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The prostate is in the pelvis.
I am convinced single fraction RT will work as well for prostate cancer, especially low to intermediate risk, as >1 fraction.
Why?
I think I could do a trial in LR and IR with same 5 yr OS while administering half a fraction of RT. The FOF-RT trial. Fraction of a fraction.I am convinced single fraction RT will work as well for prostate cancer, especially low to intermediate risk, as >1 fraction.
Admittedly this is part of the reason I’m convinced single fraction will work… but I’m not quite THAT nihilisticI think I could do a trial in LR and IR with same 5 yr OS while administering half a fraction of RT. The FOF-RT trial. Fraction of a fraction.
It will only if one assumes that the a/b for prostate cancer is truly < 3 and that the formula holds at high doses, especially in a single fraction.I am convinced single fraction RT will work as well for prostate cancer, especially low to intermediate risk, as >1 fraction.
Not being nihilistic. I'm giving half a fraction more than they need for that endpoint.Admittedly this is part of the reason I’m convinced single fraction will work… but I’m not quite THAT nihilistic
Given all the hypofrac trials SHOULD have shown superior oncologic outcomes (similar to ongoing from 70-->78Gy at 2Gy/fx) if a/b of prostate cancer was < 3 but instead have shown equivalent oncologic outcomes, the a/b of prostate cancer cannot be < 3. It may not be 10, but it's definitely not < 3.
It will only if one assumes that the a/b for prostate cancer is truly < 3 and that the formula holds at high doses, especially in a single fraction.
As we have learned thus far from Single Fx HDR data, something in the above statement is incorrect.
Given all the hypofrac trials SHOULD have shown superior oncologic outcomes (similar to ongoing from 70-->78Gy at 2Gy/fx) if a/b of prostate cancer was < 3 but instead have shown equivalent oncologic outcomes, the a/b of prostate cancer cannot be < 3. It may not be 10, but it's definitely not < 3.
I am prophylactically moving this to its own thread as I predict there will be lively dogmatic discussion in this regard.
A chain is only as strong as its weakest link! A curative dose of radiotherapy is only as curative as the BED experienced by the most relatively radioresistant tumoral clonogen.
They didn't use a big enough fractionAs we have learned thus far from Single Fx HDR data, something in the above statement is incorrect.
Given all the hypofrac trials SHOULD have shown superior oncologic outcomes (similar to ongoing from 70-->78Gy at 2Gy/fx) if a/b of prostate cancer was < 3 but instead have shown equivalent oncologic outcomes, the a/b of prostate cancer cannot be < 3. It may not be 10, but it's definitely not < 3.
@evilbooyaa should not have necessarily shown superior onc outcomes because the mathematical juice (lowered total Rx dose) didn't always keep up with the squeeze (increased fractional dose)Hmmm.
Even if the a/b was 2, 78/39 still higher BED than 60/20 for example
They didn't use a big enough fraction
If α/β for a tumor is 1.5, going from 19Gy/1fx to 20Gy/1fx gives as much BED boost as going from 70Gy/35fx to 78Gy/39fx. And 19Gy to 21Gy would be like going from 70Gy/35fx to ~86Gy/43fx. And so forth. Whether one believes the math or not, it at least serves as an idea about how far we may need to push single fraction doses in prostate to get the outcome we want.
Euthanizing men with prostate cancer by delivery 21 Gy x1 fraction to the whole brain?
44 or I'm out the door.I do not want a 21 Gy fraction delivered to my urethra or my anterior rectum wall.
Murder by cerebrovascular syndrome would be a pretty cool movie or TV crime plot I've always thought. Would be a mysterious healthy person death that would probably baffle the physicians.Euthanizing men with prostate cancer by delivery 21 Gy x1 fraction to the whole brain?
So you're telling me we are EXPANDING indications for radiotherapy!!
All about one up… basically the “name that tune” type of thing… yes, I’m old!Fractionation....the simplest safety tool, yet reviled.
Agree. Fractionation is actually the most biologically elegant strategy for improving the therapeutic ratio when dealing with XRT alone.All about one up
Agree. Fractionation is actually the most biologically elegant strategy for improving the therapeutic ratio when dealing with XRT alone.
The problem is...anyone can do it.
Lower fraction treatment is inherently riskier, usually not better for tumor control (with some exceptions) and almost always comes with a toxicity cost when keeping treatment volumes the same.
Not exciting.
SAW, Chapter 17Murder by cerebrovascular syndrome would be a pretty cool movie or TV crime plot I've always thought. Would be a mysterious healthy person death that would probably baffle the physicians.
