ASTRO 2022: Interesting presentations

[evilbooyaa]

There are some med oncs out there that will hate you if you tell them you want to irradiate half of the sacrum for an asymptomatic bone met based on a Phase II study, if the patient is scheduled to start Carbo/Pem/Pem. Frying the bone marrow in the pelvis can aggrevate cytopenia.

Sure, that's reasonable. Especially for say a myeloma patient who has years of systeimc therapy to go. It's always worth a discussion with med onc, IMO, in this situation. But improving OS with palliative RT needs to be a discussion point here, even if it is 'just' a R-PhII.

A sacrum, a scapula, a rib, something else non-weight bearing, maybe less likely to have a SRE compared to say a femoral neck, acetabulum, pubic ramus, humerus (fall on outstretched arm with cancer in it frequently bad)

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[deleted1111261]

That’s not the issue here. Because rt alone may not have cured them and if you gave them rt alone they may have needed salvage surgery on the backend anyways . Pet staging has changed what you include to 70 Gy has it not? A ton of those patients may have got 63 to that neck or even 56. Your knowledge with the pet evolves how you treat two patients with similar ct findings. Two patients who were equivalently T1N0 by CT. One may get chemo and one may get RT alone. Surgery is no different. It didn’t buy the patient chemo you just have more a priori information about that patient after surgery. You can’t ignore it.

And yes there are probably levels to positive margins. Like a diagnostic tonsillectomy in a T1N1 single node patient with a positive margin would still merit rt alone. But in the setting of a a radical tonsillectomy/oncologic surgery a positive margin is different.

I think that it is what the issue is.

The cure rate for T1N1M0 is 90% with RT alone.

Many of those (path series can confirm this) have multiple nodes, even ECE.

These are: 1) clinically stage T1N1 2) PET-CT staged 3) Generally HPV positive. These are not Cooper/Bernier patients.

Something like 50% of patients have some post-op finding after TORS that would necessitate CRT. If they truly needed chemo, then cT1N1 patients would not do so well.

What would I do? I would damn straight give 'em chemoRT if they showed up to me with a + margin. This is not oncologic thinking. This is a medico-legal issue.

My issue is "the surgeon did this". They did not. We did this, b/c this is how radoncs are trained to think (I include myself; I'm trying to get better and be more rational - it is a long process).

 

[gmsquid]

I think that it is what the issue is.

The cure rate for T1N1M0 is 90% with RT alone.

Many of those (path series can confirm this) have multiple nodes, even ECE.

These are: 1) clinically stage T1N1 2) PET-CT staged 3) Generally HPV positive. These are not Cooper/Bernier patients.

Something like 50% of patients have some post-op finding after TORS that would necessitate CRT. If they truly needed chemo, then cT1N1 patients would not do so well.

What would I do? I would damn straight give 'em chemoRT if they showed up to me with a + margin. This is not oncologic thinking. This is a medico-legal issue.

My issue is "the surgeon did this". They did not. We did this, b/c this is how radoncs are trained to think (I include myself; I'm trying to get better and be more rational - it is a long process).

it’s only about 30% who required CRT (albeit mostly ece) according to ecog 3311 and that included eligible patients who had more than one node positive clinically. In that subgroup, DFS with chemo RT was only 90% despite trimodality therapy. It’s dangerous to assume that dfs in a tors patient with a positive margin with adjuvant rt is comparable to trimodality therapy at 90% (t1n1 rt alone). When you start making generalizations from a larger more favorable population you may be under treating patients. Reverse Will rogers effect.

 

[TheWallnerus]

I think that it is what the issue is.

The cure rate for T1N1M0 is 90% with RT alone.

Many of those (path series can confirm this) have multiple nodes, even ECE.

These are: 1) clinically stage T1N1 2) PET-CT staged 3) Generally HPV positive. These are not Cooper/Bernier patients.

Something like 50% of patients have some post-op finding after TORS that would necessitate CRT. If they truly needed chemo, then cT1N1 patients would not do so well.

What would I do? I would damn straight give 'em chemoRT if they showed up to me with a + margin. This is not oncologic thinking. This is a medico-legal issue.

My issue is "the surgeon did this". They did not. We did this, b/c this is how radoncs are trained to think (I include myself; I'm trying to get better and be more rational - it is a long process).

