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[metallica81788]

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Getting dangerously close to that 1 patient: 1 author ratio and for a paper in Green Journal.... 19:14. 21% Rib fracture in IBC (or really any breast cancer treatment) is considered OK ('toxicity is favorable, modest increase in rib fracture' per the highlights)? Why would anyone use a therapy that has not shown to be oncologically more effective when it is clearly more toxic? And this is with IMPT. The cadillac of proton therapy. In contemporary patients treated within the past 6 years. Way better than passive scattering, which is like the beat up crown-vic of proton therapy. And still. Still has 21% of rib fracture. Is this considered advancing the field? Is the conclusion not "Oh, man, lots of rib fractures, maybe this isn't the best idea"? If not, why not?

But don't you dare use IMRT for breast cancer! Ever!

Financial toxicity! Fractions!

 

[Mandelin Rain]

But don't you dare use IMRT for breast cancer! Ever!

Financial toxicity! Fractions!

Intact ribs!

 

[Ray D. Ayshun]

Intact ribs!

Proton response to patient with rib fracture:

 

[thecarbonionangle]

as a devils advocate i ask this:

Sure a rib fracture is bad, i have seen it with sbrt and 60/15. Most are asymptomatic or super mild. Say the dose reported to LAD is as low as they say. Is this a good trade off? Some may say absolutely. Surgeons cause toxicity all the time like 30%+ lymphadema with ALND and XRT. Is this “insane”?

Discuss!

I don’t have any bone in this fight as I do not treat breast.

 

[RickyScott]

as a devils advocate i ask this:

Sure a rib fracture is bad, i have seen it with sbrt and 60/15. Most are asymptomatic or super mild. Say the dose reported to LAD is as low as they say. Is this a good trade off? Some may say absolutely. Surgeons cause toxicity all the time like 30%+ lymphadema with ALND and XRT. Is this “insane”?

Discuss!

I don’t have any bone in this fight as I do not treat breast.

What If pt is setup 1cm incorrectly and Bragg peak hits lad?

 

[thecarbonionangle]

What If pt is setup 1cm incorrectly and Bragg peak hits lad?

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

 

[RickyScott]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

I don’t, but are proton center doing daily imaging. I thought part of “choosing wisely“ was to avoid daily imaging in breast?

 

[Mandelin Rain]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

I don't know that it would take 1 cm.

Again, the dosimetry always looks good with protons. Especially when compared to a lousy photon plan. How that translates to the table and the biology is the issue.

You trusting your brachial plexus to the "rib melter"?

 

[elementaryschooleconomics]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

I have intentionally avoided reading any breast/proton papers because I want to keep my blood pressure below 200/100, so perhaps this has been asked and answered, but:

Are all breast patients treated with protons done so with respiratory management? I presume, logically, that it would be DIBH (regardless of laterality), but at minimum 4D, given the theoretical sensitivity of protons to a tissue/air interface and the chest wall motion with normal breathing?

Otherwise, a 1cm+ deviation of actual tissue vs the CT scan used for treatment planning seems inevitable.

 

[Mandelin Rain]

I have intentionally avoided reading any breast/proton papers because I want to keep my blood pressure below 200/100, so perhaps this has been asked and answered, but:

Are all breast patients treated with protons done so with respiratory management? I presume, logically, that it would be DIBH (regardless of laterality), but at minimum 4D, given the theoretical sensitivity of protons to a tissue/air interface and the chest wall motion with normal breathing?

Otherwise, a 1cm+ deviation of actual tissue vs the CT scan used for treatment planning seems inevitable.

Great point.

Not in this study....
CT simulation was routinely obtained in free-breathing with supine immobilization in an arms-up position

 

[communitydoc13]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

Not worried about 1 cm setup error. Worried about stopping power of lungs for protons in the setting where the rib dose is clearly greater than the docs intended and range uncertainty has already messed with their outcomes.

 

[TheWallnerus]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

You can’t have a 1cm setup error w CBCT … within one second after the shift. Six hundred seconds after the shift COULD be a different story 🙂

 

[Lamount]

Not worried about 1 cm setup error. Worried about stopping power of lungs for protons in the setting where the rib dose is clearly greater than the docs intended and range uncertainty has already messed with their outcomes.

Assuming it's an RBE issue... higher RBE's are only seen at the end of range, thus I think the lungs would likely be just fine

 

[Lamount]

You can’t have a 1cm setup error w CBCT … within one second after the shift. Six hundred seconds after the shift COULD be a different story 🙂

if such a think happened during a standard photon treatment of the breast, wouldn't overdose of the LAD be just as likely?

