Transurethral microwave thermotherapy: what role should it play versus medical management in the treatment of benign prostatic hyperplasia?

Interstitial microwave transition from hyperthermia to ablation: historical perspectives and current trends in thermal therapy

This work reviews the transition from hyperthermia to ablation for cancer treatment with interstitial microwave (MW) antennas. Early work utilising MW energy for thermal treatment of cancer tissue began in the late 1970s using single antennas applied interstitially or the use of multiple interstitial antennas driven with the same phase and equal power at 915 or 2450 MHz. The original antenna designs utilised monopole or dipole configurations. Early work in thermal therapy in the hyperthermia field eventually led to utilisation of these antennas and methods for MW ablation of tumours. Efforts to boost the radiated MW power levels while decreasing antenna shaft temperatures led to incorporation of internally cooled antennas for ablation. To address larger tumours, MW treatment utilised arrays that were simultaneously activated by either non-synchronous or synchronous phase operation, benefiting both hyperthermia and ablation strategies. Numerical modelling was used to provide treatment planning guidance for hyperthermia treatments and is expected to provide a similar benefit for ablation therapy. Although this is primarily a review paper, some new data are included. These new data show that three antennas with 2.5 cm spacing at 45 W/channel and 10 min resulted in a volume of 89.8 cm(3) when operated synchronously, but only 53.4 cm(3) non-synchronously. Efficiency was 1.1 (synchronous) versus 0.7 (non-synchronous). MW systems, treatment planning, and image guidance continue to evolve to provide better tools and options for clinicians and patients in order to provide better approach and targeting optimisation with the goal of improved treatment for the patient.

The long-term cost effectiveness of treatments for benign prostatic hyperplasia

INTRODUCTION

Excellent treatment outcomes with long-term durability and few adverse effects are expectations of treatments for chronic conditions. The long-term cost effectiveness of newer treatments for benign prostatic hyperplasia (BPH), including high-energy transurethral microwave thermotherapy (TUMT) and combination pharmaceutical therapy, has not been sufficiently studied against existing alternatives. The objective of this study was to estimate the incremental cost effectiveness of BPH treatment alternatives.

METHODS

We employed a Markov model over a 20-year time horizon and the payer's perspective to evaluate the cost effectiveness of watchful waiting (WW), pharmaceuticals (alpha-adrenoceptor antagonists [alpha-blockers], 5-alpha-reductase inhibitors [5-ARIs], combination therapy), TUMT and transurethral resection of the prostate (TURP) in treating BPH. Markov states included improvement in symptoms, no improvement in symptoms, adverse effects and death. We used data from the published literature for outcomes, including systematic reviews whenever possible. Costs were estimated using a managed-care claims database and Medicare fee schedules, and were reported in Dollars US, 2004 values. Costs and effectiveness outcomes were discounted at a rate of 3% per year. Men (aged > or =45 years) with moderate to severe lower urinary tract symptoms and uncomplicated BPH were included in the analysis, and results were stratified by age and BPH symptom levels. Outcomes included costs, QALYs, incremental cost-utility ratios and cost-effectiveness acceptability curves. Sensitivity analysis was performed on important parameters, with an emphasis on probabilistic sensitivity analysis.

RESULTS

alpha-Blockers and TUMT were cost effective for treating moderate symptoms using the threshold of Dollars US 50,000 per QALY. For example, at 65 years of age, the cost per QALY was Dollars US 16,018 for alpha-blockers compared with WW and Dollars US 30,204 for TUMT versus alpha-blockers. TURP was the most cost-effective treatment for severe symptoms (Dollars US 5824 per QALY ) versus WW. Model results were robust to changes in costs and sensitive to the assumed probabilities, utility weights, extent of improvement and life expectancy. Nevertheless, acceptability curves consistently demonstrated the same alternatives as most likely to be cost effective.

CONCLUSIONS

Our model suggests that alpha-blockers and TURP appear to be the most cost-effective alternatives, from a US payer perspective, for BPH patients with moderate and severe symptoms, respectively. TUMT was promising for patients with moderate symptoms and the oldest patients with severe symptoms, but otherwise was dominated. Value of information analysis could be used to determine the net benefit of additional research.

