After my green light surgery my PSA grew from 0,33 to 3,3 in 4 years
what are the causes of this behaviour?
Not to worry. Don't rely on a PSA. Get a cystoscope if you are really concerned, but PSA's tend to go higher as you age. A 3 reading is normal.
You say after, what was it prior to GL?
Mine was about 7.8 before laser surgery and is now 0.74.
You can expect the PSA to be vastly reduced immediately after any surgery where a considerable amount of prostate tissue is removed and as tissue regrows it is inevitable that PSA will rise in line with this regrowth.
It should eventually plateau out at a level commensurate with your age but always bear in mind that the regrowth may well continue to the point where you require another "rebore" some time in the future and an increase in PSA above the norm can be expected due the returning BPH.
My recent HoLEP revealed a low grade PCa and I fully expect my PSA to eventually rise above the norm for my age and I aim to pay a lot of attention to how fast it rises to give me all the advantages of available treatments at the earliest possible point in time.