If you are considering robotic prostate surgery, you may come across the term “positive surgical margin”. This means cancer cells are found at the edge of the tissue removed during surgery. It can increase your risk of PSA recurrence, but it does not automatically mean that your surgery has failed.
Positive margin rates vary between studies. Historical UK BAUS registry data from 2016–2019 reported a positive surgical margin rate of 16.4% after robotic radical prostatectomy, although this should be viewed as a national benchmark rather than a current 2026 rate.
What Is a Positive Surgical Margin?
After your prostate is removed, a pathologist examines the tissue and marks its outer surface with ink. A positive surgical margin means cancer cells are touching this inked edge, while a negative margin means they are not.
A positive margin does not automatically mean that your cancer had spread outside the prostate or that surgery has failed. You can have cancer confined to the prostate but still have a positive margin, so your surgeon will interpret the result alongside your stage, Grade Group and other findings.
What Is the UK Positive Surgical Margin Rate After Robotic Surgery?
The British Association of Urological Surgeons, or BAUS, provides one of the most useful UK benchmarks. Its Radical Prostatectomy Registry national summary for 2016–2019 included 34,397 procedures performed by 215 consultants at 90 hospital centres, with 29,645 (86.2%) performed robotically. The recorded positive surgical margin rate for robotic prostatectomy was 16.4%.
| BAUS 2016–2019 national data | Robotic | Laparoscopic | Open |
| Proportion of procedures | 86.2% | 7.3% | 6.5% |
| Number of procedures | 29,645 | 2,503 | 2,249 |
| Positive surgical margin rate | 16.4% | 16.4% | 15.3% |
These BAUS figures provide a useful UK benchmark based on routine practice, but they are historical rather than a current 2026 rate. The 16.4% positive margin rate should therefore be viewed as a national reference point, not a guaranteed rate for every surgeon or hospital.
What Do Large International Robotic Studies Show?
Large international robotic studies also report positive surgical margin rates of around 16%. One study of 8,095 men found a rate of 15.7%, while a 2024 long-term cohort from the EAU Robotic Urology Section Scientific Working Group included 8,141 men undergoing robot-assisted radical prostatectomy and reported positive surgical margins in 16%.
| Large robotic dataset | Number of patients | Overall positive margin rate |
| Multi-institutional RARP study | 8,095 | 15.7% |
| Long-term ERUS Scientific Working Group cohort | 8,141 | 16% |
These studies suggest that positive surgical margin rates often fall in the mid-teens overall, but the figure can vary substantially with cancer stage. For example, one large robotic study found margins in 9.45% of pT2 cancers compared with 37.2% of pT3 cancers, showing why margin rates are more meaningful when reported by pathological stage rather than as a single overall figure.
How Much Does Pathological Stage Affect Positive Margin Rates?
Pathological stage is a key predictor of positive surgical margins. In the 8,095-patient robotic study, the overall rate was 15.7%, but margins varied substantially by cancer stage.
| Pathological stage | Positive surgical margin rate |
| pT2 disease | 9.45% |
| pT3 disease | 37.2% |
Positive margins occurred in fewer than one in ten men with pT2 disease, compared with more than one in three with pT3 disease. This is because cancer extending beyond the prostate can make achieving clear margins more difficult, so margin rates should always be considered alongside the stage and complexity of the patients treated.
What Do Contemporary Stage-Specific Robotic Studies Show?
Other robotic studies also show that your cancer stage can make a major difference. In one contemporary Retzius-sparing robotic study, positive margins were found in 13.3% of men with pT2 disease compared with 28.9% of those with pT3 disease, despite most patients having intermediate- or high-risk cancer.
| Contemporary Retzius-sparing cohort | Positive margin rate |
| pT2 | 13.3% |
| pT3 | 28.9% |
| Study-defined clinically significant PSM | 8.1% overall |
Why Are Positive Margins More Common With pT3 Cancer?
With pT3 disease, the cancer has extended beyond the prostate. pT3a includes extraprostatic extension, while pT3b means that cancer has invaded the seminal vesicles. This can leave less healthy tissue between the cancer and the surrounding structures, making a clear surgical margin more difficult to achieve.
Your surgeon may also need to balance cancer removal with nerve preservation. A higher positive-margin rate in men with pT3 cancer does not automatically mean poorer surgery, as the extent and position of the tumour can make clear margins more challenging.
