Interstitial temperature measurements during transurethral microwave hyperthermia

Evaluation of three temperature measurement methods used during microwave thermotherapy of prostatic enlargement

Three temperature measurement methods used during microwave thermotherapy of prostatic enlargement are analysed and evaluated using a phantom model. A commercial transurethral microwave thermotherapy (TUMT) system that uses a radiometric thermometer for temperature control was used to heat the phantom. The transient temperature distribution was obtained by using both fibreoptic (which is considered as gold standard) and thermocouple measurements. Both methods are subject to potential measurement errors caused by electromagnetic and/or thermal interference. The error sources are analysed and the measurement methods evaluated. The radiometric temperature and especially its relation to the transient temperature distribution was evaluated based on the fibreoptic and thermocouple measurements. These measurements in principle gave equivalent temperature distributions, and thermal interference was concluded to be the largest source of measurement error. The radiometric measurement method gave qualitative rather than quantitative readings of the temperature, and an underestimation of more than 10 degrees C was obtained for some parts of the heated area. The area that gives most of the radiometric signal was relatively close to the catheter in contrast to previously published results.

TRANSURETHRAL MICROWAVE THERMOTHERAPY FOR BENIGN PROSTATE HYPERPLASIA: SEPARATING TRUTH FROM MARKETING HYPE

PURPOSE

Transurethral microwave thermotherapy (TUMT) is being used with increasing frequency by urologists as a minimally invasive therapy for benign prostatic hyperplasia (BPH). There are various modifications to this technology, with each manufacturer touting safety and efficacy. We review the rationale of TUMT, as well as the historical safety and efficacy of this approach.

MATERIALS AND METHODS

We reviewed the medical literature, including peer reviewed articles and abstracts. In addition, we analyzed promotional material distributed by various manufacturers with respect to scientific accuracy.

RESULTS

TUMT results in consistent improvement in symptoms and peak urinary flow rate. Symptom improvement ranges between 9 and 11 points, compared to a 6-point improvement in sham treated patients, and peak urinary flow rate increases 3 to 5 ml per second. The degree of coagulation necrosis is different among the various TUMT devices. Although coagulation necrosis is believed to be an important proxy for clinical success, there are few data that correlate this factor with the magnitude of either symptomatic or uroflow improvement.

CONCLUSIONS

TUMT is a safe and effective therapy for the treatment of lower urinary tract symptoms secondary to BPH. In addition, there are distinct advantages to each of the devices. However, intense marketing and hyperbole have dominated this segment of the BPH market. Ultimately, the most effective TUMT device can only be determined by direct comparison studies.

Transurethral microwave thermotherapy (TUMT) with the Targis System: a single-centre study on 78 patients with acute urinary retention and poor general health

OBJECTIVES

To evaluate the Targis System in men presenting with acute urinary retention, high prostate volume and high operative risk.

MATERIALS AND METHODS

Between August 1997 and March 2001, a total of 78 patients in poor general health status presenting with large prostate glands and acute urinary retention secondary to BPH were treated with the Targis TUMT device. Mean age, mean prostate volume, and the percentage of patients who were able to urinate spontaneously after the procedure as well as mean peak and average flow rates and mean residual urine volume were evaluated.

RESULTS

68 (87.1%) of the 78 patients were able to urinate spontaneously three months after the procedure. In 5 (7.3%) of the 68 patients urinary retention recurred within two years. Following treatment, the mean peak flow rate in the 68 successfully treated patients was 11.1 ml/s, while the mean postvoid residual volume was 46 ml.

CONCLUSION

Based on these data we recommend transurethral thermotherapy using the Targis System for patients in poor general health presenting with urinary retention and prostate volumes of more than 35 cc in whom TURP is not possible.

Correlation between central zone perfusion defects on gadolinium-enhanced MRI and intraprostatic temperatures during transurethral microwave thermotherapy

BACKGROUND AND PURPOSE

The likelihood of success of thermoablation of prostatic hyperplasia depends on delivering an optimal thermal dose, but data on the temperatures achieved with these methods are few. We sought to develop a noninvasive method for monitoring intraprostatic heat distribution.

