Hi and welcome.
Quote:
Originally Posted by nissen  what should psa be after radical surgery 6 weeks |
The answer depends on a couple of things:
- How fast does the PSA already in the blood diminish after surgery?
- Is there any (significant) source(s) of PSA remaining after surgery?
- What was the PSA just before surgery?
Let's discuss:
1. Medical studies have been performed to analyze the "half life" of PSA in the bloodstream after the prostate is removed. It's a little different in everyone, but most men have a PSA half life of 2 or 3 days. I'll explain how this gets applied, below.
2. The cancer in the prostate is the main source of PSA in the bloodstream before surgery; cancerous cells produce PSA at a rate about 20X non-cancerous prostate cells. There are a few other sources of PSA, but they should only produce small "trace" amounts. However, if you had nerve sparing surgery, the nerve bundles can produce small amounts of PSA which should be below 0.1 ng/mL, but may be measureable with the "ultra-sensitive" PSA test. Lastly, if prostate cancer remains in the body after surgery, it can be a source of PSA...and of course, this is the reason for the follow-up PSA tests after surgery.
3. The amount of PSA in the bloodstream before surgery represents the "starting point" for one to calculate the decline in the days and weeks after surgery.
Let's take as a hypothetical example 10 ng/mL as the starting point, and assume a longer half life of 3 days; here's how it would work:
10 ng/mL on surgery day
5 ng/mL 3 days later
2.5 ng/mL 3 days later, or 6 days after surgery
1.25 ng/mL 3 days later, or 9 days after surgery
0.625 ng/mL 3 days later, or 12 days after surgery
0.31 ng/mL 3 days later, or 15 days after surgery
0.16 ng/mL 3 days later, or 18 days after surgery
0.08 ng/mL 3 days later, or 21 days after surgery
So, for a typical man's half life of 3 days and starting point of 10 ng/mL, after 3 weeks the PSA result would typically below the "standard PSA test" lower detection limit of 0.1 ng/mL. A higher starting point would take longer to get below 0.1 ng/mL, but you can see how the pattern works.
Where it actually finally ends up depends on all the factors discussed in 2.
Does this help answer your question?
Have you had a post-surgery PSA test?
The short answer is that after 6 weeks (after surgery) one would want the PSA result to be below 0.1 ng/mL.
