Bone Loss and Prostate Cancer Treatment
Men treated with hormone therapy for advanced prostate cancer are at high risk for developing osteoporosisfragile bones due to loss of bone mineral density. Adding to this risk, prostate cancer tends to spread to the bones and weaken them. When that happens, the cancer is typically treated with androgen-deprivation therapy, which further contributes to bone loss because androgens help maintain bone density in men.
Research suggests that men can lose 2 to 6 percent of their bone mineral density in the first year of androgen-deprivation therapy. Bone loss continues in the second year but at a much slower rate. Bone loss can result in painful fractures and falls, loss of mobility and independence, and a reduced quality of life.
Men with other osteoporosis risk factors are at greater risk for complications. General risk factors for osteoporosis include white race, thin build, lack of weight-bearing exercise, cigarette smoking, and alcohol consumption. To detect osteoporosis early, men with advanced prostate cancer should undergo regular bone-density screening with dual-energy x-ray absorptiometry (DEXA) scanning.
What you can do about androgen deprivation therapy's double-edged sword
It seems unfair that trying to treat your prostate cancer can make you vulnerable to bone loss and fractures, but that's exactly what could happen with long-term hormone therapy. Also known as androgen deprivation therapy, or ADT, hormone therapy reduces levels of testosterone and estrogen, both of which help maintain bone density in men. Although not all men using ADT will develop osteoporosis (bone loss), an estimated 50 percent will be affected by their fourth year of treatment, and more than 80 percent will be affected after 10 years.
Using ADT for a year or more increases fracture risk as well. A 2005 study in The New England Journal of Medicine reported that among men with prostate cancer who lived for at least five years after their diagnosis, the risk of a fracture was nearly 20 percent among ADT users, compared with 13 percent for nonusers.
As the use of long-term ADT broadens to include some cancers confined to the prostate (not just those that have metastasized) even more men will be at increased risk for osteoporosis and broken bonesproblems that can cause pain and loss of mobility, reduced quality of life, and even death. The good news is that medication and lifestyle measures can help increase the strength of your bones, although you'll need to undergo periodic monitoring.
How Are Your Bones Doing?
A bone mineral density (BMD) test is the best way to learn about the health of your bones. It can show whether you have osteoporosis or are prone to fractures and how well your bones are responding to any osteoporosis drugs you may be taking. The most widely used BMD test is dual-energy x-ray absorptiometry (DXA). It takes 20 minutes and uses two x-ray beams to scan your bones for signs of bone loss.
The results are expressed as a T-score. A score of -1 or above is considered normal, and a score of -2.5 or below indicates osteoporosis. A score between -1 and -2.5 is called osteopeniameaning you have lower-than-normal bone density, but it is not severe enough to be labeled as osteoporosis.
To help keep an eye on your T-score, prostate cancer experts recommend a BMD assessment before beginning treatment with ADT. If your T-score is -1 or higher, you can wait two years before the next test. However, if your score is less than -1, you should have another BMD test in six to 12 months.