What bowel constraints do you use when treating definitive bladder?

When treating intact bladder cases to 63-64.8 Gy with shrinking fields, the max bowel dose is close to the rx dose. Old RTOG trials often just used V45 < 300 but aim for V45 <195 cc from QUANTEC. Do you have a max constraint or a V55 constraint? We use V55 < 5-10 cc from GYN cases but has not been typically possible.

3 Answers

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Radiation Oncology · UMass Memorial Medical Group

Answered on · Updated on

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...

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Radiation Oncology · Vanderbilt-Ingram Cancer Center

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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...

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Radiation Oncology · Stony Brook University School of Medicine

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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...

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