Unfortunately there are no really objective comparisons of different
methods.   What you see is statistics produced by practioners of one or
the other therapy with comparisions with (sometimes) obsolete results
for the other method.

In addition, how effective a given method is may depend on other
factors, like Gleason score and age.

The Sloan Kettering web site has nomograms which you can use to estimate
your chances of being recurrence free (defined in terms of rise in PSA)
using different methods and based on the specifics of your diagnosis.
It seems to me that it is based on good up to date research.

The usual wisdom seems to be that for up to ten years, all methods, as
they are currently practiced at the best medical centers specializing in
these methods, are about comparable.   No one knows just what happens
after ten years.  External radiation and seeds were done quite
differently in the 80s, and the long term results at that time were not
as good as surgery.   But the current methods, it is generally agreed,
are much better.   They just haven't really been in use long enough to
estimate recurrence rates 15 or 20 years down the line.

Men over 70 are generally permanently impotent after surgery (75 percent
of them), while such men treated by radiation tend to do a bit better.
The situation is very different for younger men who have a good chance
of preserving potency either way if treated by a competent doctor.

You should also look into external radiation.  I am no expert, but I
don't see any data suggesting seeds are better than external radiation.
 Also, "seeds" can mean many different things, e.g., seeds alone or
seeds in conjunction with some external radiation (and sometimes
temporary use of hormone suppressing drugs).

It is probably more important to choose the right physician to treat you
than the particular method.   The doctor should be very skilled in the
methods he uses, and he should be willing to tell you your chances with
his treatment.

Age is only one factor to consider.  Others are your PSA, Gleason, your
overall health, life expectancy for men in your family, etc.  In my
situation, age 61, PSA 4, and Gleason 6 with T1c PCa, my urologist said that
either surgery or radition (seeds or external radiation) would, as far as
comparisons can be made, be equally effective.  He said if I were 10 years
younger, he would recommend surgery; if I were 10 years older he would
recommend radiation (either form), but at my age I would have to choose
(thanks!).  I chose seeds, now scheduled for early January.  It seemed to me
to be the quickest and easiest way to go with fewest short term side
affects.  The only advantages I could see to surgery (if success rates are
indeed equal) is that it "gets the thing out," allows a more definitive
diagnosis of how bad it was, and provides more options if there should be a
recurrence in the future.

I had brachytherapy four years ago.  My most recent psa was 0.5, and the
numbers have floated between 0.8 and 0.2 in last couple of years.
Radiation Oncologist is happy with these numbers and I am also happy with
them.   Glad to share more details if desired.
John
Brachytheapy October, 1999
psa at treatment 7.4
gleason 3 + 3 = 6
age 62 at treatment
prostate size at treatment 35 cc.