We use 2 labs now and they use different assays. The tests are done with my husband going at 7am to one collection centre and then at 7:30 to the next on the same day.
Both are ultrasensitive tests - Lab 1 (Prince Alfred) uses the Immulite 2000 3rd gen whereas Lab 2 (Douglas Hanly Moir) uses Abbott Architect. Both tests are I believe calibrated to the WHO standard. However as you can see that these two tests are giving us consistantly different results and I am trying to work out what's happening.
The UK government did a comparision of PSA assays in order to make good purchasing decisions in Feb 2010 and the results were published at this website.
When they compared the tests at a known reference PSA of 1.5 (see page 9) the Abbott Architect read it as slightly under 1.5 whereas the Immulite 2nd generation read it at 2 (!) and the Immulite 3rd generation read it at 1.7. This is a much wider distribution than I expected, if they have difficultly lining up at 1.5 then I am not surprised that they have difficulty lining up when the numbers are so much smaller and presumably more difficult. They have tested quite a few different assays here so I though it would be useful to post this.
We of course hope that the Abbott one is right as it is more favourable to us (see signature below). However we understand that the trend is the most important thing so we will continue to test at both laboratories two-monthly till the end of the first year after RP.
Husband's age: 52. Sydney Australia.
Family history: Mat. grandfather died of PC at 72. Mat. uncle died of PC at 60. He has hereditary PC.
PSA: Aug07 - 2.5|Feb08 - 1.7|Oct09 - 3.67 (free PSA 27%)|Feb10 - 4.03 (free PSA 31%) |Jun10 - 2.69. DRE normal.
Biopsy 28Apr10: negative for a diagnosis of PC however 3 focal ASAPs “atypical, suspicious but not diagnostic” for PC. Review of biopsy by experienced pathologist, 1/12 core: 10% 3+3 (left transitional), 1/12 core: ASAP (left apex)
Nerve sparing RP, 20Aug10 with Dr Stricker. Post-op path: 3+4 (ISUP 2005). Neg (margins, seminal vesicles, extraprostatic extension). Multifocal, with main involvement in the fibro-muscular zone. T2C.
Post RP PSA,
Lab 1: Sep10 – 0.02|Nov10 – 0.03|Dec10 – 0.03
Lab 2: Nov 10 - 0.01|Dec10 – 0.01
Post Edited (An38) : 1/10/2011 2:40:15 PM (GMT-7)