RESUMO
OBJECTIVE: To evaluate the utility of bone scintigraphy in the assessment of newly diagnosed, untreated prostate cancer. PATIENTS AND METHODS: The probability of a positive bone scan for metastases was analysed for different threshold values of pre-treatment concentrations of prostate specific antigen (PSA), clinical stage, tumour grade based on biopsy, and age in 128 men (mean age 69 years, range 50-90) with newly diagnosed, untreated prostate cancer. The overall survival probabilities estimated from PSA level, extent of bone metastases, tumour grade, clinical stage, and age were calculated using the product-limit method. RESULTS: The positive predictive values of PSA level for bone metastases at thresholds of 10 and 20 ng/mL were poor (27.5 and 47.5%, respectively) whereas similar threshold levels of PSA gave negative predictive values of 100 and 94%, respectively, for a positive bone scan. In a univariate analysis, the overall survival was significantly affected by the extent of bone scan pathology (P < 0.001), the pre-treatment level of PSA (P < 0.001) and tumour grade (P = 0.01), whereas a multivariate analysis identified, in order of significance, tumour grade (P = 0.003), bone scan findings (P = 0.007) and PSA levels (P = 0.03) as independent prognostic factors. CONCLUSIONS: Bone scintigraphy seems to be unnecessary in the evaluation of newly diagnosed, untreated prostate cancer in patients with no clinical signs of bone pathology and serum PSA levels of < or = 10 ng/mL. However, the bone scan accurately assesses bone metastases and the prognostic significance of bone scan findings is superior to that of serum PSA level.
