NanoKnife Focal Therapy for Prostate Cancer in Nashville

NanoKnife Focal Therapy for Prostate Cancer in Nashville

A plain-language guide to irreversible electroporation (IRE) from Adnan Dervishi, MD, urologist in Nashville

 

Hearing "prostate cancer" can be scary. It can feel even more confusing when one option is removing the prostate and another is radiation. For some men, there may be a middle path called focal therapy. This page explains one type of focal therapy, NanoKnife, so you can have a better conversation about your choices.

 

You usually have time to decide. Most prostate cancers found by screening grow slowly. For many men with lower- or intermediate-risk cancer, there is time to get more tests, get a second opinion, and make a calm, informed choice. Your doctor can tell you how much time is reasonable for your situation.

 

What Is NanoKnife Focal Therapy?

Think of a lumpectomy for breast cancer, or removing only a tumor from a kidney. Focal therapy uses the same idea. Instead of treating the whole prostate, it treats only the area where the significant cancer is, plus a safety margin around it. The rest of the prostate is left alone.

This is possible because of better imaging. An MRI can often show the main tumor (called the "index lesion"). A targeted (fusion) biopsy can then confirm where the cancer is and how aggressive it is. (Learn how prostate cancer is diagnosed today.) Research suggests the main tumor usually drives the risk of cancer growing or spreading. Smaller, low-grade spots elsewhere are often less of a concern, but they still need to be watched.

MRI often underestimates how big a tumor really is. Studies comparing MRI with the removed prostate found tumors were often larger than they looked on the scan. That's why doctors plan a safety margin around the visible spot.

 

How Irreversible Electroporation (IRE) Works

NanoKnife uses a method called irreversible electroporation (IRE). Other focal treatments use heat (HIFU) or freezing (cryotherapy). NanoKnife doesn't rely mainly on heat or cold.

• Thin needles are placed around the tumor.

• Very short electrical pulses pass between the needles.

• The pulses make tiny permanent holes in the walls of the cells in that zone, so those cells die. Over time, the body clears them away.

Because it doesn't rely on heat, IRE is designed to lower the risk of damage to nearby structures like the urethra (the urine tube), nerves and blood vessels. That may be helpful for tumors near the urethra or in the front of the prostate. Still, no study has directly compared NanoKnife with other focal treatments for side effects.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​Video: How NanoKnife works (2:45). Courtesy of AngioDynamics, the maker of NanoKnife.​​​​​​​​​​​

​

 

Is NanoKnife FDA-Cleared?

Yes. The FDA has cleared NanoKnife for prostate tissue ablation through its 510(k) process (most recently in 2024 and 2026). The clearance is for ablating tissue; it is not a specific FDA approval as a cancer treatment. Your urologist can explain how it fits with other prostate cancer options.

 

Who May Be a Candidate for NanoKnife?

Focal therapy is not right for everyone. In general, men who may be considered:

• Have intermediate-risk prostate cancer (often Grade Group 2, sometimes Grade Group 3)

• Have a tumor that is visible on MRI and confirmed by a targeted biopsy

• Have cancer limited to one area of the prostate, without spread outside it

• Have a life expectancy long enough that controlling the cancer while protecting quality of life matters

Men with low-risk cancer are usually best served by active surveillance (close monitoring). Men with high-risk or more widespread cancer usually need whole-gland treatment. The American Urological Association (AUA/ASTRO) guideline says ablation may be considered for select, well-informed patients, and encourages clinical trials when possible.

Before deciding, your doctor may recommend a repeat or "confirmatory" biopsy, and sometimes other imaging. This helps make sure there isn't significant cancer elsewhere in the prostate that focal therapy would miss.

 

NanoKnife vs. Active Surveillance vs. Surgery or Radiation

 

Approach

Active surveillance: Watch closely with PSA tests, MRI and biopsies. Treat only if the cancer changes.

NanoKnife focal therapy: Treat only the main tumor plus a margin. Keep monitoring afterward.

Surgery or radiation (whole gland): Treat the entire prostate.

 

What studies show

Active surveillance: In one large UK MRI-based program, about 72% of men were still on surveillance at 5 years. Men with an MRI-visible tumor or Gleason pattern 4 were more likely to need treatment.

NanoKnife focal therapy: In the U.S. PRESERVE trial (121 men), 71% had no cancer on biopsy of the treated area at 1 year (84% by a looser expert definition). In one Sydney center, 84% avoided surgery or radiation at 5 years and 69% at 8 years.

