Clinical Implications of Tumor Size and Local Extent of Primary Prostatic Lesions in Prostate Cancer Patients with Metastases: Value of Endorectal Magnetic Resonance Imaging in Patients with Metastases

Objectives: To investigate the clinical significance of local assessment by endorectal magnetic resonance imaging (MRI) in prostate cancer patients with metastases. Methods: The local extent and tumor size were determined by endorectal MRI in 95 prostate cancer patients with metastases, and their clinical implications were assessed. Results: The maximum diameter and tumor volume significantly correlated with the local extent of disease but not with extent of disease (EOD) on bone scan. In univariate analyses, EOD, serum prostate-specific antigen level, serum alkaline phosphatase level, and hemoglobin level were significantly associated with disease-specific survival, whereas tumor size and local extent of primary lesions were not. In a multivariate analysis EOD on bone scan was a significant prognostic factor. Conclusions: Tumor size and local extent of the primary lesion estimated by endorectal MRI were not associated with disease-specific survival. Assessment of the primary lesion by endorectal MRI is of limited value in predicting the prognosis of prostate cancer patients with metastases.