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Researchers use lasers to detect and destroy tumor cells in melanoma patients (ieee.org)
203 points by headalgorithm on June 12, 2019 | hide | past | favorite | 40 comments

I've had two melanomas luckily early stage, I will likely get more so I am being checked 4-6 times a year plus doing molesafe.

I'm at Sloan Memorial because I have more than a thousand moles. One thing we are using laser for is called Confocal wich basically allow them to see my cells live without having to do a biopsy.

One of the two melanomas was found that way.

I am always hopeful about new advances but I have learned that this is a long game and hopefully I am around long enough to reap the benefits if it goes seriusly wrong.

Yes, this is exciting news. I've had melanoma once and one incident of basal cell. I get checked regularly and had three of four biopsies in the third and fourth stages of progression towards melanoma.

Wonder why none of the doctors I've visited have mentioned Molesafe? I'll check it out when I get home.

edit: Because Molesafe is NY/NJ only.

Dysplastic Naevus Syndrome? There is a bunch of doctors/researchers who are telling that there isn't such a thing as dysplatic naevus. Well, of course you have that special looking mole, but the term "dysplatic" is misleading and also the concept that there is a development of moles from benign to cancerous. A mole was either always a melanoma (or a melanoma inside a mole) or it was and is a normal mole (and will be one).

I hope I can remember to ask my Dr. about this next time I go in.

My dermatologist is Dr. Marghoo, he writes a lot of the books on melanomas and is one of the biggest experts in the world in this matter. I think he would say it exist but I can ask him next time.


Thanks for mentioning MoleSafe. I just looked it up and that does indeed seem promising.

It seems surprising that the laser has such selective activity on CTCs versus healthy cells. Why are these cells so much more absorbtive? Is this specific to melanoma CTCs (more pigment)?

I also wonder how they did this measurement. Seems like you'd need to take pre- and post-laser measurements of healthy and CTC counts in the bloodstream to have high confidence that it is disproportionately damaging CTCs. To what extent does this damage healthy cells?

Head researcher in 2003 pioneered the use of laser-induced vapor nanobubbles around overheated plasmonic nanoparticle clusters to kill single tumor cells without harming neighboring normal cells.


Wow. That sounded like something from a comic book.

Make it so, Geordi.

Even if it damaged/killed a small percentage of healthy cells, as long as it kills a much higher percentage of CTCs, hook me up. Good cells are replenished. So are the bad ones. Its an arms race!

The title should be updated to read "circulating tumor cells". Major biologic difference.

I'm not sure if this is silly or not but why is it not possible to target cancer cells with a bunch of weak lasers distributed around a person pointing at the same location in 3d space and just selectively zapping them? We have real time MRIs and CT scans. Can't we just lie people with cancer down daily and shoot them with incredibly precise beams of light to cook the cancer cells alive? Maybe just cauterizing the blood pathways that are feeding tumors in the first place?

I'm seriously hoping someone can tell me why this idea is stupid.

The problem with lasers in the optical spectrum is the scattering of the light by tissue.

More penetrating radiation is far less scattered and retains its energy density deep into the body. By concentrating several high energy (x-ray, positrons) sources at the same point, the combined energy at that point can be high enough to cause tumor destruction, while the energy along the path of the individual beams is not high enough to damage healthy tissues.

The technique can be applied to optical sources, but it's much more difficult because of the scattering.

It's not stupid, and we already do this. There are many different forms of radiation therapy (https://en.wikipedia.org/wiki/Radiation_therapy), and they're commonly used in breast and brain cancers.


Also for whomever else reading this thread, I’ve been privy to quite a few medical tech startups and let me please share, it’s much simpler than one might imagine to create new medical tech. It’s a remarkably underserved area, the requirements are not quite as hard to get through as it would seem from first glance and I’ve been appalled at many of the systems that are in current use at many hospitals. We’re talking Stone Age level in a lot of ways! If you’re humble, willing to go in and actually listen to the doctors and nurses to identify the real problems and willing to create robust solutions it’s practically the Wild West of opportunities.

What I've always wondered is: how many medical "$100 bills laying on the street" are there to pick up, if you don't care about the need to commercialize (and thus go through FDA rigamarole for) a therapeutic approach, but just want to improve your own health, or the health of someone you love, as a one-off?

For pharmaceuticals specifically this is what people call "nootropics"—but there's so much to medicine other than searching for new chemicals to put into people's bodies.

I've got to assume that, for example, there's just as many things a clever hardware hacker could do to with e.g. masers or ultrasound or electrolysis or ferromagnetic nanoparticles, to influence the course of a disease; or things a clever biochemist could do by, say, encapsulating existing drugs (or even ordinary non-drug substances) in novel delivery vehicles like cyclodextrin molecules or gel matrices.

