- There must be a confirmed rise in PSA shown by 2 PSA values at least 1 week apart, higher than a reference value noted within 12 months of study entry. Interim PSA values during the immediate pre-study 12-month interval may demonstrate a "fluctuation" including a decline; however the study baseline PSA must have show a rise within the pre-study 12-months period. Baseline PSA must be determined within 4 weeks of study entry. At least 3 PSA values are necessary to calculate PSA doubling time via PSADT calculator.