A retrospective analysis after low-dose-rate prostate brachytherapy with permanent 125I seed implant: clinical and dosimetric results in 70 patients

Aims and background

To evaluate the biochemical disease-free survival (bDFS) rate after 125I permanent-implant prostate brachytherapy.

Methods

Patients with a diagnosis of prostate adenocarcinoma and adequate PSA follow-up were selected for this retrospective study. Brachytherapy with permanent 125I seeds was performed as monotherapy, with a prescribed dose of 145 Gy to the prostate. Patients were stratified into recurrence risk groups according to the National Comprehensive Cancer Network (NCCN) guidelines. Biochemical failure was defined using the American Society of Therapeutic Radiology and Oncology (ASTRO) guidelines. The post-implant D90 (defined as the minimum dose covering 90% of the prostate) was obtained for each patient. Two cutoff points were used to test the correlation between D90 and bDFS results: 130 Gy and 140 Gy. bDFS was calculated from the implant date to the date of biochemical recurrence. Univariate and multivariate analysis were performed using the SPSS software and included clinical stage, pretreatment PSA, Gleason score (GS), androgen deprivation therapy, D90, and risk groups. In the univariate analysis we used a cutoff point of 5.89 ng/mL for PSA and 5 for GS.

Results

From June 2003 to April 2007, 70 patients were analyzed. The patients' distribution into recurrence risk groups was as follows: 39 patients (56%) in the low-risk group, 23 patients (33%) in the intermediate-risk group, and 8 patients (11%) in the high-risk group. At a median follow-up of 47 months (range, 19–70 months) bDFS was 88.4%, with a global actuarial 5-year bDFS of 86%. Disease-related factors including initial PSA level, GS and risk group were significant predictors of biochemical failure (P = 0.01, P = 0.01, P = 0.006, respectively). In multivariate analysis, risk group (P = 0.005) and GS (P = 0.03) were statistically significant.

Conclusion

Our data are in agreement with those in the literature and, despite the short follow-up, confirm the advantage of brachytherapy for patients at low and intermediate risk of recurrence.

Needle position during (125)I seed implantation: accurately recognized by sagittal transrectal ultrasonography [corrected]

PURPOSE

The aim of this study was to assess the variation of probe rotation angles for detecting a single needle using sagittal images of transrectal ultrasonography (TRUS).

MATERIALS AND METHODS

A phantom study was performed. One needle was inserted through each of 10 holes of the template, and variations in the probe rotation angles for detecting the needle were measured.

RESULTS

The mean variation of probe rotation for detecting a single needle was 17.0 degrees (range 4 degrees -25 degrees ). Slightly broader variation was seen for the needle in holes farther away from the probe.

CONCLUSION

Probe rotation angles for detecting a single needle displayed considerable variation. Seed locations recognized on sagittal imaging by TRUS are thus indeterminate, and real-time dose calculations using TRUS for (125)I seed implantation should be used with care.

Comparison of intraoperative ultrasound with postimplant computed tomography--dosimetric values at Day 1 and Day 30 after prostate brachytherapy

PURPOSE

To compare the results of intraoperative dosimetry with those of postimplant computed tomography (CT)-based dosimetry after (125)I prostate brachytherapy.

METHODS AND MATERIALS

We treated 412 prostate cancer patients with (125)I prostate brachytherapy, with or without external beam radiotherapy at our institution. Neoadjuvant hormone therapy was administered to 331 patients (80.3%). Implantation was performed using an intraoperative interactive technique. Postimplant dosimetry was performed on Day 1 and Day 30 using CT imaging. The dosimetric results for the prostate, urethra, and rectum were compared among intraoperative ultrasound, and CT scans of Day 1 and Day 30.

RESULTS

The mean intraoperative minimal dose received by 90% of the prostate volume (D(90)) was 118.8% of the prescribed dose vs. 106.4% for Day 1 (p < 0.01) and 119.2% for Day 30 (p = 0.25). There were no significant correlations between the intraoperative D(90) and the postimplant D(90) values (intraclass correlation coefficients=0.42 and 0.33 for Day 1 and Day 30, respectively). Prostatic edema at Day 1 had the largest effect on the Day 1 D(90) (p < 0.01). The factor significantly affecting the Day 30 D(90) was neoadjuvant hormone therapy (p < 0.01). The mean Day 30 D(90) for the hormone-treated patients was 117.9%, compared with 124.6% for those who remained hormone naïve. The intraoperative and postimplant dosimetric values differed significantly for the urethra and rectum.

CONCLUSIONS

Our results demonstrate that there are no significant differences between the D(90) assessments obtained intraoperatively and at Day 30 postoperatively. Furthermore, there are no definite correlations between intra- and postimplantation dosimetric values. Other D(90) values differed significantly between the intraoperative and postimplant dosimetry. This study suggests that dosimetry has negligible clinical utility for informing patients, at discharge, of whether or not their implants are adequate.

Long-Term Urinary, Sexual, and Rectal Morbidity in Patients Treated with Iodine-125 Prostate Brachytherapy Followed Up for a Minimum of 5 Years

OBJECTIVES

To define the long-term morbidity in patients with prostate cancer who underwent iodine-125 brachytherapy.

METHODS

A total of 325 men with localized prostate cancer treated with iodine-125 brachytherapy had a median follow-up of 7 years (range 5 to 15). The American Urological Association symptom score, erectile function status, rectal bleeding incidence, and presence of urinary incontinence were collected prospectively before implantation and every 6 months thereafter. Comparisons were made between the pretreatment and treatment-related factors and their associations with quality-of-life changes. Associations were tested using the Student t, chi-square, and Wilcoxon signed rank tests.

RESULTS

The median prostate volume and maximal dose to 90% of the prostate was 36.6 cm3 and 167 Gy, respectively. Of the 325 men, 15.7% experienced prostate-specific antigen failure and 4% started androgen deprivation therapy. The mean total symptom and bother scores increased from baseline (P <0.001) to 6 months after implantation, steadily decreased, and were unchanged at the last follow-up visit (P = 0.6). There were no significant associations among patient age, race, hormonal therapy use, prostate size, radiation dose, and urinary morbidity. Incontinence occurred in 4 (1.2%) of the 325 patients at the last follow-up visit and was associated with transurethral resection of the prostate (odds ratio 8.8, 95% confidence interval 1.3 to 62, P = 0.008). Before implantation, 77.2% were able to have an erection adequate for intercourse and 50.6% were able to at the last follow-up visit. A significant correlation was found between potency preservation and age (P <0.001). Rectal bleeding occurred in 78 men (24%) 1 to 3 years after implantation. Nine patients (2.8%) complained of minor bleeding beyond 5 years, which was associated with greater radiation doses (P = 0.023).

CONCLUSIONS

The preservation of urinary, sexual, and rectal quality of life is excellent at long follow-up for patients implanted with iodine-125.