What medical miracles have been performed once, on a rat in a university research center somewhere, but have never even attempted commercialization?

Spent the last few hours trying to track down this book to no avail but short answer: you’re spot on!

Off the cuff in line with your thinking that’s been a life saver for me over the last 20 years... super glue. Locktite gel blue resealable squeeze bottle. Have saved myself at least a dozen trips to the hospital for stitches with this stuff with only one complication last time due to my negligence. Take-away: yes wounds can actually go septic if you don’t properly clean them prior to dressing and yes wounds need to breathe and be dry to heal.

On the pharmaceutical side I can’t speak too much to, but I’m firmly convinced after 15 years of personal experimenting that diet (real food, not too much, mostly blah blah blah) and stress management via lifestyle design are the miracles we read about. Add to that mild physical activity, drinking lots of water, good sleep, good mental & physical hygiene and it’s practically a wonder drug.

Thank you for the link. I was reading this section and it seems that accuracy https://en.wikipedia.org/wiki/Radiation_therapy#Medical_uses and movement are the main things that hold it back. I hope they can remedy that.

There are some other limitations as well. Radiation therapy can cause scarring in different tissue types. The scarring can sometimes be problematic depending on the location and extent. Second, the radiation itself can lead to the development of secondary cancers. Often, younger patients with lymphoma receive radiation to the neck area, which can cause thyroid cancers later in life. Despite these drawbacks, radiation therapy is massively beneficial and great for patients. The whole therapy is delivered in ~30 minute sessions over the course of a few weeks, and the entire procedure is painless.

I'm not a doctor, but I once did a college report on Optical Coherence Tomography a long time ago.

The body scatters light. Just like the body scatters sound. Maybe sometime in the future we will have precision devices that can access every frequency of electromagnetism and sound waves to observe and manipulate every cubic millimeter inside a person's body. But that technology doesn't seem to be coming anytime soon.

Anyone who has actually worked with lasers will tell you that lasers are not quite as precise as we'd like ;)

Much like any other form of electromagnetic radiation, they are subject to inverse square law.

Something similar is already done with ionizing radiation.


Could this be made a lot more efficient by combining with dialysis, i.e. targeting the cells in a dedicated blood-pumping machine with more surface area, no skin layer and less worries about collateral damage?

The beauty of it is that no blood need be removed. That is a huge improvement in terms of patient experience.

The problem with fighting cancer is selectively destroying cancer cells while leaving normal cells alone. This article unfortunately says nothing about how this device does so (or even whether it does).

Without some handle on this aspect, side effects (some of which might show up much later) could be a major problem with this treatment.

No time to plow through the original paper - does anyone know?

Yes, the linked article addresses exactly that:

The laser, beamed at a vein, sends energy to the bloodstream, creating heat. Melanoma CTCs absorb more of this energy than normal cells, causing them to heat up quickly and expand.

This thermal expansion produces sound waves, known as the photoacoustic effect, and can be recorded by a small ultrasound transducer placed over the skin near the laser. The recordings indicate when a CTC is passing in the bloodstream.

The same laser can also be used to destroy the CTCs in real time. Heat from the laser causes vapor bubbles to form on the tumor cells. The bubbles expand and collapse, interacting with the cell and mechanically destroying it.

And? Won't the migrating cells just keep coming unless you target the original cancer too? It seems like a very temporary improvement at best.

Missing part of the idea here.

No one gets their cancer cured, just hopefully into remission. No matter the therapy there will always be a few cancer cell populations that evade treatment. This is why cancer patients are monitored for life.

When will this be generally available everywhere?

An old XKCD is, as usual, highly relevant: https://xkcd.com/1217/

Granted, this is actually a trial in humans, so that's good! But if you look at the study, the focus is on detecting circulating cancer cells; attempting to use the technology to destroy them is relegated to one paragraph near the end. There they note that this seemed to happen by accident, to a limited degree, in 6 out of the 18 patients; so they tried again in a single patient, whose melanoma cell melanin content was particularly favorable for this process, and it again seemed to work ("up to a 48-fold reduction" in circulating melanoma cells.)

They went on to do in vitro tests to try and show it would work in general, aiming the laser at a test tube full of blood; this worked, which is encouraging, but it shouldn't be taken as a strong indicator of anything practical. (And even there, they note that the melanin content of the tumor cells is important to the treatment's effectiveness.)

