Registry initiative now holds data on > 500 CyberKnife patients

A multi-institutional “Registry for Prostate Cancer Radiosurgery” (RPCR) was initially set up in July 2010 to track clinical and functional outcomes of men with localized prostate cancer treated with the CyberKnife stereotactic body radiation therapy system (SBRT) at academic and community-based centers throughout the U.S.

Apparently, according to an article in The Sacramento Bee last Friday, this registry program now contains data on more than 500 patients, based on an observational trial protocol that can be found on the Clinical web site. To be eligible for inclusion in this registry, patients must have low- or intermediate-risk, localized prostate cancer. Men diagnosed with high-risk disease are not eligible for inclusion in this database.

According to Dr. Mark Perman, the principal investigator for this registry-based trial, “The RPCR continues to grow rapidly and we are on track to have 20 centers participating by the end of this year. I anticipate that the registry will become a mechanism for clinicians to measure the quality of the care they provide against a national benchmark of community-based and academic radiosurgery centers.”

The registry has been designed to collect clinical data related to diagnosis and patient selection for treatment with SBRT, clinical treatment, patient outcomes over time, and quality of life. According to the information on the trial protocol on, the registry will follow patients for at least 3 years. However, The “New” Prostate Cancer InfoLink hopes that follow-up will be for rather longer than that. It may take at least 10 years to be able to get data that is good enough to know the curative potential of CyberKnife therapy for men with early-stage, localized prostate cancer.

Registry-based studies of this type hold considerable potential as mechanisms to develop comparative effectiveness and outcomes data through which to gain insights into the relative value of different types of first-line therapy for well-defined groups of patients with localized prostate cancer. Unfortunately, to date, the registries that have been set up are commonly limited to a single type of treatment — like the CyberKnife registry mentioned above. In an ideal world, such registries would be used to collect pre-defined data over time on well-characterized men undergoing a variety of older and newer types of treatment. It would then be possible to compare “apples to apples.”

Single-therapy registries will, as Dr. Perman states, make it possible to define baseline and quality outcomes standards for that specific type of treatment … but they don’t offer any help in comparing (say) outcomes of patients treated with CyberKnife radiation to those treated with high-dose, hypofractionated, intensity-modulated radiation therapy (IMRT) or the newer forms of proton beam radiation therapy. We also note that most of the sites enrolling patients into this registry trial are based in south Florida, and that some of the clinical sites with the most experience of the use of CyberKnife in the treatment of prostate cancer are not (at least yet) participating in this registry.

3 Responses

  1. I will be passing this information on to the radiation oncologists who provide the CyberKnife procedure here in Wichita, KS.

  2. I think I have solved my puzzlement over the meanings of “stereotactic” from an authoritative source, the American Society for Therapeutic Radiology and Oncology (ASTRO), specifically, an article for laymen, and a technical paper about prostate cancer applications.

    From the latter: (a) “The term stereotactic refers to precise positioning of the target volume within three-dimensional … space … usually … using some external frame of reference that can be related to the treatment machine.” This morphs into the official definition of stereotactic body radiotherapy (SBRT) as (b) “a total course of therapy [to a body target like prostate] comprising five or fewer treatments” (CPT code 77373 or 77435 for reimbursement purposes). The road from (a) to (b) is explained as follows: “Stereotactic positioning can be precise, and as a result, stereotactic radiotherapy commonly uses higher doses per fraction and fewer fractions (hypofractionation) than conventional radiation.”

    Furthermore, “The term body is used to distinguish the technique from … stereotactic radiosurgery used for … treatment of central nervous system lesions … consisting of five or fewer treatments.”

    SBRT is not synonymous with any particular mode of therapy, like CyberKnife. All CyberKnife treatments of prostate cancer may be SBRT, but all SBRT is not CyberKnife.

    I hope some time to find a clear explanation of the criterion for being precise enough to be called stereotactic and how that degree of precision is proven for various modalities.

  3. Thanks Herb. For many of us non-radiation oncologists, much of the technological mumbo jumbo means about as much as listening to our children or grandchildren talking about what they can do on their iPhone and iPad apps!


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