Unresectable Rectal Cancer- Thoughts on Dose?

[ramsesthenice]

Atypical case here. Have a guy who presented with liver mets and an awful rectal tumor invading through the pelvic floor into the pyriformus muscle on the right and with anterior disease invading the bilateral SVs with a bladder fistula. Clearly not resectable. He was given a diverting ostomy and started on chemo. Over the last year they slammed him with 12 cycles of FOLFOX + Pantitumamab and then 8 cycles of FOLFIRI + Bev. He tolerated it all like a champ and had a pretty good response. Now he has pelvic only disease but is not now (and never will be) resectable because he still has invasion through the pelvic floor into surrounding muscles and anterior structure involvement. Still diverted and doing well. I am going to treat his pelvis with chemoradiation but I am trying to decide how high to go. He has pelvic only disease but its still pretty advanced and realistically this is almost certainly palliative. I feel like being a little more aggressive than usual but don't want to overdo it and cause excessive toxicity (though he is diverted which will offset a lot of what can go wrong). I am kinda feeling 60 Gy to gross disease. Other thoughts?

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[medgator]

59-63 with xeloda. Have had some decent responses. If they can't handle long course, I do 50/20 or 40/15

 

[OTN]

59.4 in 1.8s w Xeloda is what I do. I’ve been able to have a few cases where we were able to achieve long term control.

 

[medgator]

I feel like adeno deserves 60+. My favorite kind of evidence

 

[seper]

Liver mets at diagnosis? I won't go above 55.8 Gy. Not sure if Xeloda would help since 5FU has been already given.

 

[BobbyHeenan]

With no ostomy/rectum intact and decently functional I'd stop at 54-55.8 Gy.

With the ostomy and no plans ever for re=connection I think 60ish sounds good.

In reality not sure 5-6 Gy matters but here we are.

 

[Palex80]

I'd take into consideration how his sphinter function is. With a pelvin floot involvement it may be gone. Which means he will always require the colostomy, irrelevant of how well the tumor responds to your treatment. In that case you can take it to 60 Gy and beyond.
If you think he still has sufficient sphincter function and there's a chance the colostomy will be reversed then I wouldnt push it higher than 59.4 Gy.

 

[RickyScott]

I have gone to 60 Gy several times with xeloda in elderly pts and no issues.

 

[RadOncDoc21]

I have gone to 60 Gy several times with xeloda in elderly pts and no issues.

Same here, I get creative and usually end up doing some IMRT SiB type of plan because I’m so great.

 

[RickyScott]

Same here, I get creative and usually end up doing some IMRT SiB type of plan because I’m so great.

pet for treatment planning helps a lot in this area and guiding hot spots sib/etc and limiting amount of anus in field

 

[evilbooyaa]

pet for treatment planning helps a lot in this area and guiding hot spots sib/etc and limiting amount of anus in field

Guys it's extensive tot he point of going into pelvic floor muscles and anterior structures. This guy's sphincter function is already toast based on the description of the tumor itself. Blast away with Xeloda. I think 60 is fine, could understand the argument for 59.4 although an 'official' dose-response has never been identified.

 

[RickyScott]

Guys it's extensive tot he point of going into pelvic floor muscles and anterior structures. This guy's sphincter function is already toast based on the description of the tumor itself. Blast away with Xeloda. I think 60 is fine, could understand the argument for 59.4 although an 'official' dose-response has never been identified.

pet may help define residual disease target after so much neoadjuvant chemo for boosting/sib. Even if pet/gtv areas are getting 3-5% more per fraction, it translates into a lot more cell kill at the end, and makes planning a bit more interesting...

 

[ramsesthenice]

Thanks all. I have seen a little bit of everything that has been going through my head here but it seems like the majority favor something around 60 so I will probably go with that.

 

[Babyyoda_XRT]

60/30 SIB to GTV 66-70/30

 

[RadOncDoc21]

60/30 SIB to GTV 66-70/30

yes yes... and to baby yoda...yes!! Well, maybe the 70 is a little hot for me but if baby yoda says it, who am I to disagree.

 

[evilbooyaa]

I like star wars as much as the next person but derailing of threads for star wars quotes/memes is not OK. Next star wars OT will result in dings.

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