Cyberknife is simply a brand name machine for SBRT, which was approved by the FDA for multi-modal cancer treatments in 2001, so it's been used for PCa treatment since even before that time in clinical trials if memory serves. Tall Allen also knows quite a bit about
SBRT, he chose SBRT for his PCa treatment in fact, and I think we would all agree, if Tall Allen chose this treatment modality, well, that in and of itself says a lot does it not? It's not for everyone for sure, given it doesn't have the long history that some other treatment modalities offer, but then again, those other treatment modalities come with much higher and more severe SE's as a general rule.
Here's a link to the nine year SBRT results:
/prostatecancerinfolink.net/2016/01/06/nine-year-outcomes-after-treatment-with-sbrt/SBRT for PCa was modeled after HDR-BT. As another poster outlined, hypo-fractionated RT is the future for RO - based upon evidenciary medical practices over the last 30 years, primarily due to BED calculations (Biological Equivalent Dose for low alpha/beta ratio cancers). Even the NHS in the U.K. recently announced that they will be migrating away from traditional hyper-fractionated RT to hypo-fractionated RT based upon very large studies that show no compromise of treatment efficacy while significantly lowering treatment cost, patient inconvenience, SE profiles, etc.
From a business perspective, remember that SBRT costs
less than traditional hyper-fractionated RT overall, requiring only five office visits, and fewer follow up office visits, all of which takes money out of the RO's pockets as compared to traditional IMRT/IGRT/EBRT 80 Gy 44 weekday treatment regimens. Even PBRT is in clinical trials now to move to hypo-fractionation.
I wouldn't say that SBRT is a new radical treatment based upon the data available. It's relatively new when compared to traditional ORP, RALP, EBRT, LDR-BT, HDR-BT, etc., but it's not much newer than some of the other newer forms of RT, such as IMRT/IGRT, and it's really just the next evolution of RT based upon solid research from HDR-BT studies from the 90's and the 2000's.
I looked at SBRT during my treatment investigation stage, and ultimately chose HDR-BT monotherapy, but if I were to have chosen a beam therapy, I would most likely have gone with SBRT since it is a non-invasive form of HDR-BT monotherapy. Again, to each his own, and always remember that some patients respond well to RT and others do not, so RT isn't for everyone. Unfortunately at this point in time we don't have the tests to determine which patients will respond well to RT, and which types of PCa respond best to RT from a treatment efficacy perspective, but we are getting closer every day. Eventually, tests will become available that will be able to accurately predict individual patient response to RT and whether your specific PCa will respond well to RT and allow for long term remission. Those tests are probably still years away though.