December 5. 2005. According to a recent article published in Urology, further evidence indicates that treatment with Zometa (zoledronic acid) for one year prevents bone loss in patients with advanced prostate cancer who are undergoing hormone therapy.
Current treatment options for prostate cancer include expectant management (active watchful waiting), external beam or seed implant (brachytherapy) radiation, surgery, chemotherapy, and/or androgen deprivation therapy (also referred to as hormonal therapy). Androgen deprivation therapy is designed to block testosterone from stimulating the growth of hormone-dependent types of prostate cancer.
Three bisphosphonates widely used by cancer patients at risk of fractures are Pamidronate (Aredia; Novartis Pharmaceuticals), Zoledronate (Zometa; Novartis Pharmaceuticals), and Alendronate (Fosamax; Merck Co).
Alll three of these drugs have been linked to painful refractory bone exposures (osteonecrosis) in the jaws. The condition is rare but can be devastatingly painful.
Cancer patients may be at special risk of developing this condition because they may be taking a mix of drugs with or without radiotherapy.
One recent article notes, "In many cancer patients chemotherapy and medications like steroids have also to be applied. Agreement exists that these drugs can initiate vascular endothelial cell damage and accelerate disturbances in the microcirculation of the jaws possibly resulting in thrombosis of nutrient end arteries."
Some cancer patients who have never received bisphosphonates still develop osteonecrosis of the jaw.
Patients are recommended to undergo thorough dental care before starting a bisphosphonate. Extractions, if necessary, should be done ahead of time. Pre-therapy dental care reduces the risk, and non-surgical dental procedures can prevent new cases.
If the condition does develop, dental surgeons at University of Miami say, "effective control to a pain free state without resolution of the exposed bone is 90.1% effective using a regimen of antibiotics along with 0.12% chlorohexidine antiseptic mouthwash."
Treatment with androgen deprivation therapy can become an almost chronic necessity. The treatment may be started before a primary treatment such as radiotherapy or surgery and may continue for many months beyond. Patients who experience recurrence of prostate cancer or who are found to have advanced systemic disease at time of diagnosis may remain on continuous or intermittent hormonal therapy for years.
Some drugs that bring a man's testosterone down to the castrate levels necessary to control the cancer have almost immediate adverse effects on bone mineral density.
The GnRH and LHRH agonist classes of drugs (Lupron, Zoladex and related) have been shown to cause osteoporosis (fragile bones) within months. The longer these drugs are taken, the higher a man's risk of fractures.
Estrogenic hormonal drugs for prostate cancer, including DES (diethylstilbestrol) and estradiol patches or gel, do less damage to bone mineral density but are less widely used on account of marketing and longstanding concern about possible cardiovascular side effects.
Medical complications such as hip or spinal fractures can become particularly difficult for prostate cancer patients since serious fractures require surgery and/or immobilization, bringing risk of further complications. During the recovery period active treatment for the cancer may be interrupted. Furthermore, some fractures are associated with severe pain some with permanent disability and loss of mobility. All carry increased medical costs.
Studies have revealed that treatment with the bisphosphonate drug Zometa slows loss of bone mineral density when given at the start of androgen deprivation therapy. A recent study has also indicated that treatment with Zometa after androgen deprivation therapy has begun also reduces bone loss. However, studies continue to evaluate Zometa's performance.
Researchers from several institutions in the U.S. recently conducted a clinical trial to further evaluate whether treatment with Zometa can reduce bone loss in men with prostate cancer that has already spread to the bone. This study included 221 patients who were receiving hormone therapy. On trial, all men received treatment with Zometa for one year.
- Bone mineral density increased by 7.7% in the lumbar spine.
- Bone mineral density increased by 3.6% in the hip.
- Joint pain, nausea, fatigue and back pain were the most frequent side effects reported.
- The median time to a skeletal event (bone fracture, osteoporosis, etc.) had not been reached.
- Nearly 12% of patients experienced a skeletal-related event.
These results provide further evidence that Zometa actually increases bone mineral density in prostate cancer patients who have already been receiving hormone therapy. Men who are diagnosed with prostate cancer and are to undergo hormone therapy or who have already been receiving hormone therapy may wish to speak with their physician regarding their individual risks and benefits of treatment with Zometa or other bisphosphonates.
