How quickly should PSA drop to undetectable after prostate surgery and what levels indicate recurrence?
Executive summary
After radical prostatectomy, most authorities say PSA should fall to very low or undetectable levels within weeks to a few months; commonly cited benchmarks are “undetectable” or <0.1 ng/mL by about 4–8 weeks, though some guidelines still recommend confirming at ~3 months because clearance can take longer [1] [2] [3] [4]. Biochemical recurrence after prostatectomy is most often defined as a confirmed PSA ≥0.2 ng/mL (with a repeat >0.2 ng/mL), and clinicians also consider PSA kinetics (doubling time) and timing of the rise when deciding whether and how urgently to act [5] [6] [7].
1. How fast should PSA fall after prostate removal — the conventional view
Textbooks and patient guides state that when the prostate is removed the main source of PSA is gone and levels “should drop to almost zero within about 4–6 weeks” and often be undetectable on standard assays; many clinicians therefore wait 6–8 weeks to check PSA because small amounts can persist for weeks [3] [2] [1]. Several patient-facing sources and expert summaries reiterate that an undetectable or very-low nadir (commonly cited cutoffs include <0.05–0.1 ng/mL on routine assays) is the expected result after radical prostatectomy [7] [2] [1].
2. Newer data urging longer wait times to avoid overtreatment
A 2025 multi‑center analysis reported in JAMA Oncology and summarized in press releases and news coverage argues that checking PSA too soon (the common 1.5–2 month window) can misclassify patients as having persistent PSA and prompt unnecessary salvage therapy; the authors recommend extending monitoring beyond the early weeks because some men — especially those with very high preoperative PSA — may take longer than three months to clear PSA completely [4] [8] [9]. CancerNetwork and Mass General Brigham coverage emphasize that premature labeling of persistence risks overtreatment [8] [4].
3. What counts as “persistence” vs. biochemical recurrence — multiple thresholds exist
There is active debate about the numeric definitions: many major urology groups and consensus panels use biochemical recurrence after prostatectomy as a confirmed PSA ≥0.2 ng/mL (repeat >0.2), and imaging/treatment decisions often hinge on that threshold [5] [10]. At the same time, ultrasensitive assays detect far lower PSAs and some recent work presented at meetings proposed lower cutoffs to define PSA persistence after surgery (for example, one AUA‑reported analysis suggested 0.04 ng/mL as a candidate cutoff using ultrasensitive assays) — these lower thresholds are not yet universally adopted [11].
4. How clinicians interpret low but detectable PSA values
Experts caution that a tiny detectable PSA shortly after surgery is not automatically a sign of incurable disease; clinicians weigh the absolute level, whether it rises on serial tests, PSA doubling time, pathology features (Gleason/grade, margins, stage), and time from surgery to PSA rise before committing to salvage therapy [1] [12] [13]. Some institutional series show that patients with very low persistent PSAs can still have good long‑term outcomes, supporting a nuanced, risk‑stratified approach [13].
5. When is action typically recommended — imaging and treatment triggers
Consensus and trial criteria commonly use PSA thresholds to trigger imaging or trials: PSMA PET sensitivity increases with higher PSA (positive rates rise substantially above 0.2–0.5 ng/mL), and many centers consider PSMA imaging or early salvage radiotherapy around PSA values in the 0.2 ng/mL range, although some will act earlier in high‑risk patients or delay imaging until PSA rises further depending on PSA doubling time and other risk factors [14] [5] [6]. Large trials and guideline panels emphasize that biochemical recurrence alone does not mandate immediate systemic therapy — kinetics and risk inform timing [5] [15].
6. Practical takeaways for patients and clinicians
Expect PSA to be very low or undetectable after prostatectomy, but do not overinterpret a single early measurement: many experts now advise confirming low/ persistent results with repeat testing and, when appropriate, waiting up to 3 months before labeling persistence to avoid overtreatment [1] [4] [8]. If PSA reaches or reliably exceeds 0.2 ng/mL (confirmed), that meets the commonly used biochemical recurrence definition and typically prompts further evaluation (imaging, assessment of PSA doubling time, pathology review) and discussion of salvage options [5] [14].
Limitations and disagreements in reporting: sources agree that PSA should fall to near zero after surgery but disagree on exact timing and numeric cutoffs — standard clinical practice uses ≥0.2 ng/mL to define recurrence whereas newer data and ultrasensitive assays are driving debate about lower thresholds and longer monitoring windows to prevent unnecessary treatment [1] [11] [4] [5]. Available sources do not mention a single universally accepted ultrasensitive cutoff adopted by all guideline bodies.