A new study finds that many men on androgen deprivation therapy for prostate cancer aren't being screened or treated for osteoporosis, even when they have additional risk factors for the condition.
Tawee Tanvetyanon, MD, Senior Fellow in Oncology and Hematology at Loyola University Chicago Stritch School of Medicine, reviewed the records of 184 patients at the Edward Hines, Jr. Veterans Administration Hospital who were treated with goserelin injections for at least one year. Most of the men (78%) were over age 70, and many had other risk factors for osteoporosis, including longer-term use of androgen deprivation therapy (65.9% for 25 months or more), presence of bone metastases (10.3%), presence of spinal or hip fractures (10.9%), smoking (16.3%), and steroid use (7.6%).
Despite these characteristics, however, only 16 men (8.7%) had received a dual-energy x-ray absorptiometry (DXA) bone scan to check for osteoporosis in the previous 3 years. Of those men, 8 (50%) had osteoporosis and 4 (25%) had osteopenia. A smaller number of patients (4.9%) were prescribed oral bisphosphonates, while 0.5% received intravenous bisphosphonates. Calcium and vitamin D supplements were given to 8.7% of men. The results were published in the journal Cancer (2005;103:237–241).
These findings don't come as a complete surprise, Tanvetyanon said, because there are no established guidelines for treating or preventing osteoporosis in this patient group, even though osteoporosis is a well-known complication of androgen deprivation therapy.
“It is not a new problem,” he said. “There certainly is a movement toward establishing a guideline for how to detect and intervene with osteoporosis in these patients, but a lot remains to be defined.”
One issue, said Kenneth Pienta, MD, is continuing controversy about the actual fracture rate in prostate cancer patients with treatment-induced osteoporosis. Pienta, who was not involved with Tanvetyanon's research, is a Professor of Medicine and Urology at the University of Michigan and an ACS Clinical Research Professor.
“If you look at x-rays of patients undergoing androgen deprivation therapy, over time you can see a significant increase in fractures by x-ray, but almost all of those are subclinical,” he said. “There is an increase in the number of clinically relevant fractures, but the actual incidence of those is fairly low and it increases with time. So the question becomes, who do you screen and when do you screen people?”
Not all men are at risk of osteoporosis, Pienta observed. Previous research has suggested that the incidence of osteoporotic fractures ranges from 5% after 22 months of hormone therapy to 40% after 15 years.
“That means 60% of men never have a problem,” Pienta said. “But we need to be aware that this can be a problem and needs to be followed in patients.” However, there are no firm prevention guidelines for treatment-related osteoporosis, either, he added.
In his own practice, Pienta gives men with osteoporosis risk factors a DXA scan before they begin androgen deprivation therapy; men with no other risk factors for osteoporosis get a scan after two years.
Tanvetyanon, however, recommends that all men get a DXA scan before beginning androgen deprivation therapy. And he said all men starting this treatment should be given calcium and vitamin D, unless these are contraindicated. Men who already have osteoporosis or osteopenia should be treated, if warranted, he added.
“The decision to treat depends on the individual patient,” Tanvetyanon stressed. Calcium, for instance, might interfere with absorption of other medications a patient may be taking for comorbid conditions. Oral bisphosphonates, though generally safe, can cause gastric side effects; intravenous bisphosphonates cannot be used in patients with renal impairment.