If I were still a university lecturer, then my words to you would be:

"Ok, you've got a hypothesis, but simply asserting it's true doesn't make it true. You have to prove it. So how do you go about proving it?   What evidence do you need to gather?  What experiments must you do to gather than evidence?  What evidence would disprove your hypothesis?"

Give all these questions some thought and decide what you need to do to prove yourself right (or wrong).

I also suggest that you treat yourself to a subscription to New Scientist magazine, which will help you keep abreast of the latest developments in science, such as the possibility that a common microbe that causes gingivitis is implicated in the development of many diseases, including certain cancers. 

I'll leave that to you, my head hurts and I'm tired, the least I need is to put my brain into overdrive, it's already overactive enough as it is.

As I said before, I haven't got a degree or a diploma in medical science.

I trust that scientists have already contained a number of people in a setting where this hypothesis would have been put to the test, I'm waiting for someone to come along and tell me that I'm wrong, I highly doubt that I am correct.

Edit: I should also point out that, yes organisms have been proven to cause cancer, I was not asserting that cells have malfunctioned only due to man-made harmful substances, this could be what has caused the natural occurence of cancer.

The point I was trying to make was that we have increased the likelihood that it will occur.

Edit 2:

To answer your question "So how do you go about proving it?" as you pointed out, a common microbe is the cause for certain types of cancers, if I am correct then the types of cancers found in remains will only have been caused by something which naturally occurs (or harmful substances produced at the time, such as carbon monoxide from fires).

Hi acoster,

You may wish to take a look at this page which explains more about what cancer is and how it occurs. As a major research charity we've been investigating the causes of cancer for many years, and our scientists and working tirelessly to discover treatments and cures. You might find this information on our website a useful start if you're interested in the science of Cancer Research UK.

All the best,

Ben
Cancer Chat Moderator