The T1N1 patient above got TORS *and* a neck dissection, not just TORS. (TORS alone probably a different discussion.) I think it's a fair point that a positive margin here could be a marker for >T1 disease and not just a marker for an underaggressive biopsying. And again, the neck dissection "buys" ~doubling the RT tx volume now. The surgeon did a lot "buying" here imho!

 

[deleted1111261]

it’s only about 30% who required CRT (albeit mostly ece) according to ecog 3311 and that included eligible patients who had more than one node positive clinically. In that subgroup, DFS with chemo RT was only 90% despite trimodality therapy. It’s dangerous to assume that dfs in a tors patient with a positive margin with adjuvant rt is comparable to trimodality therapy at 90% (t1n1 rt alone). When you start making generalizations from a larger more favorable population you may be under treating patients. Reverse Will rogers effect.

Okay, then fine - aren't you now making the argument that everyone should get upfront TORS so you don't miss (the patients with a chemo need)?

 

[grenz]

The T1N1 patient above got TORS *and* a neck dissection, not just TORS. (TORS alone probably a different discussion.) I think it's a fair point that a positive margin here could be a marker for >T1 disease and not just a marker for an underaggressive biopsying. And again, the neck dissection "buys" ~doubling the RT tx volume now. The surgeon did a lot "buying" here imho!

I think there’s an argument that a positive margin in a hypoxic bed of tissue does require chemo, whereas if it was untouched tissue you wouldn’t need chemo to cure it. I don’t think that it’s purely true that the surgery reveals you would have had worse outcomes with RT alone. I think that TORS is very user dependent, and positive margins truly can be a mark of poor surgeon or poor pathologic frozen margin assessment. The pathologic assessment is an underappreciated aspect of TORS quality. Great surgeons personally walk the specimen down to pathology to orient the margins.

 

[deleted1111261]

I think there’s an argument that a positive margin in a hypoxic bed of tissue does require chemo, whereas if it was untouched tissue you wouldn’t need chemo to cure it. I don’t think that it’s purely true that the surgery reveals you would have had worse outcomes with RT alone. I think that TORS is very user dependent, and positive margins truly can be a mark of poor surgeon or poor pathologic frozen margin assessment. The pathologic assessment is an underappreciated aspect of TORS quality. Great surgeons personally walk the specimen down to pathology to orient the margins.

So, the surgery itself causes the patient to have a higher risk of recurrence ?

 

[thesauce]

.

ASTRO towing the big rad Onc line....

Why the hashtag for hemonc? What do they have to do with prostate cancer?

 

[OTN]

Why the hashtag for hemonc? What do they have to do with prostate cancer?

JFC ASTRO.

J. F. C.

"NEW STANDARD OF CARE" suggests it is the only standard of care. Great. Way to give Evicore ammo, so that insurers can make more money while our patients suffer the consequences. How the same people push SpaceOAR for no benefit completely ignore worse toxicity with hypofractionation is so far beyond me it's like we are in completely different scientific universes.

 

[communitydoc13]

The T1N1 patient above got TORS *and* a neck dissection, not just TORS. (TORS alone probably a different discussion.) I think it's a fair point that a positive margin here could be a marker for >T1 disease and not just a marker for an underaggressive biopsying. And again, the neck dissection "buys" ~doubling the RT tx volume now. The surgeon did a lot "buying" here imho!

I'm assuming you are saying that they "found" multiple positive neck nodes and that changes algorithm for contra neck XRT?

In general, I will still treat ipsi neck with multiple neck nodes (within reason) with small, well lateralized tonsil primary. i believe series indicate that nature of primary most important for contra disease?

 

[deleted1111261]

They are doubling down on pushing away community practitioners.

They made a bet that we are okay with being consistently rolled over. And they are right - b/c vast majority just go along with it.

This is not a bad study or a good study. It is a study. It is nothing to celebrate about.

We already know that there is one benefit to hypoFx for prostate - speed of completion. There is one potential drawback that keeps coming up - acute toxicity. More than 1 study shows this. It is okay to be patient centered and discuss all options. It is not okay to make a more toxic treatment standard of care.

 

[gmsquid]

Okay, then fine - aren't you now making the argument that everyone should get upfront TORS so you don't miss (the patients with a chemo need)?

