Boston - A new estrogentype drug can strengthen bones and lower cholesterol for women who are past menopause. But the drug, raloxifene, does not control hot flashes or vaginal bleeding, according to research appearing in yesterday's New England Journal of Medicine. The study of 601 women used one of the new "designer estrogen" drugs developed as a substitute for the female hormone, estrogen. Because estrogen therapy can increase the risk of breast cancer by nearly 50 per cent, only about 20 per cent of the women who could benefit from it take it.