Researchers Use Lasers To Detect and Destroy Tumor Cells In Melanoma Patients (ieee.org) 66
An anonymous reader quotes a report from IEEE Spectrum: Tumor cells that spread cancer via the bloodstream face a new foe: a laser beam, shined from outside the skin, that finds and kills these metastatic little demons on the spot. In a study published today in Science Translational Medicine, researchers revealed that their system accurately detected these cells in 27 out of 28 people with cancer, with a sensitivity that is about 1,000 times better than current technology. That's an achievement in itself, but the research team was also able to kill a high percentage of the cancer-spreading cells, in real time, as they raced through the veins of the participants. If developed further, the tool could give doctors a harmless, noninvasive, and thorough way to hunt and destroy such cells before those cells can form new tumors in the body.
Researchers led by Vladimir Zharov, director of the nanomedicine center at the University of Arkansas for Medical Sciences, tested their system in people with melanoma, or skin cancer. 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.
Researchers led by Vladimir Zharov, director of the nanomedicine center at the University of Arkansas for Medical Sciences, tested their system in people with melanoma, or skin cancer. 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.
Still invasive (Score:2)
That's really cool, and I love everything about it. But it doesn't get any more invasive than "heating and bubbling and shockwaving your blood through your skin". That's pretty invasive to me. Especially when you consider the risks of bubble in your blood, and lasers through your skin.
Re:Still invasive (Score:5, Informative)
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Wouldn't you count lasers through your skin as surgically entering? Isn't the laser just a very skinny scalpel?
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does a nanometer count? does burning away a yuctometer count?
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If they were strong enough to boil my blood, I would say yes.
I would any significant "penetration" as an invasion.
Re: Still invasive (Score:2, Insightful)
3 time melanoma patient. Iâ(TM)ll try lasers over chemo any day
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They should invent nanosharks to swim through my blood and devour the bad things.
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Already kind of done in 1966 in the Fantastic Voyage:
https://en.wikipedia.org/wiki/... [wikipedia.org]
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I'll take nano-Raquel Welch's over nanosharks every time.
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Re:Still invasive (Score:5, Informative)
The bubbles will be steam bubble which will almost immediately collapse once the heat source is removed, totally unlike an air embolism. The risk seems pretty small to me assuming some basic safety precautions like a limit on intensity and total energy.
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I'd like to read further about this. From the article: "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."
What about the cells' contents? Does this process release the cells' defective DNA into the bloodstream, and what happens then?
Re:Still invasive (Score:4, Informative)
What do you think happens with normal cells? Basically a cell that decides it needs to die basically dies and its cell walls rip open spewing the inner cellular stuff into the bloodstream or lymphatic system. The cellular stuff is recycled by several organs - the spleen, the kidneys and liver all gather the materials and transform or expel it out of the body.
The DNA does absolutely nothing - it's raw DNA and no cell absorbs that. Viruses encase their DNA or RNA material inside a protein shell. The protein shell is what encourages cells to take in the virus, which then dissolves inside the cell so the raw RNA/DNA can then incorporate itself into the cell's DNA or hijack the replication mechanism (for RNA).
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> What do you think happens with normal cells? Basically a cell that decides it needs to die basically dies and its cell walls rip open spewing the inner cellular stuff into the bloodstream or lymphatic system. The cellular stuff is recycled by several organs - the spleen, the kidneys and liver all gather the materials and transform or expel it out of the body.
Not exactly. "Normal", or programmed cell death goes by the name of "apoptosis" and is a careful process where the cell digests itself and ejects
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Does this process release the cells' defective DNA into the bloodstream, and what happens then?
Not much. The kidneys sort it out. It is cancer, not a virus, and not contagious. ... I think.
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What then is your opinion of radiation therapy for cancer? That is also deemed non-invasive, and operates on very similar principles.
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Yeah, I'd put radiation as invasive. Really, if it directly manipulates my insides, I'm going to count that. For example, a deep message can break bones just like a punch. I'd certainly consider a punch to be invasive, so I'd probably put an intensely-deep massage as invasive too.
In my little head, it comes down to whether or not I need to consider inner-body safety.
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It has nothing to do with the relative safety, potential for harm, or physiological effects of the procedure.
Limited to melanoma (Score:5, Interesting)
Physician and researcher here. This is clever and useful. However, the press release glosses over limitations (as usual).
After skimming the paper, the big ones that jump out are:
1) Limited to melanoma. Absolutely will not be effective for any other type of cancer. Both the heating effect and subsequent detection rely on the presence of melanin, the pigment that makes melanoma tumors brown. Melanoma is the only type of cancer that makes melanin.
2) Melanoma is capable of NOT making melanin given an evolutionary selection pressure, which this laser killing would provide. There are likely already a small fraction of cells present in melanoma tumors which do not make melanin. So these will survive, and if in the blood, metastasize without detection or killing by this system.
