The threshold for the start of investigations is PSA > 4 - given that 12% of men will get prostate cancer in their lifetimes then it's quite common and in most cases there are no symptoms whatsoever. The good news is that IF it is PCa then it will have been caught early and there are lots of treatment options.
Typically the process goes as follows
PSA blood test - repeat every 3 months if > 4
Urine test to check for infection
DRE to check for surface abnormalities
Echo if needed to check for size
MRI to investigate for lesions
Bone scintigraphy to look for any bone mets
Biopsy to remove cores from the prostate to estimate how far the cancer has developed
Then it comes down to the 4 main treatment options
Active Surveillance - basically keeping an eye on it to see if/how it progresses
Brachytherapy - inserting 60 radioactive seeds into the prostate to kill the cancer cells
Radical Prostatectomy - if the cancer is fairly well contained then cut it out
Hormone Therapy/Radiation Therapy - if cancer has spread outside the prostate then hit it with radiation and reduce testosterone with drugs.