PATIENTS AND METHODS

Thirteen patients ranging from 50 to 76 (mean 61.3+/-8.1) years were enrolled in this study, all of whom had evidence of obstruction by uroflowmetry and pressure-flow studies. The mean total volume of the gland was 40.3+/-13.1 cc, while the mean adenoma volume was 20.4+/-10.1 cc, as estimated by preoperative transrectal ultrasonography. All the patients were treated with the Urologix Targis device for at least 45 minutes. Continuous temperature mapping was performed during the therapy using spatially dispersed thermosensors at 16 prostatic sites. The patients were evaluated 5 to 12 days postoperatively with MRI of the prostate utilizing a pelvic phased-array coil at 1.5 T.

RESULTS

Postprocedure MRI demonstrated a mean perfusion defect of 28.1+/-2.1% and 63.6+/-34% of the total gland and transition zone volumes, respectively. The mean anteroposterior (AP) and transverse diameters of the perfusion defects, as measured on the MRI images, were 29.2+/-5.2 mm and 32.7+/-5.9 mm, respectively. The maximum mean peak temperatures were 66.8+/-13 degrees C and were recorded at 4 mm from the urethra. No temperatures higher than 45 degrees C were recorded beyond 15 mm on either side of the urethra in the AP direction and beyond 16 mm on either side of the urethra in the transverse diameter. This perfusion defect was persistent for 27.7+/-5.2 mm in the superoinferior diameter, which is equivalent to the length of the antenna (28 mm).

CONCLUSION

Perfusion defect diameters as measured by postprocedure MRI accurately represent the prostatic tissues exposed to temperatures of > or =45 degrees C for 45 minutes or more. So, MRI provides an accurate, noninvasive method for screening the effective heat pattern generated in the prostate during transurethral microwave thermotherapy.

Intraprostatic temperature monitoring during transurethral microwave thermotherapy: status and future developments

Transurethral microwave thermotherapy is being applied as a minimally invasive treatment for alleviating the symptoms of urinary outlet obstruction associated with benign prostatic hyperplasia. Treatment progress has traditionally been guided in its effective power by rectally and urethrally measured temperatures, whereas intraprostatic temperatures would be preferred for feedback purposes. A critical evaluation is presented of intraprostatic thermometry techniques that have been suggested, the techniques currently being used and investigated, and the problems that remain to be solved. Techniques for noninvasive temperature measurement and detecting tissue response during thermal therapy are discussed in more detail. Results presented in the literature have shown magnetic resonance imaging and ultrasonic imaging to be adequate thermometry modalities. For treatment monitoring of transurethral microwave thermotherapy, ultrasonic imaging is especially promising. Future research will indicate whether the promise evolves into a sound clinical technique.

Detailed interstitial temperature mapping during treatment with a novel transurethral microwave thermoablation system in patients with benign prostatic hyperplasia

PURPOSE

To delineate in detail the temperature changes in the prostate gland and adjacent structures during treatment with a newly designed microwave thermoablation system in patients with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

Microwave thermoablation treatment was administered to 22 BPH patients at two centers in the U.S. and Argentina using the Urologix Targis targeted transurethral thermoablation system. Continuous temperature measurements were made with widely spatially dispersed fiber optic thermosensors at 11 to 24 prostatic sites in each patient using a recently described accurate stereotactic method. Urethral and rectal temperatures were also measured.

