Intra-prostatic vasculature studies: can they predict the outcome of transurethral microwave thermotherapy for the management of bladder outflow obstruction?

Can color doppler predict the uniformity of HIFU-induced prostate tissue destruction?

BACKGROUND

Tissue blood perfusion influences the results of some hyperthermia and thermotherapy procedures, but its role in the outcome of prostate cancer treatment by high-intensity focused ultrasound (HIFU) has not been evaluated yet. We evaluated preoperative prostate color Doppler as a predictor of the efficacy of HIFU treatment.

METHODS

Thirty-five patients underwent pre- and post-contrast color Doppler examination of the prostate before HIFU treatment. Specific software was used to calculate, on color Doppler images, the color pixel density (CPD), and the specific flow (SF, i.e., mean velocity x CPD) in different regions of interest. Post-treatment sextant biopsies were obtained in 31 patients, 5.8 +/- 2.8 months after HIFU treatment.

RESULTS

No significant correlation was found between the uniformity of HIFU-induced tissue destruction observed on control biopsies and the pre-treatment CPD/SF values in any region of interest, either before or after contrast injection. On the other hand, history of radiation therapy was significantly associated with homogeneous tissue destruction and history of hormone therapy was significantly associated with incomplete tissue destruction.

CONCLUSIONS

Color Doppler cannot predict the uniformity of HIFU-induced tissue destruction. History of radiation therapy was found to be a factor of favorable prognosis and history of hormone therapy was found to be a factor of poor prognosis in our population.

Evaluation of Microwave Thermotherapy With Histopathology, Magnetic Resonance Imaging and Temperature Mapping

PURPOSE

Interstitial temperature mapping was used to determine the heat field within the prostate by the Coretherm (ProstaLund, Lund, Sweden) transurethral microwave thermotherapy device. Gadolinium enhanced magnetic resonance imaging (MRI) and histopathology were used to determine the extent and pattern of coagulation necrosis following treatment. The cell kill assessment feature of the device was compared with MRI and histopathology.

MATERIALS AND METHODS

A total of 12 patients were treated, including 5 with adenocarcinoma of the prostate and 7 with benign prostatic hyperplasia. Temperature sensors were inserted from the perineum to map the temperature distribution. The 5 patients with adenocarcinoma underwent prostatectomy and subsequent histopathology 3 to 6 weeks after treatment. MRI and cell kill calculations were performed in all patients.

RESULTS

Therapeutic temperatures were found in a bowl-like shape with a wide circumference of highest temperatures at the base of the prostate, and decreasing temperature and circumference toward the apex. Tissue necrosis assessed by histopathology, MRI and cell kill calculations overlapped reasonably well in shape and size. Histopathology showed that the prostatic urethra was destroyed by treatment.

CONCLUSIONS

Coretherm microwave treatment causes significant tissue necrosis of the prostate, bladder neck and urethral mucosa. The cell kill calculation provides an on-line estimate of the amount of necrosis caused during treatment.

Efficacy and safety of intraprostatic temperature-controlled microwave thermotherapy in patients with benign prostatic hyperplasia: results of a prospective, open-label, single-center study with 1-year follow-up

BACKGROUND AND PURPOSE

Different devices for transurethral microwave thermotherapy (TUMT) are currently available for the treatment of benign prostatic hyperplasia (BPH). We evaluated the efficacy and safety of the Prostalund Feedback Treatment (PLFT), which continuously records the intraprostatic temperature, and its impact on sexual function of the patients.

PATIENTS AND METHODS

A total of 41 patients with lower urinary tract symptoms attributed to BPH were entered in this prospective open-label, single-center study of PLFT. The initial evaluation was performed according to a standard protocol. At 3, 6, and 12 months, the International Prostate Symptom Score (IPSS), bother score, sexual function, and peak flow rate (Qmax) were recorded. In addition, determination of prostate volume by transrectal ultrasonography (TRUS) and measurement of residual urine volume were repeated at the 6- and 12-month visits. All adverse events were also recorded. Patients with IPSS of < or =7, > or =50% improvement in IPSS from baseline, a Qmax of > or =15 mL/sec, or > or =50% improvement in Qmax from baseline were judged responders to the treatment.

RESULTS

Thirty-three of the patients completed the 12-month visit. The response rate was 88% (29 of 33 patients). There was a statistically significant decrease in IPSS at the 12-month visit, the mean IPSS being 7.1 v 21.9 at baseline (P<0.001). The mean IPSS was 10.3 and 7.6 at the 3- and 6-months' follow-up, respectively. The bother score presented a similar improvement, with a decrease from a mean of 4.2 at baseline to a mean of 1.4 after 12 months (P<0.001). The mean Qmax improved from 8.4 mL/sec at baseline to 15.9 mL/sec, 19.2 mL/sec, and 17.8 mL/sec at 3, 6, and 12 months, respectively (P<0.001). The mean change in prostate volume, as determined by TRUS, was 16 mL at 6 months and 19 mL at 12 months (P<0.001). The procedure was well tolerated. The mean post-treatment catheterization time was 17.90 days. Bladder spasms and urinary tract infection were the most common adverse events. Coitus ability remained practically unchanged after treatment (from 71% to 74.3%), but the number of patients with ejaculation decreased (from 78% to 51.4%).

CONCLUSION

Our results indicate that PLFT is an effective and safe treatment for most patients with BPH.

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.

Quantification of prostate shrinkage after microwave thermotherapy: a comparison of calculated cell-kill versus 3D transrectal ultrasound planimetry

PURPOSE

To compare prostate shrinkage after transurethral microwave thermotherapy (TUMT) with calculated cell-kill.