Intermediate term biochemical-free progression and local control following 125iodine brachytherapy for prostate cancer

PURPOSE

We determined the 10-year biochemical and local control results for I prostate brachytherapy in men followed a minimum of 4 years.

MATERIALS AND METHODS

A total of 279 men with T1-T2 prostate cancer with a minimum followup of 4 years were implanted with I from 1990 to 1998 using the real-time technique. Patients were treated with the implant alone (215 or 72.5%) or with the implant and 6 months of hormone therapy (64 or 27.6%). Of the men 185 (66.3%) agreed to ultrasound guided biopsy (6 to 12 cores) a minimum of 2 years after implantation. All patients with increasing prostate specific antigen (PSA), evidence of local recurrence or a prior positive biopsy underwent repeat biopsy yearly until biopsy became negative or there was clear evidence of biochemical (PSA) progression. The radiation dose delivered to 90% of the gland (D90) was determined 30 days after implantation by computerized tomography based dosimetry. Biochemical failure was defined as 3 consecutive PSA increases. Survival curves were calculated by the Kaplan-Meier method. Cross tabulations were tested by Pearson chi-square analysis. The effect of multiple variables was tested by the log rank test (Cox regression).

RESULTS

Median patient age was 67 years (range 42 to 82) and median followup was 6 years (range 4 to 12). Of the patients 49 (17.6%) experienced failure, for a 10-year freedom from failure (FFF) rate of 78%. Univariate analysis for 10-year FFF demonstrated that initial PSA (p = 0.001), stage (p = 0.002), risk group (p <0.001), hormone therapy (p = 0.013) and D90 (p <0.001) were significant. Multivariate analysis demonstrated that D90 (p <0.001) and risk group (p = 0.013) were the only significant variables. The RR of PSA failure was 3.0 (95% CI 2.0 to 4.4, p <0.001) and 5.6 (95% CI 3.1 to 10, p <0.001) for doses below 140 and 120 Gy, respectively. Of the 185 patients 166 (90%) had a negative post-implantation prostate biopsy. FFF was 85% vs 21% in those with a positive biopsy (p <0.001). Patients with a D90 of at least 140 Gy had a positive biopsy rate of 4.8% compared to 20.5% in those with a lower dose (p <0.001). The RR for positive biopsy at doses less than 140 and 120 Gy was 2.6 (95% CI 1.6 to 4.4, p = 0.002) and 4.3 (95% CI 2.3 to 8.1, p <0.001), respectively.

CONCLUSIONS

These data demonstrate high biochemical and local control in men with T1-T2 prostate cancer treated with I brachytherapy. The delivered radiation dose and risk category are important predictors of success. Patients receiving a dose of at least 140 Gy have a 90% chance of biochemical FFF and a 95.2% likelihood of local control.

A technical evaluation of the Nucletron FIRST system: conformance of a remote afterloading brachytherapy seed implantation system to manufacturer specifications and AAPM Task Group report recommendations

The Fully Integrated Real‐time Seed Treatment (FIRST™) system by Nucletron has been available in Europe since November 2001 and is being used more and more in Canada and the United States. Like the conventional transrectal ultrasound implant procedure, the FIRST system utilizes an ultrasound probe, needles, and brachytherapy seeds. However, this system is unique in that it (1) utilizes a low‐dose‐rate brachytherapy seed remote afterloader (the seedSelectron), (2) utilizes 3D image reconstruction acquired from electromechanically controlled, nonstepping rotation of the ultrasound probe, (3) integrates the control of a remote afterloader with electromechanical control of the ultrasound probe for integrating the clinical procedure into a single system, and (4) automates the transfer of planning information and seed delivery to improve quality assurance and radiation safety. This automated delivery system is specifically intended to address reproducibility and accuracy of seed positioning during implantation. The FIRST computer system includes two software environments: SPOT PRO™ and seedSelectron™; both are used to facilitate treatment planning and brachytherapy seed implantation from beginning to completion of the entire procedure. In addition to these features, the system is reported to meet certain product specifications for seed delivery positioning accuracy and reproducibility, seed calibration accuracy and reliability, and brachytherapy dosimetry calculations. Consequently, a technical evaluation of the FIRST system was performed to determine adherence to manufacturer specifications and to the American Association of Physicists in Medicine (AAPM) Task Group Reports 43, 53, 56, 59, and 64 and recommendations of the American Brachytherapy Society (ABS). The United States Nuclear Regulatory Commission (NRC) has recently added Licensing Guidance for the seedSelectron system under 10 CFR 35.1000. Adherence to licensing guidance is made by referencing applicable AAPM Task Group recommendations. In general, results of this evaluation indicated that the system met its claimed specifications as well as the applicable recommendations outlined in the AAPM and ABS reports.

PACS number(s): 87.53.Xd, 87.53.Jw

Does prior transurethral resection of prostate compromise brachytherapy quality: A dosimetric analysis

PURPOSE

To evaluate, in a retrospective review, prostate brachytherapy dosimetry outcomes relative to the transurethral resection of the prostate (TURP) cavity size to address the theoretical concern that an intraprostatic cavity may hinder adequate radioactive source placement.

METHODS AND MATERIALS

A total of 73 patients who underwent prostate brachytherapy as part of their treatment of localized prostate cancer had a history of a prior TURP. Of these 73 patients, 37 underwent (125)I implantation, 19 (103)Pd implantation, and 17 partial (103)Pd implantation. The dose was calculated using the dose to 90% of the prostate gland (D(90)) from the 1-month post-implant dosimetric analysis. The doses were normalized relative to 100% of the prescription dose. Archived transrectal ultrasound images were used to determine the maximal length and width of the visible residual TURP cavities. The prolate spheroid or symmetric egg shape was used to calculate each residual cavity volume. The derived volume of the TURP cavity was divided by the measured ultrasound volume of the prostate at brachytherapy, creating a percentage of volume measurement for each prostate. All p values, unless otherwise specified, were generated by comparing patients without a visible TURP defect with the subgroups of patients with a visible defect using the Student t test.

RESULTS

A visible residual TURP defect was noted on the operative transrectal ultrasound images of 55 (75%) of the 73 patients with a history of TURP before brachytherapy. The 18 patients without a visible TURP defect had a median D(90) of 96% and were used for subsequent statistical comparison. Thirty-six patients with a TURP defect <10% of the entire prostate volume had a median D(90) of 109% (p = 0.02). Thirteen patients with a TURP defect between 10% and 20% of the prostate volume had a median D(90) of 112% (p = 0.03). Six patients with a TURP defect >20% of the prostate volume had a D(90) of 89% (p = 0.43).

CONCLUSION

A visible residual TURP cavity that is assumed to have a prolate spheroid shape and occupy >/=10% of a prostate volume did not appear to be a statistically significant hindrance to proper dosimetric outcome.

