Metastasis on Bone Scan With Low Prostate Specific Antigen (≤ 20 ng/ml) and Gleason’s Score (< 8) in Newly Diagnosed Pakistani Males with Prostate Cancer: Should We Follow Western Guidelines?

Aim: To find out diagnostic correlation of prostate specific antigen (PSA) and Gleason’s score (GS) with bone metastasis (BM) in newly diagnosed prostate cancer (PC) patients in Pakistan. Materials and
Methods: This retrospective study included 204 newly diagnosed PC patients who were referred for BS for staging.
Results: The mean age, mean PSA and incidence of BM on BS were 71 ± 09 years, 111.01 ± 58.45 ng/ml and 67/204 (33%), respectively. The mean GS of the studied population was 7 ±1. According to PSA levels, patients were divided into 5 groups: < 10 ng/ml (77/204), > 10 - ≤ 20 ng/ml (42/204), > 20 - ≤ 50 ng/ml (22/204), > 50 - ≤ 100 (25/204) and > 100 ng/ml (38/204). The incidence of positive BS (%) for BM and mean GS (score ± SD) for each group were 14%, 7 ±1; 10%, 6±1; 32%, 7 ±1; 56%, 8 ±1 and 82%, 8 ±1 respectively (significant p value). PSA and GS were statistically significant predictors of BM on BS and their predictive value was additive (p < 0.0001). Age was not a predictive factor (non-significant p value). Sensitivity and specificity of PSA at a cut-off 48 ng/ml were 68.3% and 86.1% respectively, while GS at a cut-off >6 was more sensitive (88.9%) and less specific (56.2%) for diagnosing BM.
Conclusions: (1) There is an overall increased incidence of BM in newly diagnosed patients with PC and even at serum PSA level ≤ 20 ng/ml and GS < 8; (2) PSA and GS are independent predictors for BM but age is not; (3) in view of possible aggressive behavior of PC in local population, one must be careful in adopting Western guidelines for using BS in newly diagnosed Asian males with PC having PSA ≤ 20 ng/ml and GS < 8.