Table of Contents

Chapter 8: Managing Bone Metastases and Pain

b. Treating Bone Metastases

There are a few different kinds of treatments for prostate cancer bone metastases. Because they all work in different ways, your doctors might choose to use more than one in your treatment regimen. That doesn’t mean your metastases are harder to treat or that your prognosis is worse. All it means is that your doctors want to be sure that they will be able to help keep your bones as strong and healthy as possible.

Before beginning any treatment regimen for bone metastases, your doctors will likely discuss with you the importance of maintaining a healthy diet and lifestyle. They will want to ensure that you’re taking in adequate amounts of calcium and vitamin D, and that you’re exercising regularly. Even though none of these are treatments for bone metastases, they will all help you maintain strong bones and help to minimize bone loss and osteoporosis, which can make treating your bone metastases more challenging.

Men who experience pain from a bone metastasis will often be treated with radiation targeted directly to the metastasis. This will kill the prostate cancer cells that are sitting there and thereby relieve the pain. Note that the goal of radiation therapy that is used to treat bone metastases is completely unrelated to any radiation that you might or might not have received earlier in your prostate cancer treatment. Regardless of whether you had surgery, radiation, chemotherapy, or any other type of treatment up until now for your prostate cancer, radiation to the bones can be used to relieve the pain from bone metastases.

External beam radiation therapy uses x-rays to kill the cancer cells sitting in your bones. This type of treatment, sometimes referred to as spot radiation, is mapped out and planned very precisely by the radiation oncologist to ensure that the x-rays are targeting the metastasis and are not causing damage to the surrounding bone and muscle tissue. A procedure known as hemi-body radiation, which is used less frequently, targets much larger areas of the lower half of the body, which is where prostate cancer bone metastases more typically grow.

A somewhat different approach uses radiopharmaceuticals to target the bone metastases. These radioactive drugs, either samarium (Quadramet) or strontium (Metastron), are injected into your body through a vein and settle in the bone metastases, at which point they release radiation to the local area and kill the cancer cells. Researchers have shown that strontium can be very effective at relieving pain when used immediately after the chemotherapy drug doxorubicin (Adriamycin), so your doctors might decide to combine the two approaches in an attempt to give you the most relief possible.

External beam radiation therapy and radiopharmaceuticals are known as directed palliative treatments, meaning that they are used to relieve pain in a specific area of the body. Drugs known as bisphosphonates are systemic therapies that have been shown to relieve pain throughout the body and to slow the onset of complications from bone metastases in men with prostate cancer.

Under normal circumstances, bone cells are destroyed and created at a constant rate. Increasing the activity of osteoblasts, cells that form new bone cells, ultimately results in an overgrowth of bone tissue; increasing the activity of osteoclasts, cells that destroy bone cells, ultimately results in porous, brittle bone tissue. In men with prostate cancer bone metastases, both of these processes occur at faster than normal rates, leading to both an overgrowth of bone tissue and weakened and brittle bones. The combination of these two processes makes the bones unstable, and therefore prone to fracture.

Bisphosphonates are drugs that are designed to help reset the balance in the bone between bone growth and bone destruction. Zoledronic acid (Zometa) is a bisphosphonate given intravenously that can delay the onset of complications associated with prostate cancer bone metastases and relieve pain. It is typically given once every three weeks as a 15-minute infusion. Another intravenous bisphosphonate known as pamidronate (Aredia) is less frequently used, and has been shown to have limited benefit in this setting.

Many men feel flu-like symptoms after the first few infusions of zoledronic acid, including fatigue, nausea and vomiting, and generalized aches and pain, but they usually fade within a few days. Also, the drug can cause kidney problems in some men, so your doctor might take some blood before each infusion to make sure that your kidneys are working properly.

Finally, be sure to tell your dentist that you’re taking zoledronic acid before you have any sort of dental surgery. The bone tissue in your jaw can be affected by the drug, and removing a tooth or having some other kind of procedure that requires your dentist to cut into your jaw can cause some additional damage to the bone. Remember: It’s important that all of your doctors have a complete record of your medical history, especially a list of all medications and supplements that you might be taking, so they can know how best to help you.

Other bisphosphonates are sometimes used in men with prostate cancer to prevent or slow bone loss while taking hormone therapy. These drugs, alendronate (Fosamax) and risedronate (Actonel), are given in pill form, and are also used to counteract the bone loss of osteoporosis in postmenopausal women or in women who are taking hormone therapy for breast cancer. If another doctor started you on a bisphosphonate to help fight off bone loss from hormone therapy, be sure to tell your oncologist. It’s important that all of your doctors and nurses have a complete list of the medications you’re taking so they can know how best to help you.

Because bone metastases affect so many men with prostate cancer, researchers are working hard to find new therapies that can minimize the pain and complications resulting from the metastases. Most of these new drugs work by blocking the prostate cancer cells from interacting with the bone tissue, with the hope of slowing or preventing the development of bone metastases and thereby improving the outcomes in men with prostate cancer.