Why cant the immune system kill cancer?

Cancer is basically your cells that have became rogue when they were damaged or mutated, but instead of committing suicide like most cells do, they instead continued to replicate their new modified coding of DNA which is now replicating at a high rate creating tumors. The immune system doesn't do anything because it sees it as just another part of your body.

That is why cancer is so hard to treat, you're trying to kill an cluster of human tissue, but doing so requires you to nearly kill the human with the disease there is no true cure for it, just lots treatments and luck.

It is my belief that cancer used to be a beneficial sell an emergency high-speed rebuilding body so which mutated and become a cancer so instead of a repair so that's why the body can't kill it because it was made to heal the body

Silly. Infections of all kinds have killed millions and the immune system can't do anything.

Because cancerous cells are just our own cells, mutated. A normal immune system does not attack it's own cells. That is what happens when you have terrible auto-immune disease, which are frequently deadly. There are existing and developing drugs that try and turn the immune system into killers by recognizing specific fingerprints of cancer cells, and going after them.

Because that part of the immune system is switched off and don't recognize the cells as abnormal..

Your immune system is good at killing foriegn cells.

Cancer are your own cells behaving badly.

The immune system has no effect on cancer cells.

cancer cells are the body's own cells, the immune system doesn't automatically recognize them as foreign. also the cancer cells actively send out signals to fool the immune system

there is a fairly recent set of cancer therapies called immunotherapy where the general idea is to interfere with cancer's ability to hide from the immune system so that the immune system will indeed go after the cancer. I've heard they've been having a good deal of success with it

http://www.cancercenter.com/treatments/immunothera...

its complicated. Cancer cell often can have the same proteins on the surface of the cell that is recognized is non-foreigned, or cancer cell can decrease specific markers to make it"invisible to cancer. CANCER CELLS, especially tumors can suppress the immune system as well. Large tumors are usually not invaded by immune cells because, its too dense. Cancer cells also mutate quite rapidly to avoid the immune system.