I had my proton beam radiation in Dec 2020 and started therapy in September. Non of the doctors brought up the issue there only answer was physio therapy. I first sent a saliva sample to an online site and it then came back way low,

These are the tests I took
004598 Ferritin
CHM 004283 Luteinizing Hormone(LH)
998085 Venipuncture
CHM 004020 DHEA-Sulfate
CHM 010363 IGF-1
CHM 005009 CBC With Differential/Platelet
CHM 010322 Prostate-Specific Ag
CHM 140103 Testosterone,Free and Total
CHM 002188 Triiodothyronine (T3)
CHM 376137 TSH+T4F+T3Free
910385 Cardiovascular Report
CHM 082016 Sex Horm Binding Glob, Serum
CHM 001453 Hemoglobin A1c
CHM 322000 Comp. Metabolic Panel (14)
CHM 303756 Lipid Panel
CHM 081950 Vitamin D, 25-Hydroxy
CHM 004515 Estradiol

At first my PSA climbed a little over .1 but after 3 months it was back <.1.

Insure you talk to a doctor failure with field it may not be appropriate for you if your cancer was more advanced.