And yes, it's only targeting circulating melanoma cells. This tech can't just aim a laser at a tumor and kill it; it probably isn't useful for non-solid cancers like leukemia, either. So while this is cool and interesting, it's not a huge breakthrough in cancer treatment.

The XKCD is spot-on here.

> “In one patient, we destroyed 96 percent of the tumor cells” that crossed the laser beam, says Zharov.

Just want to clarify: tumors will generally drop hundreds of thousands to millions of cells into the blood stream on a daily basis. Most of the circulating tumor cells are already unlikely to become mets at baseline, and by the time you've found a tumor you've already seeded these cells in a number of locations throughout the body. This seeding usually occurs long before we can detect the primary tumor. We get "metastasis" when a number of other factors come into play that allow a particular CTC / bundle of CTCs to start growing into a met. For those interested, R. Weinberg's text on cancer is pretty much the authority, and he discusses this at length.

As it exists, as a therapy, it's for catching some of the horses that are making it out of the barn - after the doors have been open for a while.

To be useful as a therapy, we'd need something that can be worn 24/7 - if I catch a tumor that needs to be excised, I'd put it on your arm, and use it to deplete the circulating population to reduce the likelihood of metastasis happening in the period between detection and excision. And I'd need an RCT to show me that this is actually going to result in a reduction of metastasis, since there's every likelihood that the eventual met won't come from the CTCs seeded in the period between detection and excision.

Don't get me wrong; I'm happy to see more ways to detect and kill tumor cells. But this is still many steps away from becoming a technology with clinical application. At this stage, its relationship to useful cancer therapy is the relationship between my laser pointer from ten years ago and a sci-fi laser pistol.

What this is cool as, is as a mechanism for helping detect cancers. I'm all for having something I can slap on your arm and let me know if you've got melanoma brewing, rather than having a dermatologist manually inspect all your crevices for an overlooked mole.

These things never fail to get the same reaction from me: I get immediately excited, thinking that we've cured cancer, and then a bit depressed because this thing is probably a really long way away.

I don't work in the medical industry, but to those that do, do these headlines irritate you?

Usually the big advances are built on a number of small incremental advances. Think about modern immunotherapy like CAR-T. Rather than recap myself I'm just going to post this timeline of the milestones that led to CAR-T over many decades: https://www.mskcc.org/timeline/car-t-timeline-progress.

You'll generally be disappointed, though. "Cancer" isn't really a thing. It is a family of disorders characterized by several properties that arises from different causes. At this point in my life, I am very confident that we will never have a single general cure for cancer (killing mutated cells, repairing carcinogenic dna damage).

>do these headlines irritate you?

Sometimes, but I'm usually not exposed to these news articles unless they are posted to hn or something. I prefer to go to the journal article over these written by journalists who don't have time to dig in and do a proper summary of the findings. Usually it goes something like this:

1. Interesting thing published in decent journal, but years away from clinical trials or even animal models and things fail during those tests all the time.

2. Journalist pumps out a half assed article about how its the new silver bullet.

3. Public reads the article, picks up that its remarkably similar to the half assed article they read on tuesday about a completely different thing in a completely different disease.

4. Public complains that there's "a new cure for cancer every day."

5. Public looses confidence in scientific authority.

6. Rinse and repeat when journals push the next batch of manuscripts next week.

What's remarkable is that some of the biggest advances don't get very much coverage at all, or are covered for like a week or two and forgotten, despite the field mulling over and improving that finding for years. Clickbait-style news and scientific findings aren't compatible.

Cancer has turned out to be much harder than anyone realized 50 years ago...but the exciting thing over the last decade has been the major advances that have occurred, capitalizing on the basic biological research investments we've made. If anything, this is a story of how much we need to fund (and increase!) basic science research, even if it seems pointless in the near term.

The good news is it's been in development for a decade already and the next step seems to be human trials for effectiveness, so it's still years away, but if it works out, maybe not that many.

One very clear explanation of the problem is in a "PhD Comic" post: http://phdcomics.com/comics/archive.php?comicid=1162


Also, remember that the fight against cancer is a marathon, not a sprint. It is like curing "virus infections" or curing "bacterial infections". It's imposible to cure them all with a magic weapon. Someone makes a new antibiotic/antiviral drug, someone makes a new vaccine, someone makes a new mixture to prevent dehydration, someone makes a new procedure to detect the infections. Each is only a step. Get happy for every step, but remember that it is only a step and there are a lot ahead. (Just ignore the press titles, assume they are always linkbait.)

If you could embed a Fibre web in deep tissue and give the machine a scan technologie and a waytto move the endpoints, you could micro dose suspicious tissue.


This was an in vivo experiment.

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