A recent study published in the November 10th issue of the Journal of the National Cancer Institute reported that prostate cancer hormone treatments may raise the risk of colorectal cancer. Lowering the male sex hormones by treatment with gonadotropin-releasing hormone (GnRH) agonists (hormonal therapy) or surgical removal of the testicles to lower testosterone and PSA levels led to an increased risk of colorectal cancer of about 20-40%. The risk increased from about 19% to 31% with the increased duration of hormonal therapy. (See the NCI Cancer Bulletin, November 30th, 2010.)
Abiraterone acetate, an oral agent for hormone-resistant prostate cancer reaches a Phase III expanded access program in preparation for FDA review in 2011.
Abiraterone (from Johnson & Johnson) will soon be available at clinical recruitment centers to treat patients with metastatic hormone therapy-resistant prostate cancer who have progressed after taxane-based chemotherapy. Centers are currently recruiting in California, Connecticut, Florida, Georgia, Louisiana and New York. (See the ZeroHour newsletter and action advisory from the ZeroHour Newsletter, the project to end prostate cancer.) Abiraterone acetate is a once-daily oral agent for hormone-resistant prostate cancer. It is currently in Phase III clinical trials for men who are hormone resistant and who have had previous exposure to Taxotere. It is now believed that hormone-resistant cells still require testosterone to grow. The cells synthesize an abundance of testosterone receptors and they may even synthesize their own testosterone inside the cancer cell. Abiraterone blocks this production of testosterone within the cell. Thus, abiraterone works not only in blocking the generation of these hormones in the testes, but also elsewhere in the body, including generation of the hormones in the cancer itself. Specifically, it works by blocking the activity of CYP17, a key enzyme that helps cells produce androgen and estrogen. In an earlier Phase I trial in the United Kingdom, abiraterone significantly shrank tumors in men with advanced prostate cancer who had not responded to other treatments. The study found that the drug delayed worsening of the disease by an average of 400 days. Approximately 70-80 percent of men in the Phase I study showed declines in PSA levels and their tumors shrank, even when cancer had spread elsewhere in the body.