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Radiotherapy and visceral fat

User
Posted 17 Feb 2019 at 23:56

I'm 5+ months on hormone therapy and will almost certainly need RT (possibly with or without RP), but I'm still being diagnosed to make sure there's no spread first because with an untreated PSA of 57, they want to make really sure it hasn't spread before embarking on treatment to just the prostate.

I've been keeping myself very fit and watching what I eat to prevent putting on weight (so far, successfully - my body fat is around 13% and visceral fat 7/30, which are both low). However, this got me thinking about RT treatment. Low visceral fat means the organs don't have much excess fat between them. That might perhaps mean that it's harder for the RT to avoid other organs which will be closer to the prostate. Has anyone come across any such effect being documented? The nearest I could find was a paper about brachytherapy (which I'm not being offered) describing radiation dose to the rectum, which is indeed higher in people with lower BMI (https://ro-journal.biomedcentral.com/articles/10.1186/1748-717X-9-93).

So I'm wondering if I should try and put on some visceral fat prior to RT?

User
Posted 18 Feb 2019 at 09:23

I can't argue the logic of having a fat 'cushion' - though it would be a tough one to prove either way. 

But there are practical issues: first, to be sure you've installed enough local fat to do the job, you'd need to put on several stone overall, quickly. Might not kill you, but it'll certainly damage you.

But the key issue is this: currently, your weight is stable, and you can keep it that way over the weeks of RT. Once you starting pigging out, your weight will vary significantly over the weeks, especially as your appetite (and effort) may flag over the course of treatment. If your weight varies, your prostate 'cushion' will vary. This and the varying pressure of fat elsewhere means your prostate will move within you. So pinpointing the beam (they usually use tattoos these days) will be unreliable. And you'll end up with exactly what you set out to avoid. Only more so. Quite possibly giving maximum dose to a slightly shifted rectum.

Eat healthy, be sure your bowels work regularly, and follow fluid intake instructions to the letter (and the second). That's the best we can all do.

.

-- Andrew --

"I intend to live forever, or die trying" - Groucho Marx

User
Posted 18 Feb 2019 at 09:25

This is a better link:

Influence of body mass index and periprostatic fat on rectal dosimetry in permanent seed prostate brachytherapy

And note their caveat: "Dose to the rectum remains difficult to predict and depends on many factors, one of which is body fat distribution."

Little point in fixing (or trying to fix) one (of many) factors while messing up several others.

Edited by member 18 Feb 2019 at 09:28  | Reason: Not specified

.

-- Andrew --

"I intend to live forever, or die trying" - Groucho Marx

User
Posted 18 Feb 2019 at 09:43
Weight stability was very important to ensure the scans and dosing was applied correctly for my IMRT. I put all my weight on afterwards 😢😢
 
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