Low dose rate brachytherapy for primary treatment of localized prostate cancer: A systemic review and executive summary of an evidence-based consensus statement

PURPOSE

The purpose of this guideline is to present evidence-based consensus recommendations for low dose rate (LDR) permanent seed brachytherapy for the primary treatment of prostate cancer.

METHODS AND MATERIALS

The American Brachytherapy Society convened a task force for addressing key questions concerning ultrasound-based LDR prostate brachytherapy for the primary treatment of prostate cancer. A comprehensive literature search was conducted to identify prospective and multi-institutional retrospective studies involving LDR brachytherapy as monotherapy or boost in combination with external beam radiation therapy with or without adjuvant androgen deprivation therapy. Outcomes included disease control, toxicity, and quality of life.

RESULTS

LDR prostate brachytherapy monotherapy is an appropriate treatment option for low risk and favorable intermediate risk disease. LDR brachytherapy boost in combination with external beam radiation therapy is appropriate for unfavorable intermediate risk and high-risk disease. Androgen deprivation therapy is recommended in unfavorable intermediate risk and high-risk disease. Acceptable radionuclides for LDR brachytherapy include iodine-125, palladium-103, and cesium-131. Although brachytherapy monotherapy is associated with increased urinary obstructive and irritative symptoms that peak within the first 3 months after treatment, the median time toward symptom resolution is approximately 1 year for iodine-125 and 6 months for palladium-103. Such symptoms can be mitigated with short-term use of alpha blockers. Combination therapy is associated with worse urinary, bowel, and sexual symptoms than monotherapy. A prostate specific antigen <= 0.2 ng/mL at 4 years after LDR brachytherapy may be considered a biochemical definition of cure.

CONCLUSIONS

LDR brachytherapy is a convenient, effective, and well-tolerated treatment for prostate cancer.

The impact of age on prostate cancer progression and quality of life in active surveillance patients

Objectives

To evaluate the impact of age on overall survival (OS), freedom from distant metastasis (FDM), rates of therapeutic intervention (TI), and quality of life (QOL) in active surveillance (AS) prostate cancer patients.

Materials and methods

Three hundred and five consecutive, prospectively evaluated AS patients who underwent a staging transperineal template‐guided mapping biopsy (TTMB) prior to enrollment on AS were evaluated and stratified by age. Evaluated outcomes included OS, FDM, TI, and QOL to include urinary, bowel, sexual function, and depression. Post void residual (PVR) urine measurements were also followed. Repeat biopsy was based on PSA kinetics, abnormal digital rectal examination or patient preference.

Results

Of the 305 patients, 290 (95.1%) were Gleason 3 + 3 and 15 patients (4.9%) were Gleason 3 + 4. The median follow‐up was 5.5 years (range 1‐14 years). At 10 years, TI was 0%, 1.0%, and 11.4% for patients ≤59, 60‐69, and ≥70 years of age (P < .001). No patient has developed distant metastasis. The median time to TI was 4.71 years. No statistical differences in urinary function, bowel function, or depression were noted. Potency preservation was dependent on patient age.

Conclusion

Within the confines of the follow‐up of our series, younger patients were less likely to proceed to therapeutic intervention. In addition, patient age did not adversely impact QOL outcomes.

The ABS brachytherapy schools

The American Brachytherapy Society brachytherapy schools have been pivotal in teaching and evolving the art of brachytherapy over the past decades. Founded in 1995, the schools have consistently provided content for the major disease sites including gynecologic, prostate, and breast with ocular, vascular, head and neck, pediatric, intraluminal, systemic, and intraoperative approaches more selectively addressed. In addition, Physics schools, either coupled with clinical schools or as stand-alone venues, have provided an essential educational component for practicing physicists, a pivotal part of the brachytherapy team. Celebrating 25 years in existence, this historical overview of the American Brachytherapy Society brachytherapy schools is a tribute to the many teachers who have shared their expertise, to the many students who have been enthusiastic and interactive participants, and the staff who have made it all possible, with the reward of perpetuating the important and timely art of brachytherapy.

Incidence, grade and distribution of prostate cancer following transperineal template-guided mapping biopsy in patients with atypical small acinar proliferation

PURPOSE

To evaluate the role of transperineal template-guided mapping biopsy (TTMB) in patients with atypical small acinar proliferation (ASAP) diagnosed via transrectal ultrasound-guided needle biopsy (TRUS).

