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As we age, cancer rates go up as immune system winds down (arstechnica.com)
313 points by okket on Feb 15, 2018 | hide | past | favorite | 80 comments



I always think of these two monkeys[i] when I consider slowing down my age.

[i] http://www.slate.com/articles/health_and_science/medical_exa...


It's an interesting well-written article, but you realize that their main point was that it contradicts the earlier calorie-restriction study: "The Nature authors found no increase in lifespan; the calorically restricted animals lived no longer, statistically, than their well-fed cousins."

They try to reconcile the studies: maybe it's the natural-ingredient foods vs the refined foods, maybe it's the generous diet vs the more-than-generous free-feeding, or conceding that the monkey's don't live longer, but they live healthier.

IMO, the best paragraph from the article was this: "Many of us simply roll our eyes and click away when yet another medical study contradicts the last study—so what else is new? Coffee’s bad for you, until it’s good for you—and so is red wine. Antioxidants are essential, or they’re useless. And so on."

Other than some very basic common sense things -- like don't eat rat poison -- I never find that these kinds of studies lead to correct and actionable information about how to slow down aging or how to lead your life. And it's extremely frustrating to even try.


To even try? To try to exercise and not drink sodas is extremely frustrating? Living a healthy lifestyle is about simple choices like going to the gym or adding broccoli to your meal and avoiding junk food.


> To even try?

Sorry, I should have been clearer. I meant, to even try to keep up with the contradictory medical studies.

Yes, you should exercise; that's a common sense thing I'm referring to. But trying to decide if things like calorie restriction really work in the face of conflicting studies is frustrating.


nutritionfacts.org was created for this reason, to consolidate the evidence from nutritional studies so that you don't have to.

spoiler alert - the comprehensive review lead them to the conclusion to eat plants, unprocessed.

But anyway, it is a nice resource to get a round up of studies on a similar topic.


nutritionfacts.org is an extremely biased site that has been created by a vegan who built his whole career on speaking about health issues. While it has the word "facts" in its title nothing prevents them from cherry-picking studies to support their original views.

If you cherry-pick different studies you might actually find that consuming large amount of plants stresses our digestive system way more than a fatty steak with potatoes.


> If you cherry-pick different studies you might actually find that consuming large amount of plants stresses our digestive system way more than a fatty steak with potatoes.

You really, REALLY, believe with all information being out there nowadays that a diet of only "fatty steak with potatoes" will be healthier for humans that the "balanced WFPB diet" that is nutritionfacts.org claims is scientifically proven to be the healthiest?

I think you have nothing to back that up. Please cherry pick how you please and present your evidence.

Dr Greger, who started the non-profit nutritionfacts.org, is often attacked for being an ethical vegan. Since people reason that would impair his ability to present unbiased evidence. Though no-one has ever gotten beyond claiming he's cherry picking. I wish someone would describe a different diet that is as well supported by scientific evidence, as what nutritionfacts is doing for WFPB.

There is some scientific evidence building up in for the Keto diet. But that is --as far as I know-- not a diet for life.

On the other hand there is the raw diet movement (basically an uncooked WFPB diet), but that has little scientific and mostly anecdotal evidence.


The keto diet's main difficulties are the prevalence and preponderance of available sugary foods, the near inability to eat socially, and the extreme difficulty in adopting the diet in the first 3 weeks for people regularly consuming 200g+ of carbohydrates a day.

The raw diet is mostly a trendy thing people write about. The bioavailability of nutrients in many raw foods is just too meh.

We know what the best diet is. A plant and fish based diet with small amounts of other meat. Meat that doesn't subsist on a diet primarily of corn or other, less edible things. This diet is completely unsustainable on a global scale and would result in even more ecological havoc.

The discussion between plants or plants + meat is complicated, but for now I'm going to ignore it because there's more important considerations:

- Companies are making our produce harder to digest as they try and make products with a longer shelf life.

- Eating industrially produced meat (of any sort) is very unhealthy and in many ways unsafe.

- This entire discussion removes dairy from the equation, which is a large part of the puzzle for most people.

- The low-carb vegan and the low-carb omnivore are far better off than anyone consuming 200g+ of carbohydrates a day.