Does Prostate Cancer Grade Affect the Margin Rate?
Your Grade Group can influence margin risk because higher-grade cancers are more likely to have aggressive or extensive features. Your surgeon will interpret it alongside PSA, MRI findings and tumour location. If a margin is positive, the Gleason pattern at the margin can also help refine recurrence risk.
Does Your PSA Level Before Surgery Affect the Risk?
Your pre-operative PSA can contribute to estimating margin risk, but it cannot predict the result on its own. Higher PSA has been associated with increased positive-margin risk in robotic cohorts, so it should be interpreted alongside Grade Group, MRI findings and cancer stage.
Where Do Positive Surgical Margins Most Commonly Occur?
Positive surgical margins can occur in different parts of the prostate. Their significance depends on the location, length and other pathology findings. In the large 8,095-patient multi-institutional RARP study, the apex was the most common PSM location, followed by the posterolateral region.
- Prostate apex: Margins can occur near the apex, where the prostate lies close to the urethra and urinary sphincter.
- Posterolateral area: Margins may occur near tissues where the nerves involved in erections are located.
- Other prostate areas: Positive margins can also occur elsewhere depending on the position and extent of your tumour.
- Margin details: The location should be considered alongside the margin length, cancer grade and pathological stage.
A positive margin in one location does not automatically mean your cancer will recur. Your surgeon will interpret it together with your PSA and full pathology results.
Does the Length of a Positive Margin Matter?
Yes. A short, focal positive margin may carry a different risk from a longer area of cancer along the edge of the tissue removed. This is why your pathology report should include the extent of any positive margin.
Meta-analyses have found that longer positive margins are associated with a greater risk of biochemical recurrence. In analyses using a 3 mm threshold, margins of around 3 mm or longer were associated with higher recurrence risk than shorter margins. If your margin is positive, ask your consultant about its length, location and whether it is considered focal or extensive.
Does Having More Than One Positive Margin Matter?
Yes. If cancer reaches the surgical edge in more than one location, this is called a multifocal positive margin and may carry a higher risk of PSA recurrence than a single positive margin.
However, this does not mean that you will definitely develop further cancer. Your Grade Group, pathological stage, lymph-node results and post-operative PSA all need to be considered when assessing your individual risk.
Evidence Note
Positive-margin status is associated with biochemical recurrence, but margin features also matter. A 2024 meta-analysis of 31 studies involving 50,028 patients found higher recurrence risk with higher Gleason pattern at the margin, margin length around 3 mm or more, multifocal margins and stage above pT2.
Long-term robotic data also found that unifocal margins were not associated with mortality across the whole cohort, whereas multifocal margins were associated with cancer-specific and overall mortality, particularly in patients with adverse clinical or pathological features. Margin findings should therefore be interpreted alongside Grade Group, stage, lymph-node findings and post-operative PSA.
Does a Positive Margin Mean Cancer Was Left Behind?
Not necessarily. A positive margin means cancer cells touched the edge of the tissue removed, but it does not prove that cancer remains in your body.
Your post-operative PSA is therefore very important. An undetectable PSA that stays undetectable is reassuring, while a rising or persistent PSA may suggest that further assessment or treatment is needed.
Myth vs Fact
| Myth | Fact |
| A positive margin means prostate cancer was definitely left behind. | No. It means tumour touched the inked edge of the removed specimen; it does not prove that viable cancer remains in your body. |
| A positive margin means the cancer must have spread outside the prostate. | No. Margin status and pathological stage are separate, and pT2 cancers can also have positive margins. |
| Every positive margin carries the same recurrence risk. | No. Length, multifocality, tumour grade at the margin, stage and postoperative PSA all influence prognosis. |
| A 3 mm margin automatically means the cancer will recur. | No. Longer margins are associated with higher recurrence risk, but 3 mm is a research threshold rather than a guarantee of recurrence. |
| A positive margin automatically means you need immediate radiotherapy. | No. Current UK NICE guidance does not recommend routine immediate postoperative radiotherapy solely because a margin is positive. |
How Much Does a Positive Margin Increase Recurrence Risk?
A positive surgical margin increases your risk of PSA recurrence, but the extra risk varies between individuals. Factors such as the margin length, number of positive margins, cancer grade and pathological stage all matter.
