Sacral Fractures

[ramsesthenice]

Just want to share a change I am making. Now that I have been out for a while, I am realizing that sacral insufficiency fractures are not common, but do happen more than I would have expected. I see a couple of symptomatic fractures per year. Which again, since I treat a lot of pelvic patients the number is small. However, I went back carefully and all but one of them have something in common: they are all post-menopausal women with rectal cancer. Not a single one of them had a Gyn primary. Typically the fractures occur up near the SI joint and the nodal CTV in this area abuts the sacral fossa even for Gyn tumors. In my practice, the biggest difference between Gyn and rectal primaries is 3D vs IMRT and I really am starting to wonder if that is the difference. I know a lot of centers have been doing IMRT for rectal primaries for a long time. I had been a hold out, but I have not had trouble getting IMRT approved (even with Evicore) so I think Im making the change.

For anyone who has ever seen one, they are not usually that big of a deal. They sure can hurt but the vast majority of the time with some PT they resolve over 6-8 weeks. The only time I have had to do surgery was for a guy who had a had a history of Crohn's and had a SCC arise in an enterocutaneous fistulous tract that involved the inferior sacral surface. I cooked it. Not at all surprised he ran into trouble down the road. Even though I am saying they are not usually that big of a deal, I find it a bit striking how specific the population I am seeing this in actually is.

Bone agents could also be an option too. Again, minus the outlier I just mentioned above it is all post-menopausal women. There is clearly some predisposition. But if that were the driving factor, I should be seeing it in post-op endometrial cancers etc. And I have not.

---

Members don't see this ad.

 

[Doctorer]

Funny enough (in this situation), I just dealt with an anal cancer patient yesterday who is NED but appears to have slightly symptomatic sacral insufficiency fractures. My worst insufficiency fracture was actually in a female gyn patient who I treated with pelvic IMRT and ended up needing to be NWB for a few weeks.

All post menopausal/etc.

 

[communitydoc13]

Typically the fractures occur up near the SI joint and the nodal CTV in this area abuts the sacral fossa even for Gyn tumors. In my practice, the biggest difference between Gyn and rectal primaries is 3D vs IMRT

Very helpful post.

I still think 3D sometimes in aggregate better for a good prone setup for rectal (better bladder and integral dose). I don't bother with traditional posterior field border however. I draw out CTV and even provide small PTV and then cover. While I spare posterior upper sacrum this way, probably still getting full dose to common areas of fracture.

I'll reconsider IMRT for my older, female patients.

 

[OTN]

I've had luck with ibuprofin for PIF before

 

[ramsesthenice]

I've had luck with ibuprofin for PIF before

Yes. Anti-inflammatories do help. So can a short course of steroids if there is no contraindication. On MRI the edema can be quite impressive and I suspect that is the actual source of pain. The fractures don't actually go away.

I don't bother with traditional posterior field border however.

Good because treating based on bony anatomy alone with diagnostic 3D imaging is stupid. I remember people use to talk about going a cm past the sacrum for T4. But if its T4 because of anterior invasion, what purpose does that serve? I don't cover the whole sacrum either. When I plan a 3D rectal case, I put on the standard fields, then start pulling back based on the actual anatomy. I never just go by bony anatomy.

 

[SneakyBooger]

all post-menopausal women.

Interesting observation.

I have seen 4 rib fractures in breast cancer patients over the years, all in premenopausal women. I attributed this to the higher calcium content to result in higher dose deposition in the bone in comparison to postmenopausal women.

Thanks for sharing.

 

[TheWallnerus]

Maybe we should be putting our post menopausal rectal patients on estrogen/progesterone at initial consult if they aren't on it already.

 

[Mandelin Rain]

Interesting observation.

I have seen 4 rib fractures in breast cancer patients over the years, all in premenopausal women. I attributed this to the higher calcium content to result in higher dose deposition in the bone in comparison to postmenopausal women.

Thanks for sharing.

That's weird. I've seen exactly one rib fracture, and that was after the woman fell off a horse.

 

[communitydoc13]

Seen zero rib fractures with breast RT. Seen many, years after SBRT lung. Would not change my dosing based on these as have been universally clinically mild. (all older women btw).

 

[ramsesthenice]

That's weird. I've seen exactly one rib fracture, and that was after the woman fell off a horse.

Rib fractures are interesting. I can recall seeing quite a few during residency (the only thing in the thorax I regularly treat now is the esophagus). Funny thing is, most were asymptomatic and incidental. I am seeing the same thing with duodenal ulceration after pancreatic radiation. Now that people are living longer with triplet therapy and people are getting stent exchanges in the post-radiation setting, it is remarkable how often the endoscopists (who are really good) comment on ulcerations and mucosal distortions in people who are completely asymptomatic.

