Post RP - The rise and fall of PSA - what gives?

Has anyone experienced the rise and then fall of PSA as shown in my hubbie's profile? Since his RP, he has not taken any additional medication or done anything to explain it.

When his PSA hit 5.2 in August 2015, he had a PET scan which showed no metastatic disease.

He saw the medical oncologist following testing in Oct 2015 when the PSA showed its first decline. This was waved off as a statistical anomaly. However, this didn't really make sense to us since the upward trajectory is plainly obvious from the numbers. Now he has the results of the PSA test done last week which shows a further decrease in PSA.

Does it help to know that his urologist told hubbie that he has a very 'unusual' constitution (whatever that means)?

Any insight/suggestions would be greatly appreciated as we both don't know what to make of it.

In answer to Tall Allen's questions:

1. It was a sodium fluoride pet scan. This was only available here in B.C. because there was trial to compare NaF scans to bone scans so, by default, hubbie got a NaF scan (and the bone scan).

2. He chose not to have salvage radiation right from the start because the odds were so low for a complete cure vs. the unfavourable possibilities. QoL is his #1 priority.

3. Re: hormone therapy, as stated above, QoL was #1, the medical oncologist was quite happy to wait until the PSA hit 20 given that hubbie has no intention of opting for HT for as long as possible, if ever.

4. His T has been steady at around 20 nmol/L.

Thanks, Allen. Of course, neither one of us wants to let ourselves believe that it is REALLY good news but, as you say, we'll take it.