One historical robotic cohort reported five-year biochemical recurrence-free survival of 89.6% in men with negative margins compared with 60.7% in men with positive margins. However, this was one study, and patients with positive margins may also differ in stage, grade and other cancer characteristics. The figures should therefore illustrate the association with recurrence rather than predict your personal outcome.
Does a Positive Margin Mean You Need Radiotherapy?
A positive margin alone does not automatically mean you need immediate radiotherapy. NICE currently recommends against routine immediate post-operative radiotherapy after radical prostatectomy, even for margin-positive disease, outside a clinical trial.
If PSA later shows biochemical relapse and there are no known metastases, NICE recommends radical radiotherapy to the prostate bed. Your team will therefore consider your PSA trend together with your pathological stage, Grade Group, lymph-node findings and margin characteristics.
UK Guidance Note
NICE guidance currently recommends against immediate post-operative radiotherapy after radical prostatectomy, including in people with margin-positive disease, other than in a clinical trial. If biochemical relapse later occurs and there are no known metastases, NICE recommends radiotherapy to the prostate bed.
European EAU guidance takes a somewhat different approach for selected very high-risk pathology. It gives a weak recommendation for adjuvant radiotherapy in pN0 patients with ISUP Grade Group 4–5 and pT3 disease, with or without positive margins.
These differences show why a positive margin should be discussed in the context of your complete pathology and PSA results within the specialist multidisciplinary team rather than being used alone to determine treatment.
Does Robotic Surgery Have Lower Margin Rates Than Open Surgery?
Historical BAUS registry data recorded similar overall PSM percentages for robotic, laparoscopic and open prostatectomy: 16.4%, 16.4% and 15.3% respectively. However, these were observational national registry figures and were not designed to prove that the surgical approaches have equivalent margin risk after adjustment for cancer stage, case complexity or surgeon factors.
Robotic technology therefore does not guarantee a negative margin. Your tumour location and pathological extent, together with surgical planning and technique, all contribute to the result.
What Should You Ask Your Surgeon About Their Margin Rates?
When discussing robotic prostate surgery, ask whether your surgeon audits their positive-margin results and whether they can show them separately for pT2 and pT3 disease. An overall percentage is difficult to interpret without knowing the case mix because surgeons treating more locally advanced cancers may reasonably have higher margin rates.
If your own pathology later shows a positive margin, ask about its location, length, focality and cancer grade, as well as your post-operative PSA. These details are more useful for understanding recurrence risk than the words ‘positive margin’ alone.
Key Takeaways
- A positive surgical margin means cancer cells reach the inked edge of the removed prostate specimen; it does not prove that cancer remains in your body.
- Historical BAUS data reported an overall robotic PSM rate of 16.4%, while large international RARP cohorts have reported overall rates of approximately 15.7–16%.
- Overall percentages can be misleading because pathological stage has a major effect: one large RARP study reported PSMs in 9.45% of pT2 cancers versus 37.2% of pT3 cancers.
- Longer margins, multifocal margins and higher tumour grade at the margin are associated with greater biochemical-recurrence risk.
- A positive margin increases recurrence risk but does not mean recurrence is inevitable.
- Current NICE guidance does not recommend routine immediate postoperative radiotherapy solely because a margin is positive.
- Your postoperative PSA, pathological stage, Grade Group, margin characteristics and lymph-node findings should be considered together.
- When comparing surgeon results, ask for stage-specific margin rates, not just one overall percentage.
Frequently Asked Questions
1. What is the positive surgical margin rate after robotic prostate surgery?
Published studies generally report positive surgical margin rates in the mid-teens after robotic prostatectomy. UK data from the BAUS registry reported a rate of 16.4%, although your individual risk depends on factors such as cancer stage, Grade Group and tumour location.
2. Does cancer stage affect the risk of a positive surgical margin?
Yes, your cancer stage can have a major effect on the likelihood of a positive margin. One large robotic study reported margins in 9.45% of men with pT2 disease compared with 37.2% of men with pT3 disease.
3. Why are positive margins more common with pT3 prostate cancer?
With pT3 prostate cancer, the tumour has grown beyond the prostate or into the seminal vesicles, making clear margins more difficult to achieve. Your surgeon may also need to balance complete cancer removal with preservation of surrounding structures.
