Predicting Bone Metastasis in Prostate Cancer Patients: Value of Prostate Specific Antigen

Abstract 

Objective

Serum prostate specific antigen (PSA) concentration has been widely applied as a biomarker to diagnose and monitor prostate cancer. Technetium-99m methylene diphosphate (Tc-99m MDP) whole body bone scintigraphy is currently a well-accepted diagnostic procedure for bone metastasis in malignancy. The aim of this study was to establish a useful serum PSA cut-off value to predict the presence of bone metastasis in men with prostate cancer.

Materials and Methods

Consecutive male patients diagnosed with prostate cancer were retrospectively analyzed. All of the subjects had received both Tc-99m MDP whole body bone scintigraphy and had their serum PSA concentration measured within 1 month. The proper cut-off value was established based on statistical analysis in order to predict the possibility of bone metastasis among prostate cancer patients.

Results

In total, 101 consecutive male patients (age, 71.92 ± 0.76 years) with prostate cancer were enrolled, and 57 patients (56%) were confirmed by scintigraphic findings to have bone metastases. A serum PSA concentration of 13 ng/mL gave the best sensitivity (96.43%) and specificity (84.09%). The area under the receiver operating characteristics curve revealed excellent discriminatory power (0.93 ± 0.02; p = 0.001). The positive predictive value, negative predictive value and likelihood ratios for positive and negative test were 88.52%, 94.87%, 6.06 and 0.04, respectively. The resulting diagnostic accuracy and odds ratio were 73.87% and 142.76.

Conclusion

A cut-off value of 13 ng/mL appears to be an appropriate benchmark for stratifying metastatic bone disease in prostate cancer patients such that if a patient with newly diagnosed prostate cancer and without any skeletal symptoms has a serum PSA concentration of less than 13 ng/mL, we suggest that they would not need to undergo bone scintigraphy.

Keywords:  Bone metastasis , Prostate cancer , Prostate specific antigen

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