Hi Linkbekka,
I am so sad to read of your news and so hope that the following will help you to understand. I am not a medically trained person and hopefully others will correct anything I may have muddled below.
PSA values are a guide and not a clear determinator. My original PSA scores were 9.8 and 8 taken one month apart. My outcome was Gleason 4+4 after I had the prostate removed. Even though my prostate no longer exits my current PSA level is 0.21 and this is either because a small bit of the prostate was left behind and is generating PSA or I have spread and a new tumour is growing somewhere in my body.
It is true that a person can have a PSA of greater than 10 and not have prostate cancer; it is also possible to have a PSA of lower than 10 and have prostate cancer. This is why the country still doesn't have a PSA test mandatory for all men, as many would be alarmed and flood the system for MRI scans, and biopsy's before being told they don't have cancer.
In short the numbers larger than 1 are generally men with a prostate still in their bodies. The numbers below 1 are for guys after they had their prostate removed or after their treatment with hormones and radiotherapy/chemo. Sadly even after the operation to remove a prostate, guys have to worry about their PSA levels. A level of 0.02 is very good and the alarm bells start ringing at 0.2. They ring even louder if the doubling from PSA to PSA test is in terms of months. In my case after the operation my PSA was 0.02 and has increased to 0.21 in 2 years. From this I am likely to have a fairly aggressive tumour, but so far no scan has been able to find the potential new tumour.
I hope that helped and I wish you all the best with whatever future treatment you are about to undertake.