Breast Cancer Treatment Can Raise Osteoporosis Risk 54%, Review Finds
A review of 16 cohort studies covering almost 1.5 million people found that breast cancer survivors were 54 percent more likely to develop osteoporosis. Oncologists say the risk is real but should not stop patients from getting treatment.
Breast cancer treatment can weaken bones, and a systematic review published in Frontiers in Oncology found that people with a history of the disease were 54 percent more likely to develop osteoporosis than those who never had it.
They also had about a 50 percent higher risk of breaking a bone.
Researchers from the Henan University of Chinese Medicine analyzed 16 cohort studies that included almost 1.5 million participants. Osteoporosis is a condition marked by reduced bone density.
The result surprised no one in the field. "It's well known that treatments for breast cancer cause osteoporosis," said Dawn Hershman, deputy director of the Herbert Irving Comprehensive Cancer Center at Columbia University Medical Center.
She said the review "emphasizes that these are potentially ongoing issues for cancer survivors that they need to pay attention to."
Among individual treatments, the researchers found a higher osteoporosis risk in people taking aromatase inhibitors, a widely used class of drugs that lower estrogen levels. Results were less clear for chemotherapy and for tamoxifen, which blocks estrogen's effects on breast cancer cells.
About 8 in 10 breast cancers are hormone receptor-positive, meaning the cancer cells have receptors for estrogen, progesterone or both. Estrogen can help many of these cancers grow, so some treatments aim to reduce it.
That drop can also weaken bones, said Robert Coleman, emeritus professor of medical oncology at the University of Sheffield in England.
Before menopause, most estrogen comes from the ovaries, which doctors can temporarily suppress with medication. Chemotherapy can also disrupt ovarian function, and if the ovaries do not recover, menopause can start early.
Bone loss speeds up as estrogen falls around menopause, Hershman said. In women already past menopause, aromatase inhibitors can lower estrogen further and raise fracture risk.
Limits of the data
Hershman noted that the studies drew on data from 1998 to 2020, so the findings may not fully reflect current practice. In 2019, the American Society of Clinical Oncology published guidelines on managing osteoporosis and fracture risk in people with nonmetastatic cancer.
"In the current era, many, many women are screened for bone density" and receive advice on lowering their risk, Hershman said. "We don't know how many people are following those guidelines," she added, or whether they have helped bring down fracture rates.
Karen Daily, an oncologist and clinical professor at the University of Florida College of Medicine, stressed that the findings should not discourage anyone from being treated. The bone-loss risks are real, she said, but "they're offset by the benefits."
"Most patients don't experience a fracture from these treatments," Daily added.
