Two recent studies have raised further concerns regarding the use of androgen deprivation therapy (ADT) for patients with prostate cancer. ADT is widely prescribed for the disease, even though its use for low-risk patients remains controversial because of associated side effects, including osteoporosis, cardiovascular disease, diabetes, and obesity.
In the first study, researchers found that men receiving ADT have an increased risk of colorectal cancer.1 Silke Gillessen, MD, of the Cantonal Hospital in St. Gallen, Switzerland, and colleagues performed an observational study of men with prostate cancer identified in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. They studied 107,859menwhowere diagnosedwith prostate cancer between 1993 and 2002, with follow-up through 2004. The men received ADT either through gonadotropin-releasing hormone (GnRH) agonists or an orchiectomy.
Researchers found that there was a 30% to 40% increase in the rate of colorectal cancer for men receiving ADT compared with those who were not. In addition, the longer the men were treated with ADT, the greater their risk of developing the disease. Further study is needed to determine the risk of treatment for longer time periods, the authors note. They add that the study should have important implications, particularly for men with localized, slow-growing disease who generally receive ADT for a longer time.
In the second study, reported at the AACR International Conference on Frontiers in Cancer Prevention Research (held November 7-10, 2010, in Philadelphia, Pennsylvania), researchers found that men with a history of fracture and comorbidities are at an increased risk of fracture after long-term use of ADT. For that reason, researchers urge caution in initiating the therapy in older men with localized prostate cancer.
Grace Lu-Yao, PhD, professor of medicine at the Cancer Institute of New Jersey in New Brunswick, and colleagues analyzed data in the SEER-Medicare program to estimate fracture risk among more than 46,500 men aged 66 years and older with localized prostate cancer who received long-term ADT. The therapy is common in older men because many have comorbidities and are not suitable candidates for radical prostatectomy or radiotherapy.
The men treated with long-term ADT had a 20%increased risk of a first fracture and a 57%increased risk of a second fracture after the first 2 years of treatment. Older age, higher comorbidity, and history of fracture and stroke were associated with an increased fracture risk.
In addition, men aged 75 years or older who received GnRH for more than 2 years had 3.63 times the risk of fracture compared with men ages 66 to 74 years who were treated with ADT for fewer than 2 years.