[HN Gopher] FLASH radiotherapy's bold approach to cancer treatment
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FLASH radiotherapy's bold approach to cancer treatment
Author : marc__1
Score : 173 points
Date : 2026-03-07 15:33 UTC (7 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| tiderpenger wrote:
| I generally don't trust cancer-communication if it's juiced up
| like this incredible headline. There has been huge amounts of
| progress. We don't need silicon valley idiots starting to make
| proclamations. It's doing fine without your mediocrity.
| jjtheblunt wrote:
| (they're French, not Silicon Valley)
| bitwize wrote:
| Sounds a little too close, in both name and concept, to Therac
| for my comfort.
| NetMageSCW wrote:
| How superstitious are you? Do you avoid black cats and ladders?
| hinkley wrote:
| When corporate arrogance is involved we called it Bayesian
| inference not superstition.
| doubled112 wrote:
| I avoid any strange animal and walking under ladders.
|
| Those aren't superstition, just common sense.
| taneq wrote:
| I wouldn't call a ship "Titanic".
| Eduard wrote:
| Theryq - why would they go with this name when everyone in the
| field knows about the Therac-25 radiation overexposure incidents?
| bilbo0s wrote:
| Exactly what I thought as soon as I learned the name.
|
| It's like, man, how to kill a product?
|
| No pun intended.
|
| It could even work? But you put yourself behind such a poorly
| placed 8 ball when you do these things. Even among researchers,
| people are a little superstitious about stuff like this. It's
| always in the back of everyone's mind.
| leptons wrote:
| I doubt any of that is valid. Therac-25 happened _44 years
| ago_ , that's a very long time, and many people involved in
| cancer research today weren't even alive when it happened.
|
| "Theryq" and "Therac" are not quite the same either. The word
| "therapy" and derivatives of it using "thera" are still used
| widely across the medical industry.
|
| So I'm not really sure why anyone here is making a big deal
| about the name of the company being "Theryq".
| hinkley wrote:
| It's an s-tier case study for UX research though. Maybe the
| doctors don't remember but we do.
| Aurornis wrote:
| > Even among researchers, people are a little superstitious
| about stuff like this.
|
| Being superstitious is not common in the medical treatment
| world, where weird product names are common.
|
| A doctor isn't going to include the device's brand name in
| their decision process for treating a cancer patient.
|
| The Therac-25 case study is noted in the medical world but
| not to the same extent as in engineering. The case was a
| tragedy of bad engineering, but the doctors involved in
| directing the treatments were not at fault for the radiation
| over exposures.
| like_any_other wrote:
| > It's like, man, how to kill a product?
|
| "This name makes me uncomfortable. I think I'd rather die of
| cancer."
| deadbabe wrote:
| Redemption arc.
| accrual wrote:
| Therac-25 is a great case study for software engineers too,
| recommend reading the Wikipedia article for anyone who hasn't,
| it's not too long.
|
| > Previous models had hardware interlocks to prevent such
| faults, but the Therac-25 had removed them, depending instead
| on software checks for safety.
|
| https://en.wikipedia.org/wiki/Therac-25
|
| Another interesting part of the story is the user element. The
| issue was most often triggered by fast, experienced technicians
| who were able to key commands more quickly than Therac
| engineers anticipated:
|
| > After strenuous work, the physicist and operator were able to
| reproduce the error 54 message. They determined that speed in
| editing the data entry was a key factor in producing error 54.
| hinkley wrote:
| Therac is the first one I list and Knight Capital is the
| second. It is in fact possible to bankrupt your company by
| misusing feature toggles.
| throwyawayyyy wrote:
| I learned about Therac at college in the 90s.
|
| Some years later, I interviewed at Knight Capital, just a
| couple of weeks before their blowup. (Dreadful interview at
| which I did dreadfully, being asked to write C _over the
| phone_ by a supremely uninterested engineer. Quite a red
| flag in retrospect.)
| hinkley wrote:
| I feel like you should get yourself a merit badge printed
| for that, sewed onto your laptop bag.
| reitzensteinm wrote:
| > Quite a red flag in retrospect.
|
| No pun intended?
| ErroneousBosh wrote:
| > Therac-25 is a great case study for software engineers too,
| recommend reading the Wikipedia article for anyone who
| hasn't, it's not too long.
|
| I re-read the original paper every few months, more
| frequently if I'm working on Safety-of-Life-Critical
| equipment. Which, given my day job, means I'm re-reading it
| every couple of weeks at most.
|
| Keeps you sharp, doesn't it?
| elromulous wrote:
| The audience of this website is disproportionately aware of the
| Therac-25 compared to the general public. For the obvious
| reason, engineering, but also geographically: The Therac-25
| being a North American incident that affected Canada and the
| US. Whereas Theryc is a French company.
