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Bone Scan Staging
Not Recommended When PSA Is < 20 ng/mL
Recent studies continue
to support excluding bone scanning in the staging of men with PSA < 20
ng/mL.
A retrospective study of 420 patients (BJU
Int, 2003, Nov) at the Royal Marsden Hospital, UK, slightly broadens the
guideline already formulated by the National Institute of Clinical
Excellence. The Marsden conclusion: "Isotopic bone scans are an
unnecessary part of staging of prostate cancer if the PSA is <
20, stage < T4 and the Gleason score is < 8, unless the major Gleason
pattern is 4." Only 2 of 187 (1%) men who met these criteria had a
positive scan. A smaller study of 64 men from Tunisia found no
metastatic cases with a PSA level under 10 ng/mL. Another study of 50
patients found no positive scans in men with PSA levels less than 18 ng/mL.
This insensitivity of bone scanning for the early detection of
metastatic spread to bone was reflected in the findings of the
collaborative study by the Center for Prostate Disease Research
(Urology, March 2003) which found limited value of bone scanning in
assessing biochemical failure within three years after radical
prostatectomy. In the face of a rising PSA only 2 of 127 scans were
positive when the PSA velocity was less than 0.5 ng/mL/mo. The
Prostate Cancer Treatment Book (reviewed above) succinctly addresses
the issue of the use of bone scanning in initial staging of prostate
cancer, page 53: "In fact, if the PSA is less then 20 ng/mL and if the
Gleason score is 7 or less, the risk of detectable spread to bone is
less than 1 percent."
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