MATERIALS AND METHODS

The calculated cell-kill from 33 males with benign prostatic hyperplasia (BPH) treated with TUMT according to the ProstaLund Feedback Treatment (PLFT) method was compared to the post-treatment prostate volume change. The prostate volume was estimated with three-dimensional transrectal ultrasound (3D-TRUS) planimetry at baseline, 3, 6, and 12 months follow-up. A paired t-test was used to test the statistical significance of differences between the cell-kill volume and the prostate volume change. Linear regression was used to infer a relationship between the cell-kill and the 3D-TRUS data. The reproducibility of the 3D-TRUS method was assessed in repeated measurements.

RESULTS

The mean prostate volume at baseline (N=33) was 56.1cm(3). After 3 (N=25), 6 (N=29) and 12 months (N=23), it was 45.5 cm(3), 39.7 cm(3), and 45.1cm(3), respectively. The corresponding average cell-kill volume was 16.4 cm(3), 17.1cm(3), and 17.2 cm(3), respectively. Predicted cell-kill volume was significantly larger than prostate shrinkage at 3 (p<0.0001), 6 (p=0.0002), and 12 months (p<0.0001), and showed a strong correlation at 3 and 6 months (r=0.74, p<0.0001). Correlation at 12 months was moderate (r=0.57, p=0.0041). Examination and investigation variability both averaged 2.5%.

CONCLUSIONS

Cell-kill calculations of the PLFT method are proportional to the 3D-TRUS prostate shrinkage by a factor of 0.5 and have a precision of approximately +/-10 cm(3) for 90% of the patients during the first year after treatment.

Thermotherapy and thermoablation for benign prostatic hyperplasia

PURPOSE OF REVIEW

From all the available thermoablative methods for the treatment of symptomatic benign prostatic hyperplasia, transurethral microwave thermotherapy is considered as standard in minimally invasive management. The literature is enriched by several new studies on transurethral microwave thermotherapy, and thus this review presents up-to-date information about thermotherapy.

RECENT FINDINGS

New studies have provided significant information regarding differences in outcome for devices with different protocols and selection criteria, confirming the superiority of high-energy programmes. Furthermore, monitoring of the intraprostatic temperature promises better clinical results by means of individualization of the treatment. Long-term results have been available and allow the evaluation of the fundamental issue of treatment durability. Improvement after high-energy transurethral microwave thermotherapy remains durable for more than 2.5 years. Randomized studies comparing this treatment with other established therapies for benign prostatic hyperplasia, including medical treatment and transurethral resection of the prostate, have also contributed to an evaluation of the morbidity, and costs of treatment. Clinical outcomes with transurethral microwave thermotherapy are in the range of those obtained with transurethral resection of the prostate and are superior to those of medical management. Retreatment after transurethral resection of the prostate emerges because of complications following the procedure, whereas retreatment after transurethral microwave thermotherapy is as a result of treatment failure. In addition, the rate of failure of medical management is almost seven times higher than that for transurethral microwave thermotherapy. Thus, the latter seems to play a dominant role in the economic models used to assess the cost-efficiency of different treatment modalities for benign prostatic hyperplasia.

SUMMARY

The recent innovations in high-energy transurethral microwave thermotherapy provide better and more durable clinical outcomes and lower morbidity, and strengthen its position as an established treatment for benign prostatic hyperplasia. However, there is always room for improvement, so further research on therapeutic protocols, treatment monitoring and selection criteria are to be welcomed.

Morphological and biological predictors for treatment outcome of transurethral microwave thermotherapy

The proliferation of prostatic tissue as a result of ageing typically leads to prostatic enlargement, which often causes obstruction of urine outflow from the bladder, clinically lower urinary tract symptoms, detrusor instability, incomplete bladder emptying, urinary infection, and finally acute urinary retention. The first approach to therapy depending on the severity of the symptoms is usually medical management (phytotherapy, alpha-blockers, 5 alpha-reductase inhibitors) before surgical procedures are performed. The reference standard for treatment of benign prostatic hyperplasia is transurethral resection of the prostate, although the introduction of minimally invasive alternatives such as transurethral microwave thermotherapy has led to a new era in surgical management. Suitable patients must be selected carefully on the basis of individual parameters that predict a favourable result.

Determination and validation of the actual 3D temperature distribution during interstitial hyperthermia of prostate carcinoma

To determine the thermal dose of a hyperthermia treatment, knowledge of the three-dimensional (3D) temperature distribution is mandatory. The aim of this paper is to validate an interstitial hyperthermia treatment planning system with which the full 3D temperature distribution can be obtained in individual patients. Within a phase I study, 12 patients with prostate cancer were treated with interstitial hyperthermia using our multi electrode current source interstitial hyperthermia treatment (MECS IHT) system. The temperature distribution was measured from within the heating devices and by additional thermometry. The perfusion level was estimated and the heating implant reconstructed. The steady-state temperature distribution was calculated using our interstitial hyperthermia treatment planning system. The simulated temperature distribution was validated by individually comparing the measured and simulated thermo-sensors, both for the thermometry integrated with the heating applicators and the additional thermometry. The entire procedure was also performed on a no-flow agar-agar phantom. It was shown that the calculated temperature distribution of an individual patient during MECS interstitial hyperthermia is very heterogeneous. The validation indicates that the calculated temperature elevations match the measurements within approximately 1 degrees C. Possible improvements are more precise reconstruction, incorporation of discrete vasculature and using a temperature-dependent, heterogeneous perfusion distribution. Further technical improvements of the MECS-IHT system may also result in better temperature calculations.