Re: "Scientific Evidence"

[Bob Flood <bflood@SLAC.Stanford.EDU>]

>    I believe that the increase in the cancer rate is not so much due to
>environmental factors than to the fact that we have made advances in
>preventing death from other causes such as infectious diseases and heart
>problems. I suppose cancer is what you die of  if you don't die of anything
>else.

This is essentially correct. Cancer is a probabilistic disease - each of us
has some chance of experiencing the initiating events for cancer each year
we live. Therefore, increasing the average lifespan increases the
opportunity for the cancer process to start. Also, cancer is a rather
slow-developing disease, which means that increasing the average lifespan
increases the number of people with developing cancer who survive long
enough for the disease to be detected.

Among my training (never mind how many years ago) was a lecture in which the
point was made that the death rate due to cancer among women in the US
increased by orders of magnitude in the second half of the 19th century. It
would be very easy to make a case that industrialization and the migration
from farm communities to cities was strong associated with the increase, but
the reality is the death rate due to cancer went up because so much progress
was made in reducing deaths associated with pregnancy and childbirth. An
awful lot of women did an awful lot of dying because of childbearing until
rather recent times, and it wasn't until major progress was made on this
that the life expectancy for women caught up to and passed the life
expectancy for men.

Bottom line - to die from cancer you have to live long enough initiate and
devlop the disease.
============================
Bob Flood
Dosimetry Group Leader
Stanford Linear Accelerator Center
bflood@slac.stanford.edu


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