Study: ADT linked to higher rate of colon cancer

Men treated with androgen deprivation therapy (ADT) for prostate cancer face a 30% to 40% higher risk of colorectal cancer compared with patients who have not received this treatment, say researchers from the University of Michigan, Ann Arbor.

Researchers looked at data from 107,859 men aged 67 years and older with prostate cancer, identified through the Surveillance, Epidemiology and End Results and Medicare linked database. The team found that the risk of colorectal cancer increased the longer a man received ADT. Patients undergoing orchiectomy had the highest rates of colorectal cancer.

Overall, the risk of colorectal cancer was low-less than 1% per year even among orchiectomy patients. But any increased risk should be carefully considered when using ADT in cases when its benefit is not clear, the researchers said.

"Androgen deprivation therapy still continues to be used in situations where there are not evidence-based studies showing its benefit," said lead author Vahakn B. Shahinian, MD. "When androgen deprivation therapy is clearly known to be beneficial, people should not shy away from using it. But where there’s not solid evidence, this is potentially another harm."

Results of the study were published online in the Journal of the National Cancer Institute (Nov. 10, 2010).