I have not heard of it - which doesn't prove that it's impossible.

Perhaps your friend is confused about his brother's disease.
There are cancers that strike young people.  One of them is
testicular cancer (Lance Armstrong's disease), which is more
common in young people than among the elderly.

Or perhaps his brother has prostatitis - an inflammation or
infection of the prostate, which is not cancer.

  Alan

If the biopsy is positive then he got cancer,
which is really bad news for a young lad.
There are techniques for freezing sperms which are worthwhile to
consider.  

RR

I am inclined to assert that he does not have prostate cancer.  I have seen
over 800 people come through this newsgropu and the youngest was 37 years
old.  Only on other was less than 40.  Additionally, I have read books,
Internet sites, studies, and attended support group meetings and have never
heard a hint of anyone with this disease less than the later 30s.

Possibilities:  Your friend's brother has another cancer and is confused
(justifiably) about it's origin, or mistated it to his sister or she
mistated it to you.  Or, he had his blood tested and the lab found a DNA
strain that is currently being called "the marker" for potential development
of prostate cancer.  And, of couse, there is always the possibility that
he's pulling your leg.

If he has cancer, any cancer, at 19 years old, it is potentially
devastating.  Cancer can simply be described as cells growing our of control
and the younger one is, the more quickly cells naturally grow.  I hope he is
pulling your leg.

In theory, it is possible for a 19 year old to have prostate cancer.
However, it is extremely unlikely that any urologist would ever do a
biopsy on a 19 year old.  Ordinarily, even aggressive prostate cancers
have a doubling time of over 1 year, so if the first cancer cell
appeared at the age of 13, there would only be a total of less than 64
cancer cells at the age of 19, and the odds against finding any of
them on a biopsy is enormous, let alone having any reason to perform a
biopsy.  On the other hand, if there were a bunch of mutations present
that prevents all cell death (apoptosis) in the cancer, then it could
double every two months, which would make the cancer extremely
aggressive.  If in fact a biopsy is done on a teenager, if there is an
abnormality, the most likely finding of abnormal cells would be early
HGPIN, which should go away in time on their own, assuming that the
boy has normal levels of testosterone present.

Ed Friedman

He doesn't have prostate cancer!  I just wanted to thank everyone who
responded.  I knew it had to be a mistake.  I knew it.  Thank you to
everyone.  His prostate is just swollen, but it's not cancer and it can be
taken care of.  I am so relieved.  Thanks again.