Needle-based ablation of renal parenchyma using microwave, cryoablation, impedance- and temperature-based monopolar and bipolar radiofrequency, and liquid and gel chemoablation: laboratory studies and review of the literature

BACKGROUND AND PURPOSE

Small renal tumors are often serendipitously detected during the screening of patients for renal or other disease entities. Rather than perform a radical or partial nephrectomy for these diminutive lesions, several centers have begun to explore a variety of ablative energy sources that could be applied directly via a percutaneously placed needle-like probe. To evaluate the utility of such treatment for small renal tumors/masses, we compared the feasibility, regularity (consistency in size and shape), and reproducibility of necrosis produced in normal porcine kidneys by different modes of tissue ablation: microwaves, cold impedance-based and temperature-based radiofrequency (RF) energy (monopolar and bipolar), and chemical. Chemoablation was accomplished using ethanol gel, hypertonic saline gel, and acetic acid gel either alone or with simultaneous application of monopolar or bipolar RF energy.

MATERIALS AND METHODS

A total of 107 renal lesions were created laparoscopically in 33 domestic pigs. Microwave thermoablation (N=12) was done using a Targis T3 (Urologix) 10F antenna. Cryoablation (N=16) was done using a single 1.5-mm probe or three 17F microprobes (17F SeedNet system; Galil Medical) (N=10 single probe and N=6 three probes); a double freeze cycle with a passive thaw was employed under ultrasound guidance. Dry RF lesions were created using custom-made 18-gauge single-needle monopolar probe with two or three exposed metal tips (GelTx) (N=12) or a single-needle bipolar probe (N=6) at 50 W of 510 kHz RF energy for 5 minutes. In addition, a multitine RF probe (RITA Medical Systems) was used in one set of studies (N=6). Both impedance- and temperature-based RF were evaluated. Chemoablation was performed with 95% ethanol (4 mL), 24% hypertonic saline (4 mL), and 50% acetic acid (4 mL) as single injections. In addition, chemoablation was tested with monopolar and bipolar RF (wet RF). Tissues were harvested 1 week after ablation for light microscopy.

RESULTS

In 11 of the 15 ablation techniques, there was complete necrosis in all lesions; however, three ethanol gel lesions had skip areas, three hypertonic saline gel lesions showed no necrosis or injury, and one monopolar RF and one bipolar RF lesion showed skip areas. In contrast to impedance-based RF, heat-based RF (RITA) caused complete necrosis without skip areas. All cryolesions resulted in complete tissue necrosis, and cryotherapy was the only modality for which lesion size could be effectively monitored using ultrasound imaging.

CONCLUSIONS

Cryoablation and thermotherapy produce well-delineated, completely necrotic renal lesions. The single-probe monopolar and bipolar RF produce limited areas of tissue necrosis; however, both are enhanced by using hypertonic saline, acetic acid, or ethanol gel. Hypertonic saline gel with RF consistently provided the largest lesions. Ethanol and hypertonic saline gels tested alone failed to produce consistent cellular necrosis at 1 week. In contrast, RITA using the Starburst XL probe produced consistent necrosis, while impedance-based RF left skip areas of viable tissue. Renal cryotherapy under ultrasound surveillance produced hypoechoic lesions, which could be reasonably monitored, while all other modalities yielded hyperechoic lesions the margins of which could not be properly monitored with ultrasound imaging.

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.

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.

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.

Changing therapeutic regimens in benign prostatic hyperplasia. Clinical and economic considerations

About one-quarter of men aged 50 years and older experience voiding problems due to benign prostatic hyperplasia (BPH). Until about 10 years ago, surgery (particularly transurethral resection of the prostate) was the only effective treatment for symptomatic BPH. Over the last decade, several new treatments have been introduced. These include different types of medication (alpha-blockers and finasteride), thermotherapy, laser prostatectomy, needle ablation and vaporisation methods. The diffusion of these less invasive treatment modalities has resulted not only in a decrease in the age-adjusted surgery rates, but also in an increase of the total number of men treated for BPH. A large number of studies on clinical benefits and risks reveal that the conventional types of surgery remain the most effective treatments, whereas new interventional therapies require a shorter hospital stay and result in fewer short term complications. The efficacy of medication is lower than that of interventional treatments. Adverse effects include dizziness and orthostatic hypotension (alpha-blockers) and decreased sexual function (finasteride), but are generally mild. There is some evidence that medication and minimally invasive treatments may preclude eventual surgical treatment, but the precise effect is difficult to estimate because of differences in the study populations and the relatively short study periods. As a result of the dynamic nature of BPH treatment and the lack of long term data, the cost effects of the introduction of the various new treatments are also difficult to assess. Given the aging of the population and the growing percentage of patients with BPH for whom any type of treatment can be considered, a considerable increase of total costs can be expected. Long term prospective studies are necessary to gain insight into the most cost-effective treatment for different patient groups.

