When our bodies evolved to how they are today, the process of apoptosis was part of that evolutionary change. Cells have specific life cycles, they live and they die on a schedule. Some areas of our body have a very rapid turnover of cells through this natural programed cell death and replacement. In the oral environment squamous cells live about 14 days... not very long. Why? Because the suffer constant insults and bombardment with toxins. Nice design that they get shed and replaced with nice new ones so frequently.

I posted this at length someone else awhile back but just to BRIEFLY say it again, this is a very complex process of conversion to malignant from normal. HPV16 enters a living normal cell, it can't live on it's own for very long. It sends out a couple of onco-proteins E6 and E7. E6 heads for a gene called P53, that controls the apoptosis process. It destroys it. Now the cell is immortal. A characteristic of cancers cells of all types. E7 heads for gene RB which is the tumor suppressor gene. with that one destroyed, the immune system does not recognze the cell as aborrent and in need of destruction. With that all done, the cell duplicates, and the daughter cells are created without RB and P53, a bunch of these gther together and you have a party... a little tumor is born. Now that it is an entity and not a single cell, it needs nutrition and the process of angiogenisis begins to take place. The body actually creates new blood vessels to feed it.

This is an over simplification of the whole thing, but what you should get out of it is that there are a variety of times and places in which our immune system, if in tune, can find these defective cells and destroy them. But everyone's immune system -while of the same overall design- is unique, based on your hereditary genome and proteome, and not everyone has an immune system that recognizes everything. So we have inherited susceptibility to certain diseases. We also have inherited protection from certain diseases.

Those of us that came from Europe ancestrally, have some commonalities that people from South America or Asia do not have. We are all descendants of people who were naturally protected (there were no treatments for it) from the black plague that ravaged a major portion of that population. We have that natural genetic make up passed down to us. Other genetic lines in humanoids died off during the plague. This is essentially evolution on the genetic level that we are seeing. The problem is, that the make up that allowed your ancestors to survive the plague, may today make you susceptible to something that wasn't around then. And what once was a genetic asset is now a genetic deficit. As a species we are not static, but constantly evolving and biologically changing.