Breast cancer is a disease that occurs when the cells in the breast start to grow out of control. The breast is composed of lobules that produce milk, ducts that transport it and stroma, which includes fatty and connective tissue around the ducts, lobules, blood vessels, and lymphatic vessels. Breast cancer can affect any part of the breast, causing symptoms like a new breast lump or mass, swelling of all or part of a breast, skin irritation or dimpling, breast or nipple pain, nipple retraction, redness, scaliness, or thickening of the nipple or breast skin, and nipple discharge other than breast milk. The most common type of breast cancer is ductal carcinoma, which begins in the ducts.

The disease is diagnosed in about 291,000 women annually in the U.S., according to the estimates from the American Breast Cancer Foundation. And there are some 2,350 new cases of men with breast cancer every year. Despite the high incidence of the disease, there are treatment options. Local treatments are meant to treat the cancer without affecting the rest of the body and include surgery and radiation therapy, while systemic treatments, like chemotherapy, hormone therapy, targeted therapy, and bone-directed therapy, are focused on the use of drugs to reach cancer cells anywhere in the body.

Breast Cancer Treatment Using Bone-directed Therapy

Bone-directed therapy is used particularly in breast cancer patients when the malignant disease has spread to the bones, causing pain, bone weakening and fractures, and other problems. This type of treatment consists of the use of one of two drugs — bisphosphonates or denosumab. It may be prescribed to either female or male patients. Bisphosphonates are drugs administered intravenously to strengthen the bones and decrease the probability of fractures and pain related to metastatic breast cancer. The bisphosphonates approved by the U.S. FDA for this use include pamidronate (Aredia) and zoledronic acid (Zometa).

These drugs can also be prescribed to breast cancer patients who suffer from osteoporosis as a consequence of treatment with aromatase inhibitors or from early menopause as a side effect of chemotherapy. Denosumab works differently from bisphosphonates, but has the same effect in decreasing the risks associated with metastasized breast cancer to the bone. It is the generic name of the drug, which is commercialized under the brand names Xgeva and Prolia.

“In studies of patients with breast cancer that had spread to the bone, it seemed to help prevent problems like fractures (breaks) better than zoledronic acid. It also can help bones even after bisphosphonates stop working,” according to the American Cancer Society website. “In patients with cancer spread to bones, this drug is injected under the skin every four weeks.”

Benefits and Risks of Bone-directed Therapy for Breast Cancer

“Bone is the most common site for distant spread of breast cancer. Following a diagnosis of metastatic bone disease, patients can suffer from significant morbidity because of pain and skeletal-related events (sres). Bisphosphonates are potent inhibitors of osteoclastic function and the mainstay of bone-directed therapy for bone metastases,” wrote the authors of the study “A primer of bone metastases management in breast cancer patients,” about the benefits of bone-directed therapy. “Randomized controlled trials have shown that the beneficial effects of bisphosphonates are time-dependent; significant benefits were seen only after six months of treatment.”

There are potential side effects of bone-directed therapy. For bisphosphonates, these include flu-like symptoms and bone pain, while kidney problems, or osteonecrosis (damage) in the jaw bones (ONJ) can also occur, but are rare.

With denosumab, the treatment may result in side effects like low blood levels of calcium, phosphate, and ONJ, but there is no evidence that denosumab affects the kidneys. One of the main drawback associated with bone-directed therapy is that patients usually need to take medication for years, which usually means they need to go to the hospital for intravenous treatment.

Note: Breast Cancer News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.