The impact of technological advances on the evolution of 3D conformal brachytherapy for early prostate cancer

Permanent implantation of I-125 and Pd-103 seeds is one of the widely used treatment options for the early stage prostate cancer with minimum normal tissue complications and long-term local control of the tumor. This is possible because of several technological advances made in the past decade to better understand the procedural aspects of implantations with the desired clinical outcome and with acceptable morbidities. In addition, with the widespread use of PSA testing, more widely disseminated information about prostate cancer and increased patient awareness, over 70% of patients are diagnosed early with localized disease and therefore are candidates for definitive local therapy. Delineation of soft tissue structures including the prostate, rectum, urethra and bladder has become more accurate with the use of imaging modalities including Ultrasound and MRI, with or without the CT. A re-evaluation of the dosimetric parameters of the radioactive sources has lead to a more precise estimate of the dose delivered to the prostate and the associated critical normal structures. Technological improvements in the post implant dosimetry have helped to understand the factors, which makes an implant a "good implant" or a "poor implant". Intraoperative treatment planning with on line dosimetry is emerging as one of the best approaches for prostate brachytherapy. In addition, better software is now available producing dose-volume histograms with 3D target and normal tissue reconstruction. The combination of seed implant followed by IMRT would provide scope for differentially boosting the regions under-dosed because of uncontrollable and unexpected reasons during the implant and unsuspected micro extensions of the tumor.

What is the optimal dose for 125I prostate implants? A dose-response analysis of biochemical control, posttreatment prostate biopsies, and long-term urinary symptoms

PURPOSE

To define the optimal dose for 125I prostate implants by correlating post implant CT dosimetry findings with urinary symptoms, biochemical failure, and posttreatment biopsies.

METHODS AND MATERIALS

Patients with T1-T2, Gleason score 2-6 prostate cancer treated with I-125 brachytherapy were analyzed. Group 1 (276 patients) was observed from 18 to 108 months (median, 34 months) and had urinary symptoms prospectively assessed using the International Prostate Symptom Score (IPSS) system. Group 2 (181 patients) observed from 24 to 108 months (median, 44 months) and did not receive hormonal therapy. Implant dose was defined as the D90 (dose delivered to 90% of the prostate on a dose-volume histogram). Patients were analyzed by dose categories: <140 Gy, 140 to <160 Gy, 160 to <180 Gy, and > or =180 Gy. In Group 1, the mean pre- to postimplant IPSS scores were compared in different dose categories by using a matched paired t test. In Group 2, the effect of dose on biochemical control was tested with actuarial methods by using the American Society for Therapeutic Radiology and Oncology definition and on local control with posttreatment biopsies (113 patients).

RESULTS

A comparison of pre- with postimplant IPSS revealed no significant changes in scores in the dose groups <180 Gy except for small changes in urgency and bladder emptying in the dose group <140 Gy. In dose group >180 Gy, mean scores changed from 0.5 to 1.0 (p=0.002) for emptying, 0.76 to 1.29 (p=0.004) for weak stream, 0.24 to 0.51 (p=0.009) for straining, 1.55 to 1.82 (p=0.05) for nocturia, and 6.3 to 8.45 (p=0.0009) for the total score. Freedom from biochemical failure (FFBF) at 5 years was 68% for doses <140 Gy, 97% for 140 to <160 Gy, 98% for 160 to <180 Gy, and 95% for > or =180 Gy (p=0.0025). Overall, patients with doses <140 Gy (median follow-up, 66 months) had an FFBF of 68%, compared with 96% for patients with doses > or =140 Gy (median follow-up, 35 months; p=0.0002). Multivariate analysis found dose to be the most significant factor affecting FFBF. Positive biopsies were found in 23% for doses <140 Gy, 21% for 140 to <160 Gy, 10% for 160 to <180 Gy, and 8% for > or =180 Gy. Overall, biopsies were positive in 22% for doses <160 Gy vs. 9% for > or =160 Gy (p=0.05).

CONCLUSIONS

Optimal 125I prostate implants should deliver a D90 of 140-180 Gy, on the basis of postimplant dosimetry. Doses of <140 Gy are associated with increased biochemical failure, and doses >180 Gy with a small increase in long-term urinary symptoms.

Biochemical outcomes after prostate brachytherapy with 5-year minimal follow-up: Importance of patient selection and implant quality

PURPOSE

A prostate brachytherapy program was initiated in 1990, when comparatively little was known of the relative importance of disease- and treatment-related factors on outcome. Patients treated during the first 6 years of the program were analyzed to determine the value of patient selection and implant quality on biochemical control.

METHODS AND MATERIALS

We treated 243 patients with clinically localized prostate cancer with radioactive seed implantation and underwent 1-month CT-based dosimetric analysis. Follow-up ranged from 61 to 135 months (median 75). The Gleason score was < or =6 in 78% (n = 189), 7 in 14% (n = 35), and 8-10 in 8% (n = 19). The initial prostate-specific antigen (PSA) level was < or =10 ng/mL in 61% (n = 149), 10.1-20 ng/mL in 26% (n = 63), and >20 ng/mL in 13% (n = 31). The disease stage was T2a or less in 49% (n = 120), and Stage T2b-T2c in 51% (n = 123). A real-time ultrasound-guided technique was used with (125)I (n = 138) and (103)Pd (n = 105) isotopes. No patient underwent external beam radiotherapy as part of their primary treatment. Of the 243 patients, 60% also received hormonal ablation for at least 3 months before and 2-3 months after seed implantation. All patients included underwent a 1-month CT-based dosimetric analysis. The implant dose was defined as the dose delivered to 90% of the prostate volume on postimplant dosimetry (D(90)). On the basis of prior dose-response analyses, patients were retrospectively grouped into optimal D(90) ((125)I > or =140 Gy Task Group 43 or (103)Pd >/=100 Gy) and suboptimal D(90) ( (125)I <140 Gy or (103)Pd <100 Gy) dose groups. Biochemical failure was defined using the American Society for Therapeutic Radiology Oncology definition.

