Thursday, November 11, 2010 (Last Updated: 11/12/2010)
THURSDAY, Nov. 11 (HealthDay News) -- Men taking androgen-deprivation therapy (ADT) for prostate cancer may have a higher risk of colorectal cancer, and that risk appears to increase with longer duration of ADT, according to research published online Nov. 10 in the Journal of the National Cancer Institute.
Silke Gillessen, M.D., of the Kantonsspital in St. Gallen, Switzerland, and colleagues conducted an observational study of 107,859 men aged 67 years or older with prostate cancer diagnosed between 1993 and 2002, and follow-up through 2004. The men were either being treated with gonadotropin-releasing hormone (GnRH) agonists or had an orchiectomy.
The researchers found a 30 to 40 percent relative increase in the unadjusted rate of colorectal cancer among the men treated with ADT compared with those who were not (6.3 cases per 1,000 person-years for men with orchiectomy, 4.4 cases per 1,000 person-years for men on GnRH agonists, and 3.7 cases per 1,000 person-years for men not on ADT). Based on length of time on ADT, there was a statistically significant dose-response effect for ADT-associated colorectal cancer. After 25 months or more of ADT, the hazard ratio for colorectal cancer was 1.31 for GnRH use and 1.37 for orchiectomy, compared to no ADT treatment.
"The findings of Gillessen et al suggest that an elevated risk of colorectal cancer may be an additional consideration to weigh in the risk versus benefit profile. Their findings also reinforce the need for routine screening for colorectal cancer and the adoption of lifestyle practices such as physical activity that may help to counter some of the drawbacks of anti-androgen therapies," write the authors of an accompanying editorial.
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