What is/cause cancer?

[Cikomyr2]

So, my understanding of cancer via decades of popculture exposure.

Our cells have the ability to duplicate themselves. They do so by following the dna/rna chain blueprints they have been gifted with at birth.

Everytime new cells are created, they have a little bit less of the original DNA/RNA, and the chance of a programming runaway error increases. The more you require your cells to replicate, the more likely you are to trigger a runaway error.

Which is what us cancer: a programming error by your cells. One cell starts self-replicating erroneously because of a coding damage, and then these child-cells may or may not also have the same erroneous coding and then they also replicating. Depending on how your own defense system deals with the fake cells, depending on the geometric growth of these cells will determine if you just have a tumor without consequence or a malignant cancer that spreads across your body.

[By the way, if anything i claim above is the outright wrong please correct me].

So, understanding that. What can "cause" cancer is twofold:

- things that outright damage your RNA so your cells cant properly replicate anymore. This is like burning your stockpiles of life yet.
- things that damage you or your organs and forces your body to constantly repair itself. Slowly draining your stockpile without directly attacking them. So you end up with error-prone RNA at 45 instead of 80.

Obviously, the genes will determine thr quality of your RNA stockpiles and how long they last. Thats why someone in your family having had cancer may hint at a lower natural stockpile of that specific RNA (ex: lungs, liver, intestines). And it also explain why some smokers never develop lung cancer (just naturally gifted with a lot more lung RNA to use up).

While the true Knowers of the domain may point at this post being not technically wrong, do i have a fundamental misunderstanding of the origin of cancer?

[NichG]

The stockpiles of life thing is outright wrong, as is the focus on RNA in the later part of your post.

Basically, cells in a multicellular organism have their replication controlled to match what the organism as a whole needs. There are chemical cues that say 'grow more here' or 'stop growing', and correctly working cells basically are programmed to commit suicide if they don't get a constant 'don't kill yourself' message from the other cells around them. Those controls are what make the collection of cells behave as 'an organism' rather than as a trillion different organisms. Cancer then is cells which slip those controls, such that they behave as individual organisms rather than as part of that collective - replicating on their own schedule and ignoring the signals from the rest of the multicellular organism guiding their growth and death.

Locally, this is an evolutionary advantage - if you have something that grows all the time or a version of it that grows only sometimes, eventually you'll have more of the thing that grows all the time. So there's an evolutionary ratchet saying, if a cell ever discovers how to slip the control, eventually that cell type will dominate locally. On the other hand, that kills the multicellular organism eventually and those organ cells don't really have the ability to survive independently of the rest of the body or transfer to new hosts. So there's an evolutionary pressure to move in the direction of breaking free, but ultimately that ends up being a dead end - just at a scale larger than the individual replication dynamics of cancerous cells.

That 'dead end' aspect means that, at the group level (e.g. at the level of generations of the multicellular species, rather than generations of its cells), there's an evolutionary pressure to figure out how to stop the cell-level evolutionary process from breaking free like that. So that means that genomes have adapted to remove easy routes to cancer, up to the point where if you avoid childhood cancer, cancers tend to mostly occur after reproductive age. If you just needed one mutation to go cancerous, it'd be very common, but suppressing it out to two or three mutations has an exponential effect - basically, two or three or four or five unlucky things have to happen in concert for cancer to develop.

Every cell in your body is a chance for those five unlucky things to converge. The more your cells replicate, the more chances there are to get unlucky. If your cells are mutated by external effects, those are additional unlucky chances. Furthermore, if your cells mutate and those mutations are retained going forward rather than repaired or triggering cell death, then that exponential decrease in cancer chance becomes only a linear one (because you could have the first bit of the escape 'password' occur, and then keep that while your child cells try variants) - that part of the reason to be concerned about e.g. pre-cancerous growths and things like that, they may be populations of cells which have already partially slipped growth control and are fewer mutations away from going fully out of control.

While this story is primarily about genetic mutation, anything that disrupts the body's control over the replicative dynamics of its cells could be termed a cancer. That might mean that in some cancers its might not be specific genetic mutations causing the cells to break free but instead is some epi-genetic stuff like patterns of methylation, or something else in the surrounding context that drives those cells to grow uncontrolled, or other such things. In some cases there are viruses which modify cells to be closer to that break-free point, so those cancers are actually sort-of transmissible (in the sense that the thing provoking the cancer to become more likely is transmissible). I don't know of anything like this in humans, but in some animals there are cancers where the cancerous cells can directly infect another animal of the same species and can grow outside of their host (tasmanian devils have a cancer like this). So 'cancer' comprises a pretty diverse set of dysfunctions.