I’m not saying that. It’s pre vs post test probability. Now that you know the patient has a positive margin, you have to realize it’s not any T1N1 patient. This is the thing with Bayesian analysis. How you treat somebody without the test is different than how you do with the test. The positive margin subgroup is higher risk, but is at most 30% of the entire subgroup of cT1N1 patients.

If their cure rate is 66% with rt alone and the non positive margin group is 95%, your cure rate with rt alone for all comers is still 90%. But now you know that the patient is among that 1/3 who have bad cure, you may do better with giving them chemo.

 

[TheWallnerus]

So, the surgery itself causes the patient to have a higher risk of recurrence ?

Some people think it. There is data for this from breast cancer (never seen it for squamous though admittedly)… growth factors, etc.

 

[TheWallnerus]

I'm assuming you are saying that they "found" multiple positive neck nodes and that changes algorithm for contra neck XRT?

In general, I will still treat ipsi neck with multiple neck nodes (within reason) with small, well lateralized tonsil primary. i believe series indicate that nature of primary most important for contra disease?

No. I was taught (oncolore?) that a neck dissection bothers the lymphatic drainage pattern that one can no longer rely on relying on disease being ipsilateral.

 

[gmsquid]

No. I was taught (oncolore?) that a neck dissection bothers the lymphatic drainage pattern that one can no longer rely on relying on disease being ipsilateral.

Probably more of an issue I think in the setting of a recurrence or substantial delay to postop where a recurrence may have happened.

 

[thesauce]

JFC ASTRO.

J. F. C.

"NEW STANDARD OF CARE" suggests it is the only standard of care. Great. Way to give Evicore ammo, so that insurers can make more money while our patients suffer the consequences. How the same people push SpaceOAR for no benefit completely ignore worse toxicity with hypofractionation is so far beyond me it's like we are in completely different scientific universes.

This adds precisely 0 to our collective knowledge. NCCN already endorsed hypofrac (20-28 fractions), SBRT, and conventional fractionation for high risk. Another trial showing higher acute toxicity with similar biochemical control. I treat to 80 Gy and not 76, making it even less relevant.

 

[ramsesthenice]

I think simul was asking the same question I often ask. If we're willing to treat this population with RT alone sans op, why do we add chemo for a positive margin?

Assuming surgery didn't find anything scary I completely agree with you. I've heard some stupid arguments along the lines of, "well, surgery might affect vascularization and tumor response to radiation and we really don't know so to be safe we should just do the chemo." Counter argument...how many fewer logs of cells are present now than before surgery? taking that into account, how much worse would your SER need to be for chemo to magically be helpful? Answer...probably more than is realistic. But admittedly hypothetical.

If you felt RT would have cured them before, then I don't understand why feeling "forced" to advise for chemo.

Yes you do. Its political coercion. Can (and should) always talk to the med onc that your opinion is they don't need chemo. But if they or the surgeon persist are you going to threaten your referral base over it? You can always tell the patient you think they don't need chemo but how does it go over when the patient tells the med onc that the rad onc didn't think they needed chemo? These situations can be tricky. And since giving chemo isn't technically wrong, its often not worth the fight.

 

[RadOncDoc21]

Assuming surgery didn't find anything scary I completely agree with you. I've heard some stupid arguments along the lines of, "well, surgery might affect vascularization and tumor response to radiation and we really don't know so to be safe we should just do the chemo." Counter argument...how many fewer logs of cells are present now than before surgery? taking that into account, how much worse would your SER need to be for chemo to magically be helpful? Answer...probably more than is realistic. But admittedly hypothetical.


Yes you do. Its political coercion. Can (and should) always talk to the med onc that your opinion is they don't need chemo. But if they or the surgeon persist are you going to threaten your referral base over it? You can always tell the patient you think they don't need chemo but how does it go over when the patient tells the med onc that the rad onc didn't think they needed chemo? These situations can be tricky. And since giving chemo isn't technically wrong, its often not worth the fight.

Same goes with the surgeon, urologist, thoracic surgeon, neuro, etc. I’m always biting my tongue on how much less toxic RT would be but too much of a chicken to fight. It’s how we were trained and unfortunately the dynamics of our field.

