Breast Cancer Survivors Are at High Risk for Osteoporosis

PONTE VEDRA BEACH, Fla—Eighty percent of breast cancer survivors were found to have osteoporosis or osteopenia at the outset of a University of Nebraska Medical Center College of Nursing pilot study into preventing osteoporosis among survivors.

Although breast cancer survivors are known to be at increased risk for osteoporosis, the number with measurable bone loss was a surprise, according to two researchers who presented preliminary findings at the Oncology Nursing Society’s Sixth National Conference on Cancer Nursing Research.

Only 13 of the 30 postmenopausal participants had been screened for bone loss before entering the feasibility study, which is testing whether breast cancer survivors will comply with a regimen of weight training and medication.

Nancy L. Walt-man, PhD, ARNP; Carol D. Ott, RN, PhD, OCN; and their team of investigators at the University of Nebraska Medical Center College of Nursing are looking for alternatives to hormone replacement therapy (HRT) as an intervention for these women, who generally cannot take HRT (see related article).

Six of the initial subjects had osteoporosis and 18 had osteopenia. Yet most had no idea that they had reason to be concerned about osteoporosis, according to Dr. Ott, assistant professor at the college’s Kearny campus. "They really hadn’t realized that they were at risk because they had gone into menopause early," she told ONI in an interview.

Dr. Ott reported that the women, ages 42 to 65, also had less muscle strength than expected for their age groups, and that muscle strength corresponded to bone density. "If muscle strength was low, bone density was low," she said.

The researchers did not have data on muscle strength for healthy women the age of the participants, but found that the breast cancer survivors had less than half the mean muscle strength of younger adults. Normal loss would have been 10% to 20%, Dr. Ott said. "These women came to us pretty deconditioned," she added.

Preventive Regimen

The full regimen includes home-based strength/weight exercises (see Figure), calcium, vitamin D, and alendronate (Fosamax), a bisphosphonate used for the treatment and prevention of osteoporosis. The women had to do eight different exercises—three arm exercises, three leg exercises, and two balance exercises—twice a week. They received education about the disorder, coaching, and feedback in monthly home visits and telephone calls.

Another 11 survivors were recruited for a control group that did not do the exercises. This group has dropped to 7 women, and was actually more difficult to recruit, Dr. Ott said, because the project did not have funds to pay for their alendronate, which costs about $60 per month.

Six months into the study, 24 of the original 30 women were still complying with the full regimen, said Dr. Waltman, associate professor at the campus in Lincoln. Adherence hovered around 96%, and none of the women who dropped out of the trial were dissatisfied with the intervention. Their reasons included the cost of alendronate, personal reasons, a recurrence of breast cancer, and normal bone density in the initial testing.

Retesting found that the regimen was paying off for those who stuck with it. At 6 months, bone mass density improved from 0.85 to 0.86 g/cm² for the hip and from 0.96 to 0.97 g/cm² for the spine. Bone mass density in the forearm declined, however, from 0.52 to 0.49 g/cm². The researchers are adding more exercises for the wrist and forearm to be performed with heavier weights.

Along with increased bone density came increased muscle strength and balance, Dr. Ott said. On a simple tandem balance test—how fast the person can walk backwards for 20 feet—the experimental group went from 13 seconds to 10 seconds in the first 2 months. The balance component is important, she emphasized, because preventing falls can prevent fractures.

While the project so far has shown that breast cancer survivors can and will do weight-training exercises, the investigators are concerned that many of the women seem to be content to increase their weights from 5 lb to 8 or 10 lb and then plateau, rather than advance to 20 lb, at which point they would go on to exercise machines.

"We have found that many didn’t increase their weights fast enough and high enough, and need to be pushed to keep increasing the weights," Dr. Ott said.

The project will finish collecting 12-month results in September, after which the researchers hope to go on to a larger study.

The funding sources for the study are the Oncology Nursing Foundation, Regional West Medical Center Foundation, American Nurses Foundation, and Sigma Theta Tau International.