Cancer incidence

[LEIDHOLDT.EDWIN@FORUM.VA.GOV]

     I finished reading an epidemiology primer about 2 months ago
that made the point that, if one discounts lung cancer (the Joe Camel
effect) and corrects for the increasing average age of the population,
the net cancer incidence has not changed much over the last century.
Epidemiology is tricky stuff.  The large increase in prostate CA
incidence appears alarming until one considers such things as the 
huge increase in TURPs (trans-urethral prostate resections) for 
urinary obstruction, the use of the PSA test, the advent of rectal 
ultrasound, and increased emphasis on digital rectal exams.  (After
a TURP, the resected tissue is sent to a pathologist who looks for
cancer.  Also, an increased PSA level triggers a search for prostate
CA.  Voila, one sees an increased prostate CA incidence.)  A similar
increase in breast cancer incidence (32 % in the U.S.) was seen
during the 80s, most likely due to the marked increase in screening
mammography.
      There is an increasing incidence of non-Hodgkin's lymphoma,
which may be at least partially due to HIV infections.  I think
everyone knows the reason for the increased incidence of melanoma
and skin cancers and this increase is probably real.  However, there
has been a huge decrease in the U.S. in the incidence of stomach,
liver, and uterine cancers from 1930 until today.  My point is that,
since about 1930, correcting for the aging of the population, ignoring
lung cancer, and accounting for improved diagnosis, overall cancer
incidence has not changed greatly.
 
 
Best regards,
Ed Leidholdt
Leidholdt.Edwin@forum.va.gov
 
These opinions are my own and not those of my employer.