EBRT Machine Studies

[MSP61]

Are there any studies that compare the effectiveness and more importantly, the toxicity, of the various EBRT machines like Gamma Knife, CyberKnife, Varian TrueBeam, Varian Edge, etc. for treating prostate cancer? It seems like there is a lot of new technology that keeps being delivered, that in theory should make improvements via more precise targeting, but I'm wondering if it's actually providing benefit. I'm also wondering if all other things being equal, meaning the radiation oncologists are all experienced and competent, that one should try to find the treatment from the most current technology?

[6357axbz]

I can’t speak to the hardware question but I think you should know the following:

“Conventional external beam radiation therapy (EBRT)

EBRT involves targeted radiation beams being delivered from outside the body. It is a non-invasive method of delivering radiation to a tumour. The radiation beams are shaped as they come out of the linear accelerator and/or before they reach the patient to make sure that they are carefully directed at the cancer.

Intensity-modulated radiation therapy (IMRT)

IMRT is a special form of EBRT involving the delivery of hundreds of small radiation beams with different intensities, entering the body from a number of different angles. This form of radiation therapy was first commonly used for prostate and head and neck cancers in Australia, but is now being used for many cancer sites. It is very precise, sometimes allowing higher doses to be given safely, without causing damage to the surrounding organs.”

[Tall_Allen]

Really good points! So far, the data show they are all about the same in terms of dosimetry. UCLA is doing a randomized clinical trial comparing Viewray MRIdian to Truebeam with RapidArc. I think they will be very similar. The major advantage of Viewray is no invasive placement of fiducials is required. It may have more of an advantage with SRT than primary RT.

I think the experience and the care the RO takes in contouring and developing an optimal treatment plan is much more important. Experience is the opposite of new technology.

[Steveo3312]

The advantage of Proton compared to the other forms of beam radiation is that Proton does not travel through the target, after it hits the tumor it just stops. This is why the technology is used in head and neck cancers.

It is also popular in some pediatric cancers.

But if you are concerned about radiation exposure then LDR or HDR may be the way to go.

Less chance of secondary cancers with seed but it is more invasive then beam radiation.

When I was at Mayo I asked one of the RO attendants what is the chance that I could get a secondary cancer from Proton Pencil Beam radiation, he said about 1 and 20,000.