METHODS

In total, 132 consecutive patients with TRUS-diagnosed ASAP underwent TTMB by means of an anatomic-based technique with sampling of 24 biopsy regions. For each of the 24 regions, 1-3 biopsy cores were obtained (depending on prostate size). No patient underwent pre-biopsy MRI imaging. The Gleason score, location of each positive biopsy core, the number of biopsy cores and percent involvement of each core were recorded. Anterior versus posterior cancer distribution was determined for both low- and high-grade (Gleason score ≥7) cancer.

RESULTS

The mean patient age was 63.8 years with a mean PSA of 6.8 ng/mL. Of the 132 patients, 86 (65.2%) were diagnosed with prostate cancer. Of the entire cohort, 47 patients (54.7% of cancer patients and 35.6% of the entire cohort) were diagnosed with Gleason score ≥7. For both low- and high-grade cancers, the anterior gland and especially the anterior apex were the most common cancer locations.

CONCLUSION

In patients with ASAP, TTMB diagnosed prostate cancer in 65.2% of patients and 35.6% of the entire cohort had high-grade prostate cancer. A predilection for anterior-based cancers, especially the anterior apex, was identified. Our study may serve as a baseline reference for MRI-guided biopsy regimens.

Pathology and Quality of Life Outcomes Following Office-based Transperineal Prostate Biopsy

OBJECTIVE

To report the incidence of prostate cancer diagnosis and quality of life outcomes following transperineal prostate biopsy.

METHODS

Forty-six consecutive patients underwent office-based transperineal prostate biopsy for an elevated prostate-specific antigen and a normal digital rectal examination without prior prostate biopsy. Prior to biopsy, a repeat prostate-specific antigen was obtained to ensure persistent elevation. Silodosin (8 mg daily) was initiated the day prior to biopsy and continued for 1 week. A total of 18-20 biopsy cores were obtained per patient. All patients responded to a visual analog scale ranging from 0 to 10 immediately following the completion of both the local anesthesia and the biopsy procedure. In addition, an International Prostate Symptom Score (IPSS), Rectal Function Assessment Score, International Index of Erectile Function, Center for Epidemiologic Studies Depression Scale, and postvoid residual were obtained at baseline and 30 days following biopsy, except IPSS which was also obtained at day 7.

RESULTS

The mean patient age was 63.3 years with a mean prostate volume of 41.8 cm(3). The mean visual analog scale was 4.2 for the local anesthesia and 3.0 for the biopsy. Thirty-one patients (67.4%) were diagnosed with prostate cancer, with 18 having a Gleason score ≥ 7. Compared to baseline, no adverse changes in IPSS, Rectal Function Assessment Score, International Index of Erectile Function, Center for Epidemiologic Studies Depression Scale, or postvoid residual were detected at day 30. No patient required catheterization, developed sepsis, or required hospitalization.

CONCLUSION

Office-based transperineal prostate biopsy was well tolerated with reasonable treatment-related discomfort, a high rate of prostate cancer diagnosis, and the absence of significant morbidity including sepsis.

Is supplemental external beam radiation therapy essential to maximize brachytherapy outcomes in patients with unfavorable intermediate-risk disease?

PURPOSE

To evaluate whether supplemental external beam radiotherapy (EBRT) is essential to maximize Pd-103 brachytherapy outcomes in patients with unfavorable intermediate-risk (IR) disease.

METHODS AND MATERIALS

A total of 630 patients were assessed from two prospective randomized brachytherapy trials evaluating the role of supplemental EBRT in patients with higher risk features. Patients were stratified into unfavorable IR (primary Gleason pattern 4, ≥50% positive biopsies, or ≥2 IR features), favorable IR, and high-risk (HR) cohorts. Median follow-up was 7.5 years. The brachytherapy prescription dose was prescribed to the prostate gland with generous periprostatic margins. Biochemical failure (BF) was defined as a prostate-specific antigen >0.40 ng/mL after nadir. Patients with metastatic prostate cancer or nonmetastatic castrate-resistant disease who died of any cause were classified as dead of prostate cancer. Multiple parameters were evaluated for effect on outcomes.