Targeted transurethral microwave thermotherapy versus alpha-blockade in benign prostatic hyperplasia: outcomes at 18 months

OBJECTIVES

To compare directly the efficacy, safety, and durability of targeted transurethral microwave thermotherapy with that of alpha-blocker treatment for lower urinary tract symptoms of benign prostatic hyperplasia.

METHODS

In a randomized, controlled clinical trial, 52 patients with lower urinary tract symptoms due to benign prostatic hyperplasia received terazosin treatment and 51 underwent microwave treatment under topical anesthesia. The patient evaluation included the International Prostate Symptom Score, peak flow rate, and quality-of-life score before microwave treatment or initiation of terazosin treatment and at periodic intervals thereafter up to 18 months.

RESULTS

The mean International Prostate Symptom Score, peak flow rate, and quality-of-life score all improved significantly in both groups by 6 months. However, the magnitude of improvement was significantly greater in the microwave group than in the terazosin group. The significant between-group differences observed at 6 months in the mean International Prostate Symptom Score, peak flow rate, and quality-of-life score were fully maintained at 18 months, at which time the improvements in these three outcome measures were significantly greater (P <0.0005), by 35%, 22%, and 43%, respectively, in the microwave group than in the terazosin group. The actuarial rate of treatment failure at 18 months was significantly greater by sevenfold in the terazosin group. Adverse events were generally infrequent and readily manageable in both groups.

CONCLUSIONS

Although the initial onset of terazosin action was more rapid, the longer term clinical outcomes of targeted microwave treatment were markedly superior. The more favorable results in patients who underwent microwave treatment were maintained for at least 18 months.

Cost effectiveness of microwave thermotherapy in patients with benign prostatic hyperplasia: part II--results

OBJECTIVES

To evaluate the cost effectiveness of transurethral microwave thermotherapy relative to medical therapy (alpha-blocking agents) and transurethral resection of the prostate (TURP) for patients with moderate-to-severe benign prostatic hyperplasia (BPH) symptoms.

METHODS

A cost-effectiveness analysis was performed from the societal perspective for a hypothetical cohort of 65-year-old men with moderate-to-severe BPH symptoms. We calculated the incremental cost effectiveness of thermotherapy relative to medical therapy and TURP during 5 years after treatment initiation. Event probabilities were obtained from published reports, a consensus panel, and the Targis System (Urologix) randomized clinical trial. Costs were estimated using the national Medicare reimbursement schedules. Costs are reported in 1999 U.S. dollars. Total thermotherapy procedure costs were estimated at $2629. Quality-of-life and utility estimates were obtained by interviewing 13 patients with moderate-to-severe BPH symptoms. On the basis of their risk attitudes, patients were classified into risk-averse or non-risk-averse groups. The costs and health effects were discounted at 3% annually.

RESULTS

In a hypothetical cohort of 10,000 non-risk-averse patients who were candidates for all three modalities, the 5-year costs were highest for patients undergoing TURP and lowest for those receiving medical therapy ($7334 and $6294, respectively). The thermotherapy group exhibited the highest 5-year utility value (53.52 quality-adjusted life-months). Compared with medical therapy, thermotherapy resulted in an additional 0.23 quality-adjusted life-months, with an incremental cost of $741. This yielded an incremental cost per quality-adjusted life-year gained of $38,664 for thermotherapy compared with medical therapy. Thermotherapy had a higher utility (difference of 1.71 quality-adjusted life-months) and lower cost (difference of $299) compared with TURP and thus was dominant over TURP. The results were similar for a hypothetical cohort of 10,000 risk-averse patients.

CONCLUSIONS

From a societal perspective, thermotherapy appears to be a reasonable and cost-effective alternative to both medical and surgical treatment. However, the actual treatment decision should be based on multiple factors, only one of which is cost effectiveness.

