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Updated: Jun 3, 2026
Focal Laser Ablation of Prostate Cancer: An Office Procedure
Published on: March 30, 2021
Selective nanoparticle-directed ablation of the canine prostate
Jon A Schwartz1, Roger E Price, Kelly L Gill-Sharp
1Nanospectra Biosciences, Inc., Houston, Texas 77054, USA. jschwartz@nanospectra.com
Background And Objectives:
Prostate cancer is the most frequent cancer type and the second most common cause of cancer death among US men. This study, adapted a previously reported nanoparticle-directed photothermal treatment of brain tumors to the treatment of prostate disease by using normal canine prostate in vivo, directly injected with a suspension of nanoparticles as a proxy for prostate tumor, and by developing laser dosimetry for prostate which is marginally ablative in native tissue, yet producing photothermal coagulation in prostate tissue containing nanoparticles.
Methods:
Canine prostates were exposed by surgical laparotomy and directly injected with suspensions of nanoparticles (nanoshells) and irradiated by a NIR laser source delivered percutaneously by an optical fiber catheter and isotropic diffuser. The photothermal lesions were permitted to resolve for up to 8 days, at which time each animal was euthanized, necropsied, and the prostate taken for histopathological and elemental analysis.
Results:
Nanoparticles were retained for up to 4 hours in prostate and served as a proxy for prostate tumor. A marginally ablative laser dose of 3.0 W for 3 minutes was developed which would yield 4 mm-radius coagulo-necrotic lesions if nanoparticles were present.
Conclusion:
We have shown that the addition of nanoshells to native tissue, combined with a marginally ablative laser dose can generate ablative thermal lesions, and that the radial extent of the thermal lesions is strictly confined to within ∼4 mm of the optical fiber with sub-millimeter uncertainty. This, in turn, suggests a means of precise tumor ablation with an ability to obviate damage to critical structures limited primarily by the precision with which the optical fiber applicator can be placed. In so doing, it should be possible to realize a precise, nerve bundle and urethra sparing prostate cancer treatment using a minimally invasive, percutaneous approach.
Insights
This study demonstrates that injecting nanoparticles into canine prostates and using a specific laser dose creates precise thermal lesions, offering a new minimally invasive prostate cancer treatment. This approach spares critical structures like nerves and the urethra.
Area of Science:
- Biomedical Engineering
- Oncology
- Nanotechnology
Background:
- Prostate cancer is a leading cause of cancer death in the US.
- Current treatments can damage critical surrounding structures.
- Nanoparticle-directed photothermal therapy shows promise for targeted tumor ablation.
Purpose of the Study:
- To adapt nanoparticle-directed photothermal therapy for prostate cancer treatment.
- To develop precise laser dosimetry for prostate tissue.
- To evaluate the efficacy and safety of this approach in a canine model.
Main Methods:
- Normal canine prostates were used as a model for prostate tumors.
- Nanoparticle (nanoshell) suspensions were injected directly into the prostate.
- Percutaneous near-infrared laser irradiation was delivered via an optical fiber catheter.
- Histopathological and elemental analyses were performed post-treatment.
Main Results:
- Nanoparticles were retained in the prostate for up to 4 hours.
- A marginally ablative laser dose (3.0 W for 3 minutes) created 4 mm-radius coagulative necrotic lesions in the presence of nanoparticles.
- Thermal lesions were confined to within approximately 4 mm of the optical fiber with sub-millimeter uncertainty.
Conclusions:
- Nanoshells combined with a marginally ablative laser dose can generate precise thermal lesions in prostate tissue.
- This technique allows for highly localized ablation, minimizing damage to adjacent critical structures.
- The minimally invasive, percutaneous approach holds potential for nerve bundle and urethra-sparing prostate cancer treatment.
