The Management of Bone Loss in Breast Cancer Survivors

We have spoken of the side effects of breast cancer treatment many times before, but bone loss is a common problem even for those who don't have cancer. Breast cancer survivors are at elevated risk due to the use of aromatase inhibitors (AI) after treatment. They can lose bone mineral at a rate of 5-21 percent over the first two years of chemotherapy.¹ A recent article in the American Journal of Nurse Practitioners discusses the risk factors, assessment, and practical prevention recommendations particularly focused on cancer survivors.

Selecting a specific adjuvant endocrine therapy depends on many factors, such as tumor receptibility, risk/benefit profile, and survival outcomes. Clinical trials have noted substantial bone loss over a course of treatment that lasts five or more years. Fracture rates are three times as high with AI or Tamoxifen use. The benefits of this therapy may outweigh this risk, but cancer patients must be monitored more closely, especially during the survivorship years. Here is a simple assessment of DEXA T-scores.

WHO T-Score Definition⁴

T-Score	Definition
-1.0 or higher	Normal
-1.0 to -2.5	Osteopenia
-2.5 or lower	Osteoporosis

As oncology nurses, one of our major strengths is in patient education. Patients should be managed with sequential bone density examinations, daily calcium and vitamin D supplementation, and weight-bearing/aerobic exercise as tolerated. Encouragement from us and consulting with a physical therapist before the start of any exercise program will help with compliance and avoid unnecessary injuries.

Other risk factors in postmenopausal breast cancer survivors that warrant bone mineral density testing include:

• Induced menopause by surgery, chemotherapy, or prolonged ovarian suppression
• Age over 50
• A fragility fracture after menopause onset or known secondary cause of bone loss
• Smoking
• Rheumatoid arthritis
• Alcohol consumption of two or more units/day
• Endocrine therapy with an AI

When planning for survivorship, a multidisciplinary approach is best to address the persistent late effects many of our patients may face. A proactive approach on the part of the patient and awareness of the team can go a long way toward preventing serious long-term consequences.

Does your cancer center provide a specific followup clinic for survivors, or does someone from the cancer team take control of long-term followup recommendations? We are exploring these now ourselves.

References:

1. Knobf, MT, Visinski, S. Managing bone health in breast cancer survivors. The American Journal for Nurse Practitioners 2012; 16(7/8):6-11.
2. Neuner JM, Yen TW, et al. Fracture risk and adjuvant hormonal therapy among a population based cohort of older female breast cancer patients Osteoporos Int. 2011; 22:2847-2855.
3. Burstein, HJ, Prestrud AA, et al. American Society of Clinical Oncology Clinical Practice Guidelines: update on adjuvant endocrine therapy for women with hormone receptor-positive breast cancer. J Clin Oncol. 2010;28(3): 3784-3796.
4. North American Menopause Society: Management of Osteoporosis in post menopausal women: 2010 position statement of the North American Menopause Society. Menopause. 2010;17(1):25-54.