Benign prostatic hyperplasia: clinical overview and value of diagnostic imaging

The term benign prostatic hyperplasia has traditionally been used to describe a constellation of obstructive and irritative voiding symptoms that occur in men as they age. Such symptomatology may be due to a variety of causes, including prostatic enlargement. Thus, the term lower urinary tract symptoms has replaced BPH to describe this symptom complex. The evaluation and treatment of LUTS continues to be a significant part of urology practice in the United States, as well as a significant component of medical resource utilization. Currently, indication for treatment in patients with LUTS is most often based on subjective measurements of symptom severity and bother. Consequently, imaging does not play a major role in the evaluation of such patients. Recent data suggest that the size of the prostate gland may predict which patients with LUTS will develop progressive symptoms and complications. Moreover, both prostate size and the histologic composition of BPH may help to select patients for specific treatment options. Thus, radiologic imaging may eventually play a larger role in the diagnosis and treatment of LUTS in the future. After review of the literature, it appears that routine upper urinary tract imaging in patients with LUTS or BPH is not warranted. Selective use of such imaging tests in patients with BPH and either hematuria, laboratory evidence of renal insufficiency (elevated BUN or creatinine), or a history of urinary tract infection, urolithiasis, previous urinary tract surgery, or congenital or acquired renal disease remains indicated. Local imaging of the prostate can be performed with either MR imaging or TRUS. Although MR imaging provides excellent resolution of internal prostatic anatomy, information with respect to the ratio of glandular to stromal tissue in the prostate, and an accurate estimate of prostate volume, its use in patients with BPH is limited by its high cost and limited availability. In contrast, TRUS remains an important tool in the evaluation of patients with prostatic disease. Similar to MR imaging, TRUS provides excellent images of internal prostatic anatomy and an accurate estimate of prostate volume prior to treatment. In addition, this imaging modality is noninvasive, cost-efficient, easily adapted to office use, and able to provide guidance for transrectal prostate biopsy.

High-energy transurethral microwave thermotherapy in patients with acute urinary retention due to benign prostatic hyperplasia

OBJECTIVES

To evaluate the efficacy and safety of targeted high-energy transurethral microwave thermotherapy (HE-TUMT) in the treatment of acute urinary retention (AUR) due to benign prostatic hyperplasia (BPH).

METHODS

In this prospective cohort study, 31 patients with painful AUR due to BPH underwent HE-TUMT. Patient evaluation before treatment and during a 12-week follow-up interval included determination of International Prostate Symptom Score (IPSS), quality of life (QOL) score, peak flow rate (Qmax) by uroflowmetry, and postvoid residual urine. Patients also underwent urodynamic evaluation before treatment and at 16 weeks.

RESULTS

By 4 weeks after HE-TUMT, 29 (94%) of 31 patients had regained the ability to void spontaneously. The actuarial median time for restoration of spontaneous voiding was 3.0 weeks (95% confidence interval [CI] 2.2 to 3.8). At 12 weeks, the mean IPSS (9.4; 95% CI 8.3 to 10.5) was 50% below (P <0.0005) that before retention (18.9; 95% CI 18.2 to 19.6). Improvements in the mean QOL score were similar in pattern and relative magnitude to those in the mean IPSS. A 69% increase in mean Qmax (P <0.0005) determined by uroflowmetry was observed by 12 weeks versus 1 week after HE-TUMT. Complications were infrequent.

CONCLUSIONS

This study provides preliminary evidence that HE-TUMT may potentially afford a novel and useful option for the patient with AUR who is not a suitable candidate for surgery.

Temporary intraurethral prostatic bridge-catheter compared with neoadjuvant and adjuvant alpha-blockade to improve early results of high-energy transurethral microwave thermotherapy

OBJECTIVES

The maximal effect of transurethral microwave thermotherapy (TUMT) for lower urinary tract symptoms (LUTS) of benign prostatic hyperplasia (BPH) occurs 3 to 6 months after treatment. In the acute period after TUMT, little change in symptoms, quality of life (QOL), and peak urinary flow rate (Qmax) is observed versus baseline. Some men may also develop acute urinary retention secondary to thermally induced edema. Recent reports suggest that early results of TUMT may be improved with concomitant use of either a temporary intraurethral prostatic bridge-catheter (PBC) or neoadjuvant and adjuvant alpha-blocker therapy. This report compares the results of these two adjunctive modalities directly.

