B.C. Murray

DYSURIA AFTER PERMANENT PROSTATE BRACHYTHERAPY

PURPOSE Although numerous prostate cancer quality-of-life studies have been reported, a paucity of data exists regarding brachytherapy-related dysuria. In this study, we evaluated the incidence and temporal resolution of dysuria, along with the influence of multiple treatment, clinical, and dosimetric parameters. MATERIALS AND METHODS Five hundred eighty-one consecutive patients without a preimplant history of transurethral resection of the prostate underwent brachytherapy between January 1998 and December 2001 for clinical T1c-T3a (1997 AJCC) adenocarcinoma of the prostate gland. The evaluated population consisted of the 546 patients who had completed at least two postimplant dysuria evaluations. The median patient follow-up was 26.4 months. In all patients, alpha-blocker therapy was initiated before implantation and continued at least until the International Prostate Symptom Score (IPSS) returned to baseline. The frequency of dysuria was assessed on a 1-5 scale using the IPSS scoring criteria. The dysuria severity was scored on a 1-10 scale. The clinical parameters evaluated included age, T stage, preimplant IPSS, ultrasound volume, and elapsed time since implantation. The treatment parameters included the use of neoadjuvant hormonal manipulation, use of supplemental external beam radiotherapy, isotope, and total implanted seed strength. The dosimetric parameters included values of the minimal dose received by 90% of the prostate, the percentage of prostate volume receiving 100%, 150%, and 200% of the prescribed minimal peripheral dose, and the median and maximal urethral doses. RESULTS The incidence of dysuria peaked at 52% 1 month after implantation. The median dysuria frequency score was 0 of 5 for all patients and 2 of 5 for those reporting dysuria. The median severity score was 0 of 10 for the entire cohort and 3 of 10 for those reporting dysuria. For the entire group, both the frequency and the severity of dysuria steadily improved with time, with near complete resolution of dysuria at 45 months. For those patients reporting dysuria, neither the frequency nor the severity revealed any durable improvement for approximately 36 months. Patients with dysuria displayed higher postimplant IPSSs. Of the 7 IPSS questions, nocturia and incomplete voiding were the best surrogates for dysuria. The isotope, supplemental external beam radiotherapy, hormonal status, minimal dose received by 90% of the prostate, and urethral dose did not predict for dysuria. CONCLUSIONS After permanent prostate brachytherapy, dysuria is a relatively common event, but only rarely severe in frequency or intensity. At approximately 45 months after brachytherapy, dysuria appears to resolve in almost all patients.

Electromagnetic Tracking of Intrafraction Prostate Displacement in Patients Externally Immobilized in the Prone Position

PURPOSE To evaluate intrafraction prostate displacement among patients immobilized in the prone position using real-time monitoring of implanted radiofrequency transponders. METHODS AND MATERIALS The Calypso localization system was used to track prostate motion in patients receiving external beam radiation therapy (XRT) for prostate cancer. All patients were treated in the prone position and immobilized with a thermoplastic immobilization device. Real-time measurement of prostate displacement was recorded for each treatment fraction. These measurements were used to determine the duration and magnitude of displacement along the three directional axes. RESULTS The calculated centroid of the implanted transponders was offset from the treatment isocenter by >or=2 mm, >or=3 mm, and >or=4 mm for 38.0%, 13.9%, and 4.5% of the time. In the lateral dimension, the centroid was offset from the treatment isocenter by >or=2 mm, >or=3 mm, and >or=4 mm for 2.7%, 0.4%, and 0.06% of the time. In the superior-inferior dimension, the centroid was offset from the treatment isocenter by >or=2 mm, >or=3 mm, and >or=4 mm for 16.1%, 4.7%, and 1.5% of the time, respectively. In the anterior-posterior dimension, the centroid was offset from the treatment isocenter by >or=2 mm, >or=3 mm, and >or=4 mm for 13.4%, 3.0%, and 0.5% of the time. CONCLUSIONS Intrafraction prostate displacement in the prone position is comparable to that in the supine position. For patients with large girth, in whom the supine position may preclude accurate detection of implanted radiofrequency transponders, treatment in the prone position is a suitable alternative.

High-Risk Prostate Cancer With Gleason Score 8–10 and PSA Level ≤15 ng/ mL Treated With Permanent Interstitial Brachytherapy

PURPOSE With widespread prostate-specific antigen (PSA) screening, there has been an increase in men diagnosed with high-risk prostate cancer defined by a Gleason score (GS) ≥8 coupled with a relatively low PSA level. The optimal management of these patients has not been defined. Cause-specific survival (CSS), biochemical progression-free survival (bPFS), and overall survival (OS) were evaluated in brachytherapy patients with a GS ≥8 and a PSA level ≤15 ng/mL with or without androgen-deprivation therapy (ADT). METHODS AND MATERIALS From April 1995 to October 2005, 174 patients with GS ≥8 and a PSA level ≤15 ng/mL underwent permanent interstitial brachytherapy. Of the patients, 159 (91%) received supplemental external beam radiation, and 113 (64.9%) received ADT. The median follow-up was 6.6 years. The median postimplant Day 0 minimum percentage of the dose covering 90% of the target volume was 121.1% of prescription dose. Biochemical control was defined as a PSA level ≤0.40 ng/mL after nadir. Multiple parameters were evaluated for impact on survival. RESULTS Ten-year outcomes for patients without and with ADT were 95.2% and 92.5%, respectively, for CSS (p = 0.562); 86.5% and 92.6%, respectively, for bPFS (p = 0.204); and 75.2% and 66.0%, respectively, for OS (p = 0.179). The median post-treatment PSA level for biochemically controlled patients was <0.02 ng/mL. Multivariate analysis failed to identify any predictors for CSS, whereas bPFS and OS were most closely related to patient age. CONCLUSIONS Patients with GS ≥8 and PSA level ≤15 ng/mL have excellent bPFS and CSS after brachytherapy with supplemental external beam radiotherapy. The use of ADT did not significantly impact bPFS, CSS, or OS.

