About 16% of younger, premenopausal women treated for early-stage breast cancer broke a bone during treatment or in the years after treatment ended according to a study. This fracture rate was 60% higher than expected based on earlier research results.
The results were presented at the 2011 International Conference on Cancer-Induced Bone Disease.
Common breast cancer treatments, including chemotherapy and hormonal therapy, can weaken bones and make it more likely that a woman will break a bone during or after breast cancer treatment. Treatment-related bone problems are especially an issue for postmenopausal women, whose bone health may be worsening because of menopause. Only a small number of premenopausal women will lose bone strength because of breast cancer treatment.
Researchers looked at the bone health and bone fracture records of 345 premenopausal women who had been treated for early-stage breast cancer. Fifty-six of the women (16%) broke a bone. The bones broke during treatment or up to 12 years after treatment (the average was a little more than 3.5 years after treatment). The most common places for bones to break were the spine (vertebrae), foot, wrist, and ankle.
During the course of their treatment all the women had a bone mineral density test, a common test to measure bone health. Osteoporosis is diagnosed when bones are below a certain density level. Osteoporosis increases the risk of breaking a bone either spontaneously or because of a fall. But the bone mineral density testing showed that only 8% of the 56 women who broke a bone had osteoporosis. Another 34% of the women had some bone weakening (osteopenia), but not enough to need treatment. More than 50% of the women who broke a bone had normal bone mineral density test results.
Earlier studies of fracture risk in premenopausal women treated for early-stage breast cancer found that about 10% of the women might break a bone during or after treatment. So the 16% figure was 60% higher than what was expected based on the earlier studies.
It's not clear why this study found such a high rate of broken bones, especially because most of the women had healthy bones based on a bone mineral density test. It's possible that other factors related to breast cancer diagnosis and treatment may be increasing the risk of breaking a bone in premenopausal women treated for breast cancer, even when bones appear to be healthy. Common bone strengthening medicines wouldn't be expected to help reduce bone fracture risk.
If you're a premenopausal woman being treated (or have been treated) for breast cancer, it's a good idea to ask your doctor how your treatment plan could affect your bone health. Also ask how your bone health will be monitored and steps you can take to keep your bones as strong as possible.
The Breastcancer.org Bone Health section has detailed information on how bone health is measured, how breast cancer treatments can affect bone health, and tips to keep your bones as strong as they can be.