Breast cancer survivors may be at higher risk for falls

TORONTO - Breast cancer treatment may have an adverse effect on survivors of the disease by putting them at greater risk for falls, research suggests.

For the small study, U.S. researchers looked at 59 postmenopausal breast cancer survivors. Study participants were on average 58 years old and had either recently finished chemotherapy or were on an adjuvant endocrine therapy.

For some women, chemotherapy can cause a small but significant amount of bone loss over the course of treatment. Adjuvant hormonal therapies have been found to accelerate bone loss and contribute to higher fracture risk.

Researchers from Oregon Health & Science University in Portland surveyed the prevalence of falls among participants within the previous year and then tracked their falls over the following six-month study period.

Findings to be published in the April issue of the Archives of Physical Medicine and Rehabilitation showed 58 per cent of breast cancer survivors had experienced a fall in the previous year, with half reporting they fell more than once.

Nearly half, or 47 per cent, fell within six months after joining the study, a rate nearly double the 25 to 30 per cent annual fall rate reported for community-dwelling older adults over the age of 65.

Researchers found 76 per cent of breast cancer survivors reported falling after their cancer diagnosis within the 18-month span.

Study lead author Kerri Winters-Stone said for the past five or 10 years, there has been increasing evidence that breast cancer survivors may be at higher risk for bone fractures compared to those who haven't had the disease.

There has been research trying to understand how bone loss might be accelerated in women who have breast cancer and how that might contribute to fractures. However, there's been a lot less attention paid to falls as a potential risk factor for these increased fractures, she noted.

Winters-Stone said her research team was interested in trying to understand more about why falls may increase in women with breast cancer.

After asking participants about their fall history, they were taken through a series of physical tests to determine if they were at increased risk for falls. They included tests of muscular strength and balance.

Winters-Stone said researchers found one particular balance test discriminated between women who had and had not fallen. The test measured their ability to balance on a platform in conditions in which the only sensory system keeping their balance in check was the vestibular, or inner ear, system.

"In this particular test, women with a history of falls didn't do as well when they were required to maintain their balance with only input from their vestibular system," said Winters-Stone, an associate professor and associate scientist at the university's school of nursing and a member of the Knight Cancer Institute.

"That suggested to us there may be some deficit in the control of balance of this particular physiological system," she said in an interview from Portland.

She said women who took longer to identify differences in contrast in a visual contrast-sensitivity test were also more likely to have a history of falls. There may be something about their visual processing speed that had changed following cancer treatment that might cause this increased risk, she said.

Winters-Stone said women should be aware that there might be changes that occur as a result of chemotherapy that could affect their balance.

As they progress through treatment, they shouldn't ignore changes in balance they sense or merely attribute such changes to growing older, she noted.

"I don't think that women have to be fearful of falling, particularly since what that tends to do is cause them to restrict their activity, and we actually want women to remain as active as they can both during and after cancer treatment," she said.

"I think that women should also take note of any changes that they sense in their stability and their balance, discuss it with their oncologist and also be proactive about taking some steps to maintain balance during treatment as well as after."