The postmenopausal use of aromatase inhibitor (AI) on breast cancer patients, originally intended to prevent recurrence, raises the chance of fracture, a local study showed.

The National Health Insurance Service (NHIS) Ilsan Hospital recently unveiled the study, named “the fracture risk caused by anti-hormonal drugs in postmenopausal women with breast cancer.” The hospital used NHIS data for the study.

Although overseas studies have persistently raised the issue of AI-associated fracture risk in breast cancer patients, there have been no local study on South Koreans to point out the problem.

Aromatase inhibitors’ impact on bones (Credit: The National Health Insurance Service Ilsan Hospital)

The NHIS Ilsan Hospital’s research team analyzed data of 10,262 patients from 2002 to 2015.

The analysis showed that 5.42 percent of all the breast cancer patients had a vertebral fracture, 0.55 percent, a femoral fracture, 4.16 percent, an upper arm fracture, and 0.4 percent, a tibia fracture. About 7.3 percent of the total patients had a broken bone.

On average, a breast patient suffered a broken bone in 1,085 days or 2.97 years.

Among the breast cancer patients, those who took AIs had a 12.3 percent higher incidence of fracture than those who did not. In the case of upper arm fracture, the former group had a 24.3 percent more chance of breaking bones than the latter.

The patients who took AIs more than three years had 3.94-times higher odds of a fracture than those whose intake of AIs were less than a year. The former group showed 3.67-times higher probability of a vertebral fracture, 1.05-times more of a femoral fracture, and 3.8-times more of a tibia fracture.

Despite the broken bones, half (49.9 percent) of the patients who had a fracture did not receive a prescription for treating osteoporosis. Twelve percent of them never had a bone density test.

“Using AIs on postmenopausal women or young women who are menopausal due to chemotherapies and radiation therapies raises the chance of osteoporotic fracture,” the NHIS Ilsan Hospital’s research team said. “In this study, we concluded that the fracture incidence was higher in patients who took AIs. The longer they took, the higher the incidence went up.”

The research team noted that only 57 percent of the breast cancer patients had a bone density examination, and their cure rate was low at 35 percent.

The researchers advised that the breast cancer patients receive a bone density test for bone strength assessment, before starting chemotherapy and endocrine therapy. To prevent a fracture for patients who should take AIs, they need drugs such as a bone resorption inhibitor, the researchers said.

“After a diagnosis of breast cancer, it is important to have a proper bone density testing to use osteoporosis treatments such as bisphosphonates and to prevent fractures,” the research team said.

The team also called for active policy support to ease the social and economic burden caused by fractures.

“Such policy could include an expansion of bone density tests and broader insurance reimbursements for osteoporosis treatments,” it said.

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