eli5: Why is cancer so hard to get rid of?


Why haven’t scientists worked it out yet?

In: 4

Your body is made of cells, your muscles, your bones, your organs are all thousands and thousands of tiny cells all with a certain job to do to keep your body working.

Cancer is what we call it when those cells are damaged and stop doing their job the way they are supposed to. Instead of doing the drop of keeping your body running, that cell just starts growing and using up the resources that the rest of your body needs. And the damaged cell starts converting other cells to join it in being broken and growing uncontrollably. Soon, the part of your body that has the cancer isn’t doing its job to help you live anymore. Or, it’s dreaming all the resources you need for the rest of the body, making you very weak.

The trick is that different types of cells are going to be different types of cancer. And that we can’t use the same treatments for one type on all of the others.

Part of what makes cancer very hard to fight is that it’s not something outside of your body causing a problem, like a virus or bacteria. Your body doesn’t really realize there’s a problem because your body is the problem.

We’re getting better at coming up with ways of treating certain types of cancer, and we’re always working on improving how we handle it. However, this is a very tricky problem. And it’s more than just one problem, it’s dozens of problems because there’s dozens of types of cancer that need to be researched.

There are various reasons for cancer being so hard to treat. First there are many different types of cancer that can appear in many different places. Second cancer may start in one place but it can spread all over the body into places where removing it is impossible. Lastly it’s really hard to get rid of the actual cancer cells if you try to physically cut them out you first have the challenge of getting to the actual cancerous cells which might be in an important organ such as the brain where cutting it out would just kill the patient anyway second it is really hard to cut out every single one of the cancer cells in the body because they can be basically impossible to find. If you go for a more broad treatment like radiation yes it can kill most of the cancer cells but it also slowly kills the rest of your body as well and it isn’t guaranteed to get every single cancer cell.

Cancer is cell growth where it shouldn’t be, or too much cell growth.

In all your organs, there should be an equilibrium, e.g. cells die normally and are replaced by new cells. If more cells die than grow, your organ dies. If cells just start to grow uncontrolled and don’t stop growing when they are supposed to, you got cancer. This can happen if the cells mutate and “forget” how to react to cell-growth stop signals your DNA would usually send them. Further, these mutated cells can wander off and start growing somewhere else. Like cancerous liver cells trying hard to grow liver in your lungs.

The problem lies in getting rid of the cancerous cells – and the cancerous cells only, and not like all the other cells. We have methods to destroy cells, but it is hard to differentiate a normal cell from a cancerous cell. Science has figured out methods to get rid of cancer, and the most reliable way of doing so is to recognise the cancer early (before the cancerous cells start to wander off), localise it, and attack it right then and there. By cutting it out, or by hitting it with cell-destroying radiation.

But virtually any organ in your body can be affected by cancer, like it can happen everywhere, and depending on where the cancer is at, what surrounds it, and how the cancerous cells have mutated and grown, it gets harder or easier to do so. If you got cancer in your brain, it’s not feasible to open your skull and remove the part of cancerous brain or else you’d die. If you have breast cancer, it is possible to remove the breast with the cancer without killing you in the process. The difficulty really is “how do we kill this cell growth without killing the patient?”

Cancer is your cells in your body malfunctioning. Normally this wouldn’t be the end of the world but one part that malfunctions with cancer is the part that says to stop dividing and to die off.

Since that part malfunctions you have cells that are essentially broken constantly multiplying and they also take your nutrients.

So the reason it’s so hard is that cancer cells are your human cells. Most cancer treatment involves trying to poison the cancer or cut it out of you

If someone made a medicine that only poisoned cancer cells and left everything else unharmed you would have the cure.

Getting rid of cancer is easy. The hard part is getting rid of cancer without also killing the rest of the patient.

The problem is that “Cancer” is not s single thing, it is sort of all sorts of things that can wrong in a body that have similar results.

Cancer is when the normal way a cell in your body reproduces itself goes wrong. The DNA blueprint that your cells use to build stuff including themselves gets damaged and they process of making new cells goes wrong somehow.

Our immune system is pretty good at dealing with cells that go wrong.

However you are made up out of so many cells and they divided so often that even a tiny fraction of cases that go wrong in just the right way and don’t get caught may spell trouble.

The chances of any individual cell to become a cancer is extremely low, but if you buy enough lottery tickets for long enough you eventually win a jackpot.

Evolution has set you up that your chances of dying of cancer at a young age under normal conditions are very low. However not as much effort was invested in keeping that going at old age. The cost benefit wasn’t there for natural selection to do its thing.

As you grow older your chances of getting cancer grow higher and if you get old enough you are likely to die with cancer growing in you even if you don’t die of cancer.

Getting rid of cancer, when your immune system doesn’t can be difficult.

If you catch it early enough you can cut it out or off, kill it with poison or with radiation or otherwise destroy.

You kill cancer cells the same way you would kill healthy cells.

This is obviously not ideal.

There are parts of the human body that you can’t easily cut out of off and poisoning and irradiating the boy in the hopes that the cancer cells will die before the rest of the patient does is difficult at best.

We have some tricks that we use to target the poison or radiation so it gets to the cancerous parts more than anywhere else, but you are still doing quite some damage to the rest of the body.

Still with a little luck you kill the cancer and leave enough of the rest of patient alive to recover.

However there is another part. Once a cancer has grown enough, bits of it might come loose and wander into other parts of your body to grow there.

If you don’t find the cancer in time, notice it too late, don’t kill all of it when you have the chance etc, you have not just one cancer you have a body full of cancer.

At that point things are usually very grim.

This is why noticing and killing the cancer as soon as possible is so important.

If its found to late it may be too late for the patient.

On the other hand a lot of “not yet cancer” never develops into full blown cancer and you will find a lot of that if you look for it and may unnecessarily cut or kill parts of the body that might never have become a problem.

Finding the right balance is hard and likely to get people killed either way.

So we can’t prevent cancer because there are so many ways cells can go wrong.

We can’t find and kille all cancers in time before they spread either and our ways of killing cancer without killing the person around it are less than perfect.

However we are making progress on all fronts.

We have found a lot of things that make you more likely to get cancer and tried to get rid of them, though health and safety regulations.

We have even found things like a vaccine against virus that made people more likely to get a certain type of cancer.

So we know how to reduce chances of getting cancer.

We have also gotten much better at diagnosing cancer early enough and at killing it when we discover it.

A number of cancer diagnoses that would have been a death sentence a generation ago are now quite a bit more survivable under the same circumstances.

That leaves still a lot of people dying of cancer.

However progress is continues to be made.

One promising avenue is based on the same tech that gave us the COVID vaccine. We use it to train the immune system to kill cancer cells. If someone is found to have cancer we take samples of it and make your own immune system better at killing the cancer cells.

This is in early stages, but it is progress.

We might never completely get rid of cancer, but we can make sure that fewer people die of it.