- Hydroponically grown carrots taste gross.


> We know what the best diet is. A plant and fish based diet with small amounts of other meat.

Nope. Fish (most fish) as a central part of diet, will contribute a lot to build up of heavy metals in humans. And what is "small amounts of other meat"? 3x per week? This is basically an omnivorous diet. Compared to the SAD is probably just the junk cut out.

This, SAD-processed, is a very unhealthy diet, compared to a balanced WFPB diet. There are lots of studies to back this up.

> - Companies are making our produce harder to digest as they try and make products with a longer shelf life.

Yups.

> - Eating industrially produced meat (of any sort) is very unhealthy and in many ways unsafe.

Not a problem for those eating WFPB.

> - This entire discussion removes dairy from the equation, which is a large part of the puzzle for most people.

Dairy is a killer. Prolly more so than meat.

https://www.youtube.com/watch?v=h3c_D0s391Q

> - The low-carb vegan and the low-carb omnivore are far better off than anyone consuming 200g+ of carbohydrates a day.

Any study on this?

There is a lot of studies (long running, with large size populations) claiming the opposite. Here some arguments: http://www.masteringdiabetes.org/ketosis-ketogenic-diets-mis...

> - Hydroponically grown carrots taste gross.

Personal taste. It prolly has less phytonutrients. Not sure how this is an important consideration.


The site you linked is thick which propaganda which makes me doubt your bias and arguments. Choosing your sources is important for making a compelling argument.


One man's truth is another's propaganda, what are your sources? (I've shown mine, and I must say it's pretty convincing and lines up with what I already knew about the human body)

I'm not at all saying there's no use for keto, I just think it should never be a mainstream diet (but something applied in specific cases, under medical supervision). As far as sci evidence goes, WFPB seems to be the "best" diet for the human species as a whole.


I never said that you should _only_ eat steaks and potatoes, did I?

This diet recommends a pound of fatty meat per day: http://perfecthealthdiet.com/the-diet/

The book that describes the diet cites over 1000 studies and empirical evidence to prove that the diet is healthy. Now who am I to believe?


This website is seriously one of the best places to find science backed nutrition info. The advice comes down to: eat a balanced Whole Food Plant Based (WFPB) diet with a minimal supplementation regimen:

https://nutritionfacts.org/2011/09/12/dr-gregers-2011-optimu...


I think that individual genetics and behaviors are very important for these kind of health studies. Some things are quite clear and apply to all humans. For example: you need vitamin C in your diet or you will get scurvy. Then less general rules that might not apply to you given your genetics and behavior. Vitamin D supplements? Maybe, but probably won't hurt. Drinking Milk? Very variable on its benefits and costs to different people. Down to things that some people should do and others should not do depending on genetics and behavior (most studies these days).

Massive individual genetic testing and constant cellphone behavior monitoring might be able to produce decent studies in the future for your specific attributes, but for now advice from parents and grandparents may be the best you can do.


Why would cell phone data help?


Genuine question... answers?


Most studies use self-reported behaviors for how people behave. More invasive studies (as some people have mentioned in this comment section) show that self reporting is inaccurate and, for example, people eat many more calories than they self report. If you have some system of automatic recording of behavior, which smart-phones might be able to do, and individual DNA results, then these large scale studies might be able to tease out what is healthy behavior for people with specific DNA.


Thanks - is there any literature that you are aware of on this so I can get started?


Googling "problems with self-reporting in diet studies" gives a good listing of scientific papers for me. Of course such a search is screaming out "confirmation bias", but it is still useful I think. This[1] is one study that seems to cover what I was talking about, although I have not read it in full.

If you want to take a deep dive into a subject, search for a recent paper on the subject and as you read it the paper will reference other papers, especially in the introduction. Here is where you can find possibly a more relevant paper on the subject. Read that paper and repeat. Soon you will have a decent idea of what is going on in the field. Hard to do if you don't know the jargon and the mathematical methods though.

[1]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3025654/


I don't know about the other studies, but I assume they were short-term? I think I remember one of them being only 3 months. That could have been the issue, as I believe calorie restriction leads to a slower metabolic rate. So if you need 2,000 calories, but eat 1,500 for a year, your body should get used to eating 1,500 and maintaining your weight (after losing some initially before it adapts to fewer calories).

