A drop by half is just an average. A lot of guys drop by more than that, a lot by less. The question is: how should the new PSA be incorporated into the AS protocol? I don't know the answer but I'll provide a few comments:
• In about
half of dutasteride-treated men on AS, no cancer is found on a f/u biopsy. This, in spite of the fact that cancer should be easier to find in the smaller prostate.
• Dutasteride and finasteride (5ARis) are the only medicines known to prevent GS 6 prostate cancer (but not higher grade PC). So it might prevent multifocal bits of cancer from cropping up.
• Risk groups are, in part, based on PSA. When D'Amico first set the PSAs that define risk groups (0-10, 10-20, 20+) men were not taking 5ARis. Therefore, if a man saw his PSA drop from,say, 15 to 7.5 while taking a 5ARi, he should double it to see which risk group he falls into.
• But a slavish attachment to risk group as a criterion for AS is unwarranted. There's room for judgment. If doubling puts a man into intermediate risk, but a biopsy shows only a small amount of GS 6, the biopsy is determinative.
• On the other hand, if PSA shows a clear rising trend while taking a 5ARi, it is a better signal that a biopsy is warranted than if the PSA rose without a 5ARi. The 5ARi makes PSA a better indicator of progression.
• I would guess that PHI is a better indicator than PSA when taking a 5ARi while on AS. Since you get PSA too when you get PHI, you aren't losing anything. They haven't researched this adequately.
Allen - not an MD
•PSA=7.3, prostate volume=55cc, 8/17 cores G6 5-35% involvement
•SBRT 9 yr onc. results
•SBRT 7 yr QOL results
•treated 10/2010 at age 57 at UCLA,PSA now: 0.1,no lasting urinary, rectal or sexual SEsmy PC blog