Whether it’s SRS to SBRT, I would usually always prefer RT vs surgery especially when it comes to LC and toxicity profile but I usually let them decide and I take the scraps.

 

[OTN]

Assuming surgery didn't find anything scary I completely agree with you. I've heard some stupid arguments along the lines of, "well, surgery might affect vascularization and tumor response to radiation and we really don't know so to be safe we should just do the chemo." Counter argument...how many fewer logs of cells are present now than before surgery? taking that into account, how much worse would your SER need to be for chemo to magically be helpful? Answer...probably more than is realistic. But admittedly hypothetical.


Yes you do. Its political coercion. Can (and should) always talk to the med onc that your opinion is they don't need chemo. But if they or the surgeon persist are you going to threaten your referral base over it? You can always tell the patient you think they don't need chemo but how does it go over when the patient tells the med onc that the rad onc didn't think they needed chemo? These situations can be tricky. And since giving chemo isn't technically wrong, its often not worth the fight.

Smart advice right here. I leave the chemo decisions up to the medoncs. Sure, we'll talk and usually come to an agreement, but they don't tell me how to irradiate, and I don't tell them how to chemotherapize.

 

[thesauce]

Smart advice right here. I leave the chemo decisions up to the medoncs. Sure, we'll talk and usually come to an agreement, but they don't tell me how to irradiate, and I don't tell them how to chemotherapize.

You are very lucky that they are not telling you how to radiate. MANY do.

 

[OTN]

You are very lucky that they are not telling you how to radiate. MANY do.

Well, it's a great practice, which certainly helps. It took me, however, a few years to gain the trust of the senior medoncs, as I would expect. Once I did, then we've had a great relationship ever since. But, I didn't come charging in trying to drastically change things right away, as I knew that wouldn't work.

New medoncs know very little about solid tumor management, so I usually am able to help walk them through everything for the first year or two until they get their feet under them. By then, naturally, we've developed a good relationship.

 

[deleted1111261]

Well, it's a great practice, which certainly helps. It took me, however, a few years to gain the trust of the senior medoncs, as I would expect. Once I did, then we've had a great relationship ever since. But, I didn't come charging in trying to drastically change things right away, as I knew that wouldn't work.

New medoncs know very little about solid tumor management, so I usually am able to help walk them through everything for the first year or two until they get their feet under them. By then, naturally, we've developed a good relationship.

totally not telling a medonc what to do ..

and in this case, i would not say no chemo. medico-legally, have very little recourse. any adverse oncologic outcome will bite you in the a$$

 

[medgator]

You are very lucky that they are not telling you how to radiate. MANY do.

Most of the chemo in h&n is getting referred out by me to med onc. The way it should be. What business does an ENT have sending to MO first?

 

[deleted1111261]

Much of Oncolore is

"This thing happened once to this patient that was treated by this one doctor."

No one actually researches it.

And so you end up with "NO DEODORANT BEFORE RADIASHUN TREATMENTS"

 

[thesauce]

Most of the chemo in h&n is getting referred out by me to med onc. The way it should be. What business does an ENT have sending to MO first?

I wasn’t speaking about head neck specifically: it’s really across the board that medoncs think they can/should dictate RT. In one particularly contentious interaction, I had to ask a medonc how many of these cases they had planned.

 

[medgator]

I wasn’t speaking about head neck specifically: it’s really across the board that medoncs think they can/should dictate RT. In one particularly contentious interaction, I had to ask a medonc how many of these cases they had planned.

Honestly outside of mets and lymphoma, there's no reason a good RO should depend on MO for anything, esp when the MO is a 🤡

 

[thesauce]

Honestly outside of mets and lymphoma, there's no reason a good RO should depend on MO for anything, esp when the MO is a 🤡

Absolutely agree

 

[RadOncDoc21]

Honestly outside of mets and lymphoma, there's no reason a good RO should depend on MO for anything, esp when the MO is a 🤡

Depends on the environment also. Been in a situation where the med oncs were viewed as the only credible source for cancer information/treatment, referrals, work-up, etc. The med oncs were making a killing but bad patient care overall!

 

[medgator]

Depends on the environment also. Been in a situation where the med oncs were viewed as the only credible source for cancer information/treatment, referrals, work-up, etc. The med oncs were making a killing but bad patient care overall!