But I believe intermittent fasting where you eat the same 2,000 calories but just shorten the window of eating to allow your body to crank-up the growth hormone and start autophagy does have long-term benefits, that should lead to prolonged life.

And of course, a calorie isn't a calorie. If you eat 200g of net carbs a day, intermittent fasting probably won't prolong your life too much, but it's also going to be more difficult to do IF when you're body is used to having high-levels of blood sugar and insulin in it.


>I never find that these kinds of studies lead to correct and actionable information about how to slow down aging or how to lead your life.

I think the modern life has maxed out as much life extension as we are going to get from our nutrition and lifestyle. We need to do interventional genetic modification to see any further improvements.


>Other than some very basic common sense things -- like don't eat rat poison

Common sense is often mistaken. Here are two rat poisons which are also medicines:

Ergocalciferol -- a.k.a. Vitamin D2 (used as a supplement for many years; now D3 is preferred)

Warfarin -- oral anticoagulant widely in use today


A single study will almost never be actionable, but a series of studies, accompanied by systematic reviews, could be the basis of such recommendations.


>I never find that these kinds of studies lead to correct and actionable information about how to slow down aging or how to lead your life.

Don't salt your food _at all_ to maintain a healthy blood pressure.

>Furthermore, it also found that populations with low average daily salt intakes had low BP (blood pressure) and very little or no increase in BP with age. INTERSALT study indicates that BP increases with age only if accompanied by increased salt intake.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4105387/


Yeah I have gone and done it, I have decreased my calories by roughly 30% in the past year or so and dropped around 30 pounds in the process, plus an aggressive vitamin and supplement routine, along with taking metformin. I also workout 7 days a week including playing hockey 2, sometimes 3 days (and also working out before or after), the group I skate with is highly skilled and the intensity is pretty up there, I've been skating with them for about 15 years or so.

I just turned 50 but am regularly assumed to be 36, the age everyone always guess... including by my gf's parents who are just a few years older than me. I am a rather crazy outlier though, I actually enjoy working out and do a hundred+ pull-ups a week, and even on my light workout days tend to do at least 20 or so just to loosen up a bit.


(this may be an unpopular opinion but...)

The problem with having a healthy lifestyle is that our lives aren't statistics. Big number theory does not apply, we only have one draw, one life and if it happens that we are one of those unlucky ones to get lung cancer while never having smoked or generally lead a healthy life then we still die within a year and there's nothing we can do about it.

Any drastic lifestyle change has costs: serious time, commitment, money and we sacrifice opportunities, things that we could be doing/enjoying instead. So my advice is: for anyone deciding to drastically change their lifestyle to a "healthier" one, do so for all the _other_ reasons (feeling fit and good, looking younger, improved relationships, having more energy, etc) but not expecting for that to increase your life span. Because then you may be up for a one nasty disappointment when cancer strikes and you are left wondering why did you do all that, why did you sacrifice so much. You better have a good answer when that happens is what I'm saying. :) (and that is true no matter what lifestyle you lead)


I have two ways of thinking about death that I've found helpful.

The first is to sincerely imagine that I will die in 10 years. That's far enough away not to require drastic changes in my life — I still want to work hard on something that I'm passionate about — but close enough to remind me not to fuck around and take these years for granted. There's also a bonus that, if I do happen to run into some bad luck and have my life expectancy cut short, then it won't come as such a shock, because I've been living like it's my last decade anyway. And if that doesn't come to pass and I live a normal life, I'll feel more gratitude for it.

The second trick I use is to imagine that reincarnation is true, but that instead of "coming back" as plankton or a bug or another person, I come back as me and relive my life, over and over again, forever. In that situation, I'd want to optimize to have a great quality of life, and spend as little of it as possible worrying about my inevitable death, or agonizing over things that have gone wrong in my past. Since my rebirth is inevitable, I'd just be dooming myself to future agonizing. It sounds morbid, but I've found that this helps me to recover a bit when I feel down about something.


What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: "This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your life will have to return to you, all in the same succession and sequence—even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again, and you with it, speck of dust!"

Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: "You are a god and never have I heard anything more divine." If this thought gained possession of you, it would change you as you are or perhaps crush you. The question in each and every thing, "Do you desire this once more and innumerable times more?" would lie upon your actions as the greatest weight. Or how well disposed would you have to become to yourself and to life to crave nothing more fervently than this ultimate eternal confirmation and seal?

Friedrich Nietzsche, The Gay Science


Well damn.


That's great. But that seems like a large commitment. I don't want to die at 70 but I also don't intend on spending my life thinking and working hard on prolonging it.

I'm kind of taking the 80 / 20 approach to living healthy. Don't smoke. Don't eat too too much. Sleep well. See the doctor each year. I'll let you know how it goes.


Are you taking metformin because you're prediabetic or because you think it can extend your life expectancy (or both)?

Don't you have problems keeping warm, sleeping, and maintaining muscle mass at that level of calorie deficit?

Also wondering what your supplementations are. I take Vit D, Zinc, pre/probiotics but having an aggressive vitamin routine isn't considered ideal these days.


I told two diabetic friends about the results showing that metformin significantly reduced cancer. They looked at each other and then one said "I've got a closet full of that stuff; I never take it!" Turns out that neither were using metformin, but picked up their prescriptions religiously.

Next time we met they were both taking their metformin, although intermittently and apparently somewhat reluctantly. One of them was late for our meeting. In way of explanation he said that he had taken a metformin tablet just before driving off but, on the way, a fart proved to be untrustworthy: he had to drive back home and changed his pants.

I've heard the drug termed "metfartmin" b/c of its effects on the GI tract.


I'm assuming you're not diabetic, so how did you persuade a doctor to prescribe metformin?


Did you try https://how-old.net/ ? It usually doesn't care about hurting your feelings.


Thanks for sharing – always those poor monkeys though...

An even stronger data point to me would be the actual people of Okinawa who are (were?) among the healthiest and oldest in the world.

In addition to having a high quality diet and a rich social life in general, they are practicing “hara hachi bu” – the confucian tradition of always eating only until “about 80% full”.

https://en.m.wikipedia.org/wiki/Hara_hachi_bun_me


This is really great! Thanks for the link. I think you should post it to HN


One immediate problem with the hypothesis that cancer is caused by the loss of T cells with age is the fact that HIV also destroys T cells, and it is associated with increased risk of some types of cancer. But the cancers associated with HIV are different from those associated with aging. In particular, Kaposi sarcoma occurs 500 times more in HIV patients than the general population. So there must be something else going on besides just the loss of T cells.


Kaposi sarcoma is associated with Kaposi's sarcoma-associated herpesvirus even in the HIV cases though. It might be that losing the amount of T cells you lose with HIV or immunosuppression has a different effect than just losing some fraction of them with age with respect to that virus.


Agree. No doubt immunosenescence contributes to the increased rate of malignancy at older ages but the spectrum of cancers seen in immunosupressed individuals does not that match seen in the elderly.


The link between cancer and the immune system (the latter's role in defending against the former) is not all that clear.

Here is a cancer.com (American Cancer Society) article on the relationship between AIDS and cancer.

Source: https://www.cancer.org/cancer/cancer-causes/infectious-agent...

Firstly, they say that "In fact, some types of cancer occur so often in people with AIDS that they are considered AIDS-defining conditions".

But that's only certain specific cancers. Then there are some other cancers that occur often with AIDS but are not "AIDS-defining".

And then there is the kicker: "Of course, as people with HIV are now living longer, they are also developing other cancers that are not clearly linked to HIV but are more common in older people, such as breast, colorectal, and prostate cancer.".

So, these cancers go up in AIDS survivors due to age, even though those people have immune systems that were already shot years before.

So much for a tidy hypothesis about aging -> lower immune system -> cancer, I suppose.

As for why those afflicted with AIDS get certain cancers, one explanation (also given in above page) is that some cancers are caused by viral infections. Weakened defense against viral infections, increased cancer of that type.


How do you account for the observation that incidence of cancer in young, immunosupressed individuals (e.g. solid organ transplant recipients), whilst increased, is no way comparable to that seen in elderly individuals?


Cancer in the elderly is probably increase due to glycation of DNA and other tissues. For example : http://www.ingentaconnect.com/content/ben/cpd/2008/00000014/...


