Dr. Nguyen on the Optimal Duration of ADT in High-Risk Prostate Cancer

Paul L. Nguyen, MD, senior physician and director of Genitourinary Clinical Center for Radiation Oncology at Dana-Farber Cancer Institute, as well as a professor of radiation oncology at Harvard Medical School, discusses the optimal duration of androgen deprivation therapy (ADT) in patients with high-risk prostate cancer.

There is a lot of controversy over what the best duration of ADT is for patients with high-risk disease, says Nguyen. Two years of ADT is currently used in most randomized trials for this patient population, adds Nguyen. There is an interest in shifting toward the use of 18 months of ADT; however, the phase 3 Prostate Cancer Study IV, which compared 18 months versus 36 months of therapy, has not proven the equivalence, according to Nguyen.

Although the hazard ratio for death between 18 and 36 months on the most recent update looked reasonable, there were some issues with the study. One problem is the high dropout rate in the 36-month arm. Immediately after 18 months of treatment, numerous patients stopped receiving ADT. At 36 months, a little over half of the patients were still on therapy, says Nguyen. When there is a very high dropout rate, it tends to lean toward a bias for equivalence, concludes Nguyen.