An enlarged prostate produces more PSA, so gland size needs to be factored in.
Calculate your "PSA density" by dividing your PSA by size of your prostate.
"Free PSA" test also gives indications of the % being produced from benign causes.
My recent PSA was 11.3 and prostate size 72 to give a "PSA density" of 1.6 which is reasonable.
My June 2004 biopsy had one out of 10 G6 and high grade PIN.
Dec06 biopsy indicate all 12 samples were OK.
Biopsy readings are subjective, and small cancers can sometimes be missed.
Johns Hopkins had an interesting article on "insignificant cancers" in their winter 2003 newsletter at www.urology.jhu.edu/newsletter