He took bone biopsies of the fractured femur of 21 postmenopausal women who had been using bisphosphonates for an average of eight-and-a-half years. After analyzing the data, he found that mineral properties were reduced in the biopsied tissue by about 30 percent, which researchers believe contributes to the risk of these kinds of fractures. Essentially, the medication they say is changing the ability of the bone to remake, remodel and strengthen itself over time.

“What they found was that even though the study had limitations of small numbers and people were on the drugs for several different years that varied, they did find some specific changes they felt could account for the fractures,” Dr. Schneider says.

“It’s extremely validating,” she says.

Bone drugs may have other, important benefits

Complicating the picture for patients, other news in March 2010 has found that bisphosphonate drugs may reduce the risk breast cancer in patients who take them for more than two years.

In a study published in the British Journal of Cancer, researchers followed nearly 6,000 women between the ages of 20 and 69 in Wisconsin, half of whom had been diagnosed with invasive breast cancer.

They discovered that women who had taken bisphosphonates for more than two years saw a nearly 40 percent reduction in their risk for breast cancer.

“Definitely for women who use these drugs we observed about a one-third reduction in the risk of breast cancer,” says Polly Newcomb, PhD, the lead author and head of the Cancer Prevention Program at the Fred Hutchinson Cancer Research Center in Seattle.

Researchers don’t know exactly how these drugs are helping to prevent breast cancer, but previous research has shown that in addition to their effects on bone, bisphosphonates appear to speed the death of cancer cells.

The researchers note that women who were obese did not appear to get this benefit from the drugs, and they think that may be due to elevated estrogen levels in obese women, which increase cancer risk.

Weighing benefits and risks

So what are patients on bisphosphonates to do?

“These drugs are associated with some benefits and some risks, so certainly, you would never take these drugs to reduce your risk of breast cancer,” Dr. Newcomb says. “If other studies support this, then this might be a good side effect, but these drugs also have serious side effects, too.”

Dr. Rosenwasser agrees.

“My only recommendation is to discuss this with their doctor if they’ve been on it chronically. Not to stop it right away,” especially if you’re just getting started on the treatment, Dr. Rosenwasser says. 

“If you are diagnosed today and your doctor says to go on it, you should because this study doesn’t say anything bad happens to patients initiated on the drug. In fact, it’s the reverse. It helps. Short-term patients had good parameters.”