Why is cancer fatal?


I’m educated enough to generally understand that cancer is the result of a gene mutation, which activates rapid cell reproduction, but what about this growing/spreading tumor makes it fatal? Why can’t we just periodically remove the tumor as it continues grow, thereby (almost) completely eliminating any possible death threat from cancer?

***EDIT: thanks for all the responses to my question! Some of them are really great, and perfectly answer my question. Frankly, I was not aware that cancerous cells and tumors have, in so many ways, “a mind of their own”.***

***I’m very lucky to have been of general good health my whole life, but the threat of cancer as I age scares the daylights outta me — it literally keeps me up at night, often. I’m slightly relieved to realize that so much is known about cancer and so many different treatment options exist, depending on the diagnosis and prognosis. And I recognize this wealth of knowledge, understanding, and treatment options is growing almost by the day with modern medicine — and this helps put me at ease a little too.***

***Here’s to ongoing good health for me and you…!***

In: 10

First, many cancers are not fatal. Usually two things cause the fatal kinds of cancer. It’s in some place inopportune and inoperable for any number of reasons, or it has spread throughout the body (metastasized), or both.

You have to look for cancer at the right time in order to be able to successfully do something about it. Look too early and you won’t find it, its either not there yet or too small to detect. Look too late and its hard/impossible to track it all down and remove it.

So why not look more often? Because looking can cause harm. In false positives (no cancer but the person is told there is which results in anxiety and additional, unnecessary invasive tests and procedures). In cases where the investigative method causes damage itself or carries a risk.

There are also cases where cancers AREN’T fatal. Some develop so slowly you’re likely to die of other causes long before the cancer becomes a problem. But because we can’t be sure, we treat it and you suffer the side effects. If you hadn’t gone looking for it, and you never developed symptoms, you’d never have noticed.

Basically its hard to find cancer in the right window where its treatable and the treatment isn’t worse than the cancer itself.

Cancer cells do not function as normal cells do anymore. They also can prevent proper functioning of organs when they become prevalent enough. For example, once enough lung tissue becomes cancer cells, your lungs stop functioning. They can also disrupt blood flow.

When you surgically removed cancer tissue, you also remove healthy tissue. There is only so much you can remove before the organ no longer functions. Maybe it’s a lung or kidney where you have two, but if the cancer cannot be fully removed, it will keep spreading. Some will eventually spread to other parts of the body. Organ failure isn’t uncommon with cancer.

Frequently, cancer is suspected due to disruption of normal body function. At times, the damage is so widespread by the time it is detected that it is going to be lethal anyway, but we are getting better at catching it earlier and treating it.

Removing some tumors, like neuroendocrine tumors, can make things worse. Cancer tissue starts replacing healthy tissue, and soon enough you don’t have enough healthy tissue left. Not only that, lots of solid tumors create blood supply to themselves so they start stealing nutrients and removing them gets much, much harder.

That said, there are more and more treatments that are making cancer survivable.

Usually it spreads everywhere and starts growing everywhere. On top of that, it somehow gains mutations that allows it to defend itself against the immune system really well so its not as simple as just rapid cell reproduction.