RESULTS

The 10-year BF for favorable IR, unfavorable IR, and HR was 1.7%, 6.6%, and 15.5% (p < 0.001). At 10 years, prostate cancer-specific mortality (PCSM) and overall mortality (OM) were 0% and 20.4%, 2.1% and 23.2%, and 4.3% and 42.4% for favorable IR, unfavorable IR, and HR. Although unfavorable IR patients had a greater incidence of BF, PCSM, and OM when compared with favorable IR, neither the addition nor dose of supplemental EBRT influenced outcome.

CONCLUSIONS

Outcomes for favorable IR were superior to those with unfavorable IR. Within the confines of this study, neither the addition nor dose of supplemental EBRT influenced BF, PCSM, or OM in patients with IR disease.

Is supplemental external beam radiation therapy necessary for patients with higher risk prostate cancer treated with 103Pd? Results of two prospective randomized trials

PURPOSE

To determine the necessity and/or dose of supplemental external beam radiotherapy (EBRT) in conjunction with palladium-103 ((103)Pd) brachytherapy for high-risk prostate cancer patients.

METHODS AND MATERIALS

Trial 44/20 randomized patients to 44 Gy plus 90 Gy (103)Pd vs. 20 Gy with 115 Gy (103)Pd, and the subsequent trial randomized patients to the 20 Gy arm vs. 125 Gy (103)Pd without EBRT (20/0 trial). Eligibility criteria included clinically organ-confined disease with Gleason scores 7-9 and/or a pretreatment prostate-specific antigen (PSA) 10-20 ng/mL. The brachytherapy prescription dose was prescribed to the prostate gland with generous periprostatic margins. Biochemical failure (BF) was defined as a PSA >0.40 ng/mL after nadir. Median Day 0 minimum dose covering 90% of the prostate volume (D90) was >121.0% of the prescription dose. Multiple parameters were evaluated for effect on outcomes.

RESULTS

In 44/20 trial, 13-year BF, prostate cancer-specific mortality (PCSM), and overall mortality (OM) were 8.2%, 4.0%, and 42.8% vs. 8.0%, 1.0%. and 40.3% for the 44 and 20 Gy arms. In 20/0 trial, 8-year BF, PCSM, and OM were 2.1%, 0%, and 14.4% vs. 3.6%, 0%, and 16.1% in the 20 vs. 0 Gy arms. When stratified by either pretreatment PSA or by Gleason score, supplemental EBRT dose did not impact BF, PCSM, or OM. In multivariate analysis, BF was most closely related to percent positive biopsies and prostate volume. In both trials, patients with biochemically controlled disease had a median PSA of <0.02 ng/mL.

CONCLUSIONS

With high-quality brachytherapy dose distributions, supplemental EBRT did not influence BF or PCSM for patients with intermediate-risk disease. The number of patients with Gleason score 8-9 was too small to determine the role of supplemental EBRT in that cohort.

Impact of small prostate size on postimplant prostate dosimetry: analysis of a large community database

PURPOSE

Achieving high-quality permanent interstitial brachytherapy in smaller prostates is thought to be more difficult than in larger glands. This study evaluates 4547 implants in a large community database to test this hypothesis.

METHODS AND MATERIALS

From January 2003 to October 2010, 4547 prostate brachytherapy implants from a large community database were analyzed. The cohort was divided into three groups based on size, namely smaller (<30cm(3), n=1301), medium (30-40cm(3), n=1861), and large (>40cm(3), n=1385). Postimplant dosimetry, including D90, V100, and V100 by prostate sector, was performed for each implant. Comparison of mean V100 among small, medium, and larger prostate volume cohorts was performed using a one-way analysis of variance test.

RESULTS

For the overall cohort, the D90 was 105% and 104% for monotherapy and boost, respectively. Mean D90 for small prostates was 106% and 104% for monotherapy and boost, respectively. Mean V100 for small prostates was 91.1% and 90.0%, respectively. Coverage for small prostates was as good or slightly better than larger glands. V100 by prostate sector revealed that there were no sectors for which smaller glands had significantly inferior coverage compared with larger glands.

CONCLUSION

Although smaller prostates may in some respects be more technically difficult to implant than larger glands, a review of community-based brachytherapists reveals that with current implant techniques, good quality implants are readily achievable in men with smaller glands.

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 ± 0.6 mm vs. 0.6 ± 0.4 mm, 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 &gt; 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.

