Balancing bone health and risk

Dear Dr. Roach: I just read your column about Fosamax and wondered what you thought about Evista (raloxifene). I have been on it for 13 or 14 years because both my sisters have had breast cancer and I have osteopenia. Is this something that can be taken indefinitely, or do I need to stop? My gynecologist says to keep taking it, but I wonder what you think. — B.I.

One major concern about long-term use of alendronate (Fosamax) and other drugs of that class (called bisphosphonates) is that they shut down reabsorption of the bone so completely that people are at risk for complications such as osteonecrosis of the jaw and atypical femur fractures. These complications are uncommon, and the benefit of taking the medication outweighs the risk in most women with osteoporosis; however, prolonged use may start to cause more harm than benefit, especially in women with mild or moderate osteoporosis.

Raloxifene, by contrast, works on the bone as an estrogen, while working on the breast as an anti-estrogen. In women with both low bone mass and increased risk for breast cancer, it is a good choice. Raloxifene is not as potent an agent as Fosamax, and that’s probably a good thing for you: With osteopenia, you do not need as potent an agent, and the risk of osteonecrosis of the jaw and of atypical femur fractures appears lower with raloxifene.

Raloxifene does have its own risks. Blood clots occurred in about one woman per thousand in the six years of the study. Less than one woman per thousand had a stroke in the raloxifene group per year. Those risks need to be compared against the benefit of both the breast cancer and bone benefits. For women at increased risk of breast cancer, the potential for benefit is usually much greater than the potential for harm.