Adjuvant (post-op) radiation in T4/R+ colorectal cancer

[elementaryschooleconomics]

I have a few T4b/N+/R+ colorectal patients this month. I don't know why these are popping up, and I'm concerned it's due to COVID-related delays in screening and workup.

These are normally questions I would pose to my personal friend/colleague network. However, I suspect we'll be seeing more of this over the next few years as a consequence of the pandemic, so I thought a public conversation might be helpful to someone else down the road. I also know there are absolute GI gurus who lurk/post here, and I'm curious what they think.

My understanding of this space: much of the data came from the 80s and 90s, and INT0130 was just...meh. Technology is significantly better now. There have been a handful of database studies published in the last 5-6 years. I think this one says it best, which ends with stating that there's a "potential benefit in patients with insufficient resection (R2) and those with both pT4 status and positive margins".

The patients I'm seeing have (appropriately) sought second (and third) opinions at big places. I enjoy reading absolutely conflicting recommendations.

For those of you who treat GI: what do you do with these patients? And if you treat them, what's your favorite regimen?

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[RickyScott]

I have a few T4b/N+/R+ colorectal patients this month. I don't know why these are popping up, and I'm concerned it's due to COVID-related delays in screening and workup.

These are normally questions I would pose to my personal friend/colleague network. However, I suspect we'll be seeing more of this over the next few years as a consequence of the pandemic, so I thought a public conversation might be helpful to someone else down the road. I also know there are absolute GI gurus who lurk/post here, and I'm curious what they think.

My understanding of this space: much of the data came from the 80s and 90s, and INT0130 was just...meh. Technology is significantly better now. There have been a handful of database studies published in the last 5-6 years. I think this one says it best, which ends with stating that there's a "potential benefit in patients with insufficient resection (R2) and those with both pT4 status and positive margins".

The patients I'm seeing have (appropriately) sought second (and third) opinions at big places. I enjoy reading absolutely conflicting recommendations.

For those of you who treat GI: what do you do with these patients? And if you treat them, what's your favorite regimen?

if a postop field likely to include the residual disease, I would treat w/xeloda to 50-54 gy. Have done this once or twice for tumor near flexure or involving abdominal wall.

 

[pikachu]

I have a few T4b/N+/R+ colorectal patients this month. I don't know why these are popping up, and I'm concerned it's due to COVID-related delays in screening and workup.

These are normally questions I would pose to my personal friend/colleague network. However, I suspect we'll be seeing more of this over the next few years as a consequence of the pandemic, so I thought a public conversation might be helpful to someone else down the road. I also know there are absolute GI gurus who lurk/post here, and I'm curious what they think.

My understanding of this space: much of the data came from the 80s and 90s, and INT0130 was just...meh. Technology is significantly better now. There have been a handful of database studies published in the last 5-6 years. I think this one says it best, which ends with stating that there's a "potential benefit in patients with insufficient resection (R2) and those with both pT4 status and positive margins".

The patients I'm seeing have (appropriately) sought second (and third) opinions at big places. I enjoy reading absolutely conflicting recommendations.

For those of you who treat GI: what do you do with these patients? And if you treat them, what's your favorite regimen?

Having treated a handful of patients with T4 disease and margin positive resections with local failures that were sent in for salvage RT I think it's reasonable to think about IF you have a fixed target like the interior abdominal wall or bladder remnant or something along those lines. Ideal to have clips too and i generally review contours with the surgeon if at all possible. 54-56 Gy to + margin area with concurrent cape. It can be difficult to identify nodal volumes in these cases as the nodal dissection in a hemicolectomy generally goes the whole way back to the mesentery - would be interested to learn how others are approaching prophylactic nodal treatment or just omitting?

 

[Ray D. Ayshun]

I tend to err on the side of treating when there's a reasonably defined area known to have cancer, sidewall for instance, as the dose we go to is generally well enough tolerated. I don't do eni, as I wouldn't feel comfortable I was genuinely doing eni. But I'd love to hear from someone that does

 

[ramsesthenice]

Having treated a handful of patients with T4 disease and margin positive resections with local failures that were sent in for salvage RT I think it's reasonable to think about IF you have a fixed target like the interior abdominal wall or bladder remnant or something along those lines. Ideal to have clips too and i generally review contours with the surgeon if at all possible. 54-56 Gy to + margin area with concurrent cape. It can be difficult to identify nodal volumes in these cases as the nodal dissection in a hemicolectomy generally goes the whole way back to the mesentery - would be interested to learn how others are approaching prophylactic nodal treatment or just omitting?