4. Does a positive surgical margin mean that cancer has been left behind?
Not necessarily. A positive margin means cancer cells touched the edge of the tissue removed, but it does not prove that cancer remains in your body. Your post-operative PSA is important when assessing whether further treatment may be needed.
5. Does the length of a positive surgical margin matter?
Research shows an association between longer positive margins and higher biochemical-recurrence risk. Several studies and meta-analyses have used a threshold around 3 mm, but this is a prognostic research threshold rather than a point at which recurrence becomes certain.
6. Does having more than one positive surgical margin matter?
Yes, having positive margins in more than one location, known as multifocal margins, may increase your risk of PSA recurrence. However, your overall risk also depends on your cancer grade, stage, lymph-node results and post-operative PSA.
7. How much does a positive surgical margin increase recurrence risk?
A positive surgical margin increases your risk of PSA recurrence, but the additional risk varies between patients. The length and number of margins, cancer grade, pathological stage and your post-operative PSA all help determine your individual risk.
8. Does a positive surgical margin mean you need radiotherapy?
No. A positive surgical margin alone does not automatically mean you need radiotherapy. NICE recommends against routine immediate post-operative radiotherapy after prostatectomy even with margin-positive disease outside a clinical trial. If biochemical relapse later occurs without known metastases, salvage radiotherapy to the prostate bed may be recommended.
9. Does robotic surgery have lower positive margin rates than open surgery?
Robotic surgery does not automatically result in lower positive margin rates than open surgery. UK data found similar rates across robotic, laparoscopic and open procedures, with cancer stage, tumour location and surgical technique also affecting the outcome.
10. What should you ask your surgeon about positive surgical margins?
Ask your surgeon about their positive margin rates, ideally separated by cancer stage such as pT2 and pT3 disease. You should also ask about the location, length and grade of any margin and how your post-operative PSA will be used to assess your recurrence risk.
Final Thoughts: Understanding Positive Surgical Margins After Robotic Prostate Surgery
A positive surgical margin after robotic prostate surgery can cause concern, but it does not automatically mean surgery has failed or that cancer will return. Its significance depends on the margin’s length and location, Grade Group, pathological stage and post-operative PSA.
If you are considering robotic prostate surgery in London and would like specialist advice, you can contact our team at Prostate Clinic London to discuss your options and arrange a consultation tailored to your individual needs.
References:
- British Association of Urological Surgeons (no date) BAUS Radical Prostatectomy Registry 2016–2019: National Summary Results. Available at: https://www.baus.org.uk/_userfiles/pages/files/publications/audit/Prostatectomy%202016%20to%202019%20National%20figures.pdf
- Patel, V.R. et al. (2011) ‘Positive surgical margins after robotic assisted radical prostatectomy: a multi-institutional study’, The Journal of Urology, 186(2), pp. 511–517. Available at: https://pubmed.ncbi.nlm.nih.gov/21680001/
- Pellegrino, F. et al. (2024) ‘Assessing the impact of positive surgical margins on mortality in patients who underwent robotic radical prostatectomy: 20 years’ report from the EAU Robotic Urology Section Scientific Working Group’, European Urology Oncology, 7(4), pp. 888–896. Available at: https://www.sciencedirect.com/science/article/pii/S2588931123002870
- Guo, H. et al. (2024) ‘The impact of positive surgical margin parameters and pathological stage on biochemical recurrence after radical prostatectomy: a systematic review and meta-analysis’, PLOS ONE, 19(7), e0301653. Available at: https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0301653
- Bahouth, Z. et al. (2022) ‘Positive surgical margins rate of Retzius-sparing robot-assisted radical prostatectomy in a contemporary, unselected cohort’, The Journal of Urology, 207(3), pp. 609–616. Available at: https://pubmed.ncbi.nlm.nih.gov/34694141/
- Liss, M.A. et al. (2012) ‘Robot-assisted radical prostatectomy: 5-year oncological and biochemical outcomes’, The Journal of Urology, 188(6), pp. 2205–2211. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0022534712044461
- National Institute for Health and Care Excellence (NICE) (2019, updated 2021) Prostate cancer: diagnosis and management. NICE guideline NG131. Available at: https://www.nice.org.uk/guidance/ng131
- European Association of Urology (2026) EAU Guidelines on Prostate Cancer. EAU Guidelines Office, Arnhem, The Netherlands. Available at: https://uroweb.org/guidelines/prostate-cancer