Androgen deprivation therapy indicated to treat prostate cancer may boost colorectal cancer risk, according to a study published online November 10 in the Journal of the National Cancer Institute.

The therapy of concern is widely used to treat men with prostate cancer even through its use in men with low-risk disease remains controversial because of its adverse effects.

The adverse effects of this therapy include osteoporosis, fractures, loss of muscle, hot flashes, metabolic problems, cardiovascular disease, anemia, gynecomastia, diabetes and obesity. Diabetes and obesity are considered risk factors for colorectal cancer.

The study led by Silke Gillessen, M.D., of the Cantonal Hospital in St. Gallen, Switzerland, and colleagues showed prostate cancer patients treated with androgen deprivation therapy were 30 to 40 percent more likely than those who were not treated to develop colorectal cancer.

The data for the study came from the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute from which the researchers identified 107,859 men aged 67 years or older who were diagnosed with prostate cancer between 1993 and 2002. All the men were followed through 2004.

Androgen deprivation therapy was either gonadotropin-releasing hormone (GnRH) agonists, or an orchiectomy.

After adjustment for age and the social economic status, prostate cancer patients treated with the androgen deprivation therapy were at 30 to 40 percent increased risk of colorectal cancer, compared with those who who were not treated.

Additionally, the researchers found longer exposure to the treatment led to higher risk of colorectal cancer.

The findings suggest those with localized, slow-growing prostate cancer may need to know this potential risk when considering to receive any androgen deprivation therapy.

Prostate cancer is expected to be detected in 217,730 men and to kill 32,050 each year in the United States. Many cases of prostate cancer are not aggressive and patients, particularly those over 70 may not need any treatment because they are expected to die from another medical condition.

Colorectal cancer includes colon cancer, which is found in 102,000 Americans and rectal cancer, which is found in 40,000 Americans each year, according to the National Cancer Institute. The disease kills about 51,000 a year in the United States.

Androgen deprivation therapy reduces the amount of circulating androgens or male hormones in the body. The obvious side effect is sexual and reproductive dysfunction.

Jimmy Downs