Interstitial microwave thermal therapy for prostate cancer: method of treatment and results of a phase I/II trial

Microwave for focal therapy of prostate cancer: Non-clinical study and exploratory clinical trial

OBJECTIVE

The objective of this non-clinical study and clinical trial (phase II) was to examine the safety and efficacy of microwave tissue coagulation (MTC) for prostate cancer and assess its use in lesion-targeted focal therapy.

METHODS

In the non-clinical study using Microtaze®-AFM-712 (Alfresa-pharma Corporation) with an MTC-needle, MTC was performed by a transperineal approach to canine prostatic-targeted tissue under real-time ultrasound guidance. Using various MTC-output and irradiation-time combinations, the targeted and surrounding tissues (rectum, bladder, and fat) were examined to confirm the extent of coagulative necrosis or potential cell death, and to compare intra-operative ultrasound and pathology findings. The exploratory clinical trial was conducted to examine the safety and efficacy of MTC. Five selected patients underwent transperineal MTC to clinically single magnetic resonance imaging (MRI)-visible lesions with Gleason score 3+4 or 4+4. Prostate-specific antigen (PSA), MRI, and Expanded Prostate Cancer Index Composite questionnaire findings were compared before and 6 months after surgery.

RESULTS

The region of coagulative necrosis was predictable by monitoring of ultrasonically visible vaporization; thus, by placing the MTC-needle at a certain distance, we were able to perform a safe procedure without adverse events affecting the surrounding organs. Based on the non-clinical study, which used various combinations of both output and irradiation time, MTC with 30-W output for 60-sec irradiation was selected for the prostate. Based on the predictable necrosis, the therapeutic plan (where to place the MTC-needle to achieve complete ablation of the target and how many sessions) was strictly determined per patient. There were no serious adverse events in all patients and only temporary urinary symptoms related to MTC-therapy were observed. Furthermore, satisfaction of having undergone treatment was very high. All pre-operative MRI-visible lesions disappeared, and PSA decreased 55% 6 months after surgery.

CONCLUSION

MTC may be an option for lesion-targeted focal therapy for prostate cancer.

Focal therapy in prostate cancer: the current situation

Prostate cancer is one of the most significant pathologies in the field of urology. The adoption of screening strategies and improvements in biopsies have resulted in an increase in early-stage tumour detection.

Radical global therapies provide very good oncological results in localised prostate cancer. However, excess treatment in low- and, in some cases, intermediate-risk groups affects the quality of life of these patients.

In the case of localised prostate cancer, focal therapies offer a minimally invasive option with good results with respect to established treatments. Although this is currently not a standard treatment, it represents the therapeutic approach with the greatest potential.

This literature review has the following objectives: to define selection criteria for patients who are candidates for focal therapy, to assess the current situation and results of the different therapeutic options, and to define procedures in cases of recurrence and for follow-ups.

We concluded that focal therapy is a viable therapeutic alternative for localised prostate cancer, specifically cryosurgery and high-intensity targeted ultrasound, which have acceptable oncologic results and a lower comorbidity compared with global treatments. Studies with a high level of scientific evidence are still needed to validate these results.

The pattern of prostate cancer local recurrence after radiation and salvage cryoablation

OBJECTIVE

We assessed the pattern of local recurrence after salvage cryoablation of the prostate, and the impact of local recurrence on intermediate-term outcome.

METHODS

One hundred twenty-two patients who underwent salvage cryoablation were studied after a mean follow-up of 56 months. Serial prostate biopsy was carried out after cryoablation. The histopathology of prostate biopsies before and after cryoablation were compared. The prognostic value of post-cryoablation biopsy was assessed with the Cox regression method.

RESULTS

23.1% of patients had a positive biopsy for prostate cancer following salvage cryoablation. Most cancer recurrences occurred in the apex (51.5%), base (21.2%) and seminal vesicles (18.2%). The presence of cancer at the base of the prostate was found to be a prognostic factor for eventual biochemical failure. Overall 5-year biochemical disease-free survival (bDFS) was 28%, however patients with cancer at the base of the prostate had a 5-year bDFS of 0%.