Long-term outcomes of prostate cancer patients with Gleason pattern 5 treated with combined brachytherapy and external beam radiotherapy

PURPOSE

Recent reports have suggested relatively poor prognosis for prostate cancer patients with Gleason pattern 5 treated with dose-escalated external beam radiotherapy (XRT) and androgen deprivation therapy (ADT). We present the largest series of men with high-risk, Gleason pattern 5 prostate cancer treated with permanent interstitial brachytherapy and XRT.

METHODS AND MATERIALS

Between April 1995 and December 2008, 329 consecutive patients with National Comprehensive Cancer Network high-risk disease were treated with permanent interstitial brachytherapy. Most received XRT and ADT. Median followup was 7.2 years. The cause of death was determined for each deceased patient. Multiple clinical, treatment, and dosimetric parameters were evaluated for impact on the evaluated survival parameters.

RESULTS

At 10 years, biochemical progression-free survival, cause-specific survival (CSS), and overall survival for the group of high-risk patients as a whole was 91.1%, 95.5%, and 72.5%, respectively. There was no difference in biochemical progression-free survival between men with and without Gleason pattern 5 (89.7% vs. 91.8%; p=0.56). However, men with Gleason pattern 5 had lower prostate cancer CSS (90.3% vs. 98.1%; p=0.011). There was no difference in overall survival comparing men with and without Gleason pattern 5 disease (67.7% vs. 75.4%; p=0.14).

CONCLUSIONS

Men with high-risk, Gleason pattern 5 histology treated with brachytherapy and XRT have excellent long-term outcomes, which compare favorably to dose-escalated XRT/ADT series without brachytherapy. Nonetheless, Gleason pattern 5 results in lower CSS than high-risk disease without Gleason pattern 5.

Gleason score 7 prostate cancer treated with interstitial brachytherapy with or without supplemental external beam radiation and androgen deprivation therapy: is the primary pattern on needle biopsy prognostic?

PURPOSE

To evaluate the effect of primary Gleason pattern on biochemical progression-free survival (bPFS), cause-specific survival (CSS), and overall survival (OS) in Gleason 7 prostate cancer patients treated with low-dose-rate (LDR) interstitial brachytherapy with or without supplemental external beam radiation therapy and androgen deprivation therapy.

METHODS AND MATERIALS

We retrospectively reviewed the medical records of 932 consecutive patients with biopsy-confirmed Gleason 7 prostate cancer who received LDR interstitial brachytherapy as a component of their definitive treatment regimen. Treatment outcomes were compared between patients with primary Gleason pattern 3 and 4.

RESULTS

With a median followup of 7.4 years, the 10- and 14-year bPFS, CSS, and OS for the entire Gleason 7 study group were 95.7/95.7%, 98.6/98.6% and 77.2/64.3%, respectively. When biochemical control was evaluated as a function of primary Gleason pattern, the primary pattern 3 had a statistically higher 10- and 14-year bPFS (97.8/97.8% vs. 93.1/93.1%, p=0.006). The Gleason pattern 3 patients also trended toward a higher 10- and 14-year CSS (99.3/99.3% vs. 96.9/96.9%, p=0.058). OS was not statistically different between the two Gleason 7 cohorts.

CONCLUSIONS

Gleason 7 prostate cancer patients treated with LDR interstitial brachytherapy have an excellent long-term outcome. There was a small but statistically significant advantage in bPFS and a trend toward improved CSS in patients with a primary Gleason pattern of 3.

Effect of body mass index on intrafraction prostate displacement monitored by real-time electromagnetic tracking

PURPOSE

To evaluate, using real-time monitoring of implanted radiofrequency transponders, the intrafraction prostate displacement of patients as a function of body mass index (BMI).

METHODS AND MATERIALS

The motions of Beacon radiofrequency transponders (Calypso Medical Technologies, Seattle, WA) implanted in the prostate glands of 66 men were monitored throughout the course of intensity modulated radiation therapy. Data were acquired at 10 Hz from setup to the end of treatment, but only the 1.7 million data points with a "beam on" tag were used in the analysis. There were 21 obese patients, with BMI ≥ 30 and 45 nonobese patients in the study.

