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deleted4401
Anyone doing SIB-IMRT for preop rectal cancer? I saw some literature on 1.8 Gy/2.2 Gy x 25 fx to microscopic dz/gross dz. 38% pCR, which seemed encouraging.
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For patients who can't tolerate prone positioning on belly board (obese, some hip/knee replacement pts, etc), I do IMRT 1.8/2.0 to 45/50. I haven't felt comfortable giving >2Gy/fx with concurrent chemo and potential dose gradient across small bowel. For patients who can tolerate prone position, I have been doing standard 45/25 + 5.4-9Gy boost with 3D technique using ASTRO consensus guidelines for target volumes. Some private insurers in our region have balked at IMRT reimbursement for rectal pts.
Of note, several of the phase II trials using 5FU + oxaliplatin reported pCR rates in he 30-45% range, but no benefit was seen with addition of oxaliplatin in subsequent phase III. Patient selection a big factor in the pCR rates observed in these phase IIs.
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Like TarHeel, I do not use fraction sizes > 2.0 Gy but I do frequently use IMRT. I use the ASTRO consensus guidelines for rectal/anal cancer contouring.
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I do sequential CD's the old fashioned way (1.8 Gy per day), and use IMRT when pts can't do belly board/prone.
I've seen some people using the 1.8/2/2.2 for post-op H&N though (54/60/66) as an SIB
I've seen some people using the 1.8/2/2.2 for post-op H&N though (54/60/66) as an SIB
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deleted4401
Thanks. Might just do that 1.8 Gy/2.0 Gy. Sequential plans just don't look pretty any more.
Just curious, what's the data against it?
Are most of you doing rectal patients with 3d? Ive only had to use IMRT once.
PMID 17394942
For distal rectum, which is a fixed structure, I always use IMRT, which is anecdotally better tolerated. Middle and especially proximal rectum move so much and we recognize potential for missing tumors with IMRT.
For distal rectum, which is a fixed structure, I always use IMRT, which is anecdotally better tolerated. Middle and especially proximal rectum move so much and we recognize potential for missing tumors with IMRT.
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I am not sure, I understand you argument.
Isn't your CTV the entire mesorectum? Don't you add a PTV margin to that CTV too?
Thus, your PTV with IMRT extends into bony structures, muscles, etc. How does movement of the rectum influence its coverage with IMRT?
Or do you mean that coverage of PTV2 (in case of integrated simultaneous boost) is not guaranteed in middle and proximal rectal tumors?
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deleted4401
Yeah, for CTV1/PTV1, the volume is large and includes MRE, sacral hollow, lymph nodes - not going to miss and appear to get better bowel, femoral head, bladder, sparing. For boost, can be some issues if higher up. I don't always boost - trials range from 45.0 Gy to pelvis total to 50.4 with a boost.
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We use IMRT-SIB for most neoadjuvant rectal cases actually. Depends on location, tumor size, surgeon, etc.. but an example of SIB doses we use:
54.6/1.95 to tumor + 1 cm
50.4/1.8 to mesorectum and high risk nodes
46.2/1.65 to low-risk nodes. (risk stratification depends on location)
Concurrent with Xeloda or 5-FU. Our guys are big believers that increasing pCR rates will lead to better LC. A small in-house protocol (not yet published) looking at fractional doses above 2.0 had higher than expected toxicity.
However, Dr. Mamon said at this weeks online chart rounds that he rarely uses IMRT, so conventional 3-D still appears SOC (and my board answer).
54.6/1.95 to tumor + 1 cm
50.4/1.8 to mesorectum and high risk nodes
46.2/1.65 to low-risk nodes. (risk stratification depends on location)
Concurrent with Xeloda or 5-FU. Our guys are big believers that increasing pCR rates will lead to better LC. A small in-house protocol (not yet published) looking at fractional doses above 2.0 had higher than expected toxicity.
However, Dr. Mamon said at this weeks online chart rounds that he rarely uses IMRT, so conventional 3-D still appears SOC (and my board answer).
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You can do IMRT on the boards for anything. Just be ready to discuss it and back up what you do. I agree though that I think for rectal, I'd be less apt to say IMRT on the boards than for anal CA.
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Since recalls are contraband now (wink, wink), I guess we'll never hear any real anecdotes regarding this. I'd certainly be nervous to say IMRT in those cases you've mentioned, along with things like early-stage glottic larynx.
Nonetheless, I've never heard nor comes across recalls in the past where people failed for simply saying IMRT on a certain case. IMRT requires contouring and PTV expansion, and that should be no different when you're come up with a good 3DCRT plan with fields.
