On
this web page the UCSF Medical Center writes:
UCSF said...
Though infrequent, it may take up to two to three years for the PSA to reach its nadir. Keep in mind that the PSA may not decline steadily. Temporary increases in PSA, also called "spikes" or "bounces," may occur during the first 12 to 36 months......
If you received hormone therapy, the PSA decline and the period of decline may be prolonged. As your testosterone recovers, your PSA may rise. This increase is not considered a "bounce or spike" and is not a sign of treatment failure.
George