Influence of hormonal therapy on late rectal function after permanent prostate brachytherapy with or without supplemental external beam radiotherapy.

PURPOSE Recent clinical studies have reported a relationship between the use of hormonal therapy and degradation in rectal function after external beam radiotherapy. Using a patient-administered quality-of-life instrument, we evaluated the effect of hormonal therapy on late rectal function after permanent prostate brachytherapy with or without supplemental external beam radiotherapy. METHODS AND MATERIALS A total of 189 patients were mailed the Rectal Function Assessment Score (R-FAS), which consists of nine questions (score range 0-27, with higher scores indicative of poorer bowel function). Of the 189 surveys sent out, 187 (98.4%) were returned. Of the 187 patients, 149 (79.7%) were hormone naive, and 38 (20.3%) had received hormonal manipulation (median duration 4 months, range 3-36). The median follow-up for the entire group was 66.3 months. The effect of hormonal therapy on bowel function was evaluated by comparing the R-FAS scores across time, by each of the individual nine questions, and by means of a summary question evaluating the patients perception of overall bowel function. The two groups were also evaluated in terms of clinical, treatment, and dosimetric parameters, including follow-up, age, Gleason score, clinical stage, pretreatment prostate-specific antigen level, number of pretreatment bowel movements/d, prostate volume, and rectal dosimetry. RESULTS The two groups were well matched in all clinical, treatment, and dosimetric parameters, except the patients receiving hormonal therapy had a statistically shorter follow-up (63.9 vs. 69.4 months, p <0.001) and higher pretreatment prostate-specific antigen level (12.0 vs. 9.8 ng/mL, p = 0.024). The R-FAS scores for the hormone-naive and hormonally manipulated patients were comparable (3.76 vs. 4.55, p = 0.083). In terms of the nine individual R-FAS questions, no statistically significant difference was reported for any question when stratified by hormonal status, including rectal bleeding (p = 0.735). Only 12% and 13% of hormone-naive and hormonally manipulated patients, respectively, reported bowel function to be worse after implantation. With time, a trend for improvement in the R-FAS was noted in both cohorts. CONCLUSION After permanent prostate brachytherapy, no statistically significant difference in bowel habits was discerned when stratified by hormonal status. In addition, only 12% of brachytherapy patients reported deterioration in bowel function after implantation.

Electromagnetic transponders indicate prostate size increase followed by decrease during the course of external beam radiation therapy.

PURPOSE Real-time image guidance enables more accurate radiation therapy by tracking target movement. This study used transponder positions to monitor changes in prostate volume that may be a source of dosimetric and target inaccuracy. METHODS AND MATERIALS Twenty-four men with biopsy-proven T1c-T3a prostate cancer each had three electromagnetic transponders implanted transperineally. Their coordinates were recorded by the Calypso system, and the perimeter of the triangle formed by the transponders was used to calculate prostate volumes at sequential time points throughout the course of radiation therapy to a dose of 81 Gy in 1.8-Gy fractions. RESULTS There was a significant decrease in mean prostate volume of 10.9% from the first to the final day of radiation therapy. The volume loss did not occur monotonically but increased in most patients (75%) during the first several weeks to a median maximum on Day 7. The volume increased by a mean of 6.1% before decreasing by a mean maximum difference of 18.4% to nadir (p < 0.001 for both increase and decrease). Glandular shrinkage was asymmetric, with the apex to right base dimension varying more than twice that of the lateral dimension. For all dimensions, the mean change was <0.5 cm. CONCLUSION Real-time transponder positions indicated a volume increase during the initial days of radiation therapy and then significant and asymmetric shrinkage by the final day. Understanding and tracking volume fluctuations of the prostate during radiation therapy can help real-time imaging technology perform to its fullest potential.

Intrafraction displacement of prone versus supine prostate positioning monitored by real‐time electromagnetic tracking

Implanted radiofrequency transponders were used for real‐time monitoring of the intrafraction prostate displacement between patients in the prone position and the same patients in the supine position. Thirteen patients had three transponders implanted transperineally and were treated prone with a custom‐fitted thermoplastic immobilization device. After collecting data from the last fraction, patients were realigned in the supine position and the displacements of the transponders were monitored for 5–7 minutes. Fourier transforms were applied to the data from each patient to determine periodicity and its amplitude. To remove auto correlation from the stream of displacement data, the distribution of short‐term and long‐term velocity components were calculated from Poincaré plots of paired sequential vector displacements. The mean absolute displacement was significantly greater prone than supine in the superior–inferior (SI) plane (1.2±0.6mm vs. 0.6±0.4mm, p=0.015), but not for the lateral or anterior–posterior (AP) planes. Displacements were least in the lateral direction. Fourier analyses showed the amplitude of respiratory oscillations was much greater for the SI and AP planes in the prone versus the supine position. Analysis of Poincaré plots confirmed greater short‐term variance in the prone position, but no difference in the long‐term variance. The centroid of the implanted transponders was offset from the treatment isocenter by > 5 mm for 1.9% of the time versus 0.8% of the time for supine. These results confirmed significantly greater net intrafraction prostate displacement of patients in the prone position than in the supine position, but most of the difference was due to respiration‐induced motion that was most pronounced in the SI and AP directions. Because the respiratory motion remained within the action threshold and also within our 5 mm treatment planning margins, there is no compelling reason to choose one treatment position over the other. PACS number: 87.50.st