Prostate Cancer

Erica Heilman

When prostate cancer spreads, or metastasizes, its destination site is nearly always bone. The majority of men with prostate cancer that spreads outside of the prostate eventually experience bone metastases, and though cancer in the bone introduces the risk of fracture, spinal compression and pain, it often goes unnoticed until malignancy is fairly well established.

These complications can be treated, however, and according to Dr. Paul Matthew of the MD Anderson Cancer Center in Texas, prevention of bone involvement in men with prostate cancer should be a routine part of cancer management. "Bone complications need to be anticipated, prevented and treated effectively in these patients," says Dr. Matthew. In the following interview, he discusses the risks of these complications, and methods of prevention and treatment.

Why do bone complications occur so often in men with prostate cancer?
They occur for a number of reasons. Principally they are the result of the disease itself; the vast majority of prostate cancers spread to bone. They can also be the result of treatment itself. The treatment of prostate cancer commonly involves the use of androgen deprivation therapy, which reduces the male hormone involved in the growth of prostate cancer. This is principally achieved through medical or surgical castration, which can reduce bone mass quite considerably. This reduction in bone mass can lead to osteoporosis, which is another potential bone complication of prostate cancer.

What are the main risks of these complications in the bone?
The main risks are pain and disability. If bones are weakened, they are more prone to fracture. The location of the metastases can determine fracture risk. If there's a metastasis in a weight-bearing bone such as the femur, for example, this bone might be more prone to fracture than others.

Additionally, if the cancer is in the spine and it presses on the spinal cord, this can result in spinal cord compression, which can result in significant disability, such as paralysis. So these are important complications.

What are the goals of therapy for bone involvement?
The goal is to prevent bone complications if possible, and treat them when they occur. I think the physician in charge of a patient with prostate cancer first has to be sensitive to the possibility of these complications, and aware of the early signs of such complications.

For example, pain is a common warning sign of an impending complication in bone. If pain is coming from a weight-bearing bone, it could be a sign that fracture is imminent. If it's back pain, it could be a sign that spinal cord compression is imminent. And this would require specific diagnostic tests such as X-rays or bone scans or MRIs, to define this risk and intervene accordingly.

How is radiation therapy utilized to treat bone complications?
Radiation therapy is generally reserved for patients who have painful metastases to bone that are threatening to cause fracture or a spinal cord compression. In patients who have cord compression already, radiation can be very valuable in arresting and reversing potential neurological complications.

The traditional form of radiation therapy is external-beam radiation, in which X-ray treatment is delivered from outside the body, through the skin, directly to the area of affected bone. There are other forms of radiation therapy, such as radionuclide pharmaceuticals (usually injected into a vein) that hone in on bone specifically. These medications are useful when a patient has many bone metastases, when external-beam radiation alone cannot sufficiently treat them all.

When is surgery appropriate therapy for people with bone complications?
Surgery has a selected role in the treatment of bone complications and is basically reserved for patients who have impending fractures that cannot be addressed with radiation therapy alone. It can also be used to stabilize bone in patients who have had a fracture or spinal cord compression, taking pressure off the spinal column.

What role does pain medication play in these patients?
Bone pain can be very painful, and pain medications form the centerpiece of managing any patient with cancer-related pain, whether it's from bone complications or otherwise. It's important that physicians and patients be aware that there are ways to relieve pain in over 90% of the cases with medication, as an adjunct to other therapies, such as radiation treatment.

What are bisphosphonates and what role do they play in treating bone complications?
Bisphosphonates are medications that actually slow or stop the deterioration of bone and progression to osteoporosis. Their benefit has been clearly demonstrated in dealing with the osteoporotic complications of androgen deprivation treatment that's used early in the management of prostate cancer patients.

Studies have shown that patients who receive this drug have a lower rate of fractures, spinal cord compression and bone pain. This has not translated yet into an overall survival benefit, which is really what we would like to see, but clearly it has an important effect that we look forward to learning more about.

How will treatment of bone complications improve the outcome of people living with prostate cancer?
I think there is a specific opportunity in this disease simply because 90% of patients with prostate cancer (that spreads outside of the prostate) have bone metastases. So it's clear that the bone involvement determines how sick patients get as well as determining their mortality. A better understanding of the physiology of cancer in bone will lead to better therapeutics that may help to improve the outcome of people living with the disease.

What advice do you have for patients with prostate cancer?
I think anybody with a diagnosis of cancer—and prostate cancer in particular—needs to be aware that pain is a warning sign and must be paid close attention to. It's easy to ignore pain and call it arthritis or a strained back. We have seen too many patients who have ignored such symptoms or dismissed them and have come in with serious, irreversible bone complications.

I think it's important for patients to communicate such symptoms to their physicians promptly and ask them about what effective measures there may be to treat them. Certainly pain relief is available for virtually every single patient. And radiation, surgery, and bisphosphonates are all important and effective components in the treatment of bone complications of prostate cancer.

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