Disclosed is the use of a composition comprising degarelix in the manufacture of a medicament for the treatment of metastatic stage prostate cancer in a subject, wherein the subject has a baseline serum alkaline phosphatase (S-ALP) level of about 150IU/L or greater prior to treatment and wherein the subject shows a reduction below the baseline S-ALP level of at least 50IU/L. or greater for the period between about day 60 and day 364 of treatment.