Sunburns, Zombie Cells and Your Health: Dr. Dusan Sajic’s TEDx Talk

Key takeaways

• In a seven-minute talk at TEDxGreenhouse Road, published by TEDx Talks in July 2024, Dr. Dusan Sajic describes finding his own skin cancer in the shower, decades after a childhood of blistering sunburns.
• His point: the skin keeps a record of sun damage below the surface, and it is an organ that signals to the rest of the body, not a shell.
• He asks for three habits. Sunscreen of SPF 30 or higher every day. Checking your skin for any change, with a partner, including the scalp and back. And, for skin that carries years of sun damage, treatment that works below the surface.
• The research he points to is a 2021 randomized trial in the Journal of Clinical Investigation: one fractional laser treatment on one forearm of older adults was followed by far fewer new skin cancers on that arm than on the untreated arm during follow-up of up to 36 months.

Watch the talk

Watch on YouTube: How Sunburns and Zombie Cells Affect Your Health, TEDxGreenhouse Road (TEDx Talks, 7 minutes). TED adds a note to this video that research on senescent cells and the therapies built on it is an emerging field.

What he says

The talk opens with a bump in the shower. Dr. Sajic says he knew immediately what it was, but did not want to come to terms with it and hoped it was a bug bite or even a tick. It was a skin cancer. People ask how a dermatologist ends up with one. His answer is that dermatologists grew up the same way as everyone else: he was a child in the 1970s and a teenager in the 1980s, when, as he puts it, SPF was not a thing and a blistering sunburn was shrugged off as “just skin.”

The idea that carries the rest of the talk is that the skin always remembers. Damage from decades ago, he says, does not disappear when the burn heals. It sits below the surface. He asks the audience to stop treating skin as a superficial covering and to think of it as an organ in its own right, one that exchanges signals with the endocrine, circulatory, inflammatory and neural systems. When skin cells are unhealthy, he says, those signals change, and the rest of the body is affected.

From there he gives three habits.

1. Add no more damage. Sunscreen of SPF 30 or higher, every day, no exceptions. His comparison is brushing your teeth: nobody waits for an occasion to do it. For every excuse not to wear sunscreen, he says, there is a formulation that solves it.
2. Be proactive. Check your skin for any change, not just for cancers, because a change is a signal. Take a partner, and check the hidden places, the scalp and the back.
3. Reverse what is already there. For people like him, with years of accumulated sun damage, he says research now shows the damage below the surface can be treated rather than only hidden. This is where he introduces zombie cells.

Zombie cells are his name for senescent cells. In the talk he describes them as cells that send out toxic signals and infect the other cells around them, and he says senescent skin cells have been linked in humans to heart disease, liver damage, dementia and depression, with early research suggesting that clearing them improves the whole system. (Those links are his summary of the field, and we have not assessed them here. Our own article on what senescent cells do and what actually clears them sets out the evidence and is more cautious: the effect of senescent skin cells on distant tissue is supported by animal work and is not proven as a causal chain in humans.)

He closes with what his own cancer changed. The treatment was straightforward and the problem was over, but it convinced him that treating skin at the surface is not enough. His challenge to the audience: start treating your skin like the vital organ it is, today, not on the next vacation.

Key moments

• 0:05 The bump he found in the shower.
• 0:42 “How did you have a skin cancer? You’re a dermatologist.”
• 1:15 Growing up before sunscreen: the 1970s and 1980s.
• 1:47 “The skin always remembers.”
• 2:41 The skin as an organ that talks to other organs.
• 3:32 Habit one: SPF 30 or higher, every day.
• 4:12 Habit two: check for any change, with a partner.
• 4:32 Habit three: treat the damage below the surface.
• 4:57 The 2021 study and zombie cells.
• 6:07 What his own skin cancer changed.
• 6:30 The challenge: start today.

The study behind “reversing the damage”

The 2021 paper he refers to is a randomized controlled trial led by Dan Spandau and published in the Journal of Clinical Investigation (PubMed 34428179). It is worth knowing exactly what it tested, because the talk compresses it into one line.

• The participants were 48 adults aged 60 and over with considerable sun damage.
• Each had a single fractionated laser resurfacing treatment on one lower arm. The other arm was left untreated as the comparison.
• Both arms were checked for actinic keratoses (precancers) and non-melanoma skin cancers for up to 36 months, by assessors who did not know which arm had been treated. Follow-up thinned out over time: 48 people were seen at 3 months, 36 at 24 months and 15 at 36 months, and 14 were withdrawn after developing 20 or more actinic keratoses, all on the untreated arm.
• The treated arms developed 2 skin cancers in total. The untreated arms developed 24. Precancers were also reduced on the treated side.
• The authors’ explanation is the one he calls zombie cells: with age, senescent fibroblasts in the dermis stop producing a growth factor called IGF-1, which leaves the skin unable to respond properly to ultraviolet light. Removing those cells with the laser wound restored that response.

Three cautions the talk does not have room for. The trial was on forearms, not faces, and its endpoint was new cancers, not appearance. Its participants were almost all men (47 of 48), recruited at one US veterans’ clinic, with fair skin types, and the laser was a 2,790 nm ablative fractional device (Pearl Fractional, by Cutera), not a CO2 laser. And it was one treatment in one study, which the authors describe as a potential preventive approach for high-risk patients rather than a finished answer. If you are weighing a resurfacing treatment, our guide to what actually prevents side effects after CO2 laser covers the practical side.

Transcript

Lightly edited for grammar and readability from the talk’s captions; filler words and repeated phrases have been removed.