It all has to start somewhere. That's how it was when i first started at a practice no one really cared staffed with boomer rad oncs who wouldn't even write narcotics or bzds.

Reap what you sow. Catfish's are gonna catfish

 

[NotMattSpraker]

Looks like Pollack pointed out that reduced margins for prostate may be possible with modern CBCT (I think, I wasn't there).

Any of you misanthropes planning a trial yet?

 

[evilbooyaa]

I think that it is what the issue is.

The cure rate for T1N1M0 is 90% with RT alone.

Many of those (path series can confirm this) have multiple nodes, even ECE.

These are: 1) clinically stage T1N1 2) PET-CT staged 3) Generally HPV positive. These are not Cooper/Bernier patients.

Something like 50% of patients have some post-op finding after TORS that would necessitate CRT. If they truly needed chemo, then cT1N1 patients would not do so well.

What would I do? I would damn straight give 'em chemoRT if they showed up to me with a + margin. This is not oncologic thinking. This is a medico-legal issue.

My issue is "the surgeon did this". They did not. We did this, b/c this is how radoncs are trained to think (I include myself; I'm trying to get better and be more rational - it is a long process).

Do you have a source for this? I mean the 2-year LR rate in RTOG 0022 was 9%, so I imagine their cure rates are not going to be 90% at 5-years....

No. I was taught (oncolore?) that a neck dissection bothers the lymphatic drainage pattern that one can no longer rely on relying on disease being ipsilateral.

A patient with a HISTORY of neck dissection or other soft tissue neck surgery, yes.

Someone who literally just underwent a neck surgery, no.

Well, it's a great practice, which certainly helps. It took me, however, a few years to gain the trust of the senior medoncs, as I would expect. Once I did, then we've had a great relationship ever since. But, I didn't come charging in trying to drastically change things right away, as I knew that wouldn't work.

New medoncs know very little about solid tumor management, so I usually am able to help walk them through everything for the first year or two until they get their feet under them. By then, naturally, we've developed a good relationship.

Many med oncs who are more than 15-20 years in practice (meaning 20-25 years from med school graduation) may think all rad oncs are dumb, and that all radiation is the devil. A proportion of those folks cannot be saved. Some can with being the 3 A's, especially if it's a new practice or you're replacing one of those dumb folks who did crap radiation forever.

New Med oncs who have graduated fellowship within the past 5 years are much more likely to assume that you, a non-boomer rad onc well versed in clinical oncology, are good at what you do from the get-go, in my brief experience as an attending. Unless they trained at some big name place where they all listened to the old-timer med onc tell storeis about the dangers of radiation.

 

[deleted1111261]

Do you have a source for this? I mean the 2-year LR rate in RTOG 0022 was 9%, so I imagine their cure rates are not going to be 90% at 5-years....


A patient with a HISTORY of neck dissection or other soft tissue neck surgery, yes.

Someone who literally just underwent a neck surgery, no.


Many med oncs who are more than 15-20 years in practice (meaning 20-25 years from med school graduation) may think all rad oncs are dumb, and that all radiation is the devil. A proportion of those folks cannot be saved. Some can with being the 3 A's, especially if it's a new practice or you're replacing one of those dumb folks who did crap radiation forever.

New Med oncs who have graduated fellowship within the past 5 years are much more likely to assume that you, a non-boomer rad onc well versed in clinical oncology, are good at what you do from the get-go, in my brief experience as an attending. Unless they trained at some big name place where they all listened to the old-timer med onc tell storeis about the dangers of radiation.

https://www.nejm.org/doi/full/10.1056/nejmoa0912217

82% including stage 3-4. So I was guesstimating

 

[TheWallnerus]

A patient with a HISTORY of neck dissection or other soft tissue neck surgery, yes.

Someone who literally just underwent a neck surgery, no.

You guys are confusing me today.

So when does "underwent a neck surgery" become a "HISTORY of neck dissection." One day? One month? One year?

Imagine the rad onc note: "The patient does not have a history of neck dissection but did undergo a neck dissection recently."

The cure rate for T1N1M0 is 90% with RT alone.

https://www.nejm.org/doi/full/10.1056/nejmoa0912217
82% including stage 3-4. So I was guesstimating

Do you have a source for this? I mean the 2-year LR rate in RTOG 0022 was 9%, so I imagine their cure rates are not going to be 90% at 5-years....

