The time interval free of biochemical failure (IBF) may be a promising surrogate end point in the setting of androgen-deprivation therapy (ADT) evaluation in men with prostate cancer, according to researchers at the University of Chicago. They reported in The Journal of Clinical Oncology that IBF may serve as a valid end point in clinical trials and may also aid in risk monitoring after initial treatment.1
The investigators found that the length of the IBF could have a major bearing on trial duration. They cited several trials where findings could have been revealed 3 to 5 years earlier, if the IBF interval had been adopted and used a surrogate measure. James Dignam, PhD, the Department of Public Health Sciences, the University of Chicago, Chicago, Illinois, and colleagues conducted a trial with 1520 men that compared short-term ADT (4 months) with long-term ADT (28 months).They evaluated the IBF in relation to clinical end points of prostate cancer–specific survival (PCSS) and overall survival (OS).
The study showed that long-term ADT was superior to short-term ADT in terms of biochemical failure (BF) and the clinical end points. The researchers found that those men who did not develop BF for 3 years had relative risk reductions of 39% for OS and 73% for PCSS. When the investigators accounted for 3-year IBF status, it reduced the long-term ADT OS benefit from 12% to 6%. With the PCSS, the long-term ADT benefit dropped from 30% to 6% at 3 years.
The study also revealed that at 3 years, 50% of subsequent deaths attributed to prostate cancer occurred in men with BF compared with 19% of those who were free of BF. The researchers concluded that IBF appears to have a clear role in clinical decision making, and may provide guidance when more intensive surveillance or treatment is warranted.
- Dignam JJ, Hamstra DA, Lepor H, et al. Time Interval to Biochemical Failure as a Surrogate End Point in Locally Advanced Prostate Cancer: Analysis of Randomized Trial NRG/RTOG 9202 [published online December 7, 2018]. J Clin Oncol. doi: 10.1200/JCO.18.00154.