Read the full transcript (about 1,100 words)

A bump in the shower

So we all have our aha moment. Mine came to me a couple of years ago. I was in the shower when I found it: a bump I didn’t see or feel before. As a board-certified dermatologist, I knew immediately what it was. But like many of you, I didn’t want to come to terms with it. Maybe it’s a bug bite, or maybe even a tick. I did walk outside, after all, and it could have been a tick. As if that would be a better thing: a giant insect slowly burrowing into my skin. But that actually gave me comfort. Because what it was, was actually a skin cancer.

I know. I found it hard to believe as well, and most people will say that. They’ll say, “Well, wait a minute. How did you have a skin cancer? You’re a dermatologist. Aren’t you supposed to know better?” It was shocking for me, too. But you see, even though we dermatologists can sometimes look like superheroes, with flawless, wrinkle-free skin, we are human, too. And like many of you sitting out there listening to this talk, we weren’t always dermatologists. Many of us, myself included, grew up at a time when skin care wasn’t a thing.

The skin always remembers

I was a child in the ’70s and a teenager in the ’80s, and we took our skin for granted. SPF was not a thing. My parents would say, “Hey, go outside. Play out in the sun all day.” And I did. And I’d come home with sunburns, sometimes blistering. My parents would say, “Hey, it’s just skin. Relax. It’ll heal.” That’s what we all thought. And now, many years, in my case many decades, later, it eventually caught up to us.

You see, the skin always remembers. It’s like an elephant. It always remembers what you did. And the problem is, we do our very best to hide all that damage, and we’ve gotten very good at it. But it stays below the surface, just waiting.

And this is what I want you to focus on: changing your view and approach to skin. Not just at the surface, but going deeper, below the surface, and finding out what treatments we can do that not only enhance our beauty but make us better holistically, health-wise. We can’t go back in time. But what we can do is start treating our skin as more than just a superficial shell.

Skin is an organ, and it talks

We’re starting to think that those who use skin care or treat their skin are superficial or vain. Our skin is actually so much more than a superficial covering or a protective shield for our inner organs. It is a true organ in its own right. And the latest research is finding that it can communicate back and forth with the other organs. There are cells from the endocrine, circulatory, inflammatory and neural systems. So even though it may not look like it, our skin is constantly communicating back and forth. And the latest research is showing that when our skin cells are unhealthy, they can start sending signals to the rest of our body and affect our other organs. We’ll get to that a little later in the talk.

Three things to do now

So what can we do? How do we, right now, start treating our skin as true health care? Well, it’s simpler than you might think. There are three very simple things we can do right now to take our skin care back.

Number one: let’s not add more damage. SPF 30 or higher, every day, no exceptions. Think about it. How many people brushed their teeth last night? We all brush our teeth every day, sometimes twice a day, sometimes more. Would we brush our teeth only if we knew somebody was going to plant a big kiss on us? No. We brush those pearly whites every day. And we should do the same with sunscreen. And for those of you taking notes: no, I don’t mean brush your teeth with sunscreen. I mean use it on your skin every day, no exceptions. I promise you, for every excuse you have for not using it, there is a sunscreen made right for you.

Number two: be proactive. Listen to your skin. It’s trying to communicate. We’re not looking just for skin cancers. We’re looking for any change, because that could be a signal that something’s going on. So take a partner, make sure you check yourself out, and find those hidden zones, like your scalp and back.

And number three, especially for those of you like me who have had lots of sun damage over the years: take steps to actually reverse it. Groundbreaking research is showing that there’s more to it than that. We’re finding, for the first time, that we can reverse the damage below the skin and truly heal our skin from the bottom to the top. In fact, the Journal of Clinical Investigation, in 2021, is showing that for the first time we can truly reverse the damage and get rid of senescent zombie cells.

Zombie cells

Zombie cells, you might say? Absolutely. Recent research has found that there are these senescent cells that behave just like zombies. They send out toxic signals, infecting other cells around them and making our whole system unhealthy. Senescent skin cells have now been linked, in humans, with heart disease, liver damage, dementia and even depression. And the research, just in its infancy, is showing that once we get rid of those zombies, we can make our whole system better.

Which makes sense, doesn’t it? What if somebody a few feet away from you turned into a zombie? And then another. You wouldn’t really want to listen to what I’m saying. You would want to hide, get out of this room, maybe even get out of the city. And thanks to the research, we’re starting to uncover ways to do just that. It gets a little more complicated than that, but that’s the general idea.

What my own skin cancer changed

I found myself lucky. I had a skin cancer. It was easy. I got it treated. It’s done. The problem is over. But what it did for me was make me realize, as a dermatologist, that we need to do more. We don’t want to just treat our skin superficially. We need to investigate ways to go beyond the skin, deeper, so that we can keep our whole system healthy.

So here’s my challenge to you. Do the same. Start treating your skin like the vital organ that it is. Today, not tomorrow, not at your next vacation, not when that bump you start wishing was a tick burrowing into your skin. Right now. Our skin is an interconnected organ calling out for our help. It’s not just there protecting us. It’s always looking out for us. Let’s start looking out for it. Thank you.

Questions people ask about this talk

Where was this talk given? At TEDxGreenhouse Road, an independently organized TEDx event. The video is on the TEDx Talks YouTube channel, published on July 2, 2024.

What kind of laser was used in the study he mentions? A 2,790 nm ablative fractional resurfacing device (Pearl Fractional, by Cutera), applied in a single pass to one lower arm. It was not a CO2 laser and not a facial cosmetic treatment, and the published result is about fewer new skin cancers, not about how the skin looked.

Where are Dr. Sajic’s press and other talks? On his press page.