| tjoff wrote:
| While I do agree with your point, as a Swede not even born
| when the incidents happen I still knew about it, was brought
| up in a computer science class.
| torginus wrote:
| I feel like I have heard about this in a million different
| management anecdotes in my corporate trainings about
| management stuff/QA.
| ErroneousBosh wrote:
| > The Therac-25 being a North American incident that affected
| Canada and the US
|
| CGR who provided the accelerators and basic PDP11-based
| computing platform were a French company.
|
| > Whereas Theryc is a French company.
|
| I have been a Citroen enthusiast for about 30 years. I love
| French cars.
|
| I have repaired lots of Valeo electronics modules for
| vehicles.
|
| I'm not sticking my head in a French fucking particle
| accelerator.
| ErroneousBosh wrote:
| First thing that leapt out at me.
| bobmcnamara wrote:
| Saw at the podiatrist that someone named a shoe company Kuru,
| presumably not after the prison disease affecting gait.
| scythe wrote:
| Hey, FLASH finally hit Hacker News! I remember my professors
| talking about this in graduate school. It's a fairly well-
| established effect: the tumor selectivity of radiation is much
| better at ultra-high dose rates. It is still unclear exactly why.
| But there are a lot of studies about it:
|
| https://www.nature.com/articles/s41571-022-00697-z
| LoganDark wrote:
| My guess would be that the radiation doesn't itself care but
| that tumors have some other characteristic (like multiplying
| rapidly) that makes them more susceptible to it. Similarly to
| how you can sometimes attack them with medication that inhibits
| cell division.
| scythe wrote:
| Yeah that's the conventional dose rate effect, not the FLASH
| effect. The FLASH effect happens on timescales so short that
| ordinary considerations like the cell cycle or DNA repair
| mechanisms are inherently ruled out. Instead it might have to
| do with the type of radical species that form in normal cells
| versus tumors, possibly related to oxygenation, pH,
| glycolysis byproducts, etc.
|
| The first interaction of radiation with tissue is usually
| this:
|
| H2O + hv >> H2O+ + e- (fugitive)
|
| The radical ion H2O+ is extremely reactive and usually
| protonates another water molecule immediately:
|
| H2O+ + H2O >> H3O+ + OH*
|
| The hydroxyl radical has a half life of about a nanosecond
| and will usually be the main "reagent", diffusing until it
| runs into an organic molecule which will be oxidized and thus
| degraded. At high enough dose rates, the peak concentration
| of hydroxyl radicals and more stable radicals like superoxide
| could be much higher, leading to "nonlinear" effects, i.e.
| byproducts of multiple radicals interacting with each other
| or a protein.
| Balgair wrote:
| For the other readers in this thread, this poster really
| knows their stuff.
| amluto wrote:
| One thing I found confusing about the nature article is
| that it mostly discusses conventional linear accelerator +
| bremsstrahlung X-ray radiation versus very high dose rate
| FLASH in the form of electron beams, proton beams, or even
| carbon ion beams.
|
| Do we know that what the chemical mechanism for damage from
| charged particle beams is? Is it similar enough to compare
| directly like this? Are the timescales short enough that
| charge deposition might matter?
| sjmcmahon wrote:
| The article is a bit unclear, but we have both a very
| wide range of X-ray vs charged particle studies, and
| increasingly of conventional vs FLASH studies with a
| range of modalities (e.g. the seminal FLASH paper was
| FLASH electrons vs conventional electrons). FLASH photon
| vs conventional photons are also increasingly being
| generated, although they've been more of a pain to
| generate.
|
| So it's clear there is a temporal FLASH effect, which is
| not purely a question of radiation type.
|
| That's not to say it's necessarily exactly the same
| effect - we still don't have a perfect quantitative
| understanding of the effects of different radiation types
| even at normal dose rates, let alone when FLASH
| differences are added into the mix.
| toss1 wrote:
| Interesting the effect's reason is still unclear.
|
| I was starting to infer there was a better focusing ability so
| it could start and exit as a broad cone of radiation and keep
| the peak intensity at the tip of the focal cones at the tumor-
| tissue, and the short pulse also helped the healthy tissue.
|
| But the way this sounds, it's more like a straight beam
| delivering similar intensity to healthy and tumor tissue but
| the biological effect strongly differs between healthy vs tumor
| tissue?
| scythe wrote:
| Yes, the radiation dose under the conventional metric (energy
| divided by mass) is the same, but the effects on biological
| systems change. I included a little speculation on the
| chemistry in my response to a sibling comment.
| sejje wrote:
| > It is still unclear exactly why
|
| It'll be nice when we figure it out, then we can understand the
| unintended consequences better.
|
| Not that it should prevent its use or anything; fuck cancer.