 

[RickyScott]

if such a think happened during a standard photon treatment of the breast, wouldn't overdose of the LAD be just as likely?

When I trained prior to Ct sim, we almost certainly treated through the lad. Protons have very destructive properties at the end of the range.

 

[Mandelin Rain]

Assuming it's an RBE issue... higher RBE's are only seen at the end of range, thus I think the lungs would likely be just fine

He/she isn't worried about the lung, but rather the next, deeper organ.

 

[grenz]

A 1 cm set up error with daily CBCT would be pretty pretty bad. How often do you see that happen?

Most proton gantries do NOT have CBCT. They use orthogonal kVs aligning to bone

 

[thecarbonionangle]

Most proton gantries do NOT have CBCT. They use orthogonal kVs aligning to bone

Most old gantries yes. Newer ones have it.

 

[elementaryschooleconomics]

Great point.

Not in this study....
CT simulation was routinely obtained in free-breathing with supine immobilization in an arms-up position

...uh

Do the people designing these studies ever like, look at a patient? Or just come to the sim console when the therapists tell them the patient is wired and ready, gaze through the glass into the room, confirm a human is in there, and then carry on with their day?

People do realize the picture they see in MIM/Eclipse/Pinnacle/RayStation isn't like...real, right?

I have assumed this entire time it was breath hold. I don't know why I assume anything anymore, I'm always wrong.

 

[communitydoc13]

I have assumed this entire time it was breath hold.

Breath hold itself is a bit of a thing where it makes the plan better but sometimes more difficult to make happen. I don't know enough about practical proton treatment to understand how this would interact with treatment time itself to potentially move out of a nice window of treatment time. I have had IMRT breast/regional nodal plans where they were becoming marginal with BH.

I believe most chest wall excursion in a relaxed, free breathing patient is on the order of 4 mm or so. If they are counting on the protons stopping where they think they stop, I can understand the free breathing approach. (clearly the rib fractures are telling us something however).

 

[RickyScott]

Breath hold itself is a bit of a thing where it makes the plan better but sometimes more difficult to make happen. I don't know enough about practical proton treatment to understand how this would interact with treatment time itself to potentially move out of a nice window of treatment time. I have had IMRT breast/regional nodal plans where they were becoming marginal with BH.

I believe most chest wall excursion in a relaxed, free breathing patient is on the order of 4 mm or so. If they are counting on the protons stopping where they think they stop, I can understand the free breathing approach. (clearly the rib fractures are telling us something however).

Have treated hundreds of stage 3 lung (when we used to go over 70 gy) and sbrt (10 gy x 5) where rib got full dose and can’t remember a fracture. Must be sone major bed damage at end of Bragg peak. Can’t imagine what would happen down the road if they are hitting lad. For years protons were delivered with no image guidance.

 

[Lamount]

Have treated hundreds of stage 3 lung (when we used to go over 70 gy) and sbrt (10 gy x 5) where rib got full dose and can’t remember a fracture. Must be sone major bed damage at end of Bragg peak. Can’t imagine what would happen down the road if they are hitting lad. For years protons were delivered with no image guidance.

Really? I see fractures pretty often... usually not painful and discovered incidentally on a CT. Given the age group alone, I would imagine you must see some fractures.

 

[communitydoc13]

I do see fractures with 50/5 or 48/4 and SBRT at CW in older women. Usually asymptomatic or rarely mildly symptomatic.

 

[RickyScott]

Really? I see fractures pretty often... usually not painful and discovered incidentally on a CT. Given the age group alone, I would imagine you must see some fractures.

I am not looking unless they complain abt chest wall pain.

 

[jondunn]

I am not looking unless they complain abt chest wall pain.

they're usually right next to the treated tumor you are looking at. agree it def happens but mostly asymptomatic.

 

[Lamount]

I am not looking unless they complain abt chest wall pain.

everyone in my system gets their rad reads on our patient portal... so people freak out whenever the radiologist notes ANYTHING. Good times.

 

[jondunn]

 

[BobbyHeenan]

As mentioned, many (?most?) breast patients getting protons won't have CBCT.

I don't get too worked up about breast protons for regional nodal treatment. I think I get some pretty good DIBH plans with photons though. I have referred a hand ful over the past couple of years though (a pectus case and another lady with very challenging anatomy; another lady had residual IM node that didn't resolve with chemo et al). I've continued to follow them and do think the acute and potentially even late cosemsis/toxicity may be slightly worse....but I'm looking with biased eyes.