Other age-related cell and tissue damage that raises the risk of cells becoming cancerous, or reduces the effectiveness of internal-to-the-cell controls that can shut down and destroy cancerous cells, would be the other variable, I'd imagine.


I think far more likely that the predominant variable is the expansion of mutant clones over time to occupy large fractions of the stem cell reservoir.


Possibly so, which is a phenomenon that might explain how stochastic nuclear mutation at its given rates can possibly cause widespread enough harm to be significant. There is an interesting recent paper on that subject:

https://doi.org/10.1371/journal.pgen.1007108

"Recent single-cell studies point to the possibility that essentially all cells have unshared mutations in their genomes. In view of this extensive genetic diversity, it is perhaps not surprising that mutations that confer a proliferative advantage are readily detected as clonal populations of increasing abundance and size in the elderly. These clonal populations might lead to loss of organismal health through the functional decline of tissue and/or the promotion of disease processes, such as cancer. In this review, we summarize recent research that supports the notion that aberrant clonal expansion (ACE) resulting from cancer-associated mutations are common in noncancerous tissue and accumulate with age. We propose ACE to be a previously underappreciated aging phenotype that is universal in most organisms, affects multiple tissues, and likely helps explain why aging is the biggest risk factor for cancer."


I have shown that in elderly individuals essentially the entire epidermis stem cell compartment, whilst having normal morphology, is occupied by clonally expanded mutant stem cells:-

https://www.nature.com/articles/s41467-017-00993-8


That sounds very interesting, but after glancing at your figures, I don't see where you make this obvious.

Also, in the intro you say "the risk of skin cancer increases exponentially with age and is associated with accumulation of somatic mutations8". Your source groups ages into only 3 categories... If you look closer at the data you will see that developing most cancers becomes less common in old age (peaks at 60 - 90 years old). For cancers involving tissue like bone or reproductive organs this peaks much earlier, probably due to when the majority of cell divisions are occurring.


I worked for a cancer research startup a few years ago - I was just doing IT stuff, but I worked with a lot of oncologist/cancer research types. One of the things that they often said was that every living organism will develop cancer eventually, but most things die of other causes before that happens.


it seems plausible or maybe even likely that everyone develops cancer many times, or at least the beginnings of it, but the immune system kills it over and over.

Until it doesn't.


If the immune system has finite resources, would reducing the lifetime drain on those resources by infectious diseases delay the age at which we can expect get cancer? For example, curing the common cold and/or developing a universal flu vaccine.


"If the immune system has finite resources, would reducing the lifetime drain on those resources by infectious diseases delay the age at which we can expect get cancer?"

I would wager the opposite is true. Body systems maintain themselves and their fitness and function through use.

The obvious examples are bone and muscle tissue that become stronger through stress but are you aware that breast cancer incidence is strongly, negatively correlated to frequency and duration of breastfeeding ?

The immune system is also a bodily system and I would be surprised if it did not, also, strengthen itself and maintain its function through stresses and use.

"For example, curing the common cold and/or developing a universal flu vaccine."

Be careful what you wish for ...

We "cured" hard physical labor and traditional life patterns with lots of walking and standing. How's that working out for us ?


> We "cured" hard physical labor and traditional life patterns with lots of walking and standing. How's that working out for us ?

I'll bite -- terribly. Many of the millennial generation and younger are actively starting to revolt against these sedentary lifestyles. It's why fitness and fitness culture is so marketable these days, much more than I remember. I think the studies that came out showing the millennial were the first generation since the industrial revolution to have a decreased life expectancy versus the prior generation was a real wakeup call.


Yes, not having to do physical labour is better than being forced to do physical labour as a worker or peasant. The new problem for most people is how to eat less and get a little exercise. But this is a better problem.

I like rsync's main point though about the immune system maybe requiring usage and callibration (gojomo mentions the hygiene hypothesis). Perhaps one day we'll determine the precise amount of these required (if any) for us to be healthy without being bothered by too much sickness.


It would be interesting if the cure for/long delay of cancers was in an early and vigorous exercising of our immune system with respect to viruses---if the solution was a kind of continual vaccine for colds and viruses that needed to be updated regularly. Like an immune system gym/daily workout. I wonder if there is any research being done on that end of things.