3) The system is missing metastatic cells that have already seeded other parts of the body prior to the laser system starting blood detection. And the detection is limited only to a peripheral branch of the circulation, so it's also not scanning the whole blood volume as the heart circulates blood. So this is only detecting some small fraction of circulating cells. Even if the detection system were 100% accurate, detected all cells in the blood, and was kept active 24/7, it would still likely have missed metastatic seeding which occurred prior to realizing the patient had melanoma in the first place, unless the patient is lucky enough to have it diagnosed very early in the cancer's progression. And if the patient was that lucky, the tumor can simply be cut out - no need for blood monitoring with this system.
In sum, this is probably most useful for monitoring disease response to a different treatment (immunotherapy for example), as well as monitoring for recurrence.
Comment removed (Score:5, Insightful)
Re: Limited to melanoma (Score:5, Interesting)
That was my first thought too - can we tag things with a marker that responds to a specific frequency of light and use the same principle. I think that this has been done before with metal nanoparticles and radio frequencies.
Re: Limited to melanoma (Score:1)
If you can tag it you can kill it. There six million ways to destroy a cell. The question is how do you not mistakenly attack the wrong ones and yet consistently detect the bad ones without evolutionarily selection pressure being applied.
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Well, this would still only target cells where the laser was focused - so only if those 'wrong' cells were circulating in the bloodstream would they be killed. Not to minimize the risk, but it's sure better than trying to target tagged cells chemically with agents that reach into all body tissues.
Re: Limited to melanoma (Score:1)
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2) Melanoma is capable of NOT making melanin given an evolutionary selection pressure, which this laser killing would provide.
Not in the least! There's no possible genetic pressure that can happen here, because the melanoma is the effect of something else. It's like saying throwing out left turkey breasts at thanksgiving is going to bring about a rise in right breasted turkeys. No, you're always going to get both, because you're too far down the line to impact selection of any sort.
Melanoma isn't transmitted between humans, and it kills the human who has it, given enough time. The non-brown melanoma has no mechanism to pass along
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a sensitivity that is about 1,000 times better than current technology.
How exactly did they derive that figure? Why not 100, or 500, or 2000 times? Conveniently round factors like that make me question whether they're just making stuff up.
What he said (Score:5, Funny)
Science saving the faithful = irony (Score:2)
There's no better comment I can think of than the one a hospital's chaplain made when I told him that I was about to have laser lithotripsy [wikipedia.org] and explained what it was. He looked at me for a moment with a stunned expression and then said, "How...Star Wars."
That's pretty damn funny. Especially funny when science saves someone who makes their living telling people to believe in stuff for which there is no evidence. He's absolutely right though, it is amazing we can do stuff like that.
Interesting but (Score:1)
CTC's are not as dangerous as you would think. The last estimate I read was that less than 1 in 100,000 circulating tumor cells can survive to attach itself to tissue and form a viable tumor. Also are you going to keep a person hooked up to this device permanently until their melanoma is cured? If this laser treatment can selectively kill melanoma cells, it seems like it would be better applied to existing tumors, not randomly blasting a person's blood.
Pew pew pew (Score:2, Funny)
John Kanzius (Score:1)
Is this technology inadvertently racist? (Score:1)
Seriously, does this work on people with darker skin? It works by detecting and targeting melanin, which is the primary cause of skin color differences.
Have we just invented a cure for skin cancer that only works on pale skinned people?
Note, this type of cancer is more prevalent among pale skinned people because melanin also protects you against skin cancer, but it is still an interesting question.
I don't get it. (Score:1)
It sounds about as useful as trying to eliminate all red cars in parking garages by looking at one higway for one hour on a random Tuesday and ignoring all parking garages.
Finally! (Score:2)
"the tool could give doctors a harmless, noninvasive, and thorough way to hunt and destroy such cells before those cells can form new tumors in the body. "
Fuck the doctors, I want one to wear on my wrist 24/7.
This is racist (Score:2)
And in this case, the subject line actually applies.
My wife does laser hair removal. It relies on the exact same phenomena related here. The laser is tuned to the darker areas, resulting in dark hair follicles absorbing the vast majority of the energy and being "burned" out. A serious limitation of the technique is that it doesn't work as well on dark skin. Well, that isn't exactly true. It works BETTER on dark skin, as the dark skin will absorb more of the energy. Dark enough, and the skin will absor
Bayesian statistics of circulating tumor cells (Score:2)
For a time, I was on a small team that developed a working cancer cell sorting robot, and got exposed to the Bayesian statistics of circulating tumor cells in a deciliter of blood; that a patient with 5 or less cancer cells ,if I recall, was considered to be in remission but 6 or more was considered to be terminal, and is the threshold where the immune system is not strong enough to fight it. (It was really important to get an accurate cell count)
Cancer cells are apoptotic as they are under attack from t