RESULTS

Treatment using the microwave thermoablation system resulted in marked elevation of intraprostatic temperatures to as high as 80C in some patients with little or no elevation of urethral or rectal temperatures. Average temperature increased with radial distance from the urethra to a peak at 5 to 7 mm. and declined exponentially at greater distances. Higher maximum intraprostatic temperatures in individual patients were associated with a larger zone, up to 24.0 mm. in radius, of prostatic tissue exposed to thermoablative temperatures of 45C and higher. Along the longitudinal axis of the microwave treatment catheter, thermoablative temperatures were confined to a zone of 11.5 mm. from the microwave antenna midpoint apically and 11.3 mm. basally, that is, a range shorter than the length of the treatment catheter's microwave antenna (2.8 to 3.5 cm.). The mean temperature in the posterior sector of the prostate gland during treatment (43.6C; 95% CI, 41.1 to 46.1C) was significantly lower (p < 0.05) by 6.7C than that in the anterolateral prostate (50.3C; 95% CI, 48.3 to 52.3C), as a consequence of the preferential heating design of the treatment catheter. Intraprostatic mean temperature during treatment, as measured at all thermosensor sites without respect to spatial location, was 47.1C (95% CI, 44.2 to 50.0C), a value significantly higher (p < 0.05) than that measured in the urethra (39.6C; 95% CI, 36.6 to 42.6C) or rectum (37.7C; 95% CI, 36.7 to 38.7C). There was a strong correlation between the temporal pattern of fluctuation in urethral temperature and that of prostate temperature (r = 0.83; p < 0.001) during treatment.

CONCLUSIONS

Treatment with the microwave thermoablation system fulfilled the requirements for an effective and safe microwave-based BPH treatment modality by exposing obstructive tissue to high temperatures without endangering vulnerable adjacent tissues.

Combined external beam irradiation and external regional hyperthermia for locally advanced adenocarcinoma of the prostate

PURPOSE

To determine the safety and efficacy of combined external beam irradiation and external regional hyperthermia in the treatment of adenocarcinoma of the prostate.

METHODS AND MATERIALS

From 1987 to 1994, 30 patients received combined external beam irradiation and external regional hyperthermia for locally advanced prostate cancer. The results of the 21 patients with newly diagnosed (n = 18) or locally recurrent (n = 3) adenocarcinoma are reported herein. No patient had evidence of distant metastases. Total radiotherapy doses of 65-70 Gy to the prostate were planned using a four-field box technique. Hyperthermia treatments were delivered using an annular phased array microwave device. The treatment goal was to achieve temperatures > or = 42 degrees C in all measured points within the prostate.

RESULTS

Of the newly diagnosed patients, 16 out of 18 (89%) had T3 or T4 tumors, 11 out of 18 (61%) had Gleason scores of 7-9, and the mean pretreatment Prostate Specific Antigen (PSA) was 69 ng/ml. The median follow-up of all 21 patients was 36 months. None of the patients achieved the treatment goal of all intratumoral temperatures > or = 42 degrees C. The mean CEM 43 T90 was 2.34 min. The disease-free survival at 36 months is 25%; 12 out of 18 (67%) of the patients have relapsed. The only significant predictor of relapse was pretreatment PSA. There were no complications > Grade 3.

CONCLUSIONS

In spite of the inability to achieve high tumor temperatures, the relapse-free survival rate in this population of patients with very advanced localized prostate cancer treated with radiation therapy plus hyperthermia compares favorably with most series using radiation therapy alone. Further studies aimed at improving the ability to deliver hyperthermia to the prostate are warranted.

Prostatic microwave therapy: A pilot study for technology assessment

Objective. The Genemed Genetherm S 150 is an easy to use and comparatively inexpensive device for administering prostatic microwave therapy. This study was aimed at testing the efficacy and safety of this machine in a pilot study. Methods. Sixteen patients with benign prostatic hypertrophy participated in the study, but only fourteen were evaluable. All received one hour of microwave therapy where the mean temperature was 45.7±0.2 °C. Symptom scores (International Prostate Symptom Score and Quality of Life Assessment), peak flow rates and post void residuals were used to evaluate participants prior to and three months following their treatment. Results. The results of this study show a statistically significant improvement in mean symptom scores. There was no significant change in mean peak flow rates while a statistically significant increase in mean post void residual occurred. Individually, however, only one patient experienced an improvement in all of the above parameters. There were no undesirable side effects during or after treatment. Conclusions. We conclude that the results of this pilot study do not warrant further study of this device, despite its practicality and safety.

