rectum vs. colon

[Reaganite]

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This question seems to come up all the time...

German rectal cancer trial included any tumor with an inferior border within 16cm of the anal verge. Some other rectal CA studies included only tumors within 12cm. So what cut-off or other methods are you guys using to distinguish colon from rectum? I've got a T2N2 adenoca inferior extent of which is 15cm from the anal verge...

 

[Palex80]

The MRC/NCIC - trial included tumors up to 15 cm, so that's another trial going for a "higher" limit of the rectum.
I usually make it dependant on the endoscopy results (rigid vs. flexible give you different measurements) and try to look at the imaging too, since you can often see where the rectum is going into the sigmoid there.

In my opinion the only "true" question would be a T3N0, where one can advocate to ommit preoperative RT in very proximal tumors. When lymph nodes are present, I would go with RT in all "gray area cases" of rectum vs. sigmoid.

 

[napoleondynamite]

I use the anatomical boundary of the peritoneal reflection. If there is doubt, I think that is the role of MRI. Below the peritoneal reflection I will treat as rectal with preop, above I send for surgery.

 

[deleted4401]

What Napoleon said ... Sometimes, though it's sort of borderline, they go for surgery first and then send it if it ends up being recto-sigmoid.

 

[Gfunk6]

I use the anatomical boundary of the peritoneal reflection. If there is doubt, I think that is the role of MRI. Below the peritoneal reflection I will treat as rectal with preop, above I send for surgery.

Exactly correct. If you get the rectal patient post-op, then between the operative note and pathology there is usually little question of where the tumor is located.

Keep in mind that once a tumor passes the peritoneal reflection, the LN drainage pattern changes. You are not doing the patient any favors by irradiating his illiac LNs when most of the tumor is above the reflection.

 

[thesauce]

I use the anatomical boundary of the peritoneal reflection. If there is doubt, I think that is the role of MRI. Below the peritoneal reflection I will treat as rectal with preop, above I send for surgery.

Does the MRI distinguish this well? We rarely get them.

We use 15cm as a surrogate for the peritoneal reflection. If the tumor is higher than that, they go for surgery and (rarely) return to us if they find that it's actually below the reflection.

 

[napoleondynamite]

I think it depends on the quality of the MRI. I didn't believe this entirely until coming to Mayo, but now when I see images from the community compared with on our specific rectal protocol and read by our GI radiologist, I admit in as non presumptuous way as possible that the difference is huge and our radiologists have helped me sort this out with my own patients. We have a kind of crazy protocol though with 2 MRI's with recral gel and Ferraheme, one MRI looks specifically at the primary, a day later the nodes are evaluated with the Ferraheme.

But I agree that in instances when you're on the fence you just have to go with any other factors that can help like distance from verge, sigmoid, etc.

 

[deleted4401]

Wow- I didn't realize their were such significant differences. Even without the protocol, I find it helpful for staging. Our surgeons like them better, and I think we can get them easier than EUS. I think NCCN says either are appropriate.

 

[medgator]

Wow- I didn't realize their were such significant differences. Even without the protocol, I find it helpful for staging. Our surgeons like them better, and I think we can get them easier than EUS. I think NCCN says either are appropriate.

Yeah. My pref is eus when possible but mri is fine, especially if you don't have someone good at eus nearby (can be very operator dependent and typically requires fellowship training to be really be proficient at it)

 

[Palex80]

Yeah. My pref is eus when possible but mri is fine, especially if you don't have someone good at eus nearby (can be very operator dependent and typically requires fellowship training to be really be proficient at it)

I totally agree on that. You have to trust EUS (and the guy who did it), but you can actually look at the MRI and use it for treatment planning.