Gynecomastia Extension Study

An OptioExtension of Trial 1033US/0006 to Assess Safety, Tolerability, Efficacy of Anastrozole (ZD1033, Arimidex™) in Treatment of Gynecomastia in Pubertal Boys Given Placebo and to Conduct a Long-Term Safety Follow-Up of Non-Responding Subjects Given Anastrozole in the Previous Trial

The purpose of this study is to look at the effect of anastrozole (ZD1033, Arimidex™) in reducing gynecomastia in pubertal boys treated with placebo in Trial 1033US/0006 (another anastrozole study).

Inclusion Criteria:

• Subjects must have entered Trial 1033US/0006 and completed 6 months of treatment and one month of follow-up.
• Subjects must have gynecomastia, with one breast measuring at least 3 cm in diameter.

Exclusion Criteria:

• Subjects who have been given medications known to cause gynecomastia within the previous 3 months