CONCLUSION

Cancer recurrences occurred in areas where aggressive freezing was avoided as it might result in serious problems (e.g., urethro-rectal fistula and incontinence). Post-cryoablation biopsies and the location of persistent disease are of prognostic value.

[Local treatment of prostate cancer using thermal-ablative energy]

Thermal and thermal-ablative procedures for treating prostate cancer have been investigated systematically since approximately 1980 (apart from some historical predecessors), and numerous experimental and clinical reports have been published on this subject. Various technologies have been used, including transurethral ablation of prostatic tissue using laser or microwave energy, interstitial application of laser or microwave energy, and inductive heating of previously implanted thermoseeds or injected magnetic nanoparticles in a magnetic field. For all of these procedures, clinical studies with a total of some 350 patients have been performed. However, the results cannot be judged correctly because of a lack of adequate control parameters for the older studies and inadequately short follow-up of all studies. Conclusions regarding treatment-related morbidity seem to be possible, with a generally positive impression and low rates of adverse effects. But before such results can be generalized, patient selection bias and the technology standards that existed when the studies were performed must be taken into consideration. Various papers are reviewed and summarized. In the author's opinion, the different options for thermal and thermal-ablative treatment of prostate cancer are very promising, but in light of the existing standard procedures, feasibility must not overrule reasonableness.

Treatment planning and dose analysis for interstitial photodynamic therapy of prostate cancer

With the development of new photosensitizers that are activated by light at longer wavelengths, interstitial photodynamic therapy (PDT) is emerging as a feasible alternative for the treatment of larger volumes of tissue. Described here is the application of PDT treatment planning software developed by our group to ensure complete coverage of larger, geometrically complex target volumes such as the prostate. In a phase II clinical trial of TOOKAD vascular targeted photodynamic therapy (VTP) for prostate cancer in patients who failed prior radiotherapy, the software was used to generate patient-specific treatment prescriptions for the number of treatment fibres, their lengths, their positions and the energy each delivered. The core of the software is a finite element solution to the light diffusion equation. Validation against in vivo light measurements indicated that the software could predict the location of an iso-fluence contour to within approximately +/-2 mm. The same software was used to reconstruct the treatments that were actually delivered, thereby providing an analysis of the threshold light dose required for TOOKAD-VTP of the post-irradiated prostate. The threshold light dose for VTP-induced prostate damage, as measured one week post-treatment using contrast-enhanced MRI, was found to be highly heterogeneous, both within and between patients. The minimum light dose received by 90% of the prostate, D(90), was determined from each patient's dose-volume histogram and compared to six-month sextant biopsy results. No patient with a D(90) less than 23 J cm(-2) had complete biopsy response, while 8/13 (62%) of patients with a D(90) greater than 23 J cm(-2) had negative biopsies at six months. The doses received by the urethra and the rectal wall were also investigated.

Vascular targeted photodynamic therapy with palladium-bacteriopheophorbide photosensitizer for recurrent prostate cancer following definitive radiation therapy: assessment of safety and treatment response

PURPOSE

Tookad is a novel intravascular photosensitizer. When activated by 763 nm light, it destroys tumors by damaging their blood supply. It then clears rapidly from the circulatory system. To our knowledge we report the first application of Tookad vascular targeted photodynamic therapy in humans. We assessed the safety, pharmacokinetics and preliminary treatment response as a salvage procedure after external beam radiation therapy.

MATERIALS AND METHODS

Patients received escalating drug doses of 0.1 to 2 mg/kg at a fixed light dose of 100 J/cm or escalated light doses of 230 and 360 J/cm at the 2 mg/kg dose. Four optical fibers were placed transperineally in the prostate, including 2 for light delivery and 2 for light dosimetry. Treatment response was assessed primarily by hypovascular lesion formation on contrast enhanced magnetic resonance imaging and transrectal ultrasound guided biopsies targeting areas of lesion formation and secondarily by serum prostate specific antigen changes.

RESULTS

Tookad vascular targeted photodynamic therapy was technically feasible. The plasma drug concentration was negligible by 2 hours after infusion. In the drug escalation arm 3 of 6 patients responded, as seen on magnetic resonance imaging, including 1 at 1 mg/kg and 2 at 2 mg/kg. The light dose escalation demonstrated an increasing volume of effect with 2 of 3 patients in the first light escalation cohort responding and all 6 responding at the highest light dose with lesions encompassing up to 70% of the peripheral zone. There were no serious adverse events, and continence and potency were maintained.

