THE "NEW" PROSTATE CANCER INFOLINK

There has been a lot of media noise in the past few days about two studies suggesting that a drug called alendronate (Fosamax/Merck) may be associated with a significant risk for osteonecrosis of the jaw (ONJ).

Bisphosphonate therapy with drugs like zoledronate (Zometa) and alendronate (Fosamax) has been associated with some degree of risk for ONJ for some time. We do not know the exact reason for this risk, and it is not even certain that bisphoshonate therapy is the cause of this risk. However, many prostate cancer patients with more advanced disease receive bisphosphonate therapy to help prevent bone loss.

The two original studies on which the recent news reports have been based were published by Weinstein et al. in the New England Journal of Medicine and by Sedghizadeh et al. in the Journal of the American Dental Association.

The study by Sedghizadeh et al. is the more problematic of the two studies. These authors used an electronic medical record system at the University of Southern Califonia to determine the number of patients with a history of alendronate use and how many patients receiving alendronate were also receiving treatment for ONJ. They were able to identify 208 patients with a history of alendronate use, of whom 9 (4.3 percent or 1 in 23 alendronate patients) had active ONJ and were being treated in the university’s dental clinics. We do not know whether any of these patients also had prostate cancer. It should also be noted that, according to a comment in a report on WebMD, “patients [in this study] who developed osteonecrosis had other factors, including chemotherapy, type 2 diabetes, high blood pressure, high cholesterol, and steroid therapy. Some of these conditions are risk factors for osteonecrosis.”

The data reported by Weinstein and his colleagues is based exclusively on the use of alendronate to prevent bone resorption among healthy postmenopausal women aged 40 through 59 years of age. The study doesn’t deal specifically with ONJ, but rather with the incidence of cells known as “osteoclasts” in patients receiving alendronate therapy (particularly at higher doses and for longer periods of time). The study contained no information whatsoever about men being treated for prostate cancer. The increased incidence osteoclasts reported by Weinstein et al. was only observed in women who were receiving the highest daily dose of alendronate (10 mg/day).

The “New” Prostate Cancer InfoLink does not wish to minimize the risk that is implied by these findings, but we also do not think that every man who has been taking alendronate as an agent to prevent loss of bone density as a potential consequence of androgen deprivation should rush to their doctor to be taken off the drug.

Men with prostate cancer who are being treated with any bisphosphonate should always be particularly cautious about their dental health. We strongly suggest:

• Regular dental check-ups and special care with dental hygiene
• Making absolutely sure that your dentist is aware that you are being treated with a bisphosphonate (including the specific drug and dosage)
• Being particularly careful before scheduling any invasive dental procedure such as a tooth extraction or a possible a ”root canal”
• Being particularly careful after any traumatic injury that may lead to loss of a tooth or dental surgery to repair the injury
• A discussion with your doctor at your next visit about your personal risk for ONJ, particularly if you are on a high dose of alendronate or any other bisphosphonate

Newer or long-acting forms of bisphosphonates such as ibandronate (Boniva/Roche, used just once a month) and Reclast (a form of zoledronic acid taken just once a year) may be  being used off-label by a small proportion of  prostate cancer patients. These patients should also be cautious about their dental health and the possibility of risk for ONJ.