Risedronate, better known by the brand name Actonel, is effective for maintaining or improving the bone strength of women who have had chemotherapy for breast cancer, researchers report.

They explain in the Journal of Clinical Oncology that add-on chemotherapy has prolonged survival for women with breast cancer. However, chemotherapy brings on early menopause, which leads to the bone-thinning disease osteoporosis and to bone fractures.

To investigate the usefulness of risedronate in combating these effects, Dr. Susan L. Greenspan of the University of Pittsburgh and colleagues assigned 87 women who had undergone chemotherapy to take risedronate or a placebo once a week.

Many of the women in the study were also taking a so-called aromatase inhibitor such as letrozole to reduce the odds of a cancer relapse, and this made a difference to bone density.

For example, by the end of the 24-month study, women in the placebo group had a significant reduction in bone density of 4.8 percent at the spine and 2.8 percent at the hip if they were on an aromatase inhibitor. Those in the placebo group who were not taking an aromatase inhibitor maintained bone density at the spine, but had a significant 1.2 percent loss at the hip.

For women given risedronate, spine bone density fell by 2.4 percent and remained stable at the hip if they were also taking an aromatase inhibitor. The greatest improvement was seen in women on risedronate who were not taking an aromatase inhibitor: spine bone density rose by 2.1 percent and there was a 2.2 percent increase at the hip.

Risedronate “proved to be effective with or without the use of an aromatase inhibitor,” Greenspan and her colleagues conclude.

Further studies, they add, are needed to see whether these improvements in bone density “translate to fracture reduction for these patients.”

SOURCE: Journal of Clinical Oncology, June 1, 2008.