Surgery or radiation (whole gland): The most studied, with the longest follow-up. In the ProtecT trial, risk of dying from prostate cancer was low (about 3%) at 15 years in all groups. Surgery and radiation lowered the chance of spread compared with monitoring.

 

Trade-offs

Active surveillance: No treatment side effects, but regular tests and some uncertainty.

NanoKnife focal therapy: Fewer urinary and sexual side effects in studies so far, but long-term (10+ year) data are limited. More treatment may be needed later.

Surgery or radiation (whole gland): Higher rates of long-term urinary, bowel or sexual side effects.

Focal therapy doesn't close the door on other treatments. If cancer remains or comes back, options may include another focal treatment, surgery or radiation. Surgery after focal therapy can be more complex. (See our robotic surgery options.)

 

What to Expect on NanoKnife Procedure Day

• NanoKnife is usually done as an outpatient procedure, and most men go home the same day.

• You are fully asleep under general anesthesia, with medicine that keeps your muscles still.

• Using MRI images fused with live ultrasound, your doctor places several thin needles through the skin between the scrotum and the anus. There is no large incision.

• The electrical treatment itself usually takes well under an hour.

• A urinary catheter is placed while you are asleep.

Tell your doctor if you have a pacemaker, defibrillator or nerve stimulator, or if you take blood thinners. These need planning ahead of time.

 

Recovery After NanoKnife

First days to about 1–2 weeks (catheter phase)

• The catheter usually stays in for several days. It may stay longer for larger prostates or repeat treatments. Your care team will tell you when it comes out.

• Never remove the catheter yourself. Swelling inside the prostate can make it hard to urinate if it comes out too soon.

• Much of the early discomfort comes from the catheter: bladder spasms and a strong urge to urinate. Some men also feel soreness in the area between the legs, like after a hard workout.

• Your care team will give you medicines for comfort and to help prevent infection.

Weeks 2–6

• Urinating more often or more urgently is common for the first few weeks after the catheter comes out.

• Light pink urine can happen. Heavy bleeding is uncommon.

• If your urine has been clear and then turns pink for a day or two, a small scab inside may be healing. This often clears on its own, but call us so we can check.

Months 3–12

• PSA: Your PSA blood test is usually checked a few months after treatment. In PRESERVE, PSA dropped by a median of about two-thirds by 6 months. PSA won't go to zero, because healthy prostate tissue remains.

• Urination: On average, urinary symptom scores in PRESERVE stayed about the same or improved slightly at 12 months. Leakage was uncommon: about 97% of men were continent before treatment and 95% at 12 months.

• Erections: Erections may be weaker for the first few months. In PRESERVE, 84% of men who had good erections before treatment kept erections good enough for sex at 12 months.

• Ejaculation: The amount of fluid may decrease.

 

Follow-Up After Focal Therapy

Focal therapy means ongoing monitoring, much like active surveillance:

• Regular PSA tests

• An MRI, often around 1 year

• A follow-up biopsy, often around 1 year, to check the treated area and the rest of the prostate

• Sometimes other scans. A small, harmless fluid-filled space can form where tissue was treated, and on some scans it can look like something it isn't. Your doctor will use the right tests in the right order to sort this out.

 

Risks and Limitations

Every treatment has risks. With NanoKnife they may include:

• Urinary infection, blood in the urine, burning, or frequent or urgent urination

• Trouble urinating after the catheter is removed

• Changes in erections or ejaculation

• Rare serious problems, such as injury to the rectum or urethra

• Cancer remaining or returning, either in the treated area or elsewhere in the prostate, which may need more treatment

In the PRESERVE trial, 12% of men had a serious (grade 3 or higher) side effect of any cause in the first year. Three of these were judged to be related to the procedure.

 

Important things to know about the evidence:

• PRESERVE was a single-group study with no comparison group, and it was funded by the device maker.

• No randomized trial has yet compared NanoKnife with surgery, radiation or active surveillance.

• Long-term (10+ year) cancer-control data for focal therapy are still limited.

 

Questions to ask your urologist

• What is my risk group? Is active surveillance reasonable for me?

• Is my tumor visible on MRI and limited to one area?

• Do I need a confirmatory biopsy or other imaging first?

• How would focal therapy compare with surgery or radiation for someone like me?

• What follow-up will I need, and what happens if cancer is found later?

 

NanoKnife FAQs

 

What is NanoKnife?

NanoKnife is a type of focal therapy for prostate cancer. It uses irreversible electroporation (IRE), which sends very short electrical pulses between thin needles to destroy cells in a targeted area of the prostate, without relying mainly on heat or freezing.