| slibhb wrote:
| > Currently, the most plausible theory emerging from her team's
| research points to metabolism: Healthy and cancerous cells may
| process reactive oxygen species--unstable oxygen-containing
| molecules generated during radiation--in very different ways.
|
| Reminds me of this which I (think) was linked here a while ago:
| https://www.nature.com/articles/s12276-020-0384-2
|
| It really does feel like all these piecemeal cancer treatments
| are converging on something resembling a cure.
| hinkley wrote:
| There was also a study that showed that chemotherapy efficacy
| was enhanced by fasting before treatment.
|
| It seems that when calories are scarce, healthy cells turtle up
| while cancer cells keep consuming, so fasting reduces
| absorption rates in healthy tissues and thus collateral damage.
| sl_convertible wrote:
| Healthy cells CAN turtle-up, whereas cancer cells engage in
| unregulated reproduction. Also, some cancer cells can only
| consume glucose. Which, in a fasted state, would mean that
| the majority of energy would be in ketones(if the individual
| were metabolically healthy), starving the cancer cells to
| death.
| arijun wrote:
| Why wouldn't a strict keto diet not be a cure for those
| cancers?
| nick__m wrote:
| Because the cancers cells adapt! (fast reproduction and
| high mutation rate of the cancerous cells make that
| process quicker than antibiotics resistance)
| cyberax wrote:
| There was a study that chemotherapy works best in the
| _morning_. Derek Lowe had an article about this:
| amelius wrote:
| What is the intensity at the focal point versus areas surrounding
| it?
| hinkley wrote:
| I recall someone was analyzing the refractive index of various
| tissues in order to tighten the target area for multi beam
| radiation therapy. Particularly for brain cancers. By hitting
| from multiple angles the dosage in surrounding tissues is
| lower, and by calculating how the head lenses the beam you
| reduce the high dose area in the middle, like a 3d Venn
| diagram.
|
| But I don't remember is whether that experiment became SOP or
| not.
| s0rce wrote:
| Won't the effective index of all materials be basically 1 for
| the high energy electrons involved here?
| hinkley wrote:
| Seems not in this case. But I believe the use case was deep
| brain tumors, like the hippocampus, where any beam
| alignment problems could be life altering.
| the8472 wrote:
| The sidebar mentions heavier particles having a pronounced
| Bragg Peak[0] and also existing approaches like multi-beam
| targeting. The FLASH effect in the article is yet another tool
| to limit the surrounding damage.
|
| [0] https://en.wikipedia.org/wiki/Bragg_peak
| mv4 wrote:
| Does this have to do with cell division?
| hinkley wrote:
| Cellular metabolism from the look of it. Cellular division and
| metabolism are linked but not synonymous.
|
| However that's the current theory, of a long line of theories
| that did not pan out.
| owenthejumper wrote:
| The major issue isn't the speed of delivery, and the cancer.
|
| The key question is how do you spare normal tissue, and how do
| you prove the normal tissue is spared in the long term. Current
| answer is: You break it apart into multiple sessions, the anti-
| thesis of FLASH.
|
| Source: my wife is a radiation oncologist.
| nick__m wrote:
| from the article (pay attention to the part in italics):
|
| FLASH radiotherapy flips the conventional approach on its head,
| delivering a single dose of ultrahigh-power radiation in a
| burst that typically lasts less than one-tenth of a second. _In
| study after study, this technique causes significantly less
| injury to normal tissue than conventional radiation does,
| without compromising its antitumor effect._
| sjmcmahon wrote:
| That phrasing isn't perfectly clear, as there's two things at
| play.
|
| If you're delivering a large dose D all at once, FLASH spares
| normal tissue compared to conventional rate irradiations,
| with maintained anti-tumour effect.
|
| But, you can instead deliver your treatment in a number of
| smaller doses, say n "fractions" of dose d. This also spares
| normal tissue (1). This latter approach - fractionation - is
| the way radiotherapy was delivered for most of its history.
| But at these low doses, FLASH sparing is small to negligible.
|
| So, we have two demands in tension - and its unclear which is
| actually optimal. Some of the early results in FLASH showed
| huge sparing, but lots of more recent studies have shown more
| modest effects which may not be worth giving up benefits of
| fractionation for(2). And to date I think we have basically
| no meaningful in-human data to guide this, so there's still a
| lot of uncertainty.
|
| 1 - Fractionation also spares tumours, a bit, but you can
| offset this by increasing the total dose a bit and still see
| benefit.
|
| 2 - There is a general move to somewhat larger, fewer
| fractions even in normal radiotherapy, although almost all of
| these are still below the threshold where FLASH sparing is
| seen.
| MeteorMarc wrote:
| Hopefully, this will turn out better than proton therapy, which
| held similar promises of improvement.
| https://pmc.ncbi.nlm.nih.gov/articles/PMC11506991/
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