RESULTS

Mean displacements were least in the left-right lateral direction (0.56 ± 0.24 mm) and approximately twice that magnitude in the superior-inferior and anterior-posterior directions. The net vector displacement was larger still, 1.95 ± 0.47 mm. Stratified by BMI cohort, the mean displacements per patient in the 3 Cartesian axes as well as the net vector for patients with BMI ≥ 30 were slightly less (<0.2 mm) but not significantly different than the corresponding values for patients with lower BMIs. As a surrogate for the magnitude of oscillatory noise, the standard deviation for displacements in all measured planes showed no significant differences in the prostate positional variability between the lower and higher BMI groups. Histograms of prostate displacements showed a lower frequency of large displacements in obese patients, and there were no significant differences in short-term and long-term velocity distributions.

CONCLUSIONS

After patients were positioned accurately using implanted radiofrequency transponders, the intrafractional displacements in the lateral, superior-inferior, and anterior-posterior directions as well as the net vector displacements were smaller, but not significantly so, for obese men than for those with lower BMI.

Long-term outcome for very high-risk prostate cancer treated primarily with a triple modality approach to include permanent interstitial brachytherapy

PURPOSE

To evaluate outcome in the most unfavorable subset of high-risk prostate cancer patients treated with a combination of supplemental external beam radiation therapy (EBRT) and brachytherapy.

METHODS AND MATERIALS

Very high-risk prostate cancer was defined as follows: any Gleason score 10, Gleason score 8-9 with >50% of the biopsy cores positive for malignancy, Gleason score 8-9 with a prostate-specific antigen (PSA) >20ng/mL, any clinical stage T3, or any PSA >40ng/mL. One hundred thirty-one patients were identified who met the aforementioned criteria. The median followup was 6.6 years. One hundred twenty (91.6%) patients received supplemental EBRT and 100 (76.4%) received androgen deprivation therapy (median duration, 19.5 months; range, 4-36 months). The median postimplant day 0 D(90) (i.e., the minimum percentage of the prescription dose that covers the planning target volume) was 121.9% of prescription dose. Multiple clinical treatment and dosimetric parameters were evaluated for impact on the evaluated survival parameters.

RESULTS

The median pretreatment PSA and Gleason score were 11.0ng/mL and 8. One hundred ten (84%) patients had a Gleason score ≥8. At 9 and 12 years, the cause-specific survival, biochemical progression-free survival, and overall survival were 91.0% and 86.5%, 87.3% and 87.3%, and 70.5% and 60.5%, respectively. The most common cause of death was heart disease (22.2%) with deaths from nonprostate cancer (12.7%) and prostate cancer (8.3%) being less likely.

CONCLUSIONS

Permanent interstitial brachytherapy usually with supplemental EBRT and androgen deprivation therapy results in excellent biochemical control and cause-specific survival in the most unfavorable subset of high-risk prostate cancer patients. Death from diseases of the heart was more than twice as likely as death from prostate cancer.

Higher percentage of positive biopsy cores and Gleason score are associated with a greater degree of prostate gland shrinkage after neoadjuvant cytoreductive therapy

PURPOSE

To determine whether adverse pathologic features, including tumor grade and percent positive biopsy (PPB) cores, predict for prostate size reduction after neoadjuvant cytoreductive therapy.

METHODS AND MATERIALS

Eighty-two consecutive patients who were diagnosed with prostate cancer by transperineal template-guided mapping biopsy (TTMB) received neoadjuvant cytoreductive therapy. The median number of biopsy cores was 59. Thirty patients received a leutinizing hormone-releasing hormone agonist and bicalutamide, whereas 52 patients received bicalutamide (50mg daily) and dutasteride (0.5mg daily). A transrectal ultrasound volumetric study of the prostate gland and ellipsoid volume determinations of the prostate gland and transition zone (TZ) were obtained immediately before TTMB and at 90 days (±7 days) after the initiation of neoadjuvant medical therapy. Univariate and multivariate regression analyses were performed to identify predictors of prostate gland and TZ volume reduction.

RESULTS

At TTMB, the mean prostate volumetric and ellipsoid volumes were 55.4 cm(3) and 49.0 cm(3), respectively. After neoadjuvant medical therapy, the mean volumetric and ellipsoid prostate volumes were 30.8 cm(3) and 28.5 cm(3), respectively. On average, the prostate volume decreased by 43.9% and 41.0% on volumetric and ellipsoid measurements, respectively. The TZ volume decreased from 19.8 cm(3) to 10.1 cm(3) (mean volume reduction of 47.7%). In multivariate analysis, prostate volume cytoreduction was most closely associated with PPB (p=0.014), TTMB prostate volume (p=0.01), and drug regimen (p=0.001).