RESULTS

Disease-related factors, including initial PSA level, Gleason score, and stage, were significant predictors of biochemical failure. The actuarial 8-year freedom from biochemical failure (bFFF) rate was 80% for those with a PSA level < or =10 ng/mL, 86% for PSA 10.1-20 ng/mL, and 45% for PSA >20 ng/mL (p = 0.0019). Patients with a Gleason score of < or =6 had an 8-year bFFF rate of 81% vs. 67% for those with Gleason score 7 and 53% for those with Gleason score 8-10 (p = 0.0003). Patients with Stage T2a or less had an 8-year bFFF rate of 85% compared with 69% for those with Stage T2b-T2c (p = 0.013). The 8-year bFFF rate was 88% for low-risk patients (Stage T2a or less, Gleason score < or =6, and initial PSA level < or =10 ng/mL; n = 75), 81% for moderate-risk patients (Stage T2b or Gleason score 7 or initial PSA level >10.1-20 ng/mL; n = 70), and 65% for high-risk patients (two or more moderate-risk features or Gleason score > or =8 or initial PSA level >20 ng/mL; n = 98; p = 0.0009). Patients with optimal dose implants (n = 145) had an 8-year bFFF rate of 82% compared with 68% for those with suboptimal dose implants (n = 98; p = 0.007). Hormonal therapy did not significantly affect biochemical failure (p = 0.27). In multivariate analysis, the statistically significant variables included initial PSA level (p <0.0001), Gleason score (p = 0.024), and dose group (p = 0.046). Because our current practice limits implantation alone to low-risk patients, an analysis of this subgroup was undertaken to validate the importance of dose. In the optimal dose group, low-risk patients had an 8-year bFFF rate of 94% vs. 75% for the low-risk patients in the suboptimal dose group (p = 0.02).

CONCLUSION

With minimal follow-up of 5 years, these data continue to support the use of implantation alone in low-risk prostate cancer patients and demonstrate the importance of implant quality (dose) in achieving optimal outcomes. Low-risk patients who receive an optimal dose implant have a 94% bFFF rate at 8 years.

Comparison between two iodine-125 brachytherapy implant techniques: pre-planning and intra-operative by various dosimetry quality indicators

PURPOSE

To prospectively compare two widely used seed implant techniques: pre-planning and intra-operative planning, based on 1 month post-implant CT-based evaluation.

METHODS

We report results of a detailed 1 month post-operative dosimetric evaluation and comparison between 142 consecutive men with prostate adenocarcinoma treated by the pre-planning methodology and 214 men treated with the real-time, intra-operative seed implant method.

RESULTS

Baseline parameters patient's age, Gleason score, clinical stage, and gland volume were similar in both groups (p>0.05). Length of physicist time and operating room team time were more than double in the pre-planned group compared to the intra-operative one (205 vs 100 min). Based on day 30 post-implant CT, for patients treated with the pre-planning method, mean V90, V100 and V150 (percent prostate volume receiving 90, 100 and 150% of the prescribed dose) were 67.5, 58.35 and 21.5%, respectively, while for the intra-operative group they were 97.9, 95.2 and 45%, respectively (p<0.01). Mean D90, expressed as percent of target matched peripheral dose (minimal dose covering 90% of the gland volume) was 53% for the pre-planned group and 114% for the intra-operative group of men (p<0.01). Short-term morbidity was minimal in both groups and did not correlate with the technique employed.

CONCLUSIONS

This large-scale comparison of implant adequacy favours real-time intra-operative method. While all dosimetric parameters are significantly better with this method, no increased early morbidity was noted. Longer-term PSA-based clinical outcome should substantiate our contention of the superiority of the intra-operative method when compared to the pre-planning one.

Is intraoperative nomogram-based overplanning of prostate implants necessary?

PURPOSE

Several investigators have described intraoperative planning of prostate implants based on a nomogram. The aim of this work was to investigate the adequacy of the nomogram in predicting the total activity necessary for optimal dosimetry.

METHODS AND MATERIALS

Eighty CT-based postimplant treatment plans were performed for patients who underwent ultrasound guided I-125 permanent implants alone between April 2000 and March 2001. The cohort of 40 patients had early stage (T1-T2) prostatic carcinoma and pre-treatment prostate volumes of 19-50 cc. I-125 seeds (0.391 mCi/seed) were implanted to achieve a distribution of 75% of the activity peripherally and 25% centrally. The CT studies were obtained on the day of (CT1) and at 1 month (CT2) after implant. All patients were catheterized at CT1, and 28 patients were catheterized at CT2 to visualize the urethra. For each patient, the percentage difference (dA) between the total implanted and nomogram predicted activity for a known prostate volume was calculated. The V200 (volume receiving 200% of the prescribed dose), V150, V100, V90, D100 (maximum dose received by 100% of the volume), D90, and D80 were measured for the prostate at CT1 and CT2. For the urethra, V275, V250, V200, and V150 were evaluated, and V100 and V70 were evaluated for the rectum. The Pearson test was used to correlate the dosimetric parameters with dA. Linear regression was used to fit the correlation of the volume and dose parameters with dA.

RESULTS

The median V100 at CT1 and CT2 was 91.8% and 94.2%, respectively. The Pearson test was significant for the prostate V100 and dA measured at CT1 (p = 0.005) but not at CT2 (p = 0.106). A similar correlation was found for the prostate D90 at CT1 (p = 0.002), but not at CT2 (p = 0.076). D100 (maximum dose received by 100% of volume) for prostate did not correlate with dA at CT1 (p = 0.094) and CT2 (p = 0.148). The volume of the prostate receiving higher doses (greater than 150% and 200% of the prescribed dose) correlated with dA. There were no significant correlations between V275, V250, V200, and V150 at CT1 and CT2 as a function of dA for the urethra. V100 and V70 for the rectum correlated significantly with dA; for V100, p = 0.041 at CT1 and p = 0.014 at CT2 and for V70, p = 0.041 at CT1 and p = 0.026 at CT2. A linear regression model fitted to the prostate data obtained from CT1 with the goal of achieving a V100 of 90% and D90 of 145 Gy suggests that no increase in the number of seeds may be warranted using intraoperative planning. The implants examined showed no concomitant increase of urethral doses with increase in activity relative to the nomogram, but showed an increase in the rectal doses for the same increase in activity.

CONCLUSION

The doses evaluated at CT1 represent an underestimate, whereas those obtained at CT2 represent an overestimate of the actual delivered protracted permanent implant dose. Based on these results and consideration of the dynamic nature of the dose distribution, target coverage obtained with intraoperative planning using the nomogram predicted activity is consistent with published guidelines for a quality implant and critical structure doses are within tolerance.

Prostate-specific antigen bounce after prostate seed implantation for localized prostate cancer: descriptions and implications

PURPOSE

To calculate the actuarial risk of developing a prostate-specific antigen (PSA) bounce after prostate brachytherapy alone, using three definitions of bounce mentioned in the literature, and to explore the relationship between disease and treatment variables and the risk of developing a bounce. The impact of PSA bounce on PSA failure was also explored.

METHODS AND MATERIALS

A total of 373 patients with T1-T2 prostate cancer underwent radioactive seed implant using 125I (n = 337) or 103Pd (n = 36) without hormonal therapy or external beam RT. All patients had a minimum of 1 year (median 4, maximum 11) of follow-up and at least three follow-up PSA values. PSA bounce was defined by a rise of one or two PSA values with a subsequent fall. Three definitions of bounce were used: definition 1, rise > or = 0.1 ng/mL; definition 2, rise > or = 0.4 ng/mL; and definition 3, rise >35% of previous value.