 

[Mandelin Rain]

Rib fractures are interesting. I can recall seeing quite a few during residency (the only thing in the thorax I regularly treat now is the esophagus). Funny thing is, most were asymptomatic and incidental. I am seeing the same thing with duodenal ulceration after pancreatic radiation. Now that people are living longer with triplet therapy and people are getting stent exchanges in the post-radiation setting, it is remarkable how often the endoscopists (who are really good) comment on ulcerations and mucosal distortions in people who are completely asymptomatic.

Basically every guy after prostate radiation has some degree of mucosal distortion on colonoscopy in my experience. Vast majority are asymptomatic.

 

[ramsesthenice]

Basically every guy after prostate radiation has some degree of mucosal distortion on colonoscopy in my experience. Vast majority are asymptomatic.

Yeah, Im not talking about telangiectasias or scaring. I am talking about frank ulceration during the acute phase reaction (2-6 weeks post radiation). I, like a lot of people, told patients that ulceration is pretty uncommon based on symptomatology. It is definitely more common than I would have expected.

 

[Palex80]

Maybe we should be putting our post menopausal rectal patients on estrogen/progesterone at initial consult if they aren't on it already.

Oh and then treat the breast cancer 10 years down the road. WIN-WIN!

 

[evilbooyaa]

Interesting observation.

I have seen 4 rib fractures in breast cancer patients over the years, all in premenopausal women. I attributed this to the higher calcium content to result in higher dose deposition in the bone in comparison to postmenopausal women.

Thanks for sharing.

Do you mean a spontaneous rib fx in breast cancer patients? Did they get proton therapy?? Given to lower their risk for secondary malignancy (thus why all pre-menopausal)?

I've seen spontaneous rib fx in lung SBRT patients only. Have not seen it with definitive 60/30 lung...

To OP - Interesting... I did see one in a relatively standard gyn pelvic IMRT field at 1 year out. Som esymptoms with CT evidence, so not sure that rectal fields alone are the only driver of it...

Have not personally seen one after 45/25, but usually with some high dose (either 50.4/28 or some sort of SIB to a LN near the sacrum), but I haven't been out long enough to see all the potential 'late toxicities' as I presume many on this board

 

[deleted1111261]

1. I would treat all curative rectal cancer patients with VMAT/IMRT. Preop, post op, 25-28 fx, 5 fx. Why not spare bowel, bone marrow (these are chemo patients), etc.?

2. I strongly doubt that fracture was because of 3D. But, if that convinces you to change - sounds like a good move.

 

[ramsesthenice]

1. I would treat all curative rectal cancer patients with VMAT/IMRT. Preop, post op, 25-28 fx, 5 fx. Why not spare bowel, bone marrow (these are chemo patients), etc.?

2. I strongly doubt that fracture was because of 3D. But, if that convinces you to change - sounds like a good move.

You will note that I didn’t say 3D definitely caused these fractures. I’m going to do my best walrus here:

I have seen 7 in the last 3 years. The incidence is small and that has to be taken into account. What are the odds that all of them were in female rectal patients by chance? For simplicity, let’s assume I treat a roughly equal number of female rectal patients with 3D as I do GYN patients with IMRT (it’s probably not quite equal but for this exercise it’s close enough). In that case, it’s simply 1/2^7 (0.7%). Not likely by any stretch but also not so astronomical it defies logic. In fact, over a 3 year period, it’s almost certain if you look hard enough you will see observe at least something (probably a couple something’s) with those odds.

Further, at best 3D is contributory because we have established gender and age are clearly important as well.

To answer your question of why not use IMRT for everyone curative, it mostly boils down to carry over. Until recently (at least where I am) you couldn’t get IMRT approved for run of the mill rectal cancers. Consensus guidelines also equivocated on recommending IMRT for curative rectal cancer because of concerns about reproducibility with bladder and rectal filling (which if you ready the last cervical consensus statements from ASTRO they still do for intact cervical cancers). On top of all that, if you treat people prone (which I do) and treat based on anatomy instead of bony land marks, dose to small bowel is very rarely a problem or even significant with a good 3D plan. This is not prostate or GYN so there is rarely a reason to cover external iliacs which is where most of the small bowel dose comes from. At the end of the day, the doses are low and most people tolerate 3D treatment extremely well with relatively minor side effects which means very few individual patients are likely to benefit from IMRT. So the impetuous to change something that was working pretty well was low.

All that said, I have been mentally moving in the IMRT direction for a while. VMAT is a fast treatment and deep down you know minimizing dose to OARs probably does add up to something if you follow enough people for enough time. And the cost difference between IMRT and 3D is real, but not inordinate. It’s funny this is my breaking point but it’s the first little signal I have seen first hand it might make a difference. Even if this particular instance is by chance, I think there is plenty of other rationale to change. Funny how things work out sometimes.

