[Predictive value of prostate-specific antigen and Gleason sum for results of radionuclide bone scintigraphy in patients with prostate cancer].

OBJECTIVE

To investigate the predictive value of prostate-specific antigen (PSA) and Gleason sum for results of radionuclide bone scintigraphy in prostate cancer patients, in order to determine when to perform a radionuclide bone scintigraphy in Chinese patients with newly diagnosed prostate cancer.

METHODS

We retrospectively reviewed the charts of 624 consecutive patients with a pathology diagnosis of prostate cancer hospitalized in Department of Urology, Peking University First Hospital between Jan. 1994 and Dec. 2005, and evaluated the relationships between results of bone scintigraphy and serum tPSA, and between bone scintigraphy and Gleason sum. The receiver operating characteristics (ROC) curves were analyzed to determine the cut-off values of tPSA and Gleason sum for predicting positive results of bone scintigraphy.

RESULTS

In the study, 443 patients underwent both a radionuclide bone scan and a serum PSA test prior to treatment, of whom, 216 (48.8%) got positive results, and 338 also possessed the Gleason sum for pathological evaluation. The serum tPSA levels were significantly higher in patients with positive results of the bone scan ( median: 71.00 μg/L; range: 1.30-2 400.00 μg/L) than those with negative results ( median: 60.00 μg/L; range: 0.60-201.00 μg/L; rank P<0.001), and the Gleason sums were also significantly higher in positive-bone-scan patients than in negative-bone-scan patients (7.7±1.5 vs. 6.7±1.8, P<0.001). Linear regression analysis suggested significant positive correlation between the results of the bone scan and the two afore-mentioned parameters, respectively (lg[PSA]: r=0.933, B=0.352, P=0.001; Gleason sum: r=0.971, B=0.096, P<0.001). The incidence of a positive bone scan result was 9.0% in patients with tPSA<10 μg/L and 3.8% in patients with Gleason sum<5. When the indication for bone scan was established as tPSA>15 μg/L or Gleason sum≥7,its sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for positive results were 97.5%, 24.7%, 54.4%, 91.5% and 60.0%, respectively.

CONCLUSION

In patients with prostate cancer, their positive results of the bone scan are significantly positively correlated to their higher PSA levels and higher Gleason sums, respectively. Our analyses suggest that a patient with newly diagnosed prostate cancer would not need to undergo radionuclide bone scintigraphy when the PSA level is lower than 10 μg/L and Gleason sum is less than 5, and that a prostate cancer patient with tPSA>15 μ g/L or Gleason sum≥7 should take a bone scintigraphy.