@RealSimulD I like ~90% cure rate for T1N1!

Intensity-modulated radiotherapy in the treatment of oropharyngeal cancer: an update of the Memorial Sloan-Kettering Cancer Center experience

 

[Ray D. Ayshun]

You guys are confusing me today.

So when does "underwent a neck surgery" become a "HISTORY of neck dissection." One day? One month? One year?

Imagine the rad onc note: "The patient does not have a history of neck dissection but did undergo a neck dissection recently."

I was told in a separate thread that waiting two weeks for insurance approval isn't dangerous, so at least two weeks.

 

[Palex80]

Looks like Pollack pointed out that reduced margins for prostate may be possible with modern CBCT (I think, I wasn't there).

Any of you misanthropes planning a trial yet?

View attachment 361292

Unfortunately, I still do not see the information on CTV & PTV sizes on those slides.
The argument is simple: contouring on MRI will shrink your CTV, so the MRI arm will have a considerably smaller PTV, both due to smaller CTV and reduced CTV-PTV-margin.

 

[RickyScott]

Unfortunately, I still do not see the information on CTV & PTV sizes on those slides.
The argument is simple: contouring on MRI will shrink your CTV, so the MRI arm will have a considerably smaller PTV, both due to smaller CTV and reduced CTV-PTV-margin.

I would hope that on the CT arm they contour on the mri as well.

 

[OTN]

Unfortunately, I still do not see the information on CTV & PTV sizes on those slides.
The argument is simple: contouring on MRI will shrink your CTV, so the MRI arm will have a considerably smaller PTV, both due to smaller CTV and reduced CTV-PTV-margin.

I don't buy this at all.

We fuse MRI to CT for contouring, and my therapists and I can identify the rectum/prostate easily without on-board MRI. I see no reason why margins could be tighter with MRI vs CT.

 

[ramsesthenice]

I don't buy this at all.

We fuse MRI to CT for contouring, and my therapists and I can identify the rectum/prostate easily without on-board MRI. I see no reason why margins could be tighter with MRI vs CT.

Have not seen the presentation (and honestly don't plan on it). I do use slight tighter margins for my cases on MRI but not because the pretreatment imaging is better. Has more to do with one allowing adaptive planning and cine imaging and the other not.

 

[NotMattSpraker]

Have not seen the presentation (and honestly don't plan on it). I do use slight tighter margins for my cases on MRI but not because the pretreatment imaging is better. Has more to do with one allowing adaptive planning and cine imaging and the other not.

What margins are you using?

 

[Gfunk6]

Here's a question: Given that MRI-guided prostate SBRT can take up to one hour on the machine, how does that impact the radiobiology of the treatment? As opposed to a linac with a 6 MV FFF with a beam on time of ~90 seconds.

Discuss

 

[TheWallnerus]

Here's a question: Given that MRI-guided prostate SBRT can take up to one hour on the machine, how does that impact the radiobiology of the treatment? As opposed to a linac with a 6 MV FFF with a beam on time of ~90 seconds.

Discuss

According to Hall even though these are significant dose rate differences, there should be very minimal cell kill differences even at these disparate MUs per minute. However, per the aforementioned data and cell survival curves, there could be a noticeable difference with a sufficiently powered study. But I would need such a study for convincing me that there is a clinical difference.

 

[taserlaser]

Here's a question: Given that MRI-guided prostate SBRT can take up to one hour on the machine, how does that impact the radiobiology of the treatment? As opposed to a linac with a 6 MV FFF with a beam on time of ~90 seconds.

Discuss

I have asked the same of those doing MRL guided single fr gated lung SBRT. Linac is dead quick. I don’t think it will end up being an issue, but it does give some pause, and I agree it’s at least worth thinking about these things.

 

[ramsesthenice]

Here's a question: Given that MRI-guided prostate SBRT can take up to one hour on the machine, how does that impact the radiobiology of the treatment? As opposed to a linac with a 6 MV FFF with a beam on time of ~90 seconds.