CONCLUSIONS

Tookad vascular targeted photodynamic therapy salvage therapy is safe and well tolerated. Lesion formation is strongly drug and light dose dependent. Early histological and magnetic resonance imaging responses highlight the clinical potential of Tookad vascular targeted photodynamic therapy to manage post-external beam radiation therapy recurrence.

Morbidity and quality of life during thermotherapy using magnetic nanoparticles in locally recurrent prostate cancer: results of a prospective phase I trial

PURPOSE

To investigate the treatment-related morbidity and quality of life (QoL) during thermotherapy using superparamagnetic nanoparticles in patients with locally recurrent prostate cancer.

MATERIALS AND METHODS

Ten patients with biopsy-proven locally recurrent prostate cancer following primary therapy with curative intent and no detectable metastases were entered on a prospective phase I trial. Endpoints were feasibility, toxicity and QoL. Following intraprostatic injection of a nanoparticle dispersion, six thermal therapy sessions of 60 min duration were delivered at weekly intervals using an alternating magnetic field. National Cancer Institute (NCI) common toxicity criteria (CTC) and the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and QLQ-PR25 questionnaires were used to evaluate toxicity and QoL, respectively. In addition, prostate specific antigen (PSA) measurements were carried out.

RESULTS

Maximum temperatures up to 55 degrees C were achieved in the prostates at 25-30% of the available magnetic field strength. Nanoparticle deposits were detectable in the prostates one year after thermal therapy. At a median follow-up of 17.5 months (3-24), no systemic toxicity was observed. Acute urinary retention occurred in four patients with previous history of urethral stricture. Treatment-related morbidity was moderate and QoL was only temporarily impaired. Prostate-specific antigen (PSA) declines were observed in eight patients.

CONCLUSIONS

Interstitial heating using magnetic nanoparticles was feasible and well tolerated in patients with locally recurrent prostate cancer. Deposition of nanoparticles in the prostate was highly durable. Further refinement of the technique is necessary to allow application of higher magnetic field strengths.

Prostate gland: MR imaging appearance after vascular targeted photodynamic therapy with palladium-bacteriopheophorbide

PURPOSE

To prospectively evaluate the magnetic resonance (MR) imaging appearance of the prostate and periprostatic tissues after vascular targeted photodynamic therapy (VTP) with palladium-bacteriopheophorbide for locally recurrent carcinoma after external beam radiation therapy.

MATERIALS AND METHODS

Informed consent was obtained from all patients, and approval was obtained from the ethics review boards of all participating institutions. Nonenhanced T2-weighted and dynamic gadolinium-enhanced T1-weighted MR imaging examinations were performed at baseline and 1 week, 4 weeks, and 6 months after VTP in 25 men (age range, 58-83 years; mean age, 73 years) as part of a prospective phase I/II trial. Percentage of MR-depicted necrosis was defined as the volume of nonenhancing prostatic tissue 1 week after VTP divided by the volume of the prostate. Patterns of intra- and extraprostatic necrosis were recorded. Pearson correlation coefficients were used to test correlations between necrosis and prostate-specific antigen level.

RESULTS

Contrast material-enhanced T1-weighted MR images obtained 1 week after therapy showed necrosis in all patients. Treatment margins were irregular in 21 of 25 patients. T2-weighted images showed no clear treatment boundaries in any patient. Extraprostatic necrosis involved the puborectalis or levator ani muscles in 22, obturator internus muscle in 12, periprostatic veins in three, pubic bone marrow in four, and anterior rectal wall in nine of the 25 patients. The neurovascular bundle appeared to be spared in all patients. Percentage of MR-depicted intraprostatic necrosis was correlated with percentage decrease in prostate-specific antigen level (from baseline) at 4 weeks (r=0.41, P=.04) and 12 weeks (r=0.45, P=.02).

CONCLUSION

Contrast-enhanced MR imaging depicts irregular margins of intraprostatic treatment effect. This finding suggests varied tissue sensitivities to VTP with palladium-bacteriopheophorbide.