RESULTS

The actuarial likelihood of experiencing a PSA bounce at 5 years was 31% for definition 1, 17% for definition 2, and 20% for definition 3. The median time to develop a bounce was 19.5 months for definitions 1 and 2 and 20.5 months for definition 3. Gleason score, initial PSA level, and clinical stage did not predict for bounce using any definition. Using definition 1, younger patients (< or = 65 years) had a bounce rate at 5 years of 38% vs. 24% for older patients (p = 0.009). 125I patients receiving an implant dose of < or = 160 Gy had a bounce rate (definition 1) at 5 years of 24% vs. 38% for those receiving a dose delivered to 90% of the gland on the 1 month postimplant dose-volume histogram (D90) >160 Gy (p = 0.04). Using definition 2, prostate volume significantly affected the incidence of bounce. Patients with larger glands (>35 cm(3)) were more likely to experience a bounce (23% at 5 years) than those with smaller glands (< or = 35 cm(3)) who had a bounce rate of 11% at 5 years (p = 0.01). In a multivariate analysis of factors predicting for PSA failure, PSA bounce was not found to be significant.

CONCLUSION

PSA bounce is a common phenomenon after prostate brachytherapy and occurs at a rate of 17-31%, depending on the definition used. It is more common in younger patients, those receiving higher implant doses, and those with larger glands. PSA bounce does not predict for future PSA failure.

Practical considerations in permanent brachytherapy for localized adenocarcinoma of the prostate

Prostate brachytherapy has become an accepted treatment modality for localized prostate cancer. Long-term biochemical and biopsy data confirm the early positive impressions that brachytherapy is as valid a treatment option as radical prostatectomy or EBRT. Quality-of-life data also look promising, but more follow-up data are needed. Is brachytherapy as good as or perhaps better than radical prostatectomy? This question cannot be answered yet. Well-controlled, randomized studies are needed. In the meantime, the clinician will have to rely on the available published data.

[Iodine-125 transperineal prostate brachytherapy with preplanning technique: pre and post-implant dosimetry results analysis]

PURPOSE

Post-implant CT-based dosimetry is the only method of assessing the quality of permanent prostate brachytherapy. As a consequence of our permanent feedback with the preplanned technique, geometric and dosimetric criteria for optimal seed implantation are proposed and pre and post-implantation dosimetric results are presented.

PATIENTS AND METHODS

In 2000 and 2001, one hundred and twenty patients with early stage prostate cancer were treated with transperineal I-125 preplanned brachytherapy (RAPID Strand, Amersham Health). The prescription dose was 145 Gy to the planning target volume. For the pre-planning and post-implant dosimetry the Variseed 6.7 version software was used (Varian Medical Systems). The D90, V100 and V150 values, the position of the dose peak [Dose] peak) and the full width at half maximum (FWHM) on differential dose volume histogram from both planned and post-implant dosimetry were compared for all patients.

RESULTS

For preplanned dosimetry, the mean values for D90, V100, V150, [Dose] peak, FWMH were respectively of 199Gy, 100%, 70%, 220Gy, 113Gy. For post-implantation, these values became respectively of 157Gy, 90%, 62%, 220Gy, 194Gy.

CONCLUSION

In our practice, differences are noted between preplanned and post-implant dosimetry parameters that should be anticipated to assure optimal definitive result. A working methodology both for performing the preplanned dosimetry and for evaluating the post-implantation dosimetric results is proposed.

Prospective assessment of patient-reported long-term urinary morbidity and associated quality of life changes after 125I prostate brachytherapy

PURPOSE

Prostate brachytherapy has been reported to have less morbidity for patients than radical prostatectomy or external beam irradiation. However, to date there have been no long-term data to support these claims. With radiation doses in excess of 140 Gy required to control the tumor, disabling chronic urinary symptoms and associated quality of life (QOL) changes might be expected to occur. This study prospectively assessed the long-term effects of (125)I prostate brachytherapy on urinary morbidity.

METHODS AND MATERIALS

A total of 248 patients with a median age of 67 years (range, 43-83 years) who presented with T1-T2 prostate cancer were treated with (125)I seed implantation and followed up for a minimum of 18 months after treatment (range, 18 to 108 months; median, 31 months). There were 177 T1b-T2a cases and 41 patients with prostate-specific antigen >10 ng/ml; 20.2% were treated with hormonal therapy. All patients prospectively reported their urinary symptoms and QOL assessment on American Urological Association symptom score records before treatment and at each follow-up visit. Urinary symptoms at last follow-up were compared with pretreatment scores. Radiation doses to the prostate (dose delivered to 90% of the gland; D(90)) and urethra (D(30)) were determined by CT-based dosimetry.

RESULTS

The median prostate D(90) was 165 Gy (range, 16.5-260 Gy), and the median urethra D(30) was 192 Gy (range, 23.5-306 Gy). Mean individual scores and QOL ranged from 0.31 to 1.65 before implantation and 0.39 to 1.73 afterward. There were no significant differences between pretreatment and last mean scores for any of the categories except for a small but significant increase in urgency (p=0.01) and weak stream (p=0.03). The cohort of patients who initially presented with marked urinary symptoms (initial score >or=3) had improvement in individual scores by 31.4% to 58.2%, total score by 31.1% (p=0.0005), and QOL by 40.6% (p<0.0001).

CONCLUSIONS

This study suggests that prostate brachytherapy is associated with minimal long-term urinary morbidity. The subgroup of patients who present with marked urinary symptoms before implantation has improvement in symptoms and QOL after implantation. These data substantiate the favorable long-term QOL outcomes associated with modern brachytherapy techniques.

Comparison of intraoperative dosimetric implant representation with postimplant dosimetry in patients receiving prostate brachytherapy

PURPOSE

To compare the results of intraoperative dosimetry with those of CT-based postimplant dosimetry in patients undergoing prostate seed implantation.

METHODS AND MATERIALS

Seventy-seven patients with T1-T3 prostate cancer received an ultrasound-guided permanent seed implant (36 received (125)I, 7 (103)Pd, and 34 a partial (103)Pd implant plus external beam radiation therapy). The implantation was augmented with an intraoperative dosimetric planning system. After the peripheral needles were placed, 5-mm axial images were acquired into the treatment planning system. Soft tissue structures (prostate, urethra, and rectum) were contoured, and exact needle positions were registered. Seeds were placed with an applicator, and their positions were entered into the planning system. The dose distributions for the implant were calculated after interior needle and seed placement. Postimplant dosimetry was performed 1 month later on the basis of CT imaging. Prostate and urethral doses were compared, by using paired t tests, for the real-time dosimetry in the operating room (OR) and the postimplant dosimetry.

