HDR prostate boost question

[thesauce]

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For logistical reasons, would there be any issues with doing an HDR prostate boost interdigitated with the external beam portion like is done in other disease sites like cervical?

Also what is your boost dose and fractionation for HDR prostate boost?

 

[RADONC4285]

There is no problem interdigitating the boost. We do either single or two fractions boosts (physician dependent) : 10.5 Gy x 2 or 15 Gy x 1. Personally I like the latter because it's logistically easier and there is no convincing evidence a two fraction boost/dosing is better. For EBRT, we do 45 Gy in 25 fractions, although 46/23 is totally fine as well

 

[ramsesthenice]

For logistical reasons, would there be any issues with doing an HDR prostate boost interdigitated with the external beam portion like is done in other disease sites like cervical?

Also what is your boost dose and fractionation for HDR prostate boost?

I do 15x1 and order doesn’t really matter. The HDR can happen up front, interdigitated, or out back. Our HDR suite can get busy and I just have to do what works. The only thing with interdigitating is make sure you are using cone beam, CTOR, MR IGRT etc or use generous margins just in case you get a good bit of swelling post procedure. It’s usually not an issue but it can be pretty pronounced in some guys.

 

[Aphtalyfe]

For logistical reasons, would there be any issues with doing an HDR prostate boost interdigitated with the external beam portion like is done in other disease sites like cervical?

Also what is your boost dose and fractionation for HDR prostate boost?

We usually do HDR "boost" first and also put in fiducials/SpaceOAR during implant.

15Gy x 1 for boost. 45/25 or 37.5/15 for pelvic RT.

We have a protocol opening soon for 15Gy x 1 HDR + 5Gy x 5 pelvic RT

 

[thecarbonionangle]

The nice thing about boost first is you don’t run into a situation where you gave someone 40-50gy and then you cant place needles due to pelvic bone interferance,which you can try to avoid but models sometimes fail. You know someone is implantable and then you do the EBRT

 

[ramsesthenice]

The nice thing about boost first is you don’t run into a situation where you gave someone 40-50gy and then you cant place needles due to pelvic bone interferance,which you can try to avoid but models sometimes fail. You know someone is implantable and then you do the EBRT

I also try to do HDR upfront if I have doubts. With more experience it gets easier to assess and I can’t honestly remember the last time I was surprised to run into arch interference. The bigger problem (pun intended) is the technical challenges of treating guys after 65 years of eating an unrestrained corn-fed Midwest diet. Can you get the stepper close enough? How good is the imaging going to be? How open can you get the pelvic outlet? Haven’t had to bale on a case in years but it gives me piece of mind to know I can easily do it if I have my doubts.

There is a downside though...acute GU tox during EBRT is worse. Not unbearable, but guys do have more frequent issues with urinary hesitancy when you do the boost first. It’s not surprising if you think about it.