Half life of PSA?

[Guest guest]

One of the posters on my site raised an issue about

PSA of which I was unaware.

He drew my attention to this study - Prostate

Cancer Prostatic Dis. 2002;5(2):111-4.Clearance rates of total prostate

specific antigen (PSA) after radical prostatectomy in African-Americans and

Caucasians. Lotan Y,

Roehrborn CG. It is a small study and it is aimed at trying to resolve any

differences between what are termed PSA ‘clearance rates’ between Caucasian

and African-American patients (none was found). I found some of the other

outcomes somewhat confusing.

Table 2 shows what is termed the serum total PSA

half-life. The figures in the table are in line with another referenced study -(Eur Urol.

1998;33(3):251-4. Clearance of free and total serum PSA after prostatic

surgery. Ravery V,

Meulemans A,

Boccon-Gibod L.)

which concluded that the half-life of PSA after surgery was up

to 3 days with a mean half-life of 2.43 +/- 0.688 days for total PSA.

So, if these studies are correct, why has it been the

practise for urologist surgeons to wait for up to three months before measuring

PSA levels after surgery? From the anecdotal evidence of posts on Lists and on

my site, I know that this practise has changed and more often it seems that the

initial post-surgery PSA test is done after three or four weeks. This change

has resulted in more men having a detectable PSA level when the PSA test is

done so soon after surgery, a result which is put down to blood circulating in

the aftermath of the surgery. Surely all the men should have undetectable PSA

levels, if these studies are correct.

Another aspect that these studies seem to impact is

the accuracy of PSA tests. If the prostate is massaged by DRE (Digital

Rectal Examination) or, for example a bike ride, or is

exercised by ejaculation or any other activity that produces higher levels of

PSA, and if the half life is really 2.5 days, surely it will take the best part

of a week for that extra PSA to decay – not the 48 hours that is usually

quoted?

As the first oncologist I consulted said “There

is something to learn about PCA every day.” Anyone with any input on this?

All the best

Prostate men need enlightening, not frightening

Terry Herbert - diagnosed in 1996 and still going

strong

Read A Strange Place for unbiased information at http://www.yananow.net/StrangePlace/index.html