Obligatory Futurama reference (sorry for the pre-roll ad)

http://www.cc.com/video-clips/w4gk7d/futurama-cold-outbreak


Via mechanisms similar to either the hygiene hypothesis or hormesis, it's possible those might backfire. This is highly speculative, but:

* the hygiene hypothesis suggests that allergies and auto-immune disorders can arise from having insufficient immune-system challenges, especially when young. Lacking the calibration from an 'expected' or 'optimal' level of dirt/allergens/infectious-diseases, the immune system starts doing unwanted self-destructive things.

* hormesis is the observation that almost everything bad for you also turns out to be good in very-tiny exposures – radiation, poisons, cancer-causing chemicals, etc. It's as if tiny doses trigger beneficial self-repairs to occur even beyond the direct damage received, even as larger doses overwhelm that mechanism.

Removing mild, survivable challenges from the environment could thus leave the immune system less 'tuned' for the full spectrum of challenges it faces (like clearing early cancers). It's an adaptive dynamic system with nonlinear effects, not a simple pool of fixed exhaustible capability.


"Removing mild, survivable challenges from the environment could thus leave the immune system less 'tuned' for the full spectrum of challenges it faces"

Exactly. You want to protect people from, say, Rubella ... but I think we should proceed with caution with things like the cold and the flu ...


If you think about it, this is exactly what immunization is.


Mice raised in a germ-free environment have improved health measures and longer average life span:

http://dx.doi.org/10.1016/j.chom.2017.03.002

Not all pathogens are equal; cytomegalovirus may be far more important than the rest:

https://doi.org/10.3389/fimmu.2017.01953

And historically, reducing the burden of infectious disease already has increased life expectancy and reduced/postponed incidence of age-related disease:

http://www.slate.com/articles/health_and_science/science_of_...


I'm not sure 'finite' is the right way to think about it. I'd be more inclined to think of infections acting to 'Exercise' the immune system, similar to how jogging keeps your heart healthy, rather than using up a limited number of immune cells.


This is not known, but it's a great question. As usual, probably some genetic but also mostly epigenetic factors.

There's a huge variability in terms of your thymus (the organ that produces new T cells) getting switched off after your mid 20s. For some people its almost immediate. For others, it takes many decades: https://insight.jci.org/articles/view/93739/figure/5

Tweaking this process, without breaking anything else, would be huge to extend our lifespan with some good quality years.


Reducing immune system load is fairly straightforward, low dose antibiotics is one approach that significantly reduces the effort put forth by the immune system.

However, it does not seem to make a significant difference in lifespans.


Some types of cancer are directly caused by infectious diseases. The HPV vaccine has greatly reduced cancer rates.

Moral of this story, figure out how to tell all the anti-vaccination people they are wrong in some way they will believe. (the first is easy, the latter is impossible in my experience)


Cue the senescence guys who aim to fix accumulated damages there.


Ultimately, I think it comes down to metabolism. As you age, your metabolism slows. Coenzymes like NAD+[0] are depleted.

[0] https://www.nature.com/articles/nrneph.2017.5


Right, so just back up a step and stop the metabolism from slowing


Or cut the knot. Upload mind to digital facsimile.

Die, per nature's capricious designs.

Robo-you lives smugly without any of this nonsense and can be resurrected if the power cuts out and sent across the stars at light speed with no need for fuel or supplies--breathes

... to somewhere without air.


I don't get why people go after these virtual things


Medicinal Cocaine?


I mean, it bears repeating on account of the fact that senolytic treatments make a lot of other health problems seem like not even worth understanding


Isn't this a bit of an oversimplification? It's not like if you knock out p53 and something else you instantly get a metastatic tumor. Granted if you remove key tumor suppressor genes your probability of mutations persisting skyrockets, but that in itself doesn't create a dangerous tumor. You need many more mutations than 2 to be able to acquire the functionality to grow, persist, escape the local environment, and establish a foot hold in a new environment.

Here is the classic review paper on tumor formation: http://www.cell.com/abstract/S0092-8674(11)00127-9


I was told once (by who I don't remember):

Live long enough and you will eventually get cancer.

