Biochemical Recurrence After Radiation Therapy

Definition and Diagnosis

• The American Urological Association defines biochemical recurrence as a rise in PSA after radiation therapy, with a threshold of nadir + 2 ng/mL, also known as the Phoenix criteria 1, 2
• A consistent upward PSA trend with three consecutive rises indicates true biochemical progression, not a benign "bounce" 1, 2

Prognostic Factors

• A long time to biochemical failure (>2.5 years from completion of radiation therapy) suggests possible local rather than distant recurrence 7, 4
• A PSADT >12 months is associated with a low likelihood of prostate cancer-specific mortality over 10 years 1, 7
• Intermediate-risk disease at diagnosis (Grade Group 2, Gleason 3+4=7) has a better prognosis than high-grade disease 4, 8

Management

• The European Association of Urology recommends restaging evaluation with PSMA PET/CT imaging to detect low-volume metastatic disease or local recurrence 3, 8
• Active surveillance with close PSA monitoring every 3-4 months is appropriate for patients with PSADT >12 months and no metastatic disease 1, 7, 3, 8
• Intermittent ADT is recommended if PSADT shortens to <6-12 months, as it provides superior quality of life compared to continuous therapy 3

Critical Pitfalls to Avoid

• The American Society of Clinical Oncology advises against reflexively starting ADT based solely on rising PSA when PSADT is >12 months and PSA has not reached Phoenix criteria 7, 4, 3
• Conventional CT and bone scan have an extremely low yield at PSA levels <1.0 ng/mL, and PSMA PET is far superior for detecting occult disease 3, 8