Cancer, what exactly kills you

Hello Everyone,

Todays question is a bit in the dark side. When you have something like lung cancer, what is it that exactly kills you? Does the cancer east away your lungs until you can no longer breathe or does your body just shut down from the fight against the cancer? Sorry to be do dark, but I’m just curious.

Various things, depending on what type of cancer it is.

A very simple thing that can happen is that it is occupying and replacing/destroying normal organ tissue. You can’t live if over a certain amount of your organs is not functioning/has been replaced by a tumor.

It also depends on where the cancer masses are. If you have tumors in your brain affecting your areas of respiration and cardiac work, then you’ll also be affected, even if the masses there are smaller and occupy is a smaller amount of the brain than they would in other organs.

I’ve also wondered this. For example, skin cancer. Is the direct damage to your organ (skin) so severe you can’t keep water in (death by dehydration) or pathogens out (death by any number of other diseases) or some other cause directly caused by the cancer?

Melanoma, which is far and away the deadliest skin cancer, kills you through its metastases to other organs. The mechanism is the same as any other cancer. Tumours can also cause a wasting syndrome, where the chemicals they release and that are released against them, send your body into an energy-burning mode that causes weight loss and eventually death.

A localized (non-metastatic) skin cancer that stayed in place would likely take a long time to kill a person, but will eventually invade the surrounding muscle, cartilage, and/or bone, possibly causing significant disfigurement.

However, the most dangerous skin cancers (melanomas) spread by metastasis. The new cancers that spring up (in various internal organs, including the liver, lung, and brain) are far more likely to kill you in short order, especially if left untreated.

Are the metastasizing cancer cells transported via blood? How come you can’t “catch cancer” if exposed to that blood? Or can you?

From this thread, entitled, “Exactly how does cancer kill” (actually one of several threads on the topic), I quote myself (again):

As an example, my grandmother died of a brain tumor, which metastasized from a malignant melanoma.

One of several reasons I visit my dermatologist every six months.

Well yes metastasizing cancer is spread by blood.

Normally your immune system prevents cancer being contagious.

One person has died of another persons cancer. This was due to receiving an organ transplant that carried the cancer across, and the subsequent anti-rejection drugs let the cancer thrive.

On your last question, I don’t think you can, as the immune system would attack such a neoplasm in short order.
The reason that one’s own cancers persist is because your body has a difficult time telling apart cancerous tissue from healthy tissue. Someone else’s tissue however would be readily identified as a foreign body.

ETA: Ninja’d

I’m pretty sure this was how Mickey Mantle died too, although in this case it was the liver that had cancer in it, and because he was immune compromised, the cancer took hold and spread.

As noted, your immune system would normally destroy another person’s cancer cells.

When sufficiently suppressed, as happens in organ transplants, a transplanted cancer can kill the recipient.

And, while it does not occur in humans, Tasmanian Devils are threatened by an actual contagious cancer, called devil facial tumor disease. Devils have a relatively low genetic diversity which might contribute to the problem. The linked article discusses this. There is also canine transmissible venereal tumor, another contagious cancer, but one that a dog’s immune system can overcome on its own. And finally, there is yet another known contagious cancer in a species of hamster.

So, while it is possible for cancer to be contagious it’s uncommon with only three such known, and none of them affecting humans. Transmitting cancer between humans only occurs during high tech medical procedures like an organ transplant. It is also why cancer survivors are ruled out from organ donation.

Don’t forget that there are some viruses that are fairly easily transmitted between humans, and which also cause cancer. HPV and Hepatitis B are two examples that come to mind. Getting the virus won’t mean automatic cancer, of course, but it increases your chances by a decent amount.

My brother in laws bladder cancer metastasized. His kidneys started to shut down as the cancerous cells replaced the healthy ones - but that could be taken care of with dialysis and a drain. But it was also in his lungs - among other places - and it was the cancer in his lungs that killed him. The hospice doctor said that as the cancer cells built up around his alveoli, the osmotic process that absorbs oxygen into the blood was blocked - he suffocated to death although he was intubated.

By the way, there is a lesson here - death from kidney failure I’ve watched happen twice - it wasn’t bad to watch. You slip into a coma and pretty peacefully pass away. Suffocation is horrible - you struggle for breath. If you have terminal cancer, you might get lucky enough to pick your own death - some are easier than others - at least to watch.

My grandmother had lung cancer but died of a pulmonary embolism that we chose to have kill her - we passed on surgery knowing surgery would give her three more months of a painful and struggling life - and an embolism again, isn’t a bad way to go.

In a similar cheery vein, I’d point out that “benign” tumors can have the same lethality as malignant ones in terms of their local space-occuping or blockage-inducing effects.

For instance, you can be killed by a benign brain tumor like a meningioma or pituitary adenoma if it’s in the wrong spot and can’t be safely or completely resected.

This is worth emphasizing in a thread asking “Cancer, what exactly kills you?”. So, just to make it clear for those who may not be aware of the strong association of cancer and clots, I wanted to point out that “pulmonary embolism”, i.e. a blood clot that travels to the lungs, is a common complication, and cause of death, in cancer patients.

As I noted in my post above (#7), people with cancer almost always have a propensity to form blood clots inappropriately and spontaneously. The mechanism for this phenomenon is not clear. In any case, blood clots are a major and in my opinion, underappreciated, cause of death in people with cancer.

(For those interested in learning more about this important association, here are two free, full-text review articles: Review #1; Review #2)

Its my understanding though that often these can be discovered in healthy people and surgically removed or taken care of with blood thinners before they kill you - or when they are still deep vein thrombosis (in the legs, not in the lungs). There are complications in finding them when someone is undergoing cancer treatment (they may not notice the symptoms because so many other things are happening), but that also sometimes people make the choice we did - DVT that we decided not to treat which let loose and became a pulmonary embolism. Could have - it would have meant surgery on an 83 year old woman with advanced lung cancer who was never going outside a hospice again. Didn’t.

Again, sometimes you get to choose your death (or make the choice of death for someone you love).

The way in which cancer can cause death varies and there is no single answer to this question. The answer really depends on the type of cancer and the parts of the body affected by the cancer. Great info!

My mom died of lung cancer and it involved simple choking to death. The doctors seemed to know what was coming and gave her enough morphine to avoid pain, but why allow such extended suffering?

What is the status of a drug which blocks metastasis?

If the process is known and understood, why is there no way to prevent the cancerous cells from entering the blood, or keeping them in the blood until they die or are somehow filtered out?