“No one likes to give long-term hormonal therapy. I am optimistic that we can give shorter-term androgen deprivation therapy, but I am not sure I can state that with certainty today,” said Anthony V. D’Amico, MD, PhD, Professor of Radiation Oncology at Harvard Medical School and Chief of Genitourinary Radiation Oncology at Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston.

The study by Dr. Nabid and colleagues was not a noninferiority study designed to show whether 18 months of androgen deprivation therapy is not inferior to 36 months of androgen deprivation therapy. The noninferiority design sets a prespecified threshold on the upper limit of increased risk of death that is acceptable and not inferior to 36 months of treatment.

“Because this study was designed as a superiority—not a noninferiority—study, the upper limit was 1.56, which is a high bar to accept—a 56% increase in death,” Dr. D’Amico said. “The study showed that 36 months is not superior to 18 months, but 18 months may be inferior to 36 months. It will take up to 7.5 years of follow-up to determine if the upper limit is under 1.35, a sufficient value to accept 18 months as not inferior to 36 months,” he explained.

Longer Follow-up Needed

At present, it appears that 36 months of androgen deprivation therapy is too long, and 6 months is too short [based on European Organisation for Research and Treatment of Cancer data]. “Maybe 18 months is just right. We need longer follow-up,” Dr. D’Amico emphasized.

Comorbidity status is an important consideration, he continued. If a patient has cardiovascular disease, perhaps the 18-month course of androgen deprivation therapy is preferable, whereas if there are no comorbid conditions, 36 months might be the choice. ■

Disclosure: Dr. D’Amico reported no potential conflicts of interest.