About Cancer?

Question

Juz wanna ask a question about immunology. Was studying immunology these few days, as it is one of my exam topics for Biology. our immune system produces antibodies in the presence of antigens, until one of them is able to fit the protein of the antigen. i noe that for the first exposure to the antigen, it would take some time. however, why is it that diseases like cancer cannot be countered by the body's immune system?

Answer 1

The cancer cells disguise themselves as healthy normal cells—stealth. The anti-bodies cannot differentiate them from healthy cells.

Answer 2

I love the curiosity within your question, so I've decided to throw in my two cents.

I know my answer won't be complete, because cancer is a BIG topic, and its not fully understood. I just wanted to give you one "non-technical" and very simplistic example that may just increase your interest in this very cool topic.

Some viruses cause cancer. When a virus enters a cell, its main goal is to incorporate itself into its host's DNA. It can land just about anywhere it pleases. Where it lands makes a big difference as to whether the virus causes cancer or not.

If it lands within DNA that is not coding for a gene, it may not be so detrimental (the virus is able to replicate, but the cell will be destroyed by the immune system because the cell presents the viral antigens to the immune cells).

If the viral DNA lands within a DNA sequence of the host that codes for an essential gene, the gene product may become non-functional. Without this essential protein, the cell may die on its own (no help needed from the immune system).

Another scenario is where the viral DNA lands in an expressed gene, and the "novel" (or new) expressed protein does something that allows the cell to survive longer than it should. For instance the novel protein may function by signaling to the immune system to shut down.

This would give that one infected cell a huge growth advantage. It can now divide freely without the threat of the immune system. Wow, no checks and balances. It's a hay-day for that one cell.

Please keep in mind that this example is hugely over simplified, just to get the main points across. Oh, also, viruses are not the only suspected cause of cancer, as you probably know.

The main points are: (1) Viral DNA can incorporate itself in some critical regions of the genome. (2) Novel proteins can act in detrimental ways (including suppression of the immune system, or other mechanisms of cell control). (3) Anytime a cell has a growth advantage, it is one step closer to becoming cancerous.

So finally, I would like to agree with what others have already stated about cancer and the immune system. It is quite reasonable to suspect that cancerous cells are eliminated from your system, with out you knowing it. Its only when you are diagnosed with cancer, that you know something went wrong (maybe with the immune system, maybe some other "check and balance system, or maybe a combination) in eliminating that cell.

I am glad you asked this question. I hoped I piqued your curiosity more!

Answer 3

It does all the time. As we age or are exposed to things like too much sun, our cells deviate from their normal coding and start to divide passing along the mutated coding. In a healthy body those cells are killed and/or suppressed and homeostasis maintained.

But if the trigger persists like excessive sunlight, or if the immune system weakens from age then sometimes one of the mutant cells escapes detection and continues to divide to the point where homeostasis is compromised unless there is medical intervention and not always then as you are aware.

Answer 4

Because the body's immune system has never seen cancer before...

Answer 5

many of them are, and they are eliminated without the host being aware of it. Fast growing tumors put out enough cells to overwhelm the defense mechanisms.

Answer 6

Try the links in http://www.hot8sites.com/cancer/