Question: what type of cancers are there and how do you get it?

Chandrika Nair answered on 23 Jun 2011:

There are so many different kinds of cancer (any body part really, you can even get cancerous cells that grow into tumours within bones). Here’s an extensive list: http://www.cancer.gov/cancertopics/types/alphalist/b

Basically, cancers are the result of a cell not behaving in a proper manner (disrupted cell cycle). It doesn’t stop growing when it should, instead dividing into lots of cells and forming a ball of cells called a tumour. Along the way, it might also pick up some mutations to help it become more aggressive (eg. the ability to dettach itself and go and invade another part of your body – spreading).

There can be a genetic predisposition for cancer (which is why it’s important to know your family history).

There can be environmental factors (such as chemicals called mutagens that cause mutations in your DNA, including some that would lead your cells to continue growing when they shouldn’t and turn cancerous)

There are also viruses that induce cancer (by messing with your DNA) – for example RSV virus induces tumours in chickens!

Interestingly, all humans have some ancient virus DNA in their DNA (these viruses were once retroviruses, that have the ability to copy themselves into the DNA of their host). These are mostly inactivated and just part of our ‘junk’ DNA now, but recently it’s been suggested that some testicular cancers are actually caused by one of these ancient viruses hiding in our DNA (they’re called endogenous retroviruses).