Management of prostate cancer. Part 2: localized and locally advanced disease

Prostate cancer is the most prevalent nondermatological malignancy affecting men in the Western world. An increase in public awareness has led to earlier detection. Accepted treatments for localized prostate cancer include active surveillance, radical prostatectomy, interstitial brachytherapy, external beam radiotherapy and watchful waiting. The authors discuss the rationale for the different approaches together with outcomes including toxicity. Novel approaches are also explored. The management of locally advanced disease has long been a challenge and the evolving evidence is reviewed.

Optimizing heat shock protein expression induced by prostate cancer laser therapy through predictive computational models

Thermal therapy efficacy can be diminished due to heat shock protein (HSP) induction in regions of a tumor where temperatures are insufficient to coagulate proteins. HSP expression enhances tumor cell viability and imparts resistance to chemotherapy and radiation treatments, which are generally employed in conjunction with hyperthermia. Therefore, an understanding of the thermally induced HSP expression within the targeted tumor must be incorporated into the treatment plan to optimize the thermal dose delivery and permit prediction of the overall tissue response. A treatment planning computational model capable of predicting the temperature, HSP27 and HSP70 expression, and damage fraction distributions associated with laser heating in healthy prostate tissue and tumors is presented. Measured thermally induced HSP27 and HSP70 expression kinetics and injury data for normal and cancerous prostate cells and prostate tumors are employed to create the first HSP expression predictive model and formulate an Arrhenius damage model. The correlation coefficients between measured and model predicted temperature, HSP27, and HSP70 were 0.98, 0.99, and 0.99, respectively, confirming the accuracy of the model. Utilization of the treatment planning model in the design of prostate cancer thermal therapies can enable optimization of the treatment outcome by controlling HSP expression and injury.

Complete regression of experimental prostate cancer in nude mice by repeated hyperthermia using magnetite cationic liposomes and a newly developed solenoid containing a ferrite core

BACKGROUND

Magnetite cationic liposomes (MCLs) can be used to induce hyperthermia because they generate heat in an alternating magnetic field (AMF). This study aimed at developing more practical method for MCL hyperthermia examining the effect of MCL-induced hyperthermia on human prostate cancer in vivo.

MATERIALS AND METHODS

A newly developed AMF generator incorporating a solenoid with a ferrite core (FC) was used. Human prostate cancer cells (PC-3 and LNCap) were injected subcutaneously into nude mice. MCLs were injected into tumor nodule and the mice were exposed into AMF three times at 24-hr intervals (repeated hyperthermia; RH) until complete tumor regression was observed.

RESULTS

Irradiation with an AMF generated by newly developed device can adequately increase the temperature of tumor tissue. Frequent RH resulted in complete tumor regression in all nude mice.

CONCLUSION

RH using MCLs may be a promising new therapy for hormone-refractory human prostate cancer in the future.

Method for MRI-guided conformal thermal therapy of prostate with planar transurethral ultrasound heating applicators

A method for conformal prostate thermal therapy using transurethral ultrasound heating applicators incorporating planar transducers is described. The capability to shape heating patterns to the geometry of the prostate gland from a single element in a multi-element heating applicator was evaluated using Bioheat transfer modelling. Eleven prostate geometries were obtained from patients who underwent MR imaging of the prostate gland prior to radical prostatectomy. Results indicate that ultrasound heating applicators incorporating multi-frequency planar transducers (4 x 20 mm, f = 4.7 MHz, 9.7 MHz) are capable of shaping thermal damage patterns to the geometry of individual prostates. A temperature feedback control algorithm has been developed to control the frequency, rotation rate and applied power level from transurethral heating applicators based on measurements of the boundary temperature during heating. The discrepancy between the thermal damage boundary and the target boundary was less than 5 mm, and the transition distance between coagulation and normal tissue was less than 1 cm. Treatment times for large prostate volumes were less than 50 min, and perfusion did not have significant impact on the control algorithm. Rectal cooling will play an important role in reducing undesired heating near the rectal wall. Experimental validation of the simulations in a tissue-mimicking gel phantom demonstrated good agreement between the predicted and generated patterns of thermal damage.