Ultimately, the PCORI/RadComp study hopefully answers this.

What burns me up is seeing whole breast or right sided getting it. This absolutely goes on at many centers.

 

[IonsAreOurFuture]

RE: breath-hold, I'm not aware of proton centers doing DIBH for breast, probably because proton beams are aimed pretty much directly at the heart, and rely on the stopping in tissue to not exit into the heart. Having a little more lung in between the ribs and heart won't increase the stopping power that much.

A 1 cm shift left, right, sup, inf, or ant-post, won't change the thickness of the chest wall (path length) very much in the en face direction. It helps to start with a plan that delivers <1 Gy mean heart dose, which my left breast proton plans usually do, sometimes <50 cGy.

 

[IonsAreOurFuture]

Breath hold itself is a bit of a thing where it makes the plan better but sometimes more difficult to make happen. I don't know enough about practical proton treatment to understand how this would interact with treatment time itself to potentially move out of a nice window of treatment time. I have had IMRT breast/regional nodal plans where they were becoming marginal with BH.

I believe most chest wall excursion in a relaxed, free breathing patient is on the order of 4 mm or so. If they are counting on the protons stopping where they think they stop, I can understand the free breathing approach. (clearly the rib fractures are telling us something however).

I think protons are great but the rib fractures are a real problem in my opinion. A 7 fold increase in fractures just shouldn't be happening and is totally unacceptable. When I tell my patients about higher fracture risk, it gives them some pause.

The rib fracture paper out of Harvard/MGH shows that there is a ~20% increase in LET/RBE at end of range in the chest wall, so that 50 Gray in 25 fractions becomes 60 Gy in 25 fractions. This is well known from other papers like TG-256; RBE is 1.3+ at end-range. This creates "double trouble" because it's a larger total dose (60 Gy) but also a larger dose per fraction (2.4 Gy). Doing a quick calc yields EQD2 = 64.8 for late tissues.

Adding a boost of 10 Gy to the scar or lumpectomy cavity gives 13 Gy more, for ~78 Gy EQD2. I see how that could fracture a rib in an elderly person on aromatase inhibitors. For comparison, we limit the femurs in prostate plans to less than 10% of volume at 40 Gy so that men don't get hip fractures.

 

[RickyScott]

I think protons are great but the rib fractures are a real problem in my opinion. A 7 fold increase in fractures just shouldn't be happening and is totally unacceptable. When I tell my patients about higher fracture risk, it gives them some pause.

The rib fracture paper out of Harvard/MGH shows that there is a ~20% increase in LET/RBE at end of range in the chest wall, so that 50 Gray in 25 fractions becomes 60 Gy in 25 fractions. This is well known from other papers like TG-256; RBE is 1.3+ at end-range. This creates "double trouble" because it's a larger total dose (60 Gy) but also a larger dose per fraction (2.4 Gy). Doing a quick calc yields EQD2 = 64.8 for late tissues.

Adding a boost of 10 Gy to the scar or lumpectomy cavity gives 13 Gy more, for ~78 Gy EQD2. I see how that could fracture a rib in an elderly person on aromatase inhibitors. For comparison, we limit the femurs in prostate plans to less than 10% of volume at 40 Gy so that men don't get hip fractures.

Men don’t get fractures. How are breast fractures being detected? CT’s generally not performed after stage I/2 beast cancer. I am assuming that they are symptomatic. Maybe the real number much higher if we have CT’s every 6 months ?

 

[Mandelin Rain]

I don't believe I've ever seen a rib fracture in traditionally/moderately hypofractionated breast or thoracic radiation when delivered with photons.

I've definitely seen several with 48/4, 50/5, 60/8. But those are much high dose equivalent regimens.

There's definitely something beyond, it's an EQD2 of 64.8Gy.

 

[evilbooyaa]

Have treated hundreds of stage 3 lung (when we used to go over 70 gy) and sbrt (10 gy x 5) where rib got full dose and can’t remember a fracture. Must be sone major bed damage at end of Bragg peak. Can’t imagine what would happen down the road if they are hitting lad. For years protons were delivered with no image guidance.

Not a ton, but will support rib Fx from escalated SBRT. (18Gy x 3, 12Gy x 5). Usually its 'weaker' and then they hit it on something or cough hard.

I don't believe I've ever seen a rib fracture in traditionally/moderately hypofractionated breast or thoracic radiation when delivered with photons.