There is no good rationale for prophylactic nodal radiation. The mesenteric lymphatics are not anatomically confined (as opposed to perirectal lymphatics within the MRF) and post resection good luck even really identifying what region you think is most at risk. The goal here is local control. Keep the fields small. I’ve don’t long course chemorads as suggested above and SBRT when the anatomy works out. Fortunately it’s been quite a while since I’ve had to do this.

 

[elementaryschooleconomics]

Having treated a handful of patients with T4 disease and margin positive resections with local failures that were sent in for salvage RT I think it's reasonable to think about IF you have a fixed target like the interior abdominal wall or bladder remnant or something along those lines. Ideal to have clips too and i generally review contours with the surgeon if at all possible. 54-56 Gy to + margin area with concurrent cape. It can be difficult to identify nodal volumes in these cases as the nodal dissection in a hemicolectomy generally goes the whole way back to the mesentery - would be interested to learn how others are approaching prophylactic nodal treatment or just omitting?

This is exactly where I landed and was going to be my follow-up question, haha.

Fortunately it’s been quite a while since I’ve had to do this.

Yeah...I hope this month is a fluke and not the start of a trend.

 

[Radonc90]

- In the 1990s, these cases were quite common bc at that time, post-op chemoRT was routine until the German study came out saying preop chemoRT is better.
- Agrred with the above comments.
- The nodes are removed, sometimes they do a high ligation, which is even better. If the surgeon was smart, he/she would have put an omental flap in the pelvis for you. Problem is: most modern Colorectal surgeons are used to preop chemoRT and rarely perform an omental flap.
- This is what I do for these cases: Prone, Belly board if poss, 50.4 Gy (if neg margins), 54-56 Gy (if pos margins) + Oral Xeloda as mentioned above.
And old-school 3D 3-field, trying to do IMRT here can backfire on the pt (local recurrence = death sentence).
So, yes in my book, old-school 3D 3-field a la Bruce Minsky's fields.

 

[deleted1111261]

Target is the target - what is the difference between a 3D vs VMAT PTV if both are covered? In either case a target needs to be defined. And in either case, it needs to be covered.

I would go over the lack of evidence for it, and if surgeon and patient were pushing, would treat with well defined field (help of surgeon).

No ENI. Curious as to what “experts” do. I think many of them do treat in this scenario.

 

[Radonc90]

3D is more forgiving, even in preop case.
Even in preop case, 3D (3-field) technique is very commonly used.

Drawing a target in a post-op case is very difficult, if not impossible, even for the surgeon who did the case.

There is a basic rule of thumb (in my book), whenever dealing with a messy postop case, cover the entire pelvis
with 3D: it is much more forgiving.

A recurrence post postop RT is usually a death sentence. If the pt is lucky then exent...

 

[deleted1111261]

But that’s not answering the question. I agree that drawing a target is hard in either scenario. If you draw it too small in 3D or VMAT, you can have a miss.

If I treat something, the CTV doesn’t change because of the technique. The PTV can be variable, but that has nothing to do with 3D/IMRT. ICRU definitions remain the same.

Am I missing something? If you draw the same exact target for a 3D plan and an IMRT plan and covered both the same, how would recurrence pattern change?

If you’re saying use a generous field - I agree with that wholeheartedly.

 

[TheWallnerus]

But that’s not answering the question. I agree that drawing a target is hard in either scenario. If you draw it too small in 3D or VMAT, you can have a miss.

If I treat something, the CTV doesn’t change because of the technique. The PTV can be variable, but that has nothing to do with 3D/IMRT. ICRU definitions remain the same.

Am I missing something? If you draw the same exact target for a 3D plan and an IMRT plan and covered both the same, how would recurrence pattern change?

If you’re saying use a generous field - I agree with that wholeheartedly.

I was about to say more or less the same thing. It's just w/ colon cancer, the fields are MUCH bigger than what we are used to. The PTV (and CTV) defined by an AP/PA field... because that was what was used in most cases on INT-0130... is VERY big.

I have discussed postop RT in colon ca w/ Tepper many times, and was a tutee of Charles T., so here's my take on postop RT for colon ca...
1) Do it for T4 w/ positive margin for parts of colon that are retroperitoneal (or for sigmoid adherent to bladder); essentially, stay away from transverse. A T4 *and* a positive margin makes RT perhaps therapeutically beneficial
2) INT-0130 is not a reason to do, or not to do, postop RT... use the retrospective data (best retrospective data from MGH) to make decisions
3) Risk/benefit ratio not as favorable for T3, so turn those cases down
4) Nodal drainage patterns can be "thought of," but do not "chase"
5) It is pretty sad that for the third most common cancer we have one crappy, non-accrued, randomized RT trial!

EDIT: Above, big fields to 45, then boost to 50-54.

 

[Radonc90]

Agree with what you said Simul, but 3D is less expensive for the pt and provides the same outcome as IMRT,
assuming same PTV, which is the entire pelvis at risk, in this case...