To me it's a no-brainer. You get old, cells break down, immune system isn't what it use to be, increasing the risk of that rouge new cell becoming cancerous.



What are white blood cell counts in someone who is sixty vs one who is eighteen?

Is this where the blood transfusion concept is strong?

What is the oxygen-carrying-capacity of hemoglobin in old blood vs young blood?


Paper: https://doi.org/10.1073/pnas.1714478115

Which is a suggestive model, by the way, not direct evidence. The best direct evidence would be to restore the pace of immune cell creation - such as via regeneration of the thymus (via FOXN1, or BMP4, or tissue engineering), cell therapy to replace or increase the pool of hematopoietic stem cells, etc. - and then see what happens. This sort of thing is five years out; there are people working on it, though more of those and more funding would certainly be a good thing. It would certainly be possible to push forward a startup today based on thymic regeneration or hematopoietic stem cell transplantation; the science is more or less ready for it.

--------

T cells develop from hematopoietic stem cells as part of the lymphoid lineage and have the ability to detect foreign antigens and neoantigens arising from cancer cells. In the thymus, lymphoid progenitors commit to a specific T cell receptor and undergo selection events that screen against self-reactivity. Cells that pass these selection gates then leave the thymus, clonally expanding to form the patrolling naive T cell pool.

The vast majority of vertebrates experience thymic involution (or atrophy) in which thymic epithelial tissue is replaced with adipose tissue, resulting in decreasing T cell export from the thymus. In humans, this is thought to begin as early as 1 year of age. The rate of thymic T cell production is estimated to decline exponentially over time with a half-life of ∼15.7 years. Declining production of new naive T cells is thought to be a significant component of immunosenescence, the age-related decline in immune system function. With the recent successes of T cell-based immunotherapies, it is timely to assess how thymic involution may affect cancer and infectious disease incidence.

It is clear from epidemiological data that incidence of infectious disease and cancer increases dramatically with age, and, specifically, that many cancer incidence curves follow an apparent power law. The simplest model to account for this assumes that cancer initiation is the result of a gradual accumulation of rare "driver" mutations in one single cell. Furthermore, the fitting of this power law model (PLM) can be used to estimate the number of such mutations. Exponential curves have also been used to fit cancer incidence data, resulting in worse fits than the PLM overall. Nevertheless, it is worth noting that exponential rates close to the declining curve for thymic T cell production can be seen to emerge from the incidence data, indicating the relevance of the thymic involution timescale. While the PLM fits well, it does not account for changes in the immune system with age. To better determine the processes underlying carcinogenesis, we asked whether an alternative model, based only on age-related changes in immune system function, might partly or entirely explain cancer incidence.

Our model outperforms the power law model with the same number of fitting parameters in describing cancer incidence data across a wide spectrum of different cancers, and provides excellent fits to infectious disease data. Our hypothesis and results add to the understanding of infectious disease and cancer incidence, suggesting in the latter case that immunosenescence, rather than gradual accumulation of mutations, serves as the predominant reason for an increase in cancer incidence with age for many cancers. For future therapies, including preventative therapies, strengthening the functionality of the aging immune system appears to be more feasible than limiting genetic mutations, which raises hope for effective new treatments.

-------


[dead]


https://en.wikipedia.org/wiki/Immunosurveillance

"Cancer immunosurveillance is a process by which an organism's immune system recognizes transformed cells in order to inhibit the growth of neoplastic tissue. It comprises the first phase of immunoediting and is also known as the elimination phase."


Really? I figured as we age our cancer rates will plummet while our immune systems only strengthen, which is why the leading cause of the death in the elderly is extreme sports.


I'm with you, upvoted for voicing the absurdity of the title. The article, which I refuse to read completely, seems like mediocre pop health science and this website has devolved into giving it, at this point at least 16 hours of frontpage time.

I'll summarize it: "We don't understand cancer but we'll keep throwing shit at the wall until something sticks, and we're going to write up a bunch of shit and you shits read it so we can pay for throwing more shit."


The alternative hypothesis was the "two-hit" idea of multiple changes accumulating in DNA over time, so it's not a trivial topic to study.


Extreme sports like "the stairs".




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