Transurethral hyperthermia for benign prostatic hyperplasia: long term results

Transurethral resection of the prostate (TURP) is the only recognized treatment in patients with benign prostatic hyperplasia (BPH). Transurethral hyperthermia (TUHT) was used as an alternative treatment in patient who refused TURP. From 1987 to 1988, 21 BPH patients with moderate to severe symptoms and signs of prostatism were treated with TUHT in a phase I trial. Mean pre-treatment subjective and objective values were: total symptom score (TSS) 13.5, obstructive symptom score (OSS) 6.5, irritative symptom score (TSS) 7.0, peak flow rate (PFR) 11.6 cc/sec, post-voiding residual volume (PRV) 187 cc, and prostate volume (PV) 93 cc. TUHT was given for a total of 177 sessions (mean 8.4), each of 60 min duration at a steady state. Temperature was recorded continuously on the urethral surface, in all treatments. It ranged from Tmin 40.3 degrees C to Tmax = 49.2 degrees C and Tmean = 44.1 degrees C. The mean minimum temperature of > or = 42 degrees C was obtained in 98% of the TUHT sessions. Treatments were given on an outpatient basis without sedation or anaesthesia. Treatment tolerance was excellent with minor acute toxicity common (71% of patients), of no clinical importance and with no late complications. Of the 21 patients treated, 17 (81%) had an objective and 15 (71%) a subjective improvement recorded at 6 months post-treatment. This statistically highly significant improvement included: 61% decrease in TSS; 66% decrease in OSS; 55% decrease in ISS; 42% increase in PFR; 55% decrease in PRV; and 21% decrease in PV. Of the 17 patients with objective improvement, nine have maintained their response to TUHT for a minimum period of over six years, two relapsed at 11 and 40 months, respectively, and six patients died of cardiovascular causes maintaining their response to death. This study has demonstrated TUHT treatment efficacy with no major or clinically important toxicity in BPH patients. A relative weakness of this report is a lack of verification of objective study parameters in the patients at seven years post-treatment. Prospective randomized trials are needed to define the role of TUHT in the management of BPH patients.

Temperature-correlated histopathologic changes following microwave thermoablation of obstructive tissue in patients with benign prostatic hyperplasia

OBJECTIVES

To determine the intraprostatic pathologic changes following accurately measured doses of transurethral microwave thermal energy in patients with benign prostatic hyperplasia.

METHODS

Eight patients scheduled for prostate surgery were treated for approximately 1 hour without anesthesia using a newly designed microwave treatment catheter that allows a close impedance match to prostate tissue and concentrates thermal energy preferentially in the anterior and lateral prostate gland. Interstitial, urethral, and rectal temperatures were continuously measured using a novel stereotactic thermal mapping technique. Serial sections of prostate tissue harvested during subsequent surgery were evaluated pathologically with prostate mapping.

RESULTS

Microwave treatment resulted in marked and continuous intraprostate temperature elevation, while urethral and rectal temperatures remained low. Peak intraprostate temperatures in individual patients reached as high as 80 degrees C. Mean temperature reached a maximum of 54 degrees C at a radial distance of approximately 0.5 cm from the urethra and remained 45 degrees C or higher up to a distance of 1.6 cm. The predominant pathologic findings were uniform hemorrhagic necrosis and tissue devitalization without significant inflammation. The mean distance from the urethra to the viable-necrotic tissue border was 1.6 +/- 0.2 cm (range, 0.5 to 2.5). At this border, no more than 1 mm in thickness, temperature averaged 45.7 +/- 0.6 degrees C, and there was a suggestion that pure stromal nodules were more resistant to thermal injury.