Discuss

I had 2 SBRT cases today on our MR linac. 7.5 Gy to each with step and shoot. Beam on time was 10:15 for the first case and 9:10 for the second. Including image acquisition, optimization, and delivery, both were in and out of the room in under 30 min.

Also important to understand an important difference between the ViewRay and the Unity. On the Unity, the Gantry surrounds the MR unit and is technically VMAT compatible out of the box. Elekta prioritized getting clearance for a gaiting system over VMAT delivery but now that that is coming to completion VMAT is hopefully not too far off in the future.

 

[NotMattSpraker]

I had 2 SBRT cases today on our MR linac. 7.5 Gy to each with step and shoot. Beam on time was 10:15 for the first case and 9:10 for the second. Including image acquisition, optimization, and delivery, both were in and out of the room in under 30 min.

Also important to understand an important difference between the ViewRay and the Unity. On the Unity, the Gantry surrounds the MR unit and is technically VMAT compatible out of the box. Elekta prioritized getting clearance for a gaiting system over VMAT delivery but now that that is coming to completion VMAT is hopefully not too far off in the future.

Are they breath holding?

 

[ramsesthenice]

Are they breath holding?

No

 

[NotMattSpraker]

No

Thats honestly surprising. Here is data from my old center using a regular linac showing that even with tele-supervision enhancements the CBCT to beam on time was approximately 6-10 minutes. This basically captures the time of CBCT and physician to go to the machine, collect and review kV/fluoro, and approve. A lot of these cases were on the Edge with a much faster dose rate than the MRL.

The adaptive cases that included optimization were FAR slower.

So either you all have an amazing workflow and my old one was just very clunky (possible), or Im misunderstanding or something. Admittedly, we did not have blocked time to sit at the machine so you would have to come either from a consult room or your office, which can be far. But not THAT far...

Implementation of a Novel Remote Physician Stereotactic Body Radiation Therapy Coverage Process during the Coronavirus Pandemic

During the coronavirus 2019 disease (COVID-19) pandemic, alternative methods of care are needed to reduce the relative risk of transmission in departments. Also needed is the ability to provide vital radiation oncological care if radiation oncologists ...

www.ncbi.nlm.nih.gov

 

[seper]

Hey! I am reading on some interesting presentations at ASTRO this year, mostly from Twitter.

I thought I'd make a thread to discuss on those.

Here's the first one:


Interesting findings, although not practice changing, in my humble opinion.
It will however make me feel more comfortable irradiating asymptomatic bone mets with more than just a gut feeling to back it up.

It will be interesting to see the breakdown of the SREs in the control arm, i.e. is there a true benefit for the patients or are we merely introducing RT earlier on but not changing any other endpoints (fractures, hospitalizations, surgeries).

I would not overemphasize the overall survival benefit. KPS was also significant in the MVA and there was an imbalance in the trial with the intervention arm having more patients in excellent KPS than the control arm, something which is not uncommon in Phase II trials.



The protocol of the trial has been published before, for those of you that may have protocol-relevant questions:

Early palliative radiation versus observation for high-risk asymptomatic or minimally symptomatic bone metastases: study protocol for a randomized controlled trial - BMC Cancer

Background In patients with metastatic cancer, the bone is the third-most common site of involvement. Radiation to painful bone metastases results in high rates of pain control and is an integral part of bone metastases management. Up to one-third of inpatient consults are requested for painful...

bmccancer.biomedcentral.com

Interesting point: They randomized 93 patients, although they had "planned" to randomize only 74 per protocol. The incidence of SREs in the trial appears to have been lower that what they had thought?

DISCUSS!

Late to this discussion, but receipt of XRT is counted a "skeletal event". Thus, the observation arm is skewed towards having more skeletal events. Bad design

 

[grenz]

Late to this discussion, but receipt of XRT is counted a "skeletal event". Thus, the observation arm is skewed towards having more skeletal events. Bad design

Doesn’t the standard definition of SRE used in other modalities include RT?

 

[deleted1111261]

Doesn’t the standard definition of SRE used in other modalities include RT?

Hmm

Then everyone in intervention arm had a SRE?

 

[Ray D. Ayshun]

Late to this discussion, but receipt of XRT is counted a "skeletal event". Thus, the observation arm is skewed towards having more skeletal events. Bad design

Nobody can reduce the need for a radiation oncologist like a radiation oncologist.