Unexplained Bone Pain Is an Independent Risk Factor for Bone Metastases in Newly Diagnosed Prostate Cancer: A Prospective Study

OBJECTIVE: To determine the relationship between bone pain and bone metastases in newly diagnosed prostate cancer.

PATIENTS AND METHODS: This prospective study of bone scintigraphy enrolled 567 consecutive patients with newly diagnosed prostate cancer. The presence of all-cause bone pain, known benign bone disease, and unexplained bone pain (i.e., not related to known benign bone disease) was derived from a patient questionnaire. Univariate logistic regression models (LRMs) were used to assess the relationship between individual clinical variables (all-cause bone pain, unexplained bone pain, prostate-specific antigen [PSA], Gleason grade, T stage, and age) and bone metastases. A multivariate LRM was used to assess the relationship between bone metastases and all factors in combination. Agreement between the LRMs and bone metastases was estimated by accuracy and by Cohen's κ.

RESULTS: All-cause bone pain predicted bone metastasis in univariate but not multivariate analysis. Unexplained bone pain remained an independent predictor of bone metastases in multivariate analysis (odds ratio: 4.5; p < 0.001). PSA was the single most important predictor of bone metastases (p < 0.001).

CONCLUSIONS: Unexplained bone pain was a strong independent risk factor for bone metastasis. Guidelines should recommend staging bone scintigraphy in patients with unexplained bone pain, regardless of other risk factors.