Blocking Hormones To Treat Prostate Cancer
From Johns Hopkins Medical Letter - February 2008
Doctors diagnose 200,000 new cases of prostate cancer each year in the United States. While most of these cancers are caught before they spread, a substantial proportion of patients eventually develop advanced disease, which claims the lives of approximately 27,000 men annually.
To slow tumor growth, many doctors suppress the male hormone testosterone in their patients by prescribing androgen deprivation therapy (ADT). This suppression causes significant side effects, including impotence, osteoporosis, and heart disease. In fact, recent studies on ADT’s cardiovascular risks have made doctors rethink who should use this therapy.
But for men who have “x-ray evidence of metastatic cancer, the benefits outweight the risks,” explains H. Ballentine Carter, M.D., Professor of Medicine and Director of adult Urology at John Hopkins.
If your doctor recommends ADT, make sure to have a serious discussion about which kind of therapy you will use and what impact it will have on your body. Learning about ADT’s potential side effects — which are discussed below — and seeking coping strategies can protect your health and improve your quality of life during treatment.
Bone loss. Bone mass decreases throughout ADT; the most substantial losses occur during the first year of therapy. To reduce your risk of fracture, get your bone mineral density tested before starting ADT. Have it rechecked after each year you spend on the therapy.
Calcium and vitamin D help prevent bone loss, so talk to your doctor about supplements. All men under 65 should consume at least 1,000 mg of calcium everyday; if you’re older, take 1,500 mg. Men over 50 should take 800 IU of vitamin D. Strength training also helps maintain bone strength and muscle mass. And, of course, avoid smoking and excessive alcohol consumption.
However, lifestyle changes alone will not prevent all bone loss. Mario Eisenberger, M.D., R. Dale Hughes Professor of Oncology and Urology at John Hopkins, recommends bone-building medications called bisphophonates to patients who are at risk for osteoporosis. Dr. eisenberger gives quarterly infusion of Zometa (zoledronicacid) to men with bone metastases; preliminary data suggest once-a-year infusions may works as well. If cancer has not spread to the skeletion, your can use the oral bisphosponates Fosamax (alendronate), Boniva (ibandronate sodium), or Actonel (risedronate sodium).
Type 2 diabetes. A recent study at Johns Hopkins revealed that after just 3 months of treatment, men on ADT exhibited metabolic changes associated with type 2 diabetes. Their fat mass increased, and their cells became resistant to insulin. After a year of therapy, some patients developed hyperglycemia, the elevated blood sugar levels that define diabetes. Diabetes is a concern for several reason; It’s associated with heart disease, vision loss, and nerve damage; also, excess insulin (produced to compensate for insulin resistance) may actually stimulate tumor growth.
Dr. Carter urges, “Men should be screened for diabetes and cardiovascular disease and have their cholesterol checked long before they start on ADT so that those things can be addressed beforehand.” Blood sugar levels must be monitored throughout therapy. Making healthy food choices and exercising can keep your glucose in check, but these strategies may not suffice in the long run; your doctor may eventually prescribe diabetes medication.
Heart disease. New research reveals that without careful monitoring and preventive care, men over 66 who undergo ADT fro as little as 6 months are more likely to die of heart attacks than patients who do not receive the therapy. Fortunately, there are many ways to reduce your risk of cardiovascular disease, including diet and exercise. Your doctor may also recommend a cholesterol-lowering statin drug or daily aspirin.
Hot flashes. Exercising and eating well may reduce the incidence of hot flashes, which interfere with sleep. You can also try the antidepressant Effexor (venlafaxine) or the anticonvulsant Neurontin (gabapentin). Low doses of the female hormones estrogen and progesterone work best, but since prostate cancer is hormone sensitive, they are only used if hot flashes are severe.
Sexual dysfunction. Men undergoing ADT are likely to lose their desire for sex. Unfortunately, no drugs will improve sex drive in men on ADT, who temporarily exhibit castrate levels of testosterone. But after completing therapy, sexual function and libido usually return within a year, particularly for younger patients. In the meantime, counseling can help couples deal with their changing sexual relationships.
Another relatively new method for relieving these side effects is intermittent therapy, which allows men to take breaks from ADT. “Sometimes, I use this method,” Dr. Eisenberger notes, “in patients who have rapidly rising prostate specific antigen (PSA) levels but no evidence of metastases.”
Men on intermittent therapy take ADT until their PSA levels are virtually undetectable. Then they stay off therapy — usually for about 18 months — until PSA levels rise again. Preliminary data suggest that intermittent ADT may be as effective as continuous treatment, but further research is necessary.
Breast pain and enlargement. Fortunately, this side effect — called gynecomastia — does not occur very often. “For most men,” explains Dr. Carter, “ADT consists of drugs like Lupron (leuprolide acetate) and Zoladex (goserelinacetate), which have low rates of gynecomastia — about 3%.”
Men who go on other less common form of ADT, such as the antiandrogen Casodex (bicalutamide), frequently experience significant breast enlargement; however, these drugs are often unnecessary.
Periodontal disease. In a study of prostate cancer patients, 80.5% of men on ADT had periodontal disease, compared with only 3.7% of men on other treatments. Notably, symptoms occurred even in ADT users who brushed and flossed reqularly. While your are on this therapy, make sure to visit the dentist frequently to catch periodontal disease in its early stages.
Anemia. Anemia is common among men on ADT. For severe symptoms, your doctor may prescribe either Procrit (epoetin alfa) or Aranesp (darbepoetin alfa).
Fatigue and cognitive changes. A significant proportion of men on ADT suffer from fatigue, depression, or trouble concentrating. Some doctors refer to these symptoms as “ADT syndrome”; however, a recent study shows that this syndrome may not be a direct side effect of therapy.
Men on ADT tend to be older and have advanced cancer. These factors — not ADT — likely cause the cognitive changes experienced by patients with prostate cancer.
More studies are needed to determine the exact source of these troubling side effects. Nonetheless, don’t be surprised if you feel tired or emotionally drained while on ADT. Seek out friends and family; psychological counseling, too, can help you cope with the changes you’ll face during therapy. Other prostate cancer patients also can be an important resource, and support groups are available in most communities.
|