CONCLUSIONS

Microwave treatment can destroy obstructive prostate tissue while maintaining innocuous urethral and rectal temperatures. Temperatures of 45 degrees C or higher for approximately 1 hour cause uniform thermoablation of prostate tissue.

Transrectal and transurethral hyperthermia versus sham treatment in benign prostatic hyperplasia: a double-blind randomized multicentre clinical trial. The French BPH Hyperthermia

OBJECTIVE

To compare the safety and efficacy of hyperthermia for the treatment of benign prostatic hyperplasia (BPH), by either the transrectal or transurethral approach, relative to sham treatment.

PATIENTS AND METHODS

Two hundred patients from seven urological departments were randomized and treated in a single centre. Principal inclusion criteria were a peak flow rate (PFR) < 15 mL/s and residual urine < 300 mL/s. Comparisons were made between transurethral hyperthermia (TUH) and transurethral sham (TUS) and between transrectal hyperthermia (TRH) and transrectal sham (TRS) 12 months after treatment. Outcome was assessed by improvements in the Madsen score and PFR, and the incidence of side-effects.

RESULTS

After 12 months, 145 patients were evaluated; 12 patients withdrew during treatment, 43 withdrew during follow-up and two were lost to follow-up. Withdrawals were mainly due to side-effects during treatment (17% in the TRH and 1.5% in the TUH group) and to a lack of improvement during follow-up (14% in the TUH group, 19% in the TUS, 15% in the TRH and 10.5% in the TRS group received other treatments for BPH). Complications during treatment consisted mainly of local pain, urethral bleeding, urethral pain and acute retention, and were five times more frequent in the TRH than the TUH group (34% versus 6%). There was no improvement in PFR after TUH and TRH (response < 20%). Only TUH improved the Madsen score (TUH, +50% and TUS, +17%).

CONCLUSION

Hyperthermia was not an effective treatment for BPH.

An accurate technique for detailed prostatic interstitial temperature-mapping in patients receiving microwave thermal treatment

A minimally invasive prostatic interstitial temperature-mapping technique is described that supplies accurate, detailed information on thermal doses delivered to precisely localized tissue sites. The technique employs a comparatively large numbers of thermosensors, highly accurate placement of those thermosensors at specified three-dimensional coordinates, fiberoptic technology that avoids significant interaction between the thermosensors and the applied microwave field, and continuous temperature readout. Biplane ultrasound imaging and fluoroscopy were used to ensure stereotactic accuracy of thermosensor placement. The technique was applied in 15 patients with benign prostatic hyperplasia (BPH) undergoing a 1-hour microwave thermal treatment session. The thermal mapping procedures and microwave treatment were generally well tolerated. The mean maximum temperature in the prostate and periprostatic tissue (57.9 +/- 1.9 degrees C) was significantly higher (P < 0.001) by more than 18 degrees C than that in either the urethra (39.6 +/- 0.9 degrees C) or the rectum (40.8 +/- 1.7 degrees C). In a representative patient, microwave treatment resulted in stable elevation of temperature 5 mm radially from the urethra that averaged 66.0 +/- 0.1 degrees C. At 10 mm from the urethra, the temperature averaged 50.5 +/- 0.1 degrees C. Urethral and rectal temperatures remained at innocuous levels. In conjunction with pathologic studies, this interstitial thermal mapping method should prove useful in defining the optimal thermal doses for microwave therapy. The method should also find uses in evaluating different microwave treatment systems, which can vary markedly in thermal performance, as well as other modalities that apply heat to prostatic tissue.

Transurethral microwave thermotherapy for benign prostatic hyperplasia: a 2-year follow-up study

The authors studied the long-term effect of transurethral microwave thermotherapy (TUMT) using the Prostratron device on 30 patients with symptomatic benign prostatic hyperplasia (BPH). The maximum power output was 45 W, and the temperature within the prostate was expected to rise above 45 degrees C. The efficacy was evaluated using a specially designed scoring system based on both subjective symptoms and objective findings. Assuming that more than a 25% reduction of the total score indicates "effective," 80%, 70%, 63%, and 57% of the treatments remained effective at 8 weeks, 6 months, 1 year, and 2 years after TUMT, respectively. There were no major complications associated with TUMT during the follow-up period. Our results indicate that TUMT is an effective and long-lasting (at least 2 years) nonsurgical treatment in approximately 60% of patients.