RESULTS

The mean preimplant prostate volume was 39.8 cm(3), the postneedle planning volume was 41.5 cm(3) (p<0.001), and the 1-month CT volume was 43.6 cm(3) (p<0.001). The mean difference between the OR dose received by 90% of the prostate (D(90)) and the CT D(90) was 3.4% (95% confidence interval, 2.5-6.6%; p=0.034). The mean dose to 30% of the urethra was 120% of prescription in the OR and 138% on CT. The mean difference was 18% (95% confidence interval, 13-24%; p<0.001).

CONCLUSIONS

Although small differences exist between the OR and CT dosimetry results, these data suggest that this intraoperative implant dosimetric representation system provides a close match to the actual delivered doses. These data support the use of this system to modify the implant during surgery to achieve more consistent dosimetry results.

Permanent seed implantation for localized adenocarcinoma of the prostate

Prostate brachytherapy has become a popular treatment option for localized prostate cancer with over 44,000 procedures performed in 2000. Eighty-seven percent to 93% of patients who have a serum prostate-specific antigen less than 10 ng/mL, Gleason score of 6 or less, and low risk (disease stage < or = T2a) can be expected to have an 8 to 10 year disease-free rate. The radiation dose delivered by the implants should exceed 140 Gy in men implanted with I-125 monotherapy. Patients with intermediate- and high-risk prostate cancer would benefit from the addition of either hormonal therapy and/or external beam irradiation to the implantation of seeds. Postimplant incontinence and proctitis can be minimized by controlling high radiation doses to the urethra and rectum. Potency is preserved in 70% of men with good preimplantation erectile function. Advances in technology, such as intraoperative dosimetry, will continue to make brachytherapy an attractive treatment option for men with localized prostate cancer.

The role of endorectal coil MRI in patient selection and treatment planning for prostate seed implants

PURPOSE

To assess the role of endorectal coil magnetic resonance imaging (MRI) staging for patients undergoing seed implantation (SI) with or without external beam radiotherapy (EBRT).

MATERIALS AND METHODS

Between October 1994 and December 1998, 390 patients underwent prostate SI (98% Pd-103, 2% I-125). Seventy-six percent of patients had a prostate serum antigen (PSA) < 10, 17% had PSA of 10-20, and 7% of patients had PSA of > 20. Ten percent of patients had a Gleason score (GS) of 4-5, 54% had GS 6, 29% had GS 7, and 7% had GS >/= 8. Monotherapy was employed in 46% of patients, and the remaining 54% received combined EBRT and SI. Three hundred twenty-seven were staged by high-resolution phased array pelvic coil, or in most cases, an endorectal coil MRI. The MRI findings were used to guide stage-appropriate treatment recommendations, and to assist in the preplanning and optimization of seed distributions. The criteria utilized to determine MRI-based stage were founded on the reported literature from the University of Pennsylvania. All MRI studies were reviewed by C.A., D.B., or W.H., who were unaware of clinical stage at the time of their review. The biopsy report was available to them as the only clinical correlate.

RESULTS

Of the 327 patients staged by MRI, 70% were upstaged from the digital rectal examination-based clinical stage; 26% of T(1), T(2) patients were upstaged to T(3). Perineural invasion and the percentage of positive cores predicted for T(3) MRI stage (p < 0.0001 for both variables). MRI findings changed the overall treatment recommendation in 60/327 (18%) patients. The majority of these patients were advised to receive combined therapy instead of monotherapy after the MRI documented more extensive disease. The seed distribution was modified in 183/327 (56%) patients, mostly related to preplanned extracapsular coverage of bulky or extraprostatic disease seen on MRI. With a mean follow-up of 38 months (range 3-72), PSA freedom from progression (FFP) was 94% at 5 years. Cox regression analysis showed that only the percentage of positive cores (p = 0.001) and failure to have MRI staging (p = 0.0008) predicted for failure. Pretreatment PSA level, Gleason score, perineural invasion, and external beam radiotherapy did not significantly predict for PSA failure. We compared our MRI T(3) intermediate-risk group patients treated by combined therapy with a previous study of T(3) intermediate-risk group treated by radical prostatectomy (RP) at the University of Pennsylvania. Our 36-month PSA FFP was 94% compared with 21% for the previous study's RP patients.

CONCLUSION

MRI is a valuable staging procedure for prostate cancer patients treated by SI. PSA FFP results appear to be improved by MRI staging. MRI T(3) disease can be treated more effectively by SI + EBRT than by RP.

[Prostatic brachytherapy indications and technique]

Prostate cancer is an important health problem, mainly in elderly men. It is the second cause of death among men in USA ant the third at the "Registro del Cáncer de Tarragona", behind both the lung and colorectal cancer. About the 58% of the newly diagnosed cancers are localized, therefore, they have to be treated with curative intention. Radical prostatectomy is considered the gold standard treatment for organ confined prostate cancer in our country. On basis to the experience of American groups and the improvement of both, image techniques and dosimetric calculation, brachytherapy has been brought in as a new option in the treatment of localized prostate cancer. We started our program of brachytherapy for prostate cancer on May 2000. We have performed 51 procedures by now. Our protocol and the technique to perform a prostatic brachytherapy are described following.

Intraoperative planning and evaluation of permanent prostate brachytherapy: report of the American Brachytherapy Society

PURPOSE

The preplanned technique used for permanent prostate brachytherapy has limitations that may be overcome by intraoperative planning. The goal of the American Brachytherapy Society (ABS) project was to assess the current intraoperative planning process and explore the potential for improvement in intraoperative treatment planning (ITP).

METHODS AND MATERIALS

Members of the ABS with expertise in ITP performed a literature review, reviewed their clinical experience with ITP, and explored the potential for improving the technique.

RESULTS

The ABS proposes the following terminology in regard to prostate planning process: *Preplanning--Creation of a plan a few days or weeks before the implant procedure. *Intraoperative planning--Treatment planning in the operating room (OR): the patient and transrectal ultrasound probe are not moved between the volume study and the seed insertion procedure. * Intraoperative preplanning--Creation of a plan in the OR just before the implant procedure, with immediate execution of the plan. *Interactive planning--Stepwise refinement of the treatment plan using computerized dose calculations derived from image-based needle position feedback. *Dynamic dose calculation--Constant updating of dose distribution calculations using continuous deposited seed position feedback. Both intraoperative preplanning and interactive planning are currently feasible and commercially available and may help to overcome many of the limitations of the preplanning technique. Dosimetric feedback based on imaged needle positions can be used to modify the ITP. However, the dynamic changes in prostate size and shape and in seed position that occur during the implant are not yet quantifiable with current technology, and ITP does not obviate the need for postimplant dosimetric analysis. The major current limitation of ITP is the inability to localize the seeds in relation to the prostate. Dynamic dose calculation can become a reality once these issues are solved. Future advances can be expected in methods of enhancing seed identification, in imaging techniques, and in the development of better source delivery systems. Additionally, ITP should be correlated with outcome studies, using dosimetric, toxicity, and efficacy endpoints.

