What casues Cancer?

So We know smoking casues lung cancer, sun exposure can cause skin cancer, but for most kinds of cancer we dont know what the cause is. (so I have heard)
Seriously, seems these days everyone is getting cancer. So where is it coming from? I want the straight dope on this.

Let me ask this question… Are various forms of cancer a direct result of human creations? We are surrounded by un-natural man made things that are made of chemicals, and matterials that dont just grow in the woods - so is this what causes cancer? If I were to go live in the woods my whole life would I be safe from cancer?
Seems like there have got to be some pretty common day to day things that are causing it. What if computers cause cancer? What if hair sprey, paint fumes, pencil lead, radio waves, whatever? - If they dont know what casues cancer, do they know what dosnt cause cancer? OK… im done.

Wiki is always a good place to start. I doubt anyone is going to be able to answer so complex a question, with so many different answers, in one post on a message board. Cancer.

Yeah, your probably right - but every place to read about cancer seems to be saying - here are the techo mumbo jumbo facts - Im looking for voiced opinions.

Genetics is a big factor in my opinion. Not to mention a million other probably causes as well.

Cancer is unregulated, out of control cell growth. In the most general terms, it’s caused by something screwing up your DNA in a way that turns a cell into a sort of always-on keep divding mode. There are lots and lots of things that can do this - UV light, various chemicals, radiation, etc, etc. I spend my days at work looking for certain varieties of damage that are associated with certain cancers.

There are some manmade things, like chemicals or nuclear piles, that are carcinogenic, but there are plenty of other carcinogens that are perfectly natural - tobacco (a plant), or radon, not to mention that big UV-emitter in the sky.

If you were to go live in the woods, no, you probably won’t die of cancer. But that’s because you’d be much more likely to get eaten by a bear or fall off a cliff first. Or, more prosaically, eat something bad for you and crap yourself to death due to lack of access to antibiotics.

Forgot to include the important bit, which is that assuming you survive the bears and cliffs and fatal shittings, you’d end up getting cancer anyway. I’d WAG that the cancer rate would be very roughly the same to what it’d be in civilzation - probably a bit lower - but that’s up for fierce debate, I’m sure.

To expand a bit on Smeghead’s points.

Most people most days have one or more cells in their body sustain genetic damage. You’ve got hundreds of millions of them; a few are bound to be damaged each day for whatever reason.

In the vast majority of cases, those damaged cells either die from their damage or are destroyed by the immune system when they begin acting weird. Its the few cells which a) act weird, and b) are not detected/destroyed by the immune system which become clinical cancer.

There are a number of immune system disorders which make people very susceptible to cancer. A child born with a disorder like that may only live a few years before the hundreds of unprevented cancers starting every day eventually kill them.
So to try to get back to the OPs question, we have to ask 2 things: Have there been environmental changes compared to Olden Tymes which increase the rate of genetic damage? Are there such changes which decrease the success of the immune system?

Do solid noncontroverisal answers to those questions exist? Not that I know of, but I’m not an expert.
Net, net, I bet we’d probably find that our immune systems today are much better than they used to be, simply from having more & better food (asuming you don’t live on Cheetos & Diet Dr. Pepper.)

And, as SmegHead said, cancer is a slow process. From the first defective cell to the tumor that finally kills you can be decades. In prior years, something else normally got you first, even if it was just pneumonia.

It’s said that today the vast majority of men have prostate cancer the day they die. It doesn’t kill them, in fact it’s generally clinically invisible. But if they had lived to 150, somewhere along the way it would’ve become acute.

Everything is made of chemicals. You know how many different chemicals make up your body? Chemicals aren’t A Bad Thing. Sure, plenty of man-made chemicals are nasty, but so are plenty of natural chemicals. If you don’t believe me, go and munch some deadly nightshade or lick a poison frog*.

In basic terms, cancer is caused by uncontrolled cell division. That is caused by damage to the DNA in the cell. DNA is constantly under attack - each DNA strand is made up of millions of units that can easily be damaged by stuff floating round the body, UV light, etc etc. In fact each cell has to repair around a million bits of damage every day. Fortunately, the body is very good at repairing this damage, but with that numbering of repair processes going on, it’s inevitable that errors will eventually occur.

So why does cancer seem to be increasing? Simple - we’ve got so much better at preventing other causes of death. In days gone by, chances are you’d die at an early age, of some disease that is now easily treated, so you’d never have a chance to die of cancer!

I’m fairly confident that we’re no more likely to get cancer at a given age these days than in the past - it’s simply that we’re living longer, so more of us reach the age where we develop it. Plus, of course, we don’t know how many people in olden times died of TB, cholera, whatever, with nascent and unnoticed tumours growing somewhere inside them that would have caused problems later down the line.

  • (Don’t actually do this)

It’s difficult to die of cancer if you die of starvation, diarrhoea, measles, TB, plague, cholera, malaria, trauma or septicaemia first. That’s why it’s more common now that the average life expectancy is over 40 in most countries (a relatively small amount of cancer is found in the unders 40s).

We do know that there are genes which are designed to act as a “fail-safe” and they make a mutated cell self-destruct before it can replicate and turn into cancer (that’s basically all cancer is, a big bunch of dodgy cells replicating).

Evey day some cell somewhere in your body mutates into a poetntial cancer cell, and everyday those cells self-destruct. Cancer is what happens when they don’t.

We know that some things damage DNA, either directly, like ionising radiation, or by messing with the mechanisms that allow a cell to repair itself, or with the mechanisms that detect mutation, or with the mechanisms that detect irreparable mutations and cause those cells to die.

If you want some information on genes and cancer, this might be helpful, although the language is a little technical.

Cancer incidence and mortality RATES are actually decreasing – mortality from all types of cancers went from about 190 per 100,000 in 1990 to about 170 per 100,000 in 2003, the latest year for which we have data. New cases, from about 500 per 100,000 to about 450 per 100,000 over the same time period.

You can sniff around here if interested. . .

“Cancer” is one of those useful utility-drawer terms that provide a convenient stashing place for a bunch of things alike in some given way, yet different in others. So asking “What causes cancer?” is like asking “What causes a species to go extinct?” – there is no one right answer, but there are a bunch of valid partial answers.

At rock bottom, cancers are caused by sequences of nucleic acids that instruct cells to go forth and multiply as cancer cells instead of what they’re supposed to be. What those sequences of nucleic acids are carries varied terms depending on how they end up in charge of telling a cell to grow into a cancer cell.

If they float around the environment, protected by a protein sheath, are absorbed into the body and into a cell, and start doing their dastardly work as a result, they are cancer-causing viruses. If they come as a part of your heredity, remaining dormant until something triggers them, they are referred to as “oncogenes” – genes instructing on how to grow into a cancer. The “something that triggers them” is a carcinogen. Finally, a sublethal mutation may turn a benign gene into an oncogene, again possibly caused by a carcinogen. There may well be other modes of getting cancer-causing nucleic acid into the cell and doing its dirty work, but those seem to be the top candidates.

Any given cancer may be the result of one or more of these modes of causing cancer. There are cancers that have been tied to specific viruses, and cancers that have been tied to specific oncogenes and a given set of carcinogens. The causative mode for some cancers is not yet known. At this point, it becomes appropriate to begin talking about specific cancers and their specific causes, if known.

One Renegade Cell is a nice short book that answers this very question.