Temperature measurements and histology of the canine prostate during transurethral hyperthermia

Intraprostatic temperature measurements during transurethral hyperthermia at 44.5C were obtained in 5 dogs. Temperatures were also recorded in the bladder neck wall and the rectal wall. After completion of the temperature measurements, hyperthermia was continued for 3 hours. The prostates were then removed and taken for histologic examination immediately after hyperthermia and 1 week and 1 month later. The mean temperatures obtained in the 5 canine prostates were 44.5 +/- 0.4C at the heating electrode; 43.8 +/- 0.4C at a distance of 3 mm. from the electrode; 42.6 +/- 0.5C, 40.8 +/- 0.4C and 39.4 +/- 0.5C, 6, 9 and 12 mm. from the heating electrode, respectively, in the right, prostatic lobe. Similar temperatures were measured in the left lobe. The thermal gradient in the prostatic tissue was therefore about 4C per 1 cm. On histology, hemorrhagic necrosis of the prostatic tissue adjacent to the urethra was found. These histologic changes were found as much as 5 mm. from the heating antenna (where the temperatures measured were above 43C). The findings of our study may have major clinical importance. We found that thermal energy above 43C provides enough penetration to cause tissue damage and be clinically effective in most patients, while the thermal gradient around the heating electrode of 4C per 1 cm. is steep enough to confine histologic damage within the prostate.

Transurethral microwave hyperthermia for benign prostatic hyperplasia: the Leuven clinical experience

Local microwave hyperthermia, delivered transurethrally or transrectally, is a new treatment modality for benign prostatic hyperplasia. We started transurethral application, delivering 915-MHz microwaves at the prostatic urethra using a helical microwave antenna incorporated in a Foley catheter. This hyperthermia was given without a urethral surface cooling system. Thermophysical testing of the applicator proved therapeutic efficacy in vitro and in vivo. Pathologic studies demonstrated hyperthermia-induced lesions in the periurethral prostatic tissues and permitted us to hypothesize a working mechanism of transurethral hyperthermia. Clinical Phase I and II studies showed clinical efficacy in patients with urinary retention or prostatism secondary to benign hyperplasia, especially in bilobar or trilobar prostatic configurations. While awaiting results of further pathologic and thermophysical experimental work and ongoing Phase II and III studies, we consider transurethral hyperthermia an investigational but promising conservative treatment modality for benign prostatic hyperplasia.

Temperature steering in prostate by simultaneous transurethral and transrectal hyperthermia

Localized hyperthermia (HT) is presently under investigation as a treatment for benign prostatic hyperplasia and carcinoma of the prostate (CaP). One popular approach employs a transrectal (TR) device, a directional microwave (MW) applicator inserted into the rectum and aimed at the prostate. Alternatively, in the transurethral (TU) technique, a symmetrically radiating MW antenna is placed directly within the prostatic urethra. Used individually, TR applicators are capable of effectively heating (> 42 degrees C) the prostate up to 2 cm from the rectum, whereas TU applicators selectively heat the periurethral tissue with effective radial penetration of about 0.6 cm. Neither technique is of much value in heating the anterior prostate. In general, the highest temperatures are produced in the tissue immediately adjacent to the surface of intracavitary microwave devices. However, when MW antennas are used in arrays, the resulting heating pattern can differ significantly from that of the individual antennas. Heating at depth can be selectively enhanced and "steered" by adjusting the phase relationship between the devices. Prostatic temperature profiles were measured in 6 patients treated with TR alone, TU alone, and simultaneous TR and TU heating. In the combined treatments different phase relationships between the antennas were applied. We found that a higher temperature could be produced in the center of the prostate than on the surface of either applicator for certain phase relationships, and that the temperature profiles could be changed by shifting phase. The results of these measurements are in agreement with those of a computer simulation. Based on the above data we feel the combined use of TU and TR hyperthermia may be justified in Phase I-II trials for patients with locally advanced CaP.

