Prognosis of patients with prostate cancer and bone metastasis from the Japanese Prostatic Cancer Registry of Standard Hormonal and Chemotherapy Using Bone Scan Index cohort study

Abstract

Objective: To determine prognostic factors including the Bone Scan Index in prostate cancer patients receiving standard hormonal therapy and chemotherapy.

Methods: This multicenter Prostatic Cancer Registry of Standard Hormonal and Chemotherapy Using Bone Scan Index study involved 30 hospitals and enrolled 247 patients (age 71 ± 8 years) with metastatic hormone-sensitive prostate cancer (n = 148) under hormone therapy and metastatic castration-resistant prostate cancer (n = 99) under chemotherapy. The Bone Scan Index (%) was determined by whole-body bone scintigraphy using ^99m Tc-methylenediphosphonate. Patients were classified into tertiles and binary groups, and predictors of all-cause death including Bone Scan Index, prostate-specific antigen, and bone metabolic markers were determined using survival and proportional hazard analyses.

Results: During a mean follow-up period of 716 ± 404 days, 81 (33%) of the patients died, and 3-year mortality rates were 20% and 52% in the metastatic hormone-sensitive prostate cancer and metastatic castration-resistant prostate cancer groups, respectively. Survival analysis showed that a Bone Scan Index >3.5% was a significant determinant of death in the metastatic hormone-sensitive prostate cancer group, whereas prostate-specific antigen >55 ng/mL before chemotherapy was a determinant of prognosis in the metastatic castration-resistant prostate cancer group. A Bone Scan Index >3.5% was also associated with a high incidence of prostate-specific antigen progression in the metastatic hormone-sensitive prostate cancer group. Patients with metastatic hormone-sensitive prostate cancer and a better Bone Scan Index response (>45%) to treatment had lower mortality rates than those without such response.

Conclusion: The Bone Scan Index and hot spot number are significant determinants of 3-year mortality, and combining the Bone Scan Index with prostate-specific antigen should contribute to the management of prostate cancer patients with bone metastasis.

Keywords: Bone Scan Index; castration-resistant prostate cancer; hormone-sensitive prostate cancer; multicenter study; survival analysis.