Prostate Cancer Active Surveillance Safe After 15 Years: Landmark ProtecT Trial Update

What Is Active Surveillance for Prostate Cancer?

Active surveillance (AS) is based on the recognition that many prostate cancers — particularly those that are low-grade (Gleason 6/Grade Group 1), low-volume, and localized — grow so slowly that they may never cause symptoms or shorten life. Treating all such cancers immediately with surgery or radiation exposes many men to significant side effects (urinary incontinence, erectile dysfunction, bowel problems) without clear survival benefit. AS involves regular monitoring: PSA blood tests every 3–6 months, MRI scans periodically, and repeat biopsies as indicated, with definitive treatment offered if the cancer upgrades or progresses.

The ProtecT trial (Prostate Testing for Cancer and Treatment) is the gold-standard evidence for AS. It randomized 1,643 men diagnosed with localized prostate cancer (approximately 80% Gleason 6) between 1999 and 2009 to active monitoring, radical prostatectomy, or external beam radiotherapy. The 15-year follow-up, published in the New England Journal of Medicine in 2023, provides the longest randomized evidence comparing these three approaches.

What Did the 15-Year Results Show?

At 15 years, prostate cancer–specific mortality was low across all groups: approximately 3.1% for active monitoring, 2.2% for prostatectomy, and 2.9% for radiotherapy, with no statistically significant differences between groups. All-cause mortality was also similar across the three arms. The lack of a survival difference is the most important finding, as it establishes that active surveillance does not compromise cancer outcomes for low-risk disease.

The monitoring group did have higher rates of metastatic disease at 15 years (approximately 9% vs 5% for the treatment arms), which is expected since some cancers will progress during monitoring. However, the majority of men on active monitoring avoided radical treatment entirely over 15 years while maintaining equivalent survival. Among those who did require delayed treatment, outcomes were still excellent, with cancer-specific survival comparable to the immediate treatment groups. Quality-of-life analyses confirmed persistent advantages for the monitoring group: substantially better urinary continence and erectile function compared with the surgery group, with these differences maintained throughout the follow-up period. Men in the radiotherapy group had somewhat more bowel side effects compared with the other two groups.