I misread the original thread which said "colorectal"...I was thinking rectum all along.

Anyway, treating abdominal wall is a different deal.
Rectum pelvis is another deal.

PS: I have done about 40-50 LARs and whole bunch of APRs, I can tell you that this stuff is deadly...

 

[elementaryschooleconomics]

Agree with what you said Simul, but 3D is less expensive for the pt and provides the same outcome as IMRT,
assuming same PTV, which is the entire pelvis at risk, in this case...

I misread the original thread which said "colorectal"...I was thinking rectum all along.

Anyway, treating abdominal wall is a different deal.
Rectum pelvis is another deal.

PS: I have done about 40-50 LARs and whole bunch of APRs, I can you that this stuff is deadly...

Ah yeah, post-op rectum is something which I encounter more frequently (well, not "frequently" thankfully, but more than T4 colon).

For targets: tumor bed (anastomosis/clips +pre-op imaging), grabbing some of the bowel in the region of the resection, and any sites of invasion (abdominal wall etc). The surgeons continue to be very kind to me and drop a quilt of clips in these scenarios which makes it easier.

The nodes are more challenging. I don't want to do ENI, but for the patients with N+ disease, I'd like to include the original anatomical location of the nodes if the surgeons can tell me where they came from and it doesn't cause my PTV to be ridiculous.

I'll probably reach for VMAT here but...I'm a product of the post-IMRT era, I will VMAT anything that moves if given half a chance.

 

[Radonc90]

Abd wall RT (for T4N0) is not difficult as long as you look at the preop CT scan and figure out where it invaded the abd wall.
Then draw the CTV/PTV and treat.
Usually this is easier on the pts than treating pelvis, at least in my experience...

 

[deleted1111261]

Agree with what you said Simul, but 3D is less expensive for the pt and provides the same outcome as IMRT,
assuming same PTV, which is the entire pelvis at risk, in this case...

I misread the original thread which said "colorectal"...I was thinking rectum all along.

Anyway, treating abdominal wall is a different deal.
Rectum pelvis is another deal.

PS: I have done about 40-50 LARs and whole bunch of APRs, I can tell you that this stuff is deadly...

Ah, economic argument much different 😊

 

[Radonc90]

"Financial Toxicity" my friend lol...

 

[deleted1111261]

What would you choose if the cost was the same? I would choose VMAT (presuming physician practices modern medicine).

 

[jondunn]

What would you choose if the cost was the same? I would choose VMAT (presuming physician practices modern medicine).

bone marrow DVH will be better

 

[TheWallnerus]

I'd like to include the original anatomical location of the nodes if the surgeons can tell me where they came from and it doesn't cause my PTV to be ridiculous

Any of the data supporting RT use in colon used "PTVs" (not even a known term for all intents and purposes at the time this data appeared) which would by today's standards be thought of as ridiculous. On the VERY RARE occasions I use RT for colon, I am using a 4-field box approach "old school" and then boost my guess at the anastomosis/clips w/ 3-5cm margins. If you have a dome-of-bladder-invading sigmoid colon ca w/ positive margin in dome of bladder region, I would use IMRT on that as the targeting would be more... targetable. Abdominal wall-invading colon cancers are pretty rare T4 presentations of colon cancers nowadays, but those are more targetable too.

A lot of this is just fancy ruminating on our part because not only is the incidence of a reasonable RT indication in colon ca rare, the incidence of a referring doctor wanting an RT referral is even rarer!

 

[ramsesthenice]

I typically do 3D for these as well. Not much in the way of dose-limiting structures. When I say keep the fields small I mean really target what is at risk and don’t go chasing nodes. At the same time, don’t try to get too cute. Use generous margins and make sure you hit the target. It can done efficiently with IMRT and honestly the on table time is probably faster with IMRT than 3D. But this is not usually a situation where IMRT is going to give you clinically meaningful decreases in normal tissue exposure. There is no reason to really go out of your way avoid bowel etc. treat what you need to address what is at risk.

 

[evilbooyaa]

You're doing RT in T4 pos margin colon cancer to control the site of the positive margin and T4 area, not really the nodal burden (which historically gets "cleaned" up with surgical resction followed by chemotherapy). So I would also favor treating small field, and I think IMRT would be reasonable based on the location of where it attaches. Clips here by the surgeon in the area of the positive margin is incredibly important to give you some area of where to aim at.

This answer is for COLON cancer, which is different than the answer would be for T4 rectal cancer with positive margin - rectal cancer I would cover relevant lymph nodes as you would for a pre-op case. While "colorectal" cancer is a thing, the role of radiation is (IMO) widely different in colon cancer vs rectal.