Prostate cancer is a malignant disease that affects a man’s reproductive system. The disease occurs when the cells in the prostate start to grow out of control, affecting both the reproductive and urinary systems. The prostate is a gland below the bladder, near the rectum and around the urethra. It is partially responsible for the production of a fluid that is expelled with the sperm during ejaculation, making the semen more liquid.
The symptoms of prostate cancer include urinary problems such as a slow or weak urinary stream and the need to urinate frequently (especially at night), blood in the urine, erectile dysfunction, pain in the hips, back (spine), chest (ribs), or other areas when the cancer spreads to bones. It also can cause weakness or numbness in the legs or feet, or even loss of bladder or bowel control from the cancerous tumor pressing on the spinal cord. There are numerous options for treatment, depending on how far the disease has progressed and patients’ individual circumstances.
Bisphosphonate Therapy for Patients with Prostate Cancer
“Bone is the most common, and frequently the only, site for prostate cancer metastases; bone metastases occur in 80% of men with advanced prostate cancer. Bone metastases result in substantial morbidity, including pain, spinal cord compression, and pathologic fractures,” explain the authors of the study “Bisphosphonates in Metastatic Prostate Cancer,” regarding the evolution and spread of the disease. While the standard course of treatment in these cases is hormonal therapy, in 70% to 80% of the cases it becomes ineffective. Bisphosphonate therapy is indicated particularly for these cases.
Bisphosphonates, or bisphosphonates therapy, refers to a category of drugs that work by slowing a group of bone cells known as osteoclasts, which usually are responsible for breaking down the hard mineral structure of bones to help keep them healthy. However, osteoclasts may become overactive when prostate cancer spreads to the bones. The most common bisphosphonate drug in the U.S. is zoledronic acid (Zometa), which is administered intravenously. Other drugs are available. Bisphosphonates are known to help ease pain and high calcium levels caused by cancer metastasized to bones, as well as to slow the growth of the metastases and help delay or prevent fractures. In addition, bisphosphonates also may be used to strengthen the bones in men being treated with hormone therapy.
Benefits and Risks of Bisphosphonate Therapy in Prostate Cancer
“Bisphosphonates act predominantly by inhibiting bone-resorbing osteoclasts that are associated with the formation of osteolytic bone lesions. Prostate cancer is associated with osteoblastic (not osteoclastic) bone lesions that result in the deposition of calcium in new bone,” according to the authors of the aforementioned study. “The rationale for the use of bisphosphonates in the treatment of prostate cancer is that biochemical and histomorphometric studies have indicated that osteolysis may also be present in prostate cancer bone metastases,” said the investigators, who added that bisphosphonates decrease the level of pain and reduce the risk of skeletal events like pathologic fractures, hypercalcemia and the need for radiotherapy or surgery.
However, there are potential side effects from bisphosphonates therapy, the most common being flu-like symptoms and bone or joint pain. Patients with poor kidney function also may experience kidney problems. The American Cancer Society notes that “a rare but very serious side effect of bisphosphonates is osteonecrosis of the jaw (ONJ),” which consists of the loss of blood supply to part of the jaw bones. “This can lead to tooth loss and infections or open sores of the jaw bone that are hard to treat. Some people develop ONJ after dental work (such as having a tooth pulled) is done while on this medicine.”
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