Can histopathology predict treatment outcome following high-energy transurethral microwave thermotherapy of the prostate? Results of a biopsy study

Treatment Characteristics and Inherent Prostatic Features Do Not Predict Patient Outcome after High-Energy Transurethral Thermotherapy: A Prospective Study of ProstaLund Feedback Treatment™

PURPOSE

To determine whether treatment characteristics, intrinsic prostatic factors, and clinical parameters predict the outcome in patients treated with high-energy transurethral microwave thermotherapy (HE-TUMT).

PATIENTS AND METHODS

A series of 48 consecutive patients, 28 with an indwelling catheter, underwent ProstaLund Feedback Treatment (PLFT). The 12-month International Prostate Symptom Score response rate (IPSS < or = 7 or > or =50% improvement), peak flow rate response rate (Q(max) > or = 15 mL/sec or > or =50% improvement), and bladder outflow obstruction index response rate (BOOI <40) were correlated with treatment characteristics such as duration, average intraprostatic temperature, time with therapeutic intraprostatic temperatures (>45 degrees C), average intraprostatic blood flow, consumed energy, and recorded prostate mass destruction. Baseline parameters such as age, serum prostate specific antigen concentration, prostate volume, and pretreatment IPSS, quality of life (QOL), Q(max), postvoiding residual urine volume (PVR), and BOOI were included in the logistic regression analysis.

RESULTS

Treatment characteristics did not discriminate responders and nonresponders to HE-TUMT. For the patients without a catheter, the IPSS response (75%) was predicted by higher pretreatment IPSS (P = 0.041; relative risk [RR] = 3.4) and higher pretreatment PVR (P = 0.026; RR = 1.1). The Q(max) response (85%) was predicted by higher grades of pretreatment obstruction (P = 0.009; RR = 1.02). The BOOI response (60%) was not related to any of the factors tested. For the patients with a catheter, no outcome predictors could be identified.

CONCLUSIONS

According to our results, the intraprostatic temperature, the duration of intraprostatic temperatures in the therapeutic range, and the pattern of blood flow did not predict HE-TUMT outcome. Treatment duration, consumed energy, and the magnitude of tissue necrosis did not translate into clinical efficacy. Clinical parameters were important predictors of outcome in patients not in retention.

Intraprostatic Blood-Flow Changes during ProstaLund Feedback Treatment Measured by Positron Emission Tomography

PURPOSE

To investigate the changes in intraprostatic blood flow during ProstaLund Feedback Treatment (PLFT) using positron emission tomography (PET).

PATIENTS AND METHODS

Three patients with bladder outlet obstruction caused by benign prostatic hyperplasia were treated with PLFT using the ProstaLund device, which has the ability to calculate the intraprostatic blood flow. Treatment was given for 1 hour. Five PET scans were done during each treatment to calculate the three-dimensional blood flow using [(15)O]H(2)O as the tracer.

RESULTS

The prostatic blood flow increased steeply at the beginning of the treatment in all three patients, by as much as 100% at 20 and 35 minutes. For patients 1 and 2, there was a fast decline in intraprostatic flow at the last scan (55 minutes), clearly seen as a large zone with circulation arrest centrally in the prostate. The intraprostatic temperature was <50 degrees C during the first 30 minutes but increased to 52 degrees to 60 degrees C during the second part of the treatment. Patient 3 had high blood flow during the entire treatment. A reduction of the blood flow was seen at the end of the treatment but not to the same extent as in the other two patients. The intraprostatic temperature did not exceed 49 degrees C for this patient.

CONCLUSION

The large variations seen in intraprostatic blood flow suggest that intraprostatic temperature monitoring is mandatory to optimize the treatment. The ProstaLund bioheat model calculates the change in intraprostatic blood flow accurately.

