What bowel constraints do you use when treating definitive bladder?

I often find a V60<10 cc bowel constraint too restrictive and challenging to meet without significant compromise of tumor coverage due to the aforementioned tendency of the bowel to sit atop the bladder dome, and requisite standard PTV margins.

First and foremost, I obtain daily CBCT for these patien...

Bladder cancer used to be treated with 3D-CRT techniques of whole bladder + 1.5 cm for PTV to full bladder to doses of 64 Gy, and patients still did OK as per BC2001. Mobile bowel sitting on top of the bladder can handle more than we give it credit for.

Keep the bowel ALARA if doing IMRT and daily CB...

The SWOG S1806 trial approaches this by contouring small bowel loops (excluding large bowel) and constraining this to Max (0.03cc) <55 Gy, V50 Gy <15 Gy, V45 Gy<100cc, V40 Gy<130cc and <30%, and V30 Gy <150cc.

IMRT can help if you are running into trouble with the lower dose constraints, or alterna...