I've definitely seen several with 48/4, 50/5, 60/8. But those are much high dose equivalent regimens.

Bingo - and those who would rather give a 700% relative increase in rib fx (from 3% to 21% in terms of absolute numbers) to save the 300% relative increase in heart attacks (assuming 10% risk of MI at baseline, 10.7% with MHD of 1 vs 12.8% with MHD of 4), I'll just say I don't really get it.

 

[Mandelin Rain]

Not a ton, but will support rib Fx from escalated SBRT. (18Gy x 3, 12Gy x 5). Usually its 'weaker' and then they hit it on something or cough hard.



Bingo - and those who would rather give a 700% relative increase in rib fx (from 3% to 21% in terms of absolute numbers) to save the 300% relative increase in heart attacks (assuming 10% risk of MI at baseline, 10.7% with MHD of 1 vs 12.8% with MHD of 4), I'll just say I don't really get it.

I mean, do we have any clinical data regarding actual risk reduction with protons? Again, the pictures tell one story and IRL there's a whole 'nother story.

What if it's 700% worse? Like the rib fractures?

 

[communitydoc13]

I think protons are great but the rib fractures are a real problem in my opinion. A 7 fold increase in fractures just shouldn't be happening and is totally unacceptable. When I tell my patients about higher fracture risk, it gives them some pause.

The rib fracture paper out of Harvard/MGH shows that there is a ~20% increase in LET/RBE at end of range in the chest wall, so that 50 Gray in 25 fractions becomes 60 Gy in 25 fractions. This is well known from other papers like TG-256; RBE is 1.3+ at end-range. This creates "double trouble" because it's a larger total dose (60 Gy) but also a larger dose per fraction (2.4 Gy). Doing a quick calc yields EQD2 = 64.8 for late tissues.

Adding a boost of 10 Gy to the scar or lumpectomy cavity gives 13 Gy more, for ~78 Gy EQD2. I see how that could fracture a rib in an elderly person on aromatase inhibitors. For comparison, we limit the femurs in prostate plans to less than 10% of volume at 40 Gy so that men don't get hip fractures.

Thoughtful answer. But, would make me exclude protons from nearly all breast cases and I believe there is more uncertainty than can even be accounted for with linear corrections like this.

When we go down to the newer very hypofractionated breast schedules (5 fractions) we are clearly near threshold doses for multiple late toxicity endpoints. FAST and FAST-Forward demonstrated differences in toxicity profiles with prescriptions differences of 1.5 and 1 Gy respectively. When we are talking about 30-40% uncertainties in dose, we are talking about problems in breast.

 

[Mandelin Rain]

I believe there is more uncertainty than can even be accounted for with linear corrections like this.

^^^This.

 

[Palex80]

Choose your fire dumpster…

 

[jondunn]

 

[jondunn]

 

[radoncftw]

I guess Dan Spratt was well liked at Michigan by the residents. That is typically a good sign.

 

[RadOncDoc21]

I’m going to need more then one resident’s claim. I will need at least one from an unattractive female. I’m kidding… any male would also do!

 

[deleted1111261]

I’m going to need more then one resident’s claim. I will need at least one from an unattractive female. I’m kidding… any male would also do!

I think they do value him as an excellent teacher / mentor

 

[RadOncDoc21]

Well then, that’s good to hear! He’s already a better attending then the ones I had.

 

[RickyScott]

I’m going to need more then one resident’s claim. I will need at least one from an unattractive female. I’m kidding… any male would also do!

I am sure he was a great attending, but really what is there to learn about prostate sbrt?

 

[elementaryschooleconomics]

I am sure he was a great attending, but really what is there to learn about prostate sbrt?

If I had resident + APP coverage on my prostate/spine service I would be the RadOnc version of Socrates and argue that 500 consults/year was 0.2 FTE.

(jokes aside, I have also heard exclusively good things from the residents who rotated with him)

 

[SubserviantToABR]

Even sarcoma and Merkel is getting hypofractionated now...

 

[Radonky]

Dr.Spratt's reputation with residents is well deserved, he is an amazing mentor and teacher

 

[radoncftw]

Dr.Spratt's reputation with residents is well deserved, he is an amazing mentor and teacher

awesome to hear. i have found that most attendings <5-10 years out have been excellent.
the "big wigs" are more often than not terrible to residents.

 

[grenz]

So this HAMLET trial……

 

[medgator]

So this HAMLET trial……

Drew getting paid the same to give 0 Gy or more than that. Less work