[Radar]

To what NichG wrote I wanted to add that our organism also have defensive systems against defective cells. Since cancerous cells are not up to code (so to speak), they may trigger the immune system to destroy them just as it happens with any kind of intruding cells.

This kind of immune response is also why one needs to carefully check genetic compatibility before an organ transplant and immuno-suppressants are needed anyway so that the transplanted organ is not destroyed by the immune system.

Aside from that, there does seem to be a limit to the number of replications for a healthy cell, which is connected to the telomers (basically safety caps on end of the chromosomes) as they are getting thinner with every duplication. I'd say it looks like a planned obsolescence, but it's more that nothing in nature was expected to live past the reproductive age anyway, so this did not cause any disadvantages. At least in some types of cancer cells (not sure how common this is), telomers after replications are not getting worse and it poses an interesting question about the aging process.

[Aedilred]

To what NichG wrote I wanted to add that our organism also have defensive systems against defective cells. Since cancerous cells are not up to code (so to speak), they may trigger the immune system to destroy them just as it happens with any kind of intruding cells.

This kind of immune response is also why one needs to carefully check genetic compatibility before an organ transplant and immuno-suppressants are needed anyway so that the transplanted organ is not destroyed by the immune system.

Aside from that, there does seem to be a limit to the number of replications for a healthy cell, which is connected to the telomers (basically safety caps on end of the chromosomes) as they are getting thinner with every duplication. I'd say it looks like a planned obsolescence, but it's more that nothing in nature was expected to live past the reproductive age anyway, so this did not cause any disadvantages. At least in some types of cancer cells (not sure how common this is), telomers after replications are not getting worse and it poses an interesting question about the aging process.

I seem to remember reading once that there have been experiments on mice where they gave them telomerase to see whether that had an effect on the ageing process. The mice did seem to exhibit less senescence but also all succumbed rather prematurely to massive cancers.

There are, of course, animals which don't seem to suffer from senescence or cancer. Moray eels, lobsters and naked mole rats among others - which also suggests it's something that any class of animal can theoretically do... to unlock eternal life we just need to figure out how they do it and replicate that in humans. That "just" is doing a lot of work there.

[Eldan]

And it should be kept in mind that "no cancer" often means "we haven't found any yet/not much/not the specific kind we were looking for". Actual scientific publications on mole rats are very careful in the language there and talk about "cancer resistance", not immunity.

E.g.

Until now, it was thought that naked mole-rats almost never got cancer because their healthy cells were resistant to being converted into cancer cells. However, researchers at the University of Cambridge have shown for the first time that genes known to cause cancer in cells of other rodents can also lead naked mole-rat cells to become cancerous

[Fat Rooster]

Scishow did an interesting video on it recently.

"The origin of cancer" isn't really a thing, because cancer is a description of a state that can be the end point of many different processes. This is also why a "cure for cancer" isn't really expected to be a thing; cancer is not one disease. It would be like a cure for viruses.

That said, the body often does have protections against cancerous cells, but evolution being what it is, sometimes these systems are broken. Humans (particularly non African people) are not a particularly healthy genetic population, and even if they were evolution does not strongly prune things that mostly work. The net result is that our DNA repair processes are not particularly robust. Our genes can frequently mutate and be passed on, causing further damage to those processes. Importantly, damage to DNA repair genes does not immediately kill you. It will just make your cells vastly more susceptible to developing a mutation. The overwhelming majority of the time this will just cause the cell to fail and die, but sometimes it will result in a cancer instead. Faulty DNA repair systems in cancers also put them on evolutionary overdrive. While it will cause a huge number of cell failures, this is also why some cancers can adapt to resist treatments so fast.

One quirk worth pointing out is the difference between a single functional gene and two. If you have a single functional repair system, and it gets damaged, there is no way for it to be repaired. If you have two they can mutually repair each other. Where it can fail is if both get damaged simultaneously. Not only does this mean that a single faulty copy is far worse, it also means that the rate of DNA damage is a factor. A dose of radiation over a period of a year is massively less likely to cause a double failure than the same dose over a minute.

On a larger scale, organisms have systems for dealing with cells that do become cancerous, and these can likewise lose effectiveness or fail. This is less well studied, but is another therapeutic target. Understanding why somebody's body is not killing the cancer is harder to study than the cancer itself, but is also probably often down to faulty genetics. It would be extremely hard to show that a garbage mutated gene causes a 1% increase in all cancers (and maybe even other infections), but there are likely many genes like that related to immune response.

