Delaying ADT Safe for Prostate Cancer Patients

A large prospective, observational study shows that prostate cancer patients who had a prostate-specific antigen (PSA)-based relapse could delay androgen deprivation therapy (ADT) until symptoms presented, without affecting long-term survival.

The estimated 5-year overall survival among the group of men who had delayed ADT was 87.2% compared with 85.1% for those who had immediate ADT following a PSA-based relapse. Ten-year survival was 71.6% for both groups.

The prostate cancer-specific mortality was also similar for the two groups: the 5-year survival for the immediate and delayed ADT groups was 96% and 93.3%, respectively, and the 10-year survival was 90.2% and 89.4%, respectively. All of the patients were previously treated with radical prostatectomy or radiotherapy.

These results, based on an analysis of 2,022 patients that are part of the national prospective registry CaPSURE (Cancer of the Prostate Strategic Urologic Research Endeavor), were presented by study author Xabier Garcia-De-Albeniz, MD, of the department of epidemiology at Harvard School of Public Health, at a press briefing in advance of the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting, which will take place May 30–June 3 in Chicago.

“The role of starting ADT in these patients is not clear,” said Garcia-De-Albeniz during his presentation at the press briefing. Garcia-De-Albeniz referred to the National Comprehensive Cancer Network guideline, which states that there is “a therapeutic dilemma” regarding the role of ADT. Additionally, the potential magnitude of the benefit, particularly for asymptomatic patients, needs to be understood, according to ASCO guidelines.

The median time from primary treatment to PSA relapse was 27 months, and after relapse, patients were followed for a median of 53.2 months. The median age of the patients was 69 years.

Because this study was observational, the results need to be confirmed in a randomized trial, noted Garcia-De-Albeniz. Furthermore, these results assume that there were no confounding factors that could affect survival, such as differential behavior of the participants or health factors like diabetes or blood pressure. A phase III trial is ongoing.

“There is an emotional drive” to seek therapy for prostate cancer patients who are otherwise asymptomatic but have a PSA-based result indicating a relapse, said ASCO President-Elect Peter P. Yu, MD, medical oncologist and director of cancer research at the Palo Alto Medical Foundation in California, who moderated the session and was not involved in this study.

“Up to now we have not had clear evidence, or some evidence, that delaying treatment until there are more objective signs of disease is a safe thing to do,” Yu commented at the press briefing. “This study will now provide us with information to have a dialogue between doctors and patients about whether they should start immediate hormone therapy or whether continued observation and waiting might be a better approach.”