Just a reminder .

Humans aren't the only species that suffers from
the wayward effects of cancer.
Many generations of many species has pasted since
the first viable reproducing cell came into existence .

Throughout those generations the cells were exposed
to environmental carcinogens at least as severe as
what we encounter today .
The cummulative effect upon the genetic material of
successive generations would of been absolutely
devastating. If there weren't some mechanism to
correct the effects of environmental degradation
and the latent effects of viral loads ; then a species
would rather quickly succumb and become extinct.
Furthermore this mechanism or a variant thereof
must exist throughout the individuals entire life.

The easiest way to study this is in the simplest and
most potent form ; embryonic stem cells and possibly
their immediate microenvironment .

This mechanism may vary from species to species and
be more effective in some species in selectively
elimatating carcinogens , including viral vectors .

Just look around you the world bears testimony to
the mostly successful outcome of this mostly self
correcting mechanism .
The social structure and practices of species can
still augment or degrade this ; cleanliness and
caution are valuable traits , not unique to the
human species .

Again it is knowledge about this genetic mechanism
that we seek and the appropriate , possibly enhanced ,
application of this knowledge .