The Food and Drug Administration said Thursday it will require changes in the labeling of a family of drugs used to treat benign prostate hyperplasia to indicate that the drugs increase the risk of developing a more aggressive form of prostate cancer. The family of drugs are called 5-alpha reductase inhibitors, or 5-ARIs, and includes finasteride ( Proscar) and dutasteride ( Avodart), as well as the hair-growth drug Propecia. Dutasteride is also sold in combination with tamsulosin under the brand name Jalyn. The drugs are also increasingly used as a preventive agent for men who are at high risk of developing prostate cancer, but they are not approved for that purpose. The drugs interfere with the production of male hormones, starving the tumors of nutrients they need to grow. For use in treating prostate cancer, the FDA said, the benefits of the drugs far outweigh the risks.