In the total population, the incidence of breast cancer is in the order of 2,5 per 1000 women per year from the age of 50. In a low risk population it is as low as 0,5 per 1000 women per year while in women with dense breast tissue on mammography it may be as high as 10 breast cancers per 1000 women per year. Treatment of women at risk at young age (18 – 30 years) with human chorionic gonadotropin (hCG) led to signficantly reduced occurrence of breast cancer. It was demonstrated that the hCG treatment induced similar genetic changes in the breast cells as occur during pregnancy while the treatment did not induce pregnancy related symptoms nor did it interfere with the endocrine system. Within this project a longer-acting hCG formulation will be developed to reduce the number of required injections.