The research team, led by scientists at Georgetown Lombardi Comprehensive Cancer Center, say that the risks of serious adverse events associated with the treatment — which has been linked to impaired cognition, heart disease, diabetes and other disorders — "mitigates against any clinical or policy rationale for use of primary androgen deprivation therapy in these men."
The findings, reported Monday in the Journal of Clinical Oncology, draw from cancer registries linked with extensive electronic medical records in three, large integrated health plans. The men included in the study had prostate cancer that had not spread beyond the organ (localized) and did not have surgery or radiation therapy, considered curative treatment.
Androgen deprivation therapy suppresses the production of testosterone, the male hormone said to fuel growth of prostate cancer. The therapy improves survival when given with radiation for later stages of disease, and is considered the standard of care for men who have metastatic prostate cancer. Effectiveness of primary androgen deprivation therapy (PADT) has not been established.
"This study is the most comprehensive study on the effectiveness of PADT for men who forgo radiation and surgery for their localized prostate cancer, and it tells us there is no strong reason to use it in most patients," says the study's lead investigator, Arnold Potosky, PhD, a professor of oncology and director of health services research at Georgetown Lombardi. "We found only a small survival benefit for primary androgen deprivation therapy compared to no therapy in men diagnosed with higher-risk localized prostate cancer."
Use of primary androgen deprivation therapy for early stage prostate cancer is widespread. Despite the lack of randomized clinical trials to test its effectiveness, recent studies have reported it as the second most common treatment, after radiotherapy, for clinically localized prostate cancer among older men age 65 and older. The study did not compare androgen deprivation therapy directly to either surgery or radiation therapy, the two main curative treatment options for prostate cancer.
"Primary androgen deprivation therapy may be preferable to some men with early stage prostate cancer who would prefer to do something rather than watch and wait for further signs of progression to occur later and then need treatments," Potosky adds. "However, using PADT by itself immediately after diagnosis in the hopes of limiting cancer's progression does not extend survival, according to this study."
The researchers are now using their database of 15,170 patients to examine rates of potential side effects from the treatment.
"Given the ageing American population, more men are likely to be faced with prostate cancer so its is very important to understand the whether the risks of primary androgen deprivation therapy outweigh the survival benefit," he says. "Ultimately, this is a decision for men and their doctors to make together, and we hope that our study provides some helpful information to guide these decisions."
Potosky et al., (2014). Effectiveness of primary androgen-deprivation therapy for clinically localized prostate cancer. J. Clin. Oncol., EPub Ahead of Print, doi: 10.1200/JCO.2013.54.2043 [Abstract]