Prostate IMRT with weird bowel anatomy question

[iradi8u]

I have a 68 year old alcoholic pt (drinks a 12 pack of beer daily) with intermediate risk prostate cancer, T1cN0M0 GS 3+4 in 2 cores, several cores GS 6, PSA 15. Surgery won't touch him (cardiomyopathy) and he needs treatment. He will receive a total of 4 months of ADT. I'm planning IMRT to prostate to 79.2 Gy + proximal SVs to 54, but he has very odd anatomy. His small bowel drapes over his bladder and is nestled between his bladder and rectum. Flipping him prone didn't change anything, over-filling his bladder changed nothing on sims.
I've had to compromise some coverage of the superior aspect of the PTV (94% coverage there) and the very best we can get is a max point dose to the small bowel of 51.14 Gy. The SVs are not contributing to this problem, it's the prostate PTV. I had another radonc look at his plan and he has never seen bowel like this, but he would have no problem delivering this dose. He also has a history of causing significant bowel/bladder late effects, so I'd love other opinions.

Would you accept this point dose to a small portion of small bowel given that there are no treatment options, or would you do something different? Thanks!

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[Gfunk6]

In the IMRT era, 51.15 Gy point dose is completely acceptable.

The only other solution would be to consider a surgical mesh, but your small bowel dose appears safe enough.

 

[iradi8u]

In the IMRT era, 51.15 Gy point dose is completely acceptable.

The only other solution would be to consider a surgical mesh, but your small bowel dose appears safe enough.

Thanks, Gfunk - I can always count on you!

 

[Chartreuse Wombat]

I have a 68 year old alcoholic pt (drinks a 12 pack of beer daily) with intermediate risk prostate cancer, T1cN0M0 GS 3+4 in 2 cores, several cores GS 6, PSA 15. Surgery won't touch him (cardiomyopathy) and he needs treatment. He will receive a total of 4 months of ADT. I'm planning IMRT to prostate to 79.2 Gy + proximal SVs to 54, but he has very odd anatomy. His small bowel drapes over his bladder and is nestled between his bladder and rectum. Flipping him prone didn't change anything, over-filling his bladder changed nothing on sims.
I've had to compromise some coverage of the superior aspect of the PTV (94% coverage there) and the very best we can get is a max point dose to the small bowel of 51.14 Gy. The SVs are not contributing to this problem, it's the prostate PTV. I had another radonc look at his plan and he has never seen bowel like this, but he would have no problem delivering this dose. He also has a history of causing significant bowel/bladder late effects, so I'd love other opinions.

Would you accept this point dose to a small portion of small bowel given that there are no treatment options, or would you do something different? Thanks!

Another possibility is to lower the total dose to the PTV. The evidence for the use of STADT in this setting comes from trials that used 70 Gy (or lower e.g. RTOG 9408). RTOG 0126 has not been published but from ASTRO 2014 plenary there is no evidence of a survival benefit for 79.2 Gy compared with 70 Gy (in the absence of STADT)

 

[napoleondynamite]

max dose of up to 54 I accept routinely. In extreme circumstances, if it were a point dose and <.03cc's, I'd accept higher than that even

 

[Palex80]

I would also lower the dose. There is not much evidence, that you actually need such a high dose for this intermediate risk tumor when you are giving hormones too.
74 Gy looks like a good compromise in my opinion, 70 Gy are also an option. This patient is not going to die because of his prostate cancer, that's for sure.

 

[Mandelin Rain]

51.1 Gy over 44 fractions is probably a bit different than 51.1 Gy in 25 fractions.

 

[Phantom1]

51 max point dose to bowel using IMRT is ok. Remember for chemoradiation in bladder cancer the Bowel dose can get even higher than that. If you are concerned why not just prescribe to 78 Gy... by lowering your prescription dose slightly you can probably get better coverage on your PTV.