Application of External Microwave Thermotherapy in Urology: Past, Present, and Future

The excellent clinical results of transurethral microwave thermotherapy (TUMT) for the treatment of symptomatic benign prostatic hyperplasia (BPH) gave to TUMT the leading position among the microwave thermotherapy modalities available for the treatment of different urologic conditions. Research in TUMT has focused on operating software, temperature monitoring, intraprostatic heat distribution, cell-kill calculations, and correlations with clinical variables. Randomized comparisons of TUMT with other established therapies for BPH, including transurethral resection, have facilitated the evaluation of the clinical outcome, durability, morbidity, and costs of the treatment. The applications of microwave thermotherapy in other urologic diseases are also presented in this review.

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.

Transurethral microwave thermotherapy: the gold standard for minimally invasive therapies for patients with benign prostatic hyperplasia?

From all available minimally invasive methods for the treatment of symptomatic benign prostatic hyperplasia (BPH), transurethral microwave thermotherapy (TUMT) has gained a firm position as the most attractive option. Recent research has produced innovations in high-energy TUMT, including new treatment protocols, refined selection criteria, and monitoring of intraprostatic temperature. Furthermore, long-term results from randomized studies comparing TUMT with transurethral resection of the prostate (TURP) or medical treatment are now available. All these data indicate that more durable clinical outcomes and less morbidity can be achieved with TUMT, strengthening its position as a standard treatment for BPH. This paper describes the status of TUMT in the treatment of lower urinary tract symptoms related to BPH, focusing on variations in the outcomes with different devices, the durability of treatment outcomes, morbidity, selection criteria, and cost. The relation of TUMT to medical management and TURP also is addressed.

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.

Transurethral interstitial laser coagulation of the prostate and transurethral microwave thermotherapy vs transurethral resection or incision of the prostate: results of a randomized, controlled study in patients with symptomatic benign prostatic hyperplasia

OBJECTIVE

To compare the efficacy and frequency of complications of transurethral interstitial laser coagulation (ILC) and transurethral microwave thermotherapy (TUMT) with transurethral resection or incision of the prostate (TURP/TUIP) in patients with symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Forty-eight patients were randomized to undergo ILC, 46 to TUMT and 24 to TURP/TUIP; they were followed for 6 months and the outcome analysed on an intention-to-treat basis.

RESULTS

At 6 months the symptom scores and maximum urinary flow rate (Qmax) had improved significantly in all groups. At 6 months the mean symptom score was 9.2 in both experimental groups and 6.8 in the control group (P > 0.05); the mean Qmax was 20.6 mL/s in the control group, 16.2 in the ILC group (P > 0.05 vs control) and 13.2 in the TUMT group (P < 0.05 vs. the control group). In the TUMT group patients developing urinary retention afterward had a significantly greater increase in Qmax than those who did not. The types of complications in the three groups varied. Urinary tract infection occurred frequently in the experimental groups, especially after ILC, whereas the 'well-known' complications of TURP occurred in the control group. Overall, 36% in the ILC, 54% in the TUMT and 73% in the control group had no complications (retrograde ejaculation excluded) during the first 6 months. One patient in the TUMT group underwent TURP after 3 months, whereas no patients in the ILC or the con-trol group were re-treated for BPH within the first 6 months.

CONCLUSION

In the short term both ILC and TUMT are reasonable alternatives to standard transurethral surgery for symptomatic BPH, where the reduction of symptoms is the primary goal of treatment. However, both ILC and TUMT were associated with morbidity, although the complication profiles differed from those after TURP/TUIP. Both ILC and TUMT seem advantageous in some patients because of the reduced risk of bleeding and the eliminated risk of TUR syndrome, and because TUMT only requires local anaesthesia. Thus, as neither treatment is better in all aspects, the advantages of one technique over the other must be weighed when deciding how to treat each patient.

Transurethral microwave thermotherapy: first experiences in Poland

OBJECTIVE

To present early experiences in Poland with high-energy transurethral microwave thermotherapy (HeTUMT), considered as a serious alternative to surgery in managing benign prostatic hypertrophy (BPH).

PATIENTS AND METHODS

Sixty-one patients were treated in two centres using a commercial TUMT system. The patients were assessed at 5-6 weeks, 3 and 6 months after treatment, evaluating subjective complaints, the International Prostate Symptom Score (IPSS), urinary flow rate and postvoid residual volume.

