Researchers at Massachusetts General Hospital and the University of California San Francisco are developing a new drug that could stop the bone-thinning condition Osteoporosis and trigger the re-growth of strong bone tissue. This news is an important advance in women’s health, as 8 million women–mostly women over 50–suffer from Osteoporosis, and millions more are at risk. Post-menopausal women suffer from Osteoporosis most frequently because of lower levels of estrogen. Estrogen is crucial in maintaining bone growth, and decreased levels of this hormone during and after menopause contribute to bone thinning and weakness. Critics of this treatment of osteoporosis point out that one study had to be stopped early because lab rats receiving high dosages of the medication developed bone cancers; however, humans participating in clinical studies showed no signs of cancer after receiving the drug. The Food and Drug Administration is expected to review the drug this summer.