How long does it take for PSA to reach undetectable levels after prostatectomy?

1. What “undetectable” means and how quickly it should happen — the standard picture

Clinicians expect PSA to drop to a very low or undetectable level after the prostate is removed; official patient guidance and major cancer organizations state that PSA “should fall to a very low or even undetectable level within a couple of months” after radical prostatectomy ^[1]. Consumer-facing health sources commonly translate that into a 6–8 week timeframe for PSA to become undetectable and note ultrasensitive assays can define undetectable as <0.05 or <0.1 ng/mL depending on the lab ^[2].

2. How follow‑up testing is typically scheduled — practical timelines

Follow-up testing schedules vary: many programs draw an initial postoperative PSA around 6 weeks and then repeat it every 3 months for the first two years, shifting to less frequent checks if values stay low (every 6–12 months and later annually) ^{[6] [2]}. The American Cancer Society guidance specifically says PSA should be checked and will usually be very low or undetectable within a couple of months; frequency afterward depends on risk and results ^[1].

3. New evidence urging patience: why some experts now recommend waiting ≥3 months

A recent, large cohort study (43,000+ patients) published in JAMA Oncology and covered by multiple outlets found that measuring PSA too soon — the common 1.5–2.0 month interval — risks mislabeling patients as having persistent PSA and may lead to overtreatment with salvage radiation or hormones. Those authors and affiliated institutions now recommend measuring PSA at least 3 months after surgery before concluding persistence and initiating further therapy ^{[3] [4] [5] [7]}.

4. Competing thresholds and the role of ultrasensitive assays

There is active debate about the numeric cutoff that constitutes persistence. Some centers using ultrasensitive assays propose very low nadir goals (for example ≤0.03 ng/mL) and suggest thresholds like ≥0.04 ng/mL may optimally define persistence ^[8]. Other expert consensus definitions for biochemical recurrence use higher cutoffs (e.g., PSA ≥0.2 ng/mL with confirmatory reading) — illustrating that an “undetectable” result and a “recurrence” are defined differently depending on context and purpose ^{[9] [8]}.

5. Clinical consequences: overtreatment versus early salvage therapy

There’s tension between acting early (to improve salvage-radiation outcomes at lower PSA) and avoiding overtreatment triggered by transient or slowly falling PSA. Conference guidance and trials favor early salvage radiotherapy at lower but confirmed PSA rises for those who truly recur ^[9]. Conversely, the JAMA Oncology cohort authors warn that checking too early can prompt unnecessary salvage interventions; they found delayed measurement reduced the number mislabeled as persistent and likely reduced overtreatment ^{[3] [4]}.

6. Bottom line for patients: what to expect and discuss with your team

Expect PSA to decline to very low or undetectable levels within weeks to a couple of months after prostatectomy; many clinicians test around 6 weeks then at 3‑month intervals, but new evidence supports waiting at least 3 months to declare PSA persistence to avoid overtreatment ^{[1] [2] [3] [4]}. Ask your surgeon/urologist what assay they use, what “undetectable” means in that lab, and how they time the first postop PSA in light of recent cohort data ^{[8] [3]}.

Limitations: available sources do not mention individualized factors such as specific surgical technique, residual benign tissue, or patient comorbidities that can affect PSA kinetics in individual cases; for those details consult your treating team (not found in current reporting).