RESULTS

A complete follow-up was available in 44 patients; most had symptomatic improvement 3 months after HeTUMT but it was slightly less pronounced after 6 months. The improvement in objective variables increased up to 6 months after HeTUMT. There was > or = 50% improvement in subjective complaints in 43% of the patients, in urinary flow rate in 25% and in residual urine in half. Two patients required re-treatment for a urethral stricture and ineffective HeTUMT.

CONCLUSIONS

HeTUMT may be a useful treatment for BPH but the outcome for an individual patient seems to be unpredictable. The indications for TUMT should be reviewed individually for each patient.

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.

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

BACKGROUND

Blood perfusion regulates intraprostatic temperatures during transurethral microwave thermotherapy (TUMT). We evaluated baseline intraprostatic vasculature, as a predictor of efficacy of TUMT.

METHODS

Twenty-two patients, with lower urinary tract symptoms (LUTS) suggestive of bladder outflow obstruction, were treated with TUMT (Prostatron). At baseline, three-dimensional contrast-enhanced power-flow-Doppler prostate ultrasonography (3D-CE-PFD) was performed. Assuming that the percentage of perfused area (PPA) is a realistic measure of blood flow, it was used to quantify intraprostatic vasculature.

RESULTS

The median (range) age, prostate size, and energy delivered were 66 years (48-80), 47 cm(3) (30-121), 110 kJ (29-136), respectively. The response was 77% (5 failures). The median (range) PPA was 2.76% (0.7-11.3). No difference in PPA among good and poor responders was detected nor was any correlation between PPA and baseline parameters.

CONCLUSIONS

The baseline intraprostatic vascularization, documented by CE-PFD studies, has no predictive value for the efficacy of TUMT. It seems that "static" baseline blood flow does not reflect the "dynamic" thermoregulatory role of blood flow during treatment.

Heat treatment of the prostate: where do we stand in 2000?

Various minimally invasive modalities that are aimed at alleviating lower urinary tract symptoms employ heat-induced ablation of hyperplastic prostatic tissue. Following extensive studies, most of these modalities were eventually abandoned. High-energy transurethral microwave thermotherapy has survived, however, and has gained a firm position as a therapeutic modality, along with transurethral resection of the prostate. Recent research addressed fundamental issues of mode of action of microwave treatment, and revealed the overall efficacy of this treatment, determined new indications, and rendered high-energy transurethral microwave thermotherapy more acceptable to the patients. Insights into intraprostatic vascularization and treatment monitoring were also gained as a result of these global research efforts.

Cell-kill modeling of microwave thermotherapy for treatment of benign prostatic hyperplasia

PURPOSE

We investigated whether cell-kill modelling could be used as a mean for predicting the outcome of microwave thermotherapy for benign prostate hyperplasia (BPH).

METHODS

The two models--Henriques' damage integral and Jung's compartment model--were implemented in a computer program. Real treatment data for 22 patients with BPH who were in chronic retention were used as input, including measured intraprostatic temperatures and microwave power. To test if modelling gives results that are consistent with actual observations, comparison with transrectal ultrasound (TRUS) measurements of the prostate volume before and after treatment was made. The sensitivity of the computer model for variations in the heat cytotoxicity and the temperature probe location in the adenoma was also tested.

RESULTS

The average TRUS volume reduction 3 months after treatment was 26 cc, whereas the corresponding cell kill calculation was 27 cc. The computer model appears to be rather insensitive to minor uncertainties in heat sensitivity and location of the intraprostatic reference temperature sensors.

CONCLUSION

Cell-kill modelling appears to give results that are consistent with actual observations. The coagulated tissue volume is calculated in real time during the treatment, thereby providing an immediate prediction of the treatment outcome. By using cell-kill modelling, the endpoint of a treatment can be set individually; e.g., when a certain volume reduction has been achieved.