Recent trends in surgical treatment of localized prostate cancer

Prostate cancer and its various forms of treatment remain a source of significant controversy and morbidity despite recent advances. In response, there is an increasing trend toward the development of treatments aimed at cancer prevention and at maximizing the preservation of function without sacrificing cancer control. This article reviews the current prostate cancer literature and reports on improvements in existing surgical treatments and developing technologies aimed toward achieving these goals. Specific therapies addressed include improvements in surgical techniques, laparoscopy, robotics, cryosurgical and thermal ablation, and high-intensity focused ultrasound.

Techniques for delivery and monitoring of TOOKAD (WST09)-mediated photodynamic therapy of the prostate: Clinical experience and practicalities

Photodynamic therapy of solid organs requires sufficient PDT dose throughout the target tissue while minimizing the dose to proximal normal structures. This requires treatment planning for position and power of the multiple delivery channels, complemented by on-line monitoring during treatment of light delivery, drug concentration and oxygen levels. We describe our experience in implementing this approach in Phase I/II clinical trials of the Pd-bacteriophephorbide photosensitizer TOOKAD (WST09)-mediated PDT of recurrent prostate cancer following radiation failure. We present several techniques for delivery and monitoring of photodynamic therapy, including beam splitters for light delivery to multiple delivery fibers, multi-channel light dosimetry devices for monitoring the fluence rate in the prostate and surrounding organs, methods of measuring the tissue optical properties in situ, and optical spectroscopy for monitoring drug pharmacokinetics of TOOKAD in whole blood samples and in situ in the prostate. Since TOOKAD is a vascular-targeted agent, the design and implementation of the techniques are different than for cellular-targeted agents. Further development of these delivery and monitoring techniques will permit full on-line monitoring of the treatment that will enable real-time, patient-specific and optimized delivery of PDT.

Effect of insertion depth on helical antenna performance in a muscle-equivalent phantom

Barrett's oesophagus is considered to increase the risk of cancer 30 fold. A set of helical microwave antennas was designed to investigate their potential use in the thermal therapy of Barrett's oesophagus. For treatment, a balloon filled with muscle-equivalent material encapsulates the antenna. The effects of insertion depth and coil-spacing on the thermal distribution produced by the antennas (20-35 mm) were characterized. The 35 mm helical antenna, with a coil-spacing of 3.6 mm resulted in uniform heating for an insertion depth of 40 mm. It was observed that the resultant temperature distribution produced, by the antennas, was dependent on the insertion depth within the phantom. For all antennas studied, deeper insertion resulted in two high intensity regions, approximately 1/4 and 3/4 along the antenna length. In contrast, shallow insertion resulted in predominant tip heating with undesirable heating at the phantom entry point. However, by manipulating the coil-spacing of the helix, uniform temperature profiles were achieved for a range of insertion depths.

Curvilinear transurethral ultrasound applicator for selective prostate thermal therapy

Thermal therapy offers a minimally invasive option for treating benign prostatic hyperplasia (BPH) and localized prostate cancer. In this study we investigated a transurethral ultrasound applicator design utilizing curvilinear, or slightly focused, transducers to heat prostatic tissue rapidly and controllably. The applicator was constructed with two independently powered transducer segments operating at 6.5 MHz and measuring 3.5 mm x 10 mm with a 15 mm radius of curvature across the short axis. The curvilinear applicator was characterized by acoustic efficiency measurements, acoustic beam plots, biothermal simulations of human prostate, ex vivo heating trials in bovine liver, and in vivo heating trials in canine prostate (n=3). Each transducer segment was found to emit a narrow acoustic beam (max width <3 mm), which extended the length of the transducer, with deeper penetration than previously developed planar or sectored tubular transurethral ultrasound applicators. Acoustic and biothermal simulations of human prostate demonstrated three treatment schemes for the curvilinear applicator: single shot (10 W, 60 s) schemes to generate narrow ablation zones (13 x 4 mm, 52 degrees C at the lesion boundary), incremental rotation (10 W, 10 degrees/45 s) to generate larger sector-shaped ablation zones (16 mm x 180 degrees sector), and rotation with variable sonication times (10 W, 10 degrees/15-90 s) to conform the ablation zone to a predefined boundary (9-17 mm x 180 degrees sector, 13 min total treatment time). During in vivo canine prostate experiments, guided by MR temperature imaging, single shot sonications (6 W/transducer, 2-3 min) with the curvilinear applicator ablated 20 degree sections of tissue to the prostate boundary (9-15 mm). Multiple adjacent sonications ("sweeping") ablated large sections of the prostate (180 degrees) by using the MR temperature imaging to adjust the power (4-6.4 W/transducer) and sonication time (30-180 s) at each 10 degrees rotation such that the periphery of the prostate reached 52 degrees C before the next rotation. The conclusion of this study was that the curvilinear applicator produces a narrow and penetrating ultrasound beam that, when combined with image guidance, can provide a precise technique for ablating target regions with a contoured outer boundary, such as the prostate capsule, by rotating in small steps while dynamically adjusting the net applied electrical power and sonication time at each position.