CONCLUSION

ITP addresses many of the limitations of current permanent prostate brachytherapy and has some advantages over the preplanned technique. Further technologic advancement will be needed to achieve dynamic real-time calculation of dose distribution from implanted sources, with constant updating to allow modification of subsequent seed placement and consistent, ideal dose distribution within the target volume.

Dosimetric comparison of pre-planned and or-planned prostate seed brachytherapy

PURPOSE

To compare the dosimetry of the traditional two step procedure (volume study + treatment planning several weeks later) with that of an OR-based single procedure in which these two steps follow one another immediately. Computer generated treatment plans were used in both procedures.

METHODS AND MATERIALS

Several dosimetric parameters relating to target coverage were obtained from dose volume histograms of CT-based evaluation plans developed either 1 or 3 days following seed implantation. A total of 113 patients with early stage (T1C, T2A) prostate cancer were used for this retrospective study.

RESULTS

The fraction of target (prostate) covered by the prescription dose (144 Gy), 90% of the prescription dose (115 Gy), and the dose encompassing 90% of the target in the evaluation plan were all statistically significantly improved for OR-based plans compared to pre-planned cases.

CONCLUSION

In our hands, there is a small but significant improvement in dose coverage of the prostate when the ultrasound volume study and treatment planning are combined into a single procedure.

Postimplant dosimetry for (125)I prostate implants: definitions and factors affecting outcome

OBJECTIVE

An analysis of CT-based dosimetry was performed to assess the efficacy of the real time method of prostate implantation, explore the relationship of various dose descriptions and determine implant factors affecting outcome.

METHODS AND MATERIALS

Between 7/95 and 8/99, 297 patients underwent (125)I implants for T1-T2 prostate cancer and had CT-based dosimetry performed (TG43 formalism). Dosimetry was performed 1 month postimplant. Using a dose-volume histogram, doses delivered to 100%, 95%, 90%, and 80% of the prostate (D100, D95, D90, D80, respectively) as well as percentages of the gland receiving 240 Gy, 160 Gy, 140 Gy (V240, V160, V140, respectively) were reported. Correlations between the various dose parameters and D90 were generated. The effect of the number of seeds implanted, seeds/volume, prostate volume, experience as assessed by time (8/01/99-date of implant), ultrasound probe (mechanical sector vs. dual phased electronic), and the ratio of the CT dosimetry prostate volume/ultrasound implant volume (CT/US vol) were analyzed.

RESULTS

The median D100, D95, D90, and D80 values were 10,200 cGy, 15,655 cGy, 17,578 cGy, and 19,873 cGy, respectively. The median V240, V160, and V140 were 56%, 94%, and 98%, respectively. Correlations of dose descriptions found a close relationship of D95, D80, V240, V160, and V140 with D90 with r values of 0.928, 0.973, 0.911, 0.816, and 0.733, respectively. D100 correlated poorly with D90 (r = 0.099). Using a stepwise regression analysis, CT/US vol ratio, prostate volume, and seed number were the only significant factors affecting D90 with CT/US vol ratio having the greatest effect. The dual-phased electronic probe was associated with fewer D90 values of less than 140 Gy (2%) compared to the mechanical sector probe (14%) (p = 0.02).

CONCLUSION

CT-based dosimetry results reveal the real-time implant technique to be an effective method of prostate implantation. Factors associated with more precise implantation, such as decreased postimplant edema, new technology, and increased number of seeds will lead to higher D90 values.

A new power law for determination of total (125)I seed activity for ultrasound-guided prostate implants: clinical evaluations

PURPOSE

The intraoperative planning with peripheral loading approach is an important technique for ultrasound-guided transperineal prostate implant. In this paper a sphero-cylindrical dose model is described to generate a new power law or a look-up table for determination of the total (125)I activity required to deliver a prescription dose to a given prostate volume.

METHODS AND MATERIALS

Dose calculations were based on the new standards for (125)I seeds (model 6711) implemented by the National Institute of Standards and Technology (NIST) in 1999. Using the sphero-cylindrical dose model with peripheral loading approach, a new power law for calculating total activity of radioactive iodine required to deliver a prescribed dose for the target volume was developed. Accounting for random variation of the seed positioning in the prostate and the current air-kerma strength standard of (125)I seeds, this new power law is formulated as follows: A (mCi) = 2.15 d (cm)(2.00) where A is apparent activity in mCi, or A (U) = 1. 69 d (cm)(2.00) where A is air-kerma strength in U, required to deliver a cumulative dose of 145 Gy to a prostate gland with an average dimension, d, in centimeters.

RESULTS

The efficacy of using the new power law in prostate implants was demonstrated. For clinical evaluations of this new power law, 40 patients were chosen in 1998. The average D(90) of these 40 patients was 172.0 Gy (SD +/- 29 Gy). This means that on the average, 90% of the target volume received was 172.0 Gy. The average coverage index (CI) in this study was 94.7 (SD +/- 4.7). As a result, 94.7% of the target volume received the prescription dose. The dose homogeneity index (HI) which measured the degree of the dose inhomogeneity was 0.38 (SD +/- 0.21).

CONCLUSION

This new and simple power law or a new mCi-volume look-up table for (125)I seed prostate implantation has been developed and formulated for clinical use. Clinical evaluations expressed in quantitative parameters such as D(90), CI, and HI in prostate implants have been thoroughly analyzed and clearly demonstrated the efficacy of this approach.

Prostate brachytherapy in patients with prostate volumes >/= 50 cm(3): dosimetic analysis of implant quality

OBJECTIVES

Permanent implantation with (125)I in patients with localized prostate cancer who have prostate volumes >/= 50 cm(3) is often technically difficult owing to pubic arch interference. The objective of this study was to describe dosimetry outcomes in a group of patients who were implanted using the real-time ultrasound-guided technique who had prostate volumes >/= 50 cm(3).

MATERIALS AND METHODS

A total of 331 patients received an (125)I prostate seed implant from January 1, 1995, to June 1, 1999, of whom 66 (20%) had prostate volumes >/= 50 cm(3) at the time of the procedure. The real-time seed implant method was used in all patients and consisted of intraoperative planning and real-time seed placement using a combination of axial and sagittal ultrasound imaging. Pubic arch interference was managed using an extended lithotomy position or by angling the tip of the ultrasound probe in an anterior direction. No preimplant pubic arch CT scan study was performed and no patients were excluded from treatment because of prostate size. Implant quality was assessed using CT-based dosimetry performed 1 month postimplant. Dose-volume histograms for the prostate, bladder, rectum, and urethra volumes were generated. The target dose for these implants was 160 Gy and an adequate implant was defined as the dose delivered to 90% of the prostate (D90) >/= 140 Gy. The dose delivered to 95% of the prostate (D95) and doses to 30% of the rectal (DRECT30) and urethral (DURE30) volumes were also calculated.

