold fiducial markers, which are required for the cyberknife treatment.

Using a stereotactic technique for APBI allows smaller margins in comparison to a 3DCRT technique. The total expansions on the RAPID trial (3DCRT APBI) were 1.0 cm CTV expansion on the lumpectomy cavity and an additional 1.0 cm for PTV, for a total expansion of 2.0 cm. As a 3DCRT technique was used on the RAPID trial limited number of radiation beams were employed, no Intensity Modulated Radiation Techniques allowed, and the margins used to create a PTV were relatively large (total margin 2 cm).

As the GammaPod will allow us to minimize the volume of normal breast being irradiated, and decrease the PTV volume we hypothesize that a stereotactic technique with the GammaPod will allow us to improve on the 3 year global cosmesis rates (physician and patient) reported in the RAPID trial (3DCRT) by 40% despite 5 daily fractions of SBRT (in contrast to 38.5Gy/10 fractions 3DCRT BID on the RAPID trial) The GammaPod was FDA approved 12-2017.

Clinical Study Identifier: NCT03581136

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Recruitment Status: Open

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