Relationship of response to transurethral hyperthermia and prostate volume in BPH patients

A response to transurethral microwave hyperthermia (TUHT) at 915 MHz and its relationship to prostate volume was examined in 63 poor surgical risk benign prostatic hyperplasia (BPH) patients. All patients had moderate-to-severe obstructive signs and symptoms, and received > or = 5 TUHT one-hour sessions. Treatment temperature was controlled on the urethral surface at 45 degrees C +/- 1 degree C. Follow-up ranged from twelve to forty-four months (mean 18 months). The mean prostate volume was 57 cc (range 10-301 cc). There were 40 patients (63%) with prostate volume < or = 50 cc and 23 (37%) with a volume > 50 cc. Treatment failure was seen in 6 patients (10%). It was 10 percent in 40 patients with smaller glands and 9 percent for those 23 with larger prostates, N.S. at p = 0.49. Subjective treatment response was seen in 58 patients (92%). It was 90 percent for the 40 patients with < or = 50 cc prostates vs. 96 percent for the 23 with > 50 cc prostates, N.S. at p = 0.75. This study suggests that the initial prostate volume is not an important parameter predicting response to TUHT.

Long-term Indwelling intraurethral catheters in elderly patients with prostatic obstruction. What are the true indications?

From July 1990 to September 1992, 32 elderly male patients with benign prostatic hypertrophy complaining of chronic urinary retention were treated with polyurethane intraurethral catheters (IUC). All of them were unfit for prostatic surgery due to several complications. Indwelling lUCs were left for more than 6 months in 20 (62.5%) patients, and the longest period was 1 year and 11 months. Indwelling lUCs could not be used in patients who had undergone previous operations for prostatic hypertrophy. Comparing urodynamic study findings prior to and after insertion of the IUC results in patients with an overactive or normal bladder were significantly better than those in patients with an underactive bladder (p<0.05, chi-square test). Nine patients were urine continent, and 2 of those patients in whom an indwelling IUC could be left for more than 6 months, complained of mild urinary incontinence. Urinary tract infection disappeared in 7 patients, and improved in 11 of the 20 patients. IUC placement was successful for more than 6 months without exchange in 7 of the 20 patients. Bladder stone formation was found in one patient and was the only complication in these 20 patients. In conclusion, IUC placement can be successful for more than 6 months in patients without underactive bladder or previous prostatic operation.

Transurethral hyperthermia for benign prostatic hyperplasia patients with retention

From 1989 to 1990, 32 poor surgical risk patients with urinary retention were treated with transurethral microwave hyperthermia at the department of urology, University of Leuven in Belgium. Mean patient age was 73 years (range 58 to 90 years) and mean duration of retention was 4 weeks (range 3 to 12 weeks). Followup ranged from 13 to 82 weeks, with a mean of 31 weeks. Bilobar or trilobar hyperplasia was diagnosed in 25 patients (78%), while 7 (22%) had median lobe or median bar hypertrophy. The mean prostatic volume was 52 cc (range 25 to 150 cc). Transurethral microwave hyperthermia was given with a helical antenna at 915 MHz. once or twice per week. The mean number of transurethral microwave hyperthermia sessions was 8.9 (range 5 to 10). Each session consisted of a 60-minute treatment at a mean maximum temperature of 45.4C (range 43.7 to 47.2C), average temperature 43.9C (range 42.7 to 45.5C) and minimum temperature 42.0C (range 40.2 to 43.0C). The temperature was continuously monitored, including thermal mapping in all patients. Of the 25 patients who presented with bilobar or trilobar hyperplasia 18 (72%) were catheter-free for the duration of followup. Of the 7 median lobe or median bar patients 1 (14%) showed sufficient improvement to warrant catheter removal. This patient, however, had recurrent retention 4 months after transurethral microwave hyperthermia. In patients with bilobar and trilobar hyperplasia a strong correlation was observed among maximum temperature (p = 0.0006), average temperature (p = 0.0033) and treatment response. As expected, no such correlation existed between minimum temperature and response to treatment (p = 0.56). Our study has again demonstrated therapeutic activity in patients with benign prostatic hyperplasia treated with transurethral microwave hyperthermia. A new finding was a strong correlation between temperature and response.