I have an honest discussion with patient.Agree. Fractionation is actually the most biologically elegant strategy for improving the therapeutic ratio when dealing with XRT alone.
The problem is...anyone can do it.
Lower fraction treatment is inherently riskier, usually not better for tumor control (with some exceptions) and almost always comes with a toxicity cost when keeping treatment volumes the same.
Not exciting.
It seems increasingly obvious that hypofractionation was a ploy by “academic” centers to attract more patients to be treated by them as opposed to the community. They were never able to talk patients en masse to leave their home for a full course of standard frac RT so this was a backdoor they could use.
For many years, dose escalation in prostate cancer showed improvement after improvement. They even had studies getting up to 90+ Gy with ever-improving outcomes.
Then they jumped on the hypofrac train and everything since has all been trying to prove equivalence, as opposed to actually improving outcomes. Not a single one of these studies has improved outcomes, but the toxicities are consistently greater in all of these studies, yet they are considered a win. It is a great disservice to our specialty and our patients, but is low hanging fruit for a lazy academic to achieve promotion.
A resident from a major academic institution shared with me a recent case in which a very standard SBRT, using ethos, resulted in a fistula and cystoprostatectomy and colostomy. Have you ever seen that from standard frac? I haven’t. And now they want to try even fewer fractions?
I do 70/28. Stop being part of the problem.😉44, 39, 28, 25, 20, 5, 1...
#fractionshaming
#ROCR
#deathtoRO
#noOARnocolostomy
I do 68/25 and bruh thats if they don't have a ginormous prostate/AUA issue.
Say it loud and proud kids: "I refuse to contribute to the demise of my specialty by literally fraction shaming ourselves right into oblivion."
I have an honest discussion with patient.
I review the data between hypofrac + conventional including the toxicity difference. Have not had a patient choose hypofrac when given the choice.
Just bad another pt choose standard yesterday. It's probably 60/40 favoring hypo. This isn't breast💯 When fully and honestly informed, very few patients would choose hypofrac. A very short term improvement in convenience in exchange for increased risk of toxicity and ABSOLUTELY NO CLINICAL BENEFIT
the other elephant in the room is the RVU/revenue piece. I am constantly being scrutinized for how busy (or not busy) I am. It is nice to have some 44 Fx prostate patients on treat. I don't feel "greedy" because I have given them all of the options. I offer SBRT to all low and intermediate risk patients, but if I am treating nodes I am too chicken to do 25/5 to the whole pelvis.💯 When fully and honestly informed, very few patients would choose hypofrac. A very short term improvement in convenience in exchange for increased risk of toxicity and ABSOLUTELY NO CLINICAL BENEFIT
the other elephant in the room is the RVU/revenue piece. I am constantly being scrutinized for how busy (or not busy) I am. It is nice to have some 44 Fx prostate patients on treat. I don't feel "greedy" because I have given them all of the options. I offer SBRT to all low and intermediate risk patients, but if I am treating nodes I am too chicken to do 25/5 to the whole pelvis.
Haha. Fwiw, I hypofx virtually everyone. I'd want 44 to my prostate.
Maybe we should start up selling ourselves. “My rad onc gives more fractions because he cares about my rectum.”
That’s what I see from academic centers in PA landWe ought to ask the proton centers how many fractions they are delivering with their ultra-precise Bragg peak particles. 44 fractions???? What a shock.
Agreed, so we better stop assuming extremes if we want to kill all the cancer, right?
A chain is only as strong as its weakest link! A curative dose of radiotherapy is only as curative as the BED experienced by the most relatively radioresistant tumoral clonogen.
They didn't use a big enough fraction
If α/β for a tumor is 1.5, going from 19Gy/1fx to 20Gy/1fx gives as much BED boost as going from 70Gy/35fx to 78Gy/39fx. And 19Gy to 21Gy would be like going from 70Gy/35fx to ~86Gy/43fx. And so forth. Whether one believes the math or not, it at least serves as an idea about how far we may need to push single fraction doses in prostate to get the outcome we want. (@Palex80, the ideas go a bit kaput without α/β≤1.5 for all the cells.)
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Right, when something is way more dangerous for little to nothing to gain.At what point does it become unethical to run a single-fraction prostate trial? Given the failed trials above, I would say we are past that point.
Great points. I’m learning.Agreed, so we better stop assuming extremes if we want to kill all the cancer, right?
21Gy in 1 Fx to whole gland still failed: https://www.sciencedirect.com/science/article/pii/S1538472122001787
21Gy DIL also failed: https://www.thegreenjournal.com/article/S0167-8140(21)06144-2/fulltext
As did 20Gy in 1 Fx: https://www.sciencedirect.com/science/article/pii/S2405630822000696