You know, if I didn’t do actual research or value my residents, I would get one of them to write this up, make it sound more interesting than it is, present it at ASTRO, and publish it in PRO.

 

[communitydoc13]

What are the odds that all of them were in female rectal patients by chance?

https://ascopubs.org/doi/abs/10.1200/JCO.2017.35.15_suppl.10056

May be something else at play?

 

[communitydoc13]

Why not spare bowel, bone marrow

With an ideal prone sim and big bladder, I'm not sure you can do better than 3D at times. Bone marrow toxicity is a low dose phenomenon.

 

[ramsesthenice]

https://ascopubs.org/doi/abs/10.1200/JCO.2017.35.15_suppl.10056

May be something else at play?

If you only consider gender, this fits. They estimate a 2.8/1 male female ratio. With only 7 events, we are looking at a roughly 20% chance all would randomly be female.

I stand by the observation it’s a pretty specific group. By the time you factor all of the variables it starts to get hard (though not impossible) to chalk it up to pure chance. There are definitely multiple things at play and gender is clearly one of them.

 

[communitydoc13]

If you only consider gender, this fits. They estimate a 2.8/1 male female ratio. With only 7 events, we are looking at a roughly 20% chance all would randomly be female.

I stand by the observation it’s a pretty specific group. By the time you factor all of the variables it starts to get hard (though not impossible) to chalk it up to pure chance. There are definitely multiple things at play and gender is clearly one of them.

I was thinking that the association between colorectal CA and OP may be notably different than the association between GYN malignancies and OP? Risk factors for OP (other than gender) not particularly associated (other than perhaps negatively) with GYN malignancy.

 

[TheWallnerus]

You will note that I didn’t say 3D definitely caused these fractures. I’m going to do my best walrus here:

I have seen 7 in the last 3 years. The incidence is small and that has to be taken into account. What are the odds that all of them were in female rectal patients by chance? For simplicity, let’s assume I treat a roughly equal number of female rectal patients with 3D as I do GYN patients with IMRT (it’s probably not quite equal but for this exercise it’s close enough). In that case, it’s simply 1/2^7 (0.7%). Not likely by any stretch but also not so astronomical it defies logic. In fact, over a 3 year period, it’s almost certain if you look hard enough you will see observe at least something (probably a couple something’s) with those odds.

Further, at best 3D is contributory because we have established gender and age are clearly important as well.

To answer your question of why not use IMRT for everyone curative, it mostly boils down to carry over. Until recently (at least where I am) you couldn’t get IMRT approved for run of the mill rectal cancers. Consensus guidelines also equivocated on recommending IMRT for curative rectal cancer because of concerns about reproducibility with bladder and rectal filling (which if you ready the last cervical consensus statements from ASTRO they still do for intact cervical cancers). On top of all that, if you treat people prone (which I do) and treat based on anatomy instead of bony land marks, dose to small bowel is very rarely a problem or even significant with a good 3D plan. This is not prostate or GYN so there is rarely a reason to cover external iliacs which is where most of the small bowel dose comes from. At the end of the day, the doses are low and most people tolerate 3D treatment extremely well with relatively minor side effects which means very few individual patients are likely to benefit from IMRT. So the impetuous to change something that was working pretty well was low.

All that said, I have been mentally moving in the IMRT direction for a while. VMAT is a fast treatment and deep down you know minimizing dose to OARs probably does add up to something if you follow enough people for enough time. And the cost difference between IMRT and 3D is real, but not inordinate. It’s funny this is my breaking point but it’s the first little signal I have seen first hand it might make a difference. Even if this particular instance is by chance, I think there is plenty of other rationale to change. Funny how things work out sometimes.

You know, if I didn’t do actual research or value my residents, I would get one of them to write this up, make it sound more interesting than it is, present it at ASTRO, and publish it in PRO.

Expert walrusing

 

[SneakyBooger]

Do you mean a spontaneous rib fx in breast cancer patients? Yes.

Did they get proton therapy?? (Have you gone crazy Booya?! Do you not know me by now?! Saddens me...) -- Patients were treated with photons, 4500@180, 6xMV.

 

[evilbooyaa]

I figured it might be a patient you were seeing in follow-up after being treated with protons for breast at some proton center, never would've imagined you would've done protons for breast.

In that case, your numbers are very interesting.

I do mention weakening of ribs makign them more likely to break with any local trauma compare to the non-irradiated side, but would not expect spontaneous rib fx, not at 40-50Gy in 15-25fx...

High dose photon boosts in those patients? Were they chest wall or lumpectomy patients