Bothersome Bones

CURE, Fall 2013, Volume 12, Issue 3

Loss of bone density doesn’t have to be a secondary casualty of cancer.

In a healthy body, bones are constantly repaired and renewed, a process known as remodeling. But if something happens to interfere with that process—such as cancer or the treatment of cancer—bones can become porous and lose mass, leading to fractures and collapse.

CAUSES > Causes of cancer-related bone loss include:

Metastasis: This occurs when cancer spreads to the bone. Someone with breast cancer, for example, could have breast cancer cells replicating in bone.

Bone cancer: Cancers, such as osteosarcoma, multiple myeloma, chondrosarcoma and the Ewing sarcoma family of tumors, originate in the bone. According to the National Cancer Institute, however, primary bone cancers are relatively rare.

Cancer treatments: Certain types of chemotherapy, hormone therapy and radiation therapy are known to reduce bone density, including methotrexate, cyclophosphamide, ifosfamide, doxorubicin and aromatase inhibitors used as hormone therapy. Corticosteroids used for lymphomas, as well as part of supportive care, can also lead to bone loss.

Gender: Women have a high risk of osteoporosis. Furthermore, premature ovarian failure that results from cancers, such as breast and ovarian cancers, and certain chemotherapy and radiation treatments, can lead to early menopause, a lack of bone-supporting hormones and a loss of bone density.

Hormones: Some hormone therapy for breast and prostate cancers can reduce estrogen levels (among women) or testosterone levels (among men). These treatments, known as hormone ablation therapy, can accelerate osteoporosis.

Genetics and lifestyle: A family history of osteoporosis, as well as a sedentary lifestyle, thin body shape as well as smoking, drinking and poor nutrition can also contribute to loss of bone density.

SYMPTOMS > People with bone cancer will exhibit symptoms, such as bone pain, high levels of calcium, kidney failure and anemia-related fatigue. But bone loss among patients with secondary cancer, as well as among patients undergoing treatment, can be more difficult to pinpoint. Many times, bone loss isn’t discovered unless—and until—a patient suffers a fracture.

Because bone loss is not easily detected, it’s best for patients to be proactive.

MANAGEMENT > Bone mass can be tracked with a Dual Energy X-ray Absorptiometry (DEXA) scan. It can be performed before, during and after cancer treatment. This helps generate a baseline against which future scans can be measured. Other proactive measures include:

Adequate calcium and vitamin D intake: High-calcium foods such as green, leafy vegetables, cheese and yogurt can promote bone health, as can foods with vitamin D. Patients at risk for bone loss should be prescribed calcium and vitamin D supplements.

Weight-bearing exercise: Walking, dancing and stair climbing puts stress on bones. This, in turn, triggers the body to make more cells that form bone. Regular exercise also builds muscle.

Bone-strengthening medications: Bisphosphonates (medications that slow the rate of bone loss) can help reduce damage and promote healing. Other helpful medications include Xgeva (denosumab); selective estrogen receptor modulators, such as raloxifene, tamoxifen, toremifene, calcitonin and recombinant parathyroid hormone (teriparatide). Note that bisphosphonates and Xgeva are associated with osteonecrosis (bone death) of the jaw, although this is primarily seen in patients receiving more frequent treatment for bone metastases as opposed to lower doses used just for bone thinning.