My hope for genetic modification is that it can largely cure cancer, as well as a whole host of other diseases, just by fixing broken genes. I don't mean letting people select from a set of working copies, I mean just literally fixing broken ones in everybody by duplicating their existing working copy. There are variants of genes out there that are just garbage, in that they don't even make sense to the protein building machinery (it just stops building half way through). BRCA mutations are the best studied, and I can find no good reason not to treat them. They are a genetic scar that is passed on.

The real issue with eternal life is that we are not just fighting one process, we are actively fighting evolution. Evolution pressures genes to survive, not organisms, and favours rapid adaptation. Competing with your offspring is contrary to this, so evolution actually pushes organisms to die once they have secured their offspring (and possibly their offspring's offspring). It has achieved this by not fixing things that break, but also possibly by actively breaking things. Unfortunately, old age is not a feature not a bug, so 'fixing' it may prove difficult.

[Trafalgar]

While this story is primarily about genetic mutation, anything that disrupts the body's control over the replicative dynamics of its cells could be termed a cancer. That might mean that in some cancers its might not be specific genetic mutations causing the cells to break free but instead is some epi-genetic stuff like patterns of methylation, or something else in the surrounding context that drives those cells to grow uncontrolled, or other such things. In some cases there are viruses which modify cells to be closer to that break-free point, so those cancers are actually sort-of transmissible (in the sense that the thing provoking the cancer to become more likely is transmissible). I don't know of anything like this in humans, but in some animals there are cancers where the cancerous cells can directly infect another animal of the same species and can grow outside of their host (tasmanian devils have a cancer like this). So 'cancer' comprises a pretty diverse set of dysfunctions.

Viruses causing cancer is very interesting and often overlooked. I would just add there are environmental sources of genetic mutation that can also lead to cancer. Things like ionizing radiation, aromatic hydrocarbons, certain wavelengths of UV light, etc.

[Smoutwortel]

The stockpiles of life thing is outright wrong, as is the focus on RNA in the later part of your post.

Basically, cells in a multicellular organism have their replication controlled to match what the organism as a whole needs. There are chemical cues that say 'grow more here' or 'stop growing', and correctly working cells basically are programmed to commit suicide if they don't get a constant 'don't kill yourself' message from the other cells around them. Those controls are what make the collection of cells behave as 'an organism' rather than as a trillion different organisms. Cancer then is cells which slip those controls, such that they behave as individual organisms rather than as part of that collective - replicating on their own schedule and ignoring the signals from the rest of the multicellular organism guiding their growth and death.

Locally, this is an evolutionary advantage - if you have something that grows all the time or a version of it that grows only sometimes, eventually you'll have more of the thing that grows all the time. So there's an evolutionary ratchet saying, if a cell ever discovers how to slip the control, eventually that cell type will dominate locally. On the other hand, that kills the multicellular organism eventually and those organ cells don't really have the ability to survive independently of the rest of the body or transfer to new hosts. So there's an evolutionary pressure to move in the direction of breaking free, but ultimately that ends up being a dead end - just at a scale larger than the individual replication dynamics of cancerous cells.

That 'dead end' aspect means that, at the group level (e.g. at the level of generations of the multicellular species, rather than generations of its cells), there's an evolutionary pressure to figure out how to stop the cell-level evolutionary process from breaking free like that. So that means that genomes have adapted to remove easy routes to cancer, up to the point where if you avoid childhood cancer, cancers tend to mostly occur after reproductive age. If you just needed one mutation to go cancerous, it'd be very common, but suppressing it out to two or three mutations has an exponential effect - basically, two or three or four or five unlucky things have to happen in concert for cancer to develop.

Every cell in your body is a chance for those five unlucky things to converge. The more your cells replicate, the more chances there are to get unlucky. If your cells are mutated by external effects, those are additional unlucky chances. Furthermore, if your cells mutate and those mutations are retained going forward rather than repaired or triggering cell death, then that exponential decrease in cancer chance becomes only a linear one (because you could have the first bit of the escape 'password' occur, and then keep that while your child cells try variants) - that part of the reason to be concerned about e.g. pre-cancerous growths and things like that, they may be populations of cells which have already partially slipped growth control and are fewer mutations away from going fully out of control.

While this story is primarily about genetic mutation, anything that disrupts the body's control over the replicative dynamics of its cells could be termed a cancer. That might mean that in some cancers its might not be specific genetic mutations causing the cells to break free but instead is some epi-genetic stuff like patterns of methylation, or something else in the surrounding context that drives those cells to grow uncontrolled, or other such things. In some cases there are viruses which modify cells to be closer to that break-free point, so those cancers are actually sort-of transmissible (in the sense that the thing provoking the cancer to become more likely is transmissible). I don't know of anything like this in humans, but in some animals there are cancers where the cancerous cells can directly infect another animal of the same species and can grow outside of their host (tasmanian devils have a cancer like this). So 'cancer' comprises a pretty diverse set of dysfunctions.

