I pretty much have to go yearly just to get checked out. No spots yet, thankfully, but I'm so pale, I could be mistaken for the "visible human".
Here's the deal with the "big C". There is a vast assortment of cells in your body, but they can be summed up into three broad types. One of those types are called epithelial cells. These cells, roughly speaking, are generally "liners". They line the various surfaces of your body, both internal (like the lining of your intestine) and external (such as skin), and are really "designed"* to ablate off and be replaced quickly. As a result, they are programmed for rapid division and growth.
Cancer makes cell division & growth go haywire in any cell. Cancer in epithelial cells are bad, bad news, because you are making a cell already programmed for rapid growth/division go bezerk, and things can get out of control extremely rapidly.
Cancer of any type is bad, but anything dealing with epithelial cells can get out of hand in an astonishingly short period of time.
Richman
* Don't read anything into the usage of this word. I was an engineer before I went back for more school, and I think of everything in those terms. Nature, nurture or divine intervention, the result is the same.