METHODS

This nonrandomized retrospective comparison of results in 186 patients with LUTS of BPH is based on findings of three recently reported prospective clinical trials. All patients underwent targeted high-energy TUMT. Ninety-one patients received no further treatment (TUMT alone group), 54 an indwelling PBC for up to 1 month (TUMT + PBC group), and 41 neoadjuvant and adjuvant tamsulosin (0.4 mg daily) treatment (TUMT + tamsulosin group). The International Prostate Symptom Score (IPSS), QOL score, and Qmax were determined at baseline and 2 weeks after TUMT.

RESULTS

All three study groups experienced statistically significant improvements in mean IPSS and QOL score at 2 weeks versus baseline (P <0.0005). Nevertheless, the magnitude of improvement was greater in the TUMT + PBC group than the other two groups and greater in the TUMT + tamsulosin group than the TUMT alone group. A high proportion of the TUMT + PBC group (87.8%) attained a 50% or more IPSS improvement, compared with 4.5% of the TUMT alone group and none of the TUMT + tamsulosin group, and a similar pattern of between-group differences was noted with respect to the proportion of patients having 50% or more improvement in QOL score. The TUMT + PBC group was the only group to achieve significant Qmax improvement at 2 weeks compared with baseline. In the TUMT alone group, urinary retention 1 week or longer in duration occurred in 10 (11%) of 91 patients compared with 1 (2.4%) of 41 in the TUMT + tamsulosin group and none in the TUMT + PBC group. Early PBC removal was required in 11% of the TUMT + PBC group as a consequence of urinary retention secondary to clot formation or PBC migration.

CONCLUSIONS

Both PBC placement and neoadjuvant and adjuvant alpha-blocker treatment are effective in alleviating symptoms and improving QOL during the acute period after TUMT. PBC usage also resulted in substantial early Qmax improvement. Either of these adjunctive modalities may be appropriate to consider in the treatment of TUMT patients during the early postprocedure recovery period.

Neoadjuvant and adjuvant alpha-blockade improves early results of high-energy transurethral microwave thermotherapy for lower urinary tract symptoms of benign prostatic hyperplasia: a randomized, prospective clinical trial

OBJECTIVES

Improved long-term results with respect to symptoms, voiding function, and quality of life (QOL) in patients with lower urinary tract symptoms (LUTS) of benign prostatic hyperplasia (BPH) are achieved with targeted high-energy transurethral microwave thermotherapy (TUMT) compared with alpha-blocker treatment alone. However, maximal improvement after TUMT is not attained until 3 to 6 months after treatment. Measures to provide earlier symptom relief and improved voiding function and QOL would add to the clinical utility of TUMT. The objective of the present study was to determine whether neoadjuvant and adjuvant alpha-blockade is capable of accelerating a post-TUMT decrease in LUTS of patients with BPH.

METHODS

In this randomized, prospective study of 81 patients with LUTS of BPH, 41 underwent TUMT with neoadjuvant and adjuvant tamsulosin (0.4 mg daily) treatment, and 40 had TUMT alone. International Prostate Symptom Score (IPSS), peak urinary flow rate (Qmax), and QOL score were determined before treatment and at periodic intervals thereafter up to 12 weeks after TUMT.

RESULTS

Mean IPSS values in the TUMT plus tamsulosin group at 2 weeks (14.0, 95% confidence interval [CI] 13.1 to 14.9) and 6 weeks (8.6; 95% CI 7.7 to 9.5) were 15% and 24% lower, respectively, than those at 2 weeks (16.5, 95% CI 15.6 to 17.4) and 6 weeks (11.3, 95% CI 10.4 to 12.2) in the TUMT-alone group (P<0.0005). However, by the final evaluation at 12 weeks, no significant difference between the groups in mean IPSS was evident. A similar temporal pattern of difference between the two study groups was also observed in QOL score. No significant between-group difference in mean Qmax was evident after TUMT. Urinary retention 1 week or more in duration occurred in 5 (12%) of 40 TUMT-alone group patients compared with 1 (2%) of 41 TUMT plus tamsulosin group patients.

CONCLUSIONS

Neoadjuvant and adjuvant alpha-blocker treatment results in significantly greater early symptom reduction and QOL score improvement after TUMT, adding to the clinical utility of this minimally invasive treatment modality. In addition, post-TUMT complications such as urinary retention may be reduced.