FERROMAGNETIC THERMAL ABLATION OF LOCALLY RECURRENT PROSTATE CANCER: PROSTATE SPECIFIC ANTIGEN RESULTS AND IMMEDIATE/INTERMEDIATE MORBIDITIES

PURPOSE

Curative options for locally recurrent prostate cancer following external beam radiotherapy are limited due to the significant morbidity associated with surgical therapy. ThermoRods (Ablation Technologies, San Diego, California) are permanently implantable, 14 mm cobalt-palladium alloy rods that produce heat through oscillation of a magnetic field. The rod is designed to self-regulate the temperature to 70C by a temperature dependent magnetic transition (Curie effect). We determined whether patients with prostate cancer and local failure could be treated with thermal ablation of the prostate using this novel technology.

MATERIALS AND METHODS

A total of 14 men with an average age of 72 years (range 62 to 81) were enrolled in the study. All had biopsy proven prostate cancer with increasing prostate specific antigen (PSA) (1.0 to 10.3 ng/ml). The seminal vesicles were not routinely biopsied. Metastatic disease was assayed in all men with bone scan and in later patients with abdominopelvic computerized tomography. Patients had ThermoRods placed under transrectal ultrasound guidance, similar to brachytherapy. The pre-plan was rigorously followed to produce a 3-dimensional array with rods separated by 1 cm across the short axis. Patients were treated in a magnetic field for 1 hour. Urethral and rectal temperatures were also monitored and cooled appropriately. Serial PSA measurements and 6 month posttreatment biopsies were obtained after the procedure.

RESULTS

Average time since radiation was 4.5 years. PSA nadir values after radiation were between 0.3 and 2.2 ng/ml. Prostatic temperatures were homogeneously increased greater than 50C, while rectal and urethral temperatures did not exceed 44C at any point. The urethral catheter was removed 2 weeks postoperatively in all cases. Six months after the procedure 8 of the 14 men (57%) had a PSA decrease to less than 0.1 ng/ml. Complications included urinary retention as well as incontinence. Incontinence was generally temporary and only 1 patient (7%) had long-term incontinence. Most patients were impotent after treatment. Of the patients 21% experienced urinary retention. Five patients (36%) needed to undergo secondary procedures after therapy, including transurethral prostate resection in 2, balloon dilation in 1, cystoscopic removal of necrotic tissue in 1 and bladder irrigation in 1.

CONCLUSIONS

This novel means of thermal ablation produces significant PSA decreases in patients. Morbidity is predominantly in the form of incontinence and impotence. Incontinence is generally temporary. The use of ferromagnetic rods enables the precise control of tissue destruction with the sparing of immediately adjacent structures. The technology uses skills familiar to the urologist and avoids radiation. The durability of the PSA response and incidence of late morbidity remain to be defined.

Tissue ablation technologies for localized prostate cancer

Traditional treatments for men with localized prostate cancer have included both surgical removal and radiation therapy, with their potential adverse effects on patient quality of life. Thus, there has been increasing interest in the development of minimally invasive procedures that use various technologies to deliver lethal doses of heat or cold to the prostate in an attempt to kill cancer cells. At the same time, it is vital that these newer techniques ablate prostate tissue and spare vital periprostatic organs essential for maintaining function and quality of life. In this article, we evaluate the current status of tissue ablation modalities in the treatment of clinically localized prostate cancer, focusing on the different methods, early results, and possible future directions. Although still in the beginning stages, these newer forms of treatment offer exciting potential for first-line and second-line treatment of this common urologic malignancy.

