APBI with VeraForm® & SAVI® Brachytherapy: Marking for the Unpredictable
David Beyer MD FACR, FACRO, FASTRO
Past Chair ASTRO
(American Society of Radiation Oncology)
Director or Radiation Oncology
Cancer Centers of Northern Arizona Healthcare
Our Medical Director of the Oncology Breast Program, Dr. Beth DuPree, was first in the U.S. to adopt VeraForm, a continuous, radiopaque 3D tissue marker. Within months, its utility led to quick integration into our program’s standard daily practice. Like all centers today, patient satisfaction is a focal point and to date, we have seen no complications or toxicities by any criteria (e.g., CTCAE) while employing VeraForm. Further, we have received no complaints by patients such as palpability, discomfort, infection, hematoma, seroma or impaired cosmesis.
VeraForm continues to yield exceptional results for our planning radiation therapy (XRT) efforts with the radiation oncology team. Building on that success, we recently integrated VeraForm into our APBI program with the SAVI® brachytherapy catheter system. APBI is increasing in popularity among patients across the country, particularly given that less fractions mean less visits for them. This is particularly true in our region of Arizona where patients often travel great distances for XRT. As a fiducial marker, VeraForm is proving unique in its ability to be combined with catheter or balloon-based brachytherapy such as SAVI. Other XRT implantable markers can potentially interfere with the SAVI system, but the low-profile aspect of VeraForm, interwoven in multiple tissue planes, allows for utilization of SAVI. Further, we were more comfortable knowing that VeraForm holds a specific FDA 510(k) clearance (IYE) that anticipates use in radiotherapeutic treatment and required testing to high doses of radiation.
We have used VeraForm in our last half dozen breast cancer patients treated with APBI. At the time of surgery, Dr. DuPree outlines the tumor bed with VeraForm, implanted along the tumor bed walls approximately 5-10 mm deep in four quadrants. Since we have the flexibility to completely customize the deployment pattern to fit each patient, we came up with a unique pattern to delineate the tumor bed with use of the SAVI catheter. This is intentionally placed with interruption and spacing to avoid the anticipated path of the SAVI insertion and to avoid interference with the subsequent expansion of the device once placed in the cavity. The VeraForm is placed in a U-pattern lateral and medial in the cavity with knots at each end of the monofilament marker. The Superior and inferior borders of the cavity are marked with an inverted U-pattern. In this configuration, the cavity is expandable yet adequately marked for whole breast XRT if needed and allows for delineation of the tumor bed for future mammographic surveillance while not obscuring MRI imaging with scatter.
VeraForm and the SAVI applicator are shown in all three dimensions in the CT images below:
We can review the volume in all dimension to verify that the marked target area is within our planning target volume (PTV eval) and is receiving the minimum prescription dose.
In our growing experience, VeraForm does not interfere with this approach and has the added benefit of remaining as a permanent fiducial to identify the tumor bed for all follow-on patient imaging.
So far so good. However, VeraForm’s greatest value may be with patients who never receive their HDR treatment – patients whose pathology reveals an unfortunate positive sentinel node, positive margin, or other adverse pathologic factor. In this case, we would not place a brachytherapy catheter or remove a spacer if previously placed. It’s an infrequent event, yet, it's one that is expected to happen. Before we began using VeraForm, no marker would have been utilized, given concern for its interference with the brachytherapy applicator. However, in those cases, if a patient needed to return and begin whole breast radiation, the radiation oncologist would be left with the difficult task of trying to determine the original parameters of the lumpectomy cavity for radiation therapy.
More recently, we have seen our first patient who was found to have an unexpected positive sentinel node and therefore was no longer considered to be an appropriate APBI candidate. Since VeraForm was placed during surgery in the ‘U’ configurations, we were prepared for treatment with whole breast radiation therapy as well. The patients are aware preoperatively that by placing VeraForm, it will serve as a delineation marker (not simply a location marker) for the tumor bed to guide her external beam radiation with the same confidence as any other patient who has VeraForm implanted at the time of lumpectomy – in effect, no compromises in treatment. Therefore, our APBI patients are routinely getting VeraForm to safeguard against the expected but unpredictable pathological outcomes.
Beth Baughman DuPree, MD, FACS, ABIHM
Medical Director Oncology Service Line
Cancer Centers of Northern Arizona