CONCLUSIONS

The degree of prostate volume cytoreduction was positively associated with higher Gleason score and PPBs. Greater reductions in prostate volume may be an indicator of more aggressive cancer.

Distant metastases following permanent interstitial brachytherapy for patients with clinically localized prostate cancer

PURPOSE

Recent publications have suggested high-risk patients undergoing radical prostatectomy have a lower risk of distant metastases and improved cause-specific survival (CSS) than patients receiving definitive external beam radiation therapy (XRT). To date, none of these studies has compared distant metastases and CSS in brachytherapy patients. In this study, we evaluate such parameters in a consecutive cohort of brachytherapy patients.

METHODS AND MATERIALS

From April 1995 to June 2007, 1,840 consecutive patients with clinically localized prostate cancer were treated with brachytherapy. Risk groups were stratified according to National Comprehensive Cancer Network (www.nccn.org) guidelines. Subgroups of 658, 893, and 289 patients were assigned to low, intermediate, and high-risk categories. Median follow-up was 7.2 years. Along with brachytherapy implantation, 901 (49.0%) patients received supplemental XRT, and 670 (36.4%) patients received androgen deprivation therapy (median duration, 4 months). The mode of failure (biochemical, local, or distant) was determined for each patient for whom therapy failed. Cause of death was determined for each deceased patient. Multiple parameters were evaluated for impact on outcome.

RESULTS

For the entire cohort, metastases-free survival (MFS) and CSS at 12 years were 98.1% and 98.2%, respectively. When rates were stratified by low, intermediate, and high-risk groups, the 12-year MFS was 99.8%, 98.1%, and 93.8% (p < 0.001), respectively. CSS rates were 99.8%, 98.0%, and 95.3% (p < 0.001) for low, intermediate, and high-risk groups, respectively. Biochemical progression-free survival was 98.7%, 95.9% and 90.4% for low, intermediate, and high-risk patients, respectively (p < 0.001). In multivariate Cox-regression analysis, MFS was mostly closely related to Gleason score and year of treatment, whereas CSS was most closely associated with Gleason score.

CONCLUSIONS

Excellent CSS and MFS rates are achievable with high-quality brachytherapy for low, intermediate, and high-risk patients. These results compare favorably to alternative treatment modalities. In particular, our MFS and CSS rates for high-risk patients appear superior to those of published radical prostatectomy series.

Serum testosterone kinetics after brachytherapy for clinically localized prostate cancer

PURPOSE

To evaluate temporal changes in testosterone after prostate brachytherapy and investigate the potential impact of these changes on response to treatment.

METHODS AND MATERIALS

Between January 2008 and March 2009, 221 consecutive patients underwent Pd-103 brachytherapy without androgen deprivation for clinically localized prostate cancer. Prebrachytherapy prostate-specific antigen (PSA) and serum testosterone were obtained for each patient. Repeat levels were obtained 3 months after brachytherapy and at least every 6 months thereafter. Multiple clinical, treatment, and dosimetric parameters were evaluated to determine an association with temporal testosterone changes. In addition, analysis was conducted to determine if there was an association between testosterone changes and treatment outcomes or the occurrence of a PSA spike.

RESULTS

There was no significant difference in serum testosterone over time after implant (p = 0.57). 29% of men experienced an increase ≥ 25%, 23% of men experienced a decrease ≥ 25%, and the remaining 48% of men had no notable change in testosterone over time. There was no difference in testosterone trends between men who received external beam radiotherapy and those who did not (p = 0.12). On multivariate analysis, preimplant testosterone was the only variable that consistently predicted for changes in testosterone over time. Men with higher than average testosterone tended to experience drop in testosterone (p < 0.001), whereas men with average or below average baseline testosterone had no significant change. There was no association between men who experienced PSA spike and testosterone temporal trends (p = 0.50) nor between initial PSA response and testosterone trends (p = 0.21).

CONCLUSION

Prostate brachytherapy does not appear to impact serum testosterone over time. Changes in serum testosterone do not appear to be associated with PSA spike phenomena nor with initial PSA response to treatment; therefore, PSA response does not seem related to temporal testosterone changes.