Human papillomaviruses (HPVs)(or wart virus) fits the description of cancer helping virus.

[Willie the Duck]

So, my understanding of cancer via decades of popculture exposure.

Our cells have the ability to duplicate themselves. They do so by following the dna/rna chain blueprints they have been gifted with at birth.

Everytime new cells are created, they have a little bit less of the original DNA/RNA, and the chance of a programming runaway error increases. The more you require your cells to replicate, the more likely you are to trigger a runaway error.

I think you'd be best served by removing RNA from this for the time being. RNA* is for the most part transitory, and 'original RNA' isn't a particularly useful framing.

The 'little bit less of the original DNA' part is probably talking about telomeres. They certainly have been kinda over discussed in pop culture (unfortunately often by people who don't completely know the subject about which they are talking. Cue rant about the quality of scientific journalism...). Think of them as the aglets at the end of shoelaces -- they are endcaps which keep the end of a fiber (in this case DNA) from splitting, getting banged up, etc. And yes, normal replication of a cell causes them to shorten (it's an actual physical/chemical 'the machinery can't latch on/get in there'-type situation where DNA polymerase can't connect to and duplicate the last 50-100 nucleic acids on the "3'-5' " side of the DNA double-helix).
Now, while telomeres do act as a damage-preventer for DNA, this loss of telomeres aren't (usually) the reason for mutation. What telomeres do is help set up what is known as the Hayflick limit -- the maximum number of replications that a cell is expected to undergo before it is supposed to enter senescence (ending of cell replication) or apoptosis (self-induced cell-death).
Sometimes a cell will not have a typical process towards senescence/apoptosis, and thus when the telomeres have completely eroded the ends of the DNA will look to the cell machinery like a stand split by damage and it will try to fix it by relegating (attaching) it 'back' to... well whatever it can find. This is a form of damage and mutation and generally won't go on too long before the whole thing collapses and then the cell dies (but if it doesn't, this could be the start of a cancer process).
How telomeres more typically interact with cancer is thusly: the mechanisms of inducing senescence/apoptosis are damaged OR a process occurs which induces telomerase (a chemical needed for embryonic and adult stem cells to replenish their replication limits) to show up and replenish a cells telomeres. This gives the cells a whole new lifespan past its' planned lifespan, and that is what allows the cancerous mutations to happen. Cells aren't 'supposed' to just go on forever. Most cells accumulate damage over time. Or they have processes that really weren't intended to go on indefinitely because the cell wasn't supposed to (much like telomeres themselves, they were given enough uses for the expected life of the cell and what happens after that is not part of the 'plan'). These processes, rather than damage caused (or not prevented) by the telomeres themselves specifically are usually what causes the cancer.

Which is what us cancer: a programming error by your cells. One cell starts self-replicating erroneously because of a coding damage, and then these child-cells may or may not also have the same erroneous coding and then they also replicating. Depending on how your own defense system deals with the fake cells, depending on the geometric growth of these cells will determine if you just have a tumor without consequence or a malignant cancer that spreads across your body.

Yes, but with a secondary corollary -- one programmatic error causes the continuous replicating. Another one (potentially) causes the cells to metastasize (move from the original location and spread throughout the body).

So, understanding that. What can "cause" cancer is twofold:
- things that outright damage your RNA so your cells cant properly replicate anymore. This is like burning your stockpiles of life yet.
- things that damage you or your organs and forces your body to constantly repair itself. Slowly draining your stockpile without directly attacking them. So you end up with error-prone RNA at 45 instead of 80.
If a cell can't replicate anymore, that is a lot better than cancer. The cell just stays put (and eventually dies).
Obviously, the genes will determine thr quality of your RNA stockpiles and how long they last. Thats why someone in your family having had cancer may hint at a lower natural stockpile of that specific RNA (ex: lungs, liver, intestines). And it also explain why some smokers never develop lung cancer (just naturally gifted with a lot more lung RNA to use up).
While the true Knowers of the domain may point at this post being not technically wrong, do i have a fundamental misunderstanding of the origin of cancer?

I'm not sure if there is a language issue, but this seems like either a gross misunderstanding, or more likely the rest of use aren't catching what you are trying to say. Who are true knowers? What do you mean by stockpiles of life? RNA is not stockpiled, nor is it the primary issue surrounding cancer (it is part of the process, as it is part of all processes involving a cells genetics being expressed and used).