 

Is NanoKnife FDA-approved for prostate cancer?

The FDA has cleared NanoKnife for prostate tissue ablation through its 510(k) process. The clearance is for ablating tissue; it is not a specific FDA approval as a cancer treatment.

 

Who may be a candidate for NanoKnife?

Men who may be considered usually have intermediate-risk prostate cancer that is visible on MRI, confirmed by a targeted biopsy, and limited to one area of the prostate. Men with low-risk cancer are usually best served by active surveillance, and men with high-risk cancer usually need whole-gland treatment.

 

What is recovery like after NanoKnife?

It is usually an outpatient procedure. A urinary catheter typically stays in for several days. Bladder spasms, urgency and some soreness are common early on, and frequent urination often improves over the first few weeks.

 

Does NanoKnife affect erections or urinary control?

In the U.S. PRESERVE trial, 84% of men who had good erections before treatment kept erections good enough for sex at 12 months, and urinary control was largely preserved. Ejaculate volume may decrease. Results vary from person to person.

 

Will I need tests after NanoKnife?

Yes. Focal therapy requires ongoing follow-up with PSA tests, an MRI and usually a follow-up biopsy around one year. Some men need more treatment later, and long-term data beyond 10 years are still limited.

 

Talk With Dr. Dervishi in Nashville

If you have prostate cancer and want to know whether focal therapy may fit your situation, Dr. Dervishi can review your MRI, biopsy and PSA results with you and explain all of your options, including surveillance, surgery, radiation and focal therapy.

 

 

​

​

​

Existing patients can call (615) 622-5046. Office: 2801 Charlotte Ave, Nashville, TN 37209.

This page is for general education. It is not medical advice and does not replace a visit with your doctor. Treatment decisions depend on your own health, test results and preferences. Results vary from person to person.

 

Sources

1. George AK, Miocinovic R, Patel AR, et al. Irreversible electroporation for prostate tissue ablation in patients with intermediate-risk prostate cancer: results from the PRESERVE trial. Eur Urol. 2026;89(1):57–68. https://doi.org/10.1016/j.eururo.2025.06.003 (PubMed 40685282)

2. George AK, et al. Preliminary results from the PRESERVE trial. Cancers (Basel). 2024;16(12):2178. https://doi.org/10.3390/cancers16122178 (PubMed 38927884)

3. Two-year outcomes from the PRESERVE trial (preprint, not peer reviewed). medRxiv, May 2026. https://doi.org/10.64898/2026.05.08.26352470

4. Scheltema MJ, et al. Median 5-year outcomes of primary focal irreversible electroporation for localised prostate cancer. BJU Int. 2023;131 Suppl 4:6–13. https://doi.org/10.1111/bju.15946 (PubMed 36495481)

5. Fainberg J, et al. TARGET study. Urol Pract. 2024;11(6):983–990. https://doi.org/10.1097/UPJ.0000000000000666 (PubMed 39196716)

6. U.S. FDA 510(k) K242687 (Dec 6, 2024): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K242687 ; K253198 (Mar 24, 2026): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K253198

7. Eastham JA, et al. Clinically Localized Prostate Cancer: AUA/ASTRO Guideline (2022). https://www.auanet.org/documents/Guidelines/PDF/Localized%20Prostate%20Cancer%20Guideline.pdf

8. Stavrinides V, et al. Five-year outcomes of MRI-based active surveillance. Eur Urol. 2020;78(3):443–451. https://doi.org/10.1016/j.eururo.2020.03.035 (PubMed 32360049)

9. Priester A, et al. MRI underestimation of prostate cancer geometry. J Urol. 2017;197(2):320–326. https://doi.org/10.1016/j.juro.2016.07.084 (PubMed 27484386)

10. Ahmed HU, et al. Do low-grade and low-volume prostate cancers bear the hallmarks of malignancy? Lancet Oncol. 2012;13(11):e509–17. https://doi.org/10.1016/S1470-2045(12)70388-1 (PubMed 23117005)

11. Hamdy FC, et al. Fifteen-year outcomes after monitoring, surgery, or radiotherapy (ProtecT). N Engl J Med. 2023;388:1547–1558. https://doi.org/10.1056/NEJMoa2214122 (PubMed 36912538)

12. Donovan JL, et al. Patient-reported outcomes after monitoring, surgery, or radiotherapy (ProtecT). N Engl J Med. 2016;375:1425–1437. https://doi.org/10.1056/NEJMoa1606221 (PubMed 27626365)