Thermal Protection during Percutaneous Thermal Ablation of Renal Cell Carcinoma

Thermal injury to collateral structures is a known complication of thermal ablation of tumors. The authors present the use of CO(2) dissection and inserted balloons to protect the bowel during percutaneous radiofrequency (RF) ablation and cryotherapy of primary and locally recurrent renal cell carcinoma. These techniques offer the potential to increase the number of tumors that can be treated with RF ablation or cryotherapy from a percutaneous approach.

Histological changes of minimally invasive procedures for the treatment of benign prostatic hyperplasia and prostate cancer: clinical implications

PURPOSE

Benign prostatic hyperplasia (BPH) is near universal in aging men, creating tremendous costs in morbidity and surgical treatment. In the last decade numerous nonsurgical minimally invasive methods have emerged for ablation of prostatic tissue.

MATERIALS AND METHODS

We reviewed the recently published English language literature on minimally invasive techniques for treating BPH and cancer with an emphasis on histopathological findings.

RESULTS

We compared the spectrum of contemporary minimally invasive treatments for BPH and cancer, with an emphasis on histopathological results. Clinical results were summarized briefly for each treatment method. These procedures ablate tissue by thermal, cryogenic, chemical or enzymatic injury. The 5-year results for some techniques were promising, although long-term durability is still uncertain, and other methods were in preclinical or early clinical stages. Invariably the treated tissue was devitalized with a thin border of granulation tissue and fibrosis. These procedures have applications for BPH and prostate cancer, although some studies are limited to only 1 disease.

CONCLUSIONS

Minimally invasive procedures show promise of a durable replacement for surgical resection.

Randomized prospective trial of a novel local anesthetic technique for extensive prostate biopsy

OBJECTIVES

To determine the effectiveness of a novel technique of administering local anesthesia for extensive prostate biopsy. Little reported experience with local anesthesia for extensive prostate biopsy methods is available.

METHODS

A prospective, randomized study was performed on 50 men undergoing transrectal ultrasound-guided prostate biopsy using the five-region technique. Patients were randomized into one of two groups. One group received 22 mL of a 1% lidocaine solution injected into the neurovascular bundles, the genitourinary diaphragm, and between the rectal wall and prostate. The second group received 10 mL of 2% intrarectal lidocaine jelly. A median of 12 biopsy cores was obtained from each patient. The patients were then asked by a urology nurse unaware of the anesthesia method to grade the discomfort using a 10-point linear visual analog pain scale.

RESULTS

Twenty-three men received anesthesia with lidocaine jelly, and 27 received anesthesia with lidocaine infiltration. The mean pain scores were significantly different statistically between the lidocaine jelly and lidocaine infiltration groups with respect to overall pain (4.2 versus 0.5) and pain during the biopsy portion of the procedure (4.2 versus 0.5).

CONCLUSIONS

Extensive biopsy techniques may be comfortably performed by the urologist in an office setting using local anesthesia. The administration of 22 mL of a 1% lidocaine solution, injected at the prostatic pedicles, the genitourinary diaphragm, and the space between the prostate and rectum, allows the patient to comfortably undergo an extensive biopsy protocol in an office setting.

Ultrasound properties of human prostate tissue during heating

Changes in the ultrasound (US) properties of tissue during heating affect the delivery of US thermal therapy and may provide a basis for US image monitoring of thermal therapy. The US attenuation coefficient and backscatter power of fresh human prostate tissue were measured as the tissue was heated. Samples of human prostate were obtained directly from autopsies and heated rapidly to final temperatures of 45 degrees C, 50 degrees C, 55 degrees C, 60 degrees C and 65 degrees C. A 5.0-MHz transducer was scanned in a raster pattern over the tissue and radiofrequency (RF) data were collected at 36 uncorrelated positions. Both attenuation and backscatter were measured over the frequency range 3.5 to 7.0 MHz at each min of a 30-min heating. Little change was observed in attenuation or backscatter at 55 degrees C or less. The attenuation coefficient and backscatter power increased by factors of 1.25 and 5, respectively, during the 60 degrees C heating. During the 65 degrees C heating, the same properties showed increases by factors of 2.7 and 9.