INCIDENCE OF SKELETAL COMPLICATIONS IN PATIENTS WITH BONE METASTATIC PROSTATE CANCER AND HORMONE REFRACTORY DISEASE: PREDICTIVE ROLE OF BONE RESORPTION AND FORMATION MARKERS EVALUATED AT BASELINE

Abstract

We evaluated the incidence of skeletal complications in patients with bone metastatic prostate cancer and hormone refractory disease. We also assessed the predictive role of bone turnover markers determined at baseline. A total of 112 patients were consecutively enrolled in our study from July 1990 to July 1998 and followed until death or the last followup. Bone pain, disease extent in bone, serum prostate specific antigen, hemoglobin, and a panel of bone formation and resorption markers were assessed at baseline before any second line treatment. Skeletal complications in 34 patients (30.3%, estimated yearly incidence 12.3%) involved vertebral deformity or collapse requiring spinal orthosis in 20 (17.9%), spinal cord compression in 7 (6.2%), pathological bone fracture in 10 (8.9%), symptomatic hypercalcemia in 1 (0.9%) and symptomatic hypocalcemia in 1 (0.9%). Median time to the evidence of the initial skeletal complication was 9.5 months. These adverse events did not influence overall survival. At baseline patients with eventual skeletal complications had greater bone pain (p = 0.02), a heavier tumor load in bone (p = 0.005), lower performance status (p = 0.05), and higher serum alkaline phosphatase (p <0.02) and urinary deoxypyridoline (p <0.05) than their counterparts. Multivariate analysis revealed that only urinary deoxypyridinoline was independently associated with the onset of these events (p <0.02). The scatterplot of urinary deoxypyridinoline values in patients with and without skeletal complications enabled us to detect a cutoff of 38 pM./mM. for predicting 51% of skeletal events with only an 8% false-positive rate. Skeletal complications are common in patients with prostate cancer and hormone refractory disease. Bone loss is the major cause of onset. Baseline deoxypyridinoline at the cutoff point noted had moderate sensitivity but high specificity for predicting these adverse skeletal events.