A common prostate cancer therapy should not be used in men whose cancer has not spread beyond the prostate, according to a new study led by researchers at Henry Ford Hospital.The findings are particularly important for men with longer life expectancies because the therapy exposes them to more adverse side effects, and it is associated with increased risk of death and deprives men of the opportunity for a cure by other methods.
The research study has been published online in European Urology.
The focus of the new study is androgen deprivation therapy (ADT), in which an injectable or implanted medication is used to disrupt the body's ability to make testosterone. ADT is known to have significant side effects such as heart disease, diabetes, increased weight gain and impotence; however a growing body of evidence suggests ADT may in fact lead to earlier death.
Since the 1940s, the therapy has been a mainstay of treatment for prostate cancer that has metastasized, or spread beyond the prostate gland. Still other studies support the use of ADT when it is used as an adjuvant, or in addition to, radiation therapy for higher risk prostate cancer. No evidence exists to support the exclusive use of ADT for low risk or localized prostate cancer.
"The use of ADT as the primary treatment for localized and low risk prostate cancer increased over time, despite known harmful side effects and a lack of data to support such use," says Jesse D. Sammon, D.O., a researcher at Henry Ford Hospital's Vattikuti Urology Institute and lead author of the new study. "In the 1990's it became exceedingly common to use ADT in place of radical prostatectomy or radiation therapy."
Concerns over the possible misuse of ADT alone in the treatment of prostate cancer, as well as a growing awareness of its potential damage, led to changes in Medicare reimbursement policies for ADT in 2004.
This resulted in a 40 percent drop in reimbursement, and a reduction in inappropriate use of ADT from 38.7 percent to 25.7 percent for newly diagnosed localized prostate cancers.
"At the same time, there was a growing awareness of ADT's many possible adverse effects, including decreased libido, anemia and fatigue, and a higher risk of metabolic and cardiovascular disease," Dr. Sammon says.
"In designing our study, we hypothesized that the adverse effects of ADT might be more pronounced in men with longer life expectancies since they would likely be treated with ADT for a longer period- and be exposed to more treatment-related side effects."
Drawing on data from nations largest cancer registry (SEER) (Surveillance, Epidemiology, and End Results) the researchers then linked to records from Medicare and identified 46,376 men diagnosed with localized prostate cancer who did not undergo radical prostatectomy or radiation therapy for prostate cancer, diagnosed between 1992-2009. Among them, 38.5 percent were treated with ADT.
Further statistical analysis confirmed the study's hypothesis, notes Dr. Sammon.
"No evidence supports the use of ADT in men with low risk, localized prostate cancer, while use of this therapy is decreasing over time it is still very common," he says
"We found that primary ADT is associated with decreased survival in men with localized prostate cancer relative to men who receive no active treatment, particularly in men with longer life expectancies. So we concluded that ADT should not be used as a primary treatment for men with prostate cancer that has not spread beyond the prostate or men with moderate to high risk disease undergoing radiation therapy."