Metastatic prostate carcinoma to bone: Clinical and pathologic features associated with cancer-specific survival

BACKGROUND. The objective of this study was to examine the clinical and pathologic features of metastatic prostate carcinoma to bone in a large cohort of men, and the associations of these features with outcome. METHODS. Sixty-eight men who underwent surgery for metastatic prostate carcinoma to bone for stabilization of a pathologic fracture or impending fracture were studied. Clinical characteristics included the type of treatment for the primary and metastatic prostate carcinoma, age and serum prostate specific antigen (PSA) at the diagnosis of the metastatic prostate carcinoma, radiographic findings of the metastasis (osteoblastic, osteolytic, or mixed), and the number of metastatic sites at the time of the surgery for the metastasis. Pathologic features examined included Gleason score of the metastatic prostate carcinoma. Immunohistochemical stains for MIB-1, cytokeratin, PSA, synaptophysin, chromogranin A, serotonin, estrogen receptor, progesterone receptor, and androgen receptor were performed for all cases. The Kaplan-Meier method was used to estimate cancer-specific survival. The duration of follow-up was defined as the interval from the date of surgery for the metastasis to the date of death or last follow-up. Univariate and multivariate Cox proportional hazards models were fit to assess the features that were associated with death from prostate carcinoma. RESULTS. The average (standard deviation) time from the surgery for the metastasis to death from prostate carcinoma was 1.5 (1.9) years, ranging from 0 days to 10 years, with a median of 1 year. The estimated cancer-specific survival rates at 1 year, 2 years, and 3 years were 54.3%, 28.8%, and 22.9%, respectively. Median cancer-specific survival occurred at 1.1 years. After 4 years of follow-up, there were only seven patients left at risk for death from prostate carcinoma. Features that were found to be significantly associated with death from prostate carcinoma univariately included the interval between the diagnosis of metastasis and the surgery for metastasis (P < 0.001), androgen deprivation therapy before surgery for the metastasis (P = 0.002), presentation with metastasis (P = 0.003), the number of metastatic sites (P = 0.034), Gleason score of the metastasis (P = 0.002), and tumor positivity for chromogranin A (P = 0.041). On multivariate analysis, the interval between the diagnosis of metastasis and the surgery for metastasis (P < 0.001), Gleason score of the metastasis (P < 0.001), and tumor positivity for chromogranin A (P = 0.009) were associated significantly with death from prostate carcinoma. CONCLUSIONS. Although cancer-specific survival for patients after surgery for prostate carcinoma metastatic to bone is poor, assessments of tumor differentiation of the metastasis and chromogranin A positivity provide prognostic information.