This is a phase three multicentre, double blind, randomize parallel group, placebo-controlled study in 250 men with histologically proven cancer without bone metastases who are beginning ADT therapy and who will receive a concomitant treatment with either oral Fosamax 70 mg once a weak (n=125) or placebo (n=125) for one year. Changes in BMD, markers of bone absorption and formation are monitored.