Placeholder Image

字幕表 動画を再生する

  • Moles, birthmarks, beauty marks.

  • Most people have multiple moles, and they come in lots of different shapes and sizes.

  • Usually they're harmless, but occasionally they could be a sign of a very serious disease:

  • melanoma.

  • So, when is a mole just a mole, and how does it turn into a deadly form of cancer?

  • Now, not all melanomas start from a mole, but all moles are made up of the type of cells

  • that can become melanomas: melanocytes.

  • Hi, my name is Aaron Mangold.

  • I'm an assistant professor of dermatology at the Mayo Clinic in Arizona.

  • I specialize in cancer genomics as well as utilizing advanced forms of genetics to prognosticate

  • cancers for spread to other areas of the body, as well as for therapeutic interventions.

  • Melanocytes primarily protect skin cells from ultraviolet damage through the production of pigment called melanin.

  • Melanocytes deliver melanin to the surrounding keratinocytes, or skin cells in the epidermis, giving our skin its color.

  • When we come in contact with ultraviolet light from the sun, this melanin protects our skin

  • from damage, while also signaling to the body to produce more melanin.

  • This is why you might tan when you go out in the sun.

  • And this system works pretty well, but it's not perfect.

  • So melanocytes really have evolved over time to be extremely resistant to ultraviolet light.

  • They've become extremely resistant to acquiring mutations that in normal cells might lead

  • to apoptosis, or cell death.

  • And they also are able to circulate innately throughout the body.

  • Since melanocytes aren't as likely to die due to DNA damage from UV light, they obtain

  • mutations and can continue to grow and may cluster together, forming non-cancerous growths

  • called "nevi," or moles.

  • Those damaged melanocytes can then acquire additional mutations and continue to proliferate

  • forming a precancerous lesion or eventually a melanoma.

  • One mutation that almost all moles have is in the gene BRAF, a protein that is part of

  • cell signaling involved in cell growth.

  • But, a single BRAF mutation is not enough to cause cancer.

  • And not all melanomas even come from moles.

  • So the way that melanoma, or the way that a melanocyte becomes a melanoma, occurs through a fairly long process.

  • There's not one specific change that happens that leads to it.

  • It's a series of changes.

  • Additional mutations in genes can be caused by things like further damage due to UV light.

  • These changes prevent natural cell death and lead to uncontrolled growth of the cancerous melanoma cells.

  • Fortunately, melanomas can be removed if discovered early enough.

  • And there are ways to check if a mole is irregular, which we'll talk about a little later.

  • But, what happens if melanoma isn't caught?

  • ...the melanoma cells, they're able to acquire certain properties that make them not want

  • to stay in the skin any more.

  • And once they acquire those, they can actually go into things called lymphatics in the bloodstream and then can spread.

  • Once melanoma has reached this stage and has spread from the lymph nodes to other parts

  • of the body, it's very hard to cure.

  • It also has a high mortality rate, only 23% of patients survive past five years.

  • So it's important to identify an abnormal mole soon so that it can be removed.

  • Fortunately, there is an easy ABCDE rule to follow, which checks for asymmetry, irregular

  • borders, uneven color, increasing diameter and an evolution or change in the mole.

  • An individual might say that this lesion is just different.

  • This doesn't look like everything else on me.

  • That ugly duckling sign I think is also very useful in having some form of self body awareness

  • and say, "I want this looked at."

  • Specialists like Dr. Mangold are also starting to use immunotherapy to combat later stage

  • melanoma, using the body's natural defenses to fight the disease.

  • Normally our immune system will travel throughout the body, the immune cells will, and those

  • immune cells will look at individual normal cells and say, "How abnormal are you?”

  • ...And when they have those signals telling them that they've acquired too much damage,

  • the immune system then kills them….

  • Well, cancer cells have figured out how to use certain proteins like that that will say,

  • "Don't worry about it.

  • Everything is okay.

  • We're doing fine.

  • Leave us alone."

  • Recently, they figured out how to block those, how to block those signals that quiet the immune system.

  • And it's really revolutionized not just the care of cancer as it pertains to melanoma,

  • but cancer in general.

  • But immunotherapy is still an emerging science.

  • Doctors have to avoid making the immune system too active.

  • This would result in an autoimmune disease, or an immune system that attacks healthy cells.

  • It's really analogous to playing a musical instrument or playing a piano.

  • You have all the keys that are there.

  • Yet, you can make good music, or you can make bad music.

  • And we're trying to figure out now, how do we make good music and how do we avoid that kind of bad music?

  • While immunotherapy is still developing, there is one treatment that everyone can take part in.

  • You don't want people to lose sight of what's important, and I think it was Bert Vogelstein

  • who said this, that if you could give someone a pill and tell them, "This pill that I give

  • you is going to reduce your risk of cancer by 50%,"

  • that it would be across every news organization, every magazine cover.

  • Someone would get a Nobel Prize for it.

  • And we do have that pill.

  • That pill is primary prevention through healthy behaviors, healthy eating, different things

  • that we can do as individuals that will reduce those risks.

Moles, birthmarks, beauty marks.

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B1 中級

ほくろはどのようにしてがん化するのか? (How Do Moles Become Cancerous?)

  • 67 7
    Jerry Liu に公開 2021 年 01 月 14 日
動画の中の単語