Is bone scintigraphy necessary in initial staging of prostate cancer patients?

Our aim was to determine whether serum prostate specific antigen (PSA) and total Gleason score (GS) on biopsy in newly diagnosed prostate cancer (PCa) can predict osseous metastases and eliminate the need for a bone scan as a routine procedure in initial staging. We studied retrospectively 155 patients with previously untreated PCa who underwent bone scintigraphy. Relationship between PSA, GS and bone metastases was examined. Sensitivity, specificity, likelihood ratio (LR) and odds ratio (OR) were calculated with corresponding 95% conidence interval. Results showed that thirty of all bone scans (19.35%) were positive for metastases. This proportion was significantly higher in patients with PSA>20ng/mL (31.66% , P=0.002) vs. PSA<10ng/mL (10.52%). For PSA<10ng/mL as well as 10ng/mL≤ PSA≤ 20ng/mL the test was not a predictor for bone metastases (OR=0.36; OR=0.55). For PSA>20 ng/mL (OR=3.53) the likelihood of bone metastases was increased by 13% . The proportion of positive scintigraphy findings was significantly lower in patients with GS≤ 7 (11.47% ) vs. GS≥ 8 (48.48% , P<0.0001). The GS≥ 8 was highly predictive for bone metastases (OR=7.260). The analysis showed that GS≥ 8 increases the risk of bone metastases by 29%. In conclusion, bone scintigraphy is not necessary in asymptomatic patients with localized disease, GS≤ 6 and PSA<10ng/mL, because of the negligible risk of bone metastases in that stage. Higher levels of GS and PSA may predict bone metastases.