The effect of pro-qura case volume on post-implant prostate dosimetry

PURPOSE

To evaluate the effect of prostate brachytherapy case volume on postimplant dosimetric quality in Pro-Qura proctored programs.

METHODS AND MATERIALS

From August 1999 to December 2008, the computed tomography datasets for 6,600 prostate implants performed by 129 brachytherapists were submitted to Pro-Qura for dosimetric analysis. Brachytherapists were divided into three roughly equal-sized terciles based on total case volume. Postimplant computed tomography scans were obtained at a median of 30 days. Excellent target coverage was defined by a V100≥90% and D90≥100% minimum prescribed peripheral dose. To determine if the number of excellent implants improved with increasing case numbers, each brachytherapist's series of implants was bisected into early and late experience by a moveable critical point.

RESULTS

For the entire cohort, the mean V100 and D90 were 89.2% and 102.8%, respectively, with 47.7% of the implants scored as excellent. Brachytherapists in the highest-case tercile had a significantly greater fraction of excellent target coverage (57.9%) than did those in the two lower terciles (39.5% and 45.7%, p=0.015). Twenty-one (25.6%) of the 82 brachytherapists with sufficient case volume for dosimetric improvement analyses demonstrated quality improvement over time. Although there was no significant difference between prostate volume and seed strength, the number of seeds used was significantly greater in adequate implants.

CONCLUSIONS

The highest-volume brachytherapists were most likely to obtain excellent target coverage. We are encouraged that in general practice, nearly 48% of all implants were scored excellent. It is conceivable that with greater expert third-party involvement, an even greater percentage of cases with excellent target coverage will become reality.

The correlation between annular treatment margins and biochemical failure in prostate brachytherapy patients with optimized intraprostatic dosimetry

PURPOSE

To determine whether periprostatic treatment margins correlate with biochemical control in prostate brachytherapy patients with optimized intraprostatic dosimetry.

METHODS AND MATERIALS

Nineteen biochemically failed brachytherapy patients were matched to 74 dosimetric and clinically equivalent nonfailures. The median followup time for the entire study population was 9.4 years. Eligibility requirements included a Day 0 intraprostatic D(90) of 100% or greater and V(100) of 90% or greater, absence of androgen deprivation therapy, and no evidence of distant metastasis in biochemically failed patients. A 5-mm annulus was constructed around the perimeter of each prostate. D(90) and V(100) at the anterior, posterior, superior, inferior, right lateral, and left lateral aspects of the annulus were evaluated for patients with biochemically controlled and failed disease. Biochemical progression-free survival (bPFS) was defined as a prostate-specific antigen level of 0.40ng/mL or less after nadir. D(90) and V(100) parameters were compared between the controlled and failed groups using logistic regression. Predictors of biochemical failure were identified using Cox regression.

RESULTS

No statistically significant differences in prostate-specific antigen level, Gleason score, percent positive biopsies, or intraprostatic dosimetry were observed between the controlled and failed patients. The D(90) and V(100) at the anterior, posterior, superior, inferior, right lateral, and left lateral aspects of the annulus were not statistically different between biochemically controlled and failed groups.

CONCLUSION

In this study, there was no relationship observed between annular dosimetry and biochemical control. It is unlikely that further radial dose intensification would have altered treatment outcome in this population of patients with optimized intraprostatic dosimetry.

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.

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.

Permanent prostate brachytherapy in prostate glands <20 cm(3)

PURPOSE

To investigate the dosimetry, treatment-related morbidity, and biochemical outcomes for brachytherapy in patients with prostate glands <20 cm(3).

METHODS AND MATERIALS

From November 1996 to October 2006, 104 patients with prostate glands <20 cm(3) underwent brachytherapy. Multiple prostate, urethral, and rectal dosimetric parameters were evaluated. Treatment-related urinary and rectal morbidity were assessed from patient questionnaires. Cause-specific survival, biochemical progression-free survival, and overall survival were recorded.

RESULTS

The median patient age, follow up, and pre-treatment ultrasound volume was 64 years, 5.0 years and 17.6cm(3), respectively. Median day 0 dosimetry was significant for the following: V100 98.5%, D90 126.1% and R100 <0.5% of prescription dose. The mean urethral and maximum urethral doses were 119.6% and 133.8% of prescription. The median time to International Prostate Symptom Score resolution was 4 months. There were no RTOG grade III or IV rectal complications. The cause-specific survival, biochemical progression-free survival, and overall survival rates were 100%, 92.5%, and 77.8% at 9 years. For biochemically disease-free patients, the median most recent postbrachytherapy PSA value was 0.02 ng/mL.

CONCLUSION

Our results demonstrate that brachytherapy for small prostate glands is highly effective, with an acceptable morbidity profile, excellent postimplant dosimetry, acceptable treatment-related morbidity, and favorable biochemical outcomes.

Relationship between prostate cancer mortality and number of unfavourable risk factors in men treated with definitive brachytherapy

OBJECTIVE

To explore whether the number of unfavourable pretreatment risk factors predicts cause-specific mortality in men treated with prostate brachytherapy.

PATIENTS AND METHODS

Between April 1995 and March 2006, 739 patients were treated who had at least one of the following adverse risk factors: pretreatment prostate-specific antigen (PSA) level of >10 ng/mL, a Gleason score of > or =7, clinical stage > or =T2b, or a PSA velocity (PSAV) of >2 ng/mL/year. Supplemental external beam radiotherapy (EBRT) was delivered to 464 (62.8%) men and 301 (40.7%) received androgen deprivation therapy (ADT). Of men with more than two risk factors, 87% received EBRT and 62% received ADT.

RESULTS

The biochemical progression-free survival (bPFS), cause-specific survival (CSS) and overall survival for all patients were 95.0%, 97.9% and 70.0% at 12 years. Men with three or four risk factors had a prostate cancer-specific mortality (PCSM) at 12 years of 5.3%, vs 1.7% for men with one or two risk factors (P= 0.006). When 'percentage of positive biopsy cores >50%' replaced PSAV as a risk factor, men with two or more risk factors had a PCSM of 8.9%, vs 1.0% for men with one or two risk factors (P= 0.001). There was no difference in all-cause mortality between the groups in either analysis.

CONCLUSION

Multimodal brachytherapy results in high rates of bPFS and CSS, even for men with several unfavourable risk factors. Men with two or more unfavourable risk factors had a slightly greater risk of PCSM and no difference in all-cause mortality. The presence of three or four unfavourable intermediate-risk factors does not appear to clearly identify a group that requires further treatment intensification, although the percentage of positive cores might be more predictive than PSAV.

Postimplant rectal dosimetry is not dependent on 103Pd or 125I seed activity

PURPOSE

In this study, the effect of prostate brachytherapy seed activity on postimplant rectal dosimetry was evaluated in Pro-Qura (Prostate Brachytherapy Quality Assurance; Seattle, WA) proctored, community-based programs.

METHODS AND MATERIALS

Twenty-three hundred patients (1563 iodine-125 [(125)I] and 737 palladium-103 [(103)Pd]) from 78 brachytherapists with postimplant rectal dosimetry were identified. Seed activity was stratified into three tertiles for each isotope (≤0.300, 0.301-0.326, and >0.326 mCi/seed for (125)I and ≤1.330, 1.331-1.547, and >1.547 mCi/seed for (103)Pd). Postimplant dosimetry was performed in a standardized fashion. The rectum was contoured by outlining the outer rectal wall. The volume of the rectum receiving 100% of the prescription dose (R(100)) was calculated in cubic centimeters. The prostate V(100) and D(90) volumes were also calculated.

RESULTS

The mean prostate volume was 35.8 and 32.3 cm(3) for (125)I and (103)Pd. The median time to postimplant CT was 30 days. For (125)I, the V(100) increased from 91.0% to 93.7% (p=0.012) and the D(90) increased from 105.9% to 108.7% (p<0.001) for the lowest to the highest (125)I seed activities. In contrast, no significant changes in V(100) (p=0.751) or D(90) (p=0.200) were discerned when stratified by seed activity. For both isotopes, there was no correlation between seed activity and R(100), and R(100) was highest for the intermediate seed activities. Overall, the R(100) was lower for (103)Pd vs. (125)I (0.63 vs. 0.82 cm(3), p<0.001).

CONCLUSIONS

Within the confines of seed activities used in this study, higher activity seeds did not result in a deleterious effect on rectal dose. Higher activity seeds were associated with improved prostate dosimetry for (125)I, whereas (103)Pd dosimetry was not dependent on seed activity.