Startling Fact: PSA Testing Frequency Changes PSA Doubling Time – A Time Honored Surrogate Biomarker is Not Valid!
In our quest to understand our prostate cancer we have developed many “measures” of our disease aggressiveness and progression. Many of these measures are generally accepted has valid, but many have never been validated. One example is the prognostic nature of PSA Doubling Time (PSADT) in men with biochemically recurrent prostate cancer (BRPC or PSA only increases with negative scans). PSADT is used as common intermediate endpoint for assessing the efficacy of therapies. A number of investigational agents appear to favorably effect PSADT, slowing of PSADT has also been observed in placebo-treated men. Researchers from Johns Hopkins Hospital theorized that [...]