Bone Scan Is of Doubtful Value as a First Staging Test in the Primary Presentation of Prostate Cancer

Purpose. To determine whether axial MR imaging could replace bone scan as the primary staging test in newly diagnosed CaP. Material and Methods. We reviewed retrospectively all bone scans performed in newly diagnosed CaP patients from 2000 to 2010 in a single tertiary academic center. We recorded patient age, ethnicity, PSA at diagnosis, TNM stage, Gleason score, alkaline phosphatase, bone scan results and axial imaging if available. Results. Mean patient age was 72 years (41–96), mean PSA and alkaline phosphatase were 268.9？ng/mL and 166？IU/L, respectively. Patients were divided in four groups according to possible bony metastases on bone scan. Group 1: Negative, no metastases demonstrated. Group 2: Positive, metastases only in pelvis and/or lumbar spine. Group 3: Positive, widespread metastases including pelvis and lumbar spine. Group 4: Positive, distant metastases without pelvic or lumbar spine abnormalities. Group 4 patients were analyzed in detail, two had possible disease that was detected only outside the pelvic and lumbar spine, unfortunately follow up images were insufficient to confirm the nature of the lesions. Conclusions. Although bone scan is a useful investigation to confirm and monitor metastasic CaP, our data suggests that axial MR imaging is an adequate primary staging study in untreated disease. Bone scan is unnecessary if CT or MRI of the pelvis and abdomen are clear of metastases. 1. Introduction Prostate cancer was the most common cancer in the UK in 2008, accounting for 24% of all new male cancer diagnosis [1], and is responsible for around 12% of the deaths annually due to cancer (10.168 in 2008). It is calculated that 85% of the patients who die of prostate metastatic cancer have axial skeleton involvement [2], and the presence of these determines the treatment, prognosis, and possibly outcome. It is therefore a priority to determine which patients have developed bone compromise. It is also important to identify patients with little or no risk of metastases to avoid unnecessary investigations and procedures [3–5]. Currently, bone scan is the most commonly used test to diagnose bone metastases [5–7], although it has a low specificity due to the lack of precision in differentiating benign disease from metastatic cancer [2]. There are several studies demonstrating that only certain patients require a bone scan [3–5, 7–11] once the diagnosis has been reached (PSA level above 20？ng/mL, Gleason 4, T3-T4 disease). Also numerous studies have shown that both MRI [12–14] and CT scan [13] have a higher sensitivity and specificity than