Correlation between prostate specific antigen serum level and incidence of bone metastases in newly diagnosed prostate cancer detected in bone scan scintigraphy

Introduction: Prostate cancer is the second most common neoplasm and sixth cause of death because of neoplasms among men in Poland. The choice of most appropriate therapy among patients with prostate cancer is based on the proper staging of the disease at the time of diagnosis. In prostate cancer bone is considered the most common site for metastasis and they are related to a poorer prognosis and deterioration in quality of patient life. Thus proper staging and screening for the presence of bone metastases have a major impact on both the prognosis and choice of treatment for each individual patient. Bone scan scintigraphy is a gold standard in the detection of metastatic bone disease. Among published papers on early detection and staging of prostate cancer, much stress is placed on the cutoff value of Prostate-Specific Antigen (PSA) serum level, when we can avoid bone scintigraphy. Therefore our aims for the study were to evaluate whether there is a link between PSA values and presence of bone metastases as assessed by bone scan scintigraphy.

Material and methods: We analyzed 115 medical referrals for bone scintigraphy performed in patients with newly diagnosed prostate cancer, containing information about the most recently marked total PSA serum level. The analysis was performed taking into account 5 ranges of values of total serum PSA: ≤ 10 ng/ml, > 10 ng/ml to ≤ 20 ng/ml, > 20 ng/ml to ≤ 50 ng/ml, > 50 ng/ml to < 100 ng/ml, > 100 ng/ml.

Results: In our study among 115 patients 22 (19.13%) patients presented bone metastasis image in bone scan. Sixty-eight (59.13%) patients did not present image of metastatic disease (oncology correct distribution of radiotracer). Twenty-five (21.74%) patients required verification in more specific imaging studies to clarify the etiology of scintigraphic changes. None of patients with PSA serum level ≤ 10 ng/ml and 10 ng/ml < PSA ≤ 20 ng/ml presented scintigraphic image of bone metastasis. In all patients with PSA serum level > 100 ng/ml distribution of radiotracer was uncorrect. In group of patients with bone mestastasis there were no statistically significant differences in PSA serum level between patients with and without bone pain. There were no statistically significant differences between the age of patients with and without bone metastases.

Conclusions: PSA serum level is a strong predictor of bone metastasis in newly diagnosed prostate cancer. Bone metastasis more often occurred in patients with higher PSA serum level.