Phase I/II study of external radio frequency phased array hyperthermia and external beam radiotherapy in the treatment of prostate cancer: technique and results of intraprostatic temperature measurements

As part of an ongoing Phase I/II study at Duke University Medical Center investigating the toxicity and efficacy of external beam radiotherapy plus hyperthermia for deep-seated, locally advanced or recurrent solid tumors, 12 patients with prostate malignancies (adenocarcinoma--11, leiomyosarcoma--1) were treated with radiotherapy plus hyperthermia. Hyperthermia was given after radiotherapy using a Radio Frequency Phase/Amplitude Control Sigma 60 annular phased array device. All patients had simultaneous temperature measurements made in the rectal lumen and within the prostate during at least one hyperthermia session. Intraprostate thermometers were placed via a unique method described herein using both computerized tomography scan and a rigid sigmoidoscope for guidance. We were able to achieve the desired tumor temperature of > or = 42.5 degrees C in only 1/28 (3.5%) of hyperthermia treatments. Subjective symptoms of pain and/or pressure limited power deposition in 79% of hyperthermia treatments. Higher temperatures were achieved in the distal rectum than in the prostate in all treatments, although the differences were not statistically significant. This temperature differential could not be compensated by using phase and amplitude steering. Rectal temperatures adjacent to the prostate were predictive of prostate temperatures. We conclude that using this regional heating technique we were unable to demonstrate an ability to get an advantageous temperature differential between the prostate and normal tissue. This technique is not useful as an adjuvant to radiation therapy for prostate cancer. The usefulness of other regional heating techniques and devices should be explored.

Transurethral microwave hyperthermia: an alternative treatment for prostadynia?

A total of 15 patients with severe symptoms of prostadynia who were refractory to therapy were treated with transurethral microwave hyperthermia (TUHT) in a phase I trial. All patients had pain as the predominant symptom, 9 (60%) patients gave a history of psychological problems while frequency, urgency, dysuria, nocturia, and impotence were less common symptoms. Treatment consisted of TUHT at 915 MHz given weekly for 5 weeks with a total of 68 treatment sessions and a mean of 4.5 treatments per patient. Each treatment lasted for 60 minutes. The aim was to increase the temperature measured on the urethral surface to greater than or equal to 44 degrees C. T mean for all sessions was 45.5 degrees C. In 91% of treatments, the temperature was greater than or equal to 44 degrees C. Treatment was well tolerated in 87% patients and acute toxicity was mild. Of the 15 patients treated, 2 (13%) did not complete the treatment course due to discomfort during TUHT. Good treatment response, manifested by complete pain relief and a decrease in dysuria, was noted in 7 (47%) patients. A higher (greater than or equal to 46 degrees C) treatment temperature correlated well with good response, P less than .01. Similarly, relief of pain correlated well with the absence of a history of psychological problems, P less than .01. A decrease of obstructive micturition problems was noted in 5 of the 7 patients who had this upon presentation. This study showed evidence of therapeutic activity with the use of TUHT in patients with prostadynia refractory to therapy. The response obtained was limited to less than one-half of the patients. Complete pain relief was obtained in 4 (27%) patients. It is of interest to note that patients who had major benefit did not show evidence of psychological problems and were able to tolerate higher treatment temperatures. The latter could suggest a temperature-related response.