You can fly until you are officially diagnosed with Cancer. I had a PSA of 7 rising to 12 over eighteen months. I then had an MRI and a transperrenial biopsy after which I was told I had a Gleason score of 7 (4+3) which was industrial grade PCa. The choice is given to you over what treatment you'd prefer being surgery or Hormone/Radio however look out for a heavy bias towards people recommending surgery. I chose the alternative and had to suspend flying for treatment plus one month post hormone and then again treatment plus one month post radio therapy. In all I was off for around four months with a short revalidation in the middle. I'm pleased to say after a year that my PSA has remained well below 0.5 so hopefully I have nailed it for now.
Hormone's not too bad. You lose the ability to indulge in sex, but the nice part is you also lose interest in pursuing it. I was more interested in knowing what time the Formula one was on and without the testosterone (which the cancer feeds on) I became a calmer and more placid person. So much so my wife wants me on it permanently ;-)
I was lucky to be treated with the latest image guided intensity modulated accelerators at Christies in Manchester so the radio was a doddle. You simply lie on a table for twenty weekdays and watch a machine rotate around you. No pain, no sensation. Pull your trousers up and drive home. At the end I did have inflammation in the rectum that caused a few issues for about ten days but a good laxative helped that along. Post treatment I'm still as fat and ugly as before but can't thank the team at Christies enough.
I see you're located in London. Should you need treatment ask for the same kind of accelerator, the side effects are much less and collateral damage to the rectum is minimised. You are also located near some hospitals offering Cyberknife treatment which is much more precise and can offer treatment in five days.
One thing I would recommend is getting your AME onside as soon as possible. Strictly speaking the biopsy is an intrusive procedure so should be notified. The CAA guidelines say grounding is only required 'on confirmation' of cancer, and you haven't got it yet.
This is your guiding reference:
CAA Protocols. Oncology.
Good Luck.