Microwave thermotherapy: historical overview

The application of heat with curative aim is an old and very well-known principle in medicine. A review of the history of heat use in the treatment of prostatic disease is presented. The article is based on bibliographic research (MEDLINE Search and PubMed) and focuses on treatment of benign prostatic hyperplasia (BPH) since the first clinical documentation of transrectal hyperthermia for this condition. Then, in a chronological sequence, not only the evolution toward thermotherapy but also enhancements of the latest techniques are presented. The new advances in the field of patient selection, indications, and outcome predictors, as well as new trends in treatment are briefly considered.

Relation between intraprostatic temperature and clinical outcome in microwave thermotherapy

PURPOSE

The study was designed to explore the relation between prostatic temperature and the clinical outcome of transurethral microwave thermotherapy (TUMT).

PATIENTS AND METHODS

Forty-nine patients with symptomatic benign prostatic hyperplasia (BPH) were treated. Baseline evaluation included Madsen score, flowmetry, and pressure-flow study. Two fiberoptic thermosensors were placed in the prostate targeted to the region 10 and 20 mm below the bladder neck and 5 to 15 mm lateral to the prostatic urethra. The TUMT was carried out using either the low-energy (2.0) or high-energy (2.5) Prostasoft program. Follow-up was at 6, 12, and 26 weeks.

RESULTS

A moderate correlation between intraprostatic temperatures and energy output (r = 0.409; P < or = 0.046) and prostate volume (r = 0.303; P < or = 0.0424) was observed. Outlet obstruction was associated with higher temperatures (obstructed 49.6+/-5.8 v unobstructed 46.1+/-4.2 degrees C; P < or = 0.033). A significant relation between temperature and clinical outcome was found. Patients with intraprostatic temperatures <46 degrees, 46-50 degrees, and < or = 50 degrees C had significant differences in Madsen score change (-50%, -68% and -86%) and in maximum flow rate (+26%, +32%, and +48%). Patients with temperatures >50 degrees C had a significant improvement in obstruction status (86% to 18%). A slight worsening in voiding dynamics was observed in patients with temperatures <50 degrees C.

CONCLUSION

A significant relation exists between intraprostatic temperatures achieved during TUMT and the clinical outcome. Temperatures in excess of 50 degrees C seem to be associated with a greater improvement in lower urinary tract symptoms and bladder outlet obstruction. These data provide a sound rationale for monitoring intraprostatic temperatures and developing invasive thermometry feedback mechanisms for thermal treatments of BPH.

Clinical results of microwave thermotherapy for benign prostatic hyperplasia

Transurethral microwave thermotherapy is a truly office procedure without the need for anesthesia for the treatment of lower urinary tract symptoms caused by benign prostatic hyperplasia. Several devices have been developed. Continuous refinement of the procedure led to higher energy protocols and high-intensity dose protocols applying the heat-shock strategy. We report on the clinical results of these protocols. Symptom scores improve around 60%, whereas maximum urinary flow rate improve from an average 9 to 10 mL/sec at baseline to 14 to 15 mL/sec during follow-up. No significant differences have been shown between the outcomes with the different devices. Long-term data show satisfactory results after 4 years. Initial clinical results with the heat-shock strategy show results comparable to those of higher-energy protocols with decreased morbidity. Treatment morbidity of higher energy protocols is moderate and consists mainly of the need for catheterization and a higher percentage of retrograde ejaculation. To improve treatment efficacy, patient selection appears to be most important. Prostate size, bladder outlet obstruction, age, and prostate composition are of predictive value for treatment outcome. Further development of the treatment protocols and refinement of the urethral applicators might enhance outcome.

Transurethral microwave thermotherapy in benign prostatic hyperplasia

This article reviews the available literature and data on high-energy transurethral microwave therapy (TUMT) in the treatment of benign prostatic hyperplasia (BPH) causing lower urinary tract symptoms (LUTS). TUMT is a safe, durable, (1-hour) procedure, without the need for anesthesia. Emphasis is made on the effect and mechanism of TUMT, the different devices available including different energy protocols, and accompanying clinical results.