RESULTS

Prostate volumes in the 66 patients ranged from 50 to 93 cm(3) (median 57, mean 61 cm(3)). Total activity implanted was 27.8-89.1 mCi (median 57 mCi), with a range in activity per seed of 0.36-0.56 mCi (median 0.4 mCi). The prostate D90s and D95s ranged from 13,245 to 22,637 cGy (median 18,750) and 11,856 to 20,853 cGy (median 16,725), respectively. Only one patient (1.5%) had a D90 < 140 Gy. The DURE30 values ranged from 15,014 to 27,800 cGy (median 20,410) and the DRECT30 values were 3137-9910 cGy (median 5515).

CONCLUSION

Implantation of the large prostate can be accomplished using the real-time method. A total of 98.5% of the patients receive a high-quality implant. In addition, these implants should not put patients at increased risk for significant urinary and bowel complications because urethral and rectal doses can be kept at acceptable levels.

The American Brachytherapy Society recommendations for permanent prostate brachytherapy postimplant dosimetric analysis

PURPOSE

The purpose of this report is to establish guidelines for postimplant dosimetric analysis of permanent prostate brachytherapy.

METHODS

Members of the American Brachytherapy Society (ABS) with expertise in prostate dosimetry evaluation performed a literature review and supplemented with their clinical experience formulated guidelines for performing and analyzing postimplant dosimetry of permanent prostate brachytherapy.

RESULTS

The ABS recommends that postimplant dosimetry should be performed on all patients undergoing permanent prostate brachytherapy for optimal patient care. At present, computed tomography (CT)-based dosimetry is recommended, based on availability cost and the ability to image the prostate as well as the seeds. Additional plane radiographs should be obtained to verify the seed count. Until the ideal postoperative interval for CT scanning has been determined, each center should perform dosimetric evaluation of prostate implants at a consistent postoperative interval. This interval should be reported. Isodose displays should be obtained at 50%, 80%, 90%, 100%, 150%, and 200% of the prescription dose and displayed on multiple cross-sectional images of the prostate. A dose-volume histogram (DVH) of the prostate should be performed and the D90 (dose to 90% of the prostate gland) reported by all centers. Additionally, the D80, D100, the fractional V80, V90, V100, V150 and V200 (i.e., the percentage of prostate volume receiving 80%, 90%, 100%, 150%, and 200% of the prescribed dose, respectively), the rectal, and urethral doses should be reported and ultimately correlated with clinical outcome in the research environment. On-line real-time dosimetry, the effects of dose heterogeneity, and the effects of tissue heterogeneity need further investigation.

CONCLUSION

It is essential that postimplant dosimetry should be performed on all patients undergoing permanent prostate brachytherapy. Guidelines were established for the performance and analysis of such dosimetry.

Permanent prostate seed implant brachytherapy: report of the American Association of Physicists in Medicine Task Group No. 64

There is now considerable evidence to suggest that technical innovations, 3D image-based planning, template guidance, computerized dosimetry analysis and improved quality assurance practice have converged in synergy in modern prostate brachytherapy, which promise to lead to increased tumor control and decreased toxicity. A substantial part of the medical physicist's contribution to this multi-disciplinary modality has a direct impact on the factors that may singly or jointly determine the treatment outcome. It is therefore of paramount importance for the medical physics community to establish a uniform standard of practice for prostate brachytherapy physics, so that the therapeutic potential of the modality can be maximally and consistently realized in the wider healthcare community. A recent survey in the U.S. for prostate brachytherapy revealed alarming variance in the pattern of practice in physics and dosimetry, particularly in regard to dose calculation, seed assay and time/method of postimplant imaging. Because of the large number of start-up programs at this time, it is essential that the roles and responsibilities of the medical physicist be clearly defined, consistent with the pivotal nature of the clinical physics component in assuring the ultimate success of prostate brachytherapy. It was against this background that the Radiation Therapy Committee of the American Association of Physicists in Medicine formed Task Group No. 64, which was charged (1) to review the current techniques in prostate seed implant brachytherapy, (2) to summarize the present knowledge in treatment planning, dose specification and reporting, (3) to recommend practical guidelines for the clinical medical physicist, and (4) to identify issues for future investigation.

Does prostate brachytherapy treat the seminal vesicles? A dose-volume histogram analysis of seminal vesicles in patients undergoing combined PD-103 prostate implantation and external beam irradiation

PURPOSE

Combined brachytherapy of the prostate and external beam irradiation (EBRT) of the prostate and seminal vesicles (SV) is becoming a popular treatment for high-risk prostate cancer. Dose-volume histogram (DVH) analysis of the SV in patients undergoing this treatment was performed to determine the dose distribution to the SV and the adequacy of this treatment in patients with potential SV involvement.

METHODS AND MATERIALS

Twenty-five consecutive patients were treated with a Pd-103 implant of the prostate alone and 45 Gy of EBRT to the prostate and SV. Attempts were not made to implant the SV but seeds were routinely placed at the junction of the prostate and SV. All patients underwent CT-based postimplant dosimetric analysis 1 month after implantation. As part of this analysis, DVH were generated for the prostate and total SV volume (SVT). In addition, the SV was divided into 6-mm-thick volumes identified as SV1, SV2, SV3, SV4, and SV5 starting from the junction of the prostate and SV and extending distally. DVH were also generated for these structures. Delivered dose was defined as the D90 (dose delivered to 90% of the organ on DVH).

RESULTS

The median volumes in cc of the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 34.33, 9.75, 2.7, 3.48, 2.92, 3.18, and 1.96 respectively. The SVT contained from 0-9 seeds (median 2). There was little dose delivered to the SVT and SV volumes from the implanted prostate. The median D90 values for the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 8615 cGy, 675 cGy, 3100 cGy, 1329 cGy, 553 cGy, 246 cGy, and 67 cGy, respectively. The dose delivered to the prostate covered small percentages of SV. The percents of SV volumes covered by the prostate D90 were 11, 35, 3.3, 0, 0, and 0 for SVT, SV1, SV2, SV3, SV4, and SV5, respectively.

CONCLUSIONS

DVH analysis of the SV reveals that dose generated from an implanted prostate contributes little to the SV. Those patients at high risk for SV involvement may be undertreated with combined EBRT to prophylactic doses and prostate implantation.

Prostate brachytherapy: treatment strategies

PURPOSE

Patients who present with localized and locally advanced prostate cancer may be candidates for prostate brachytherapy. We evaluated the treatment outcomes in a diverse group of prostate cancer patients who presented with low, moderate and high risk features.

MATERIALS AND METHODS

A total of 301 patients who presented with T1 to T3 prostate cancer were treated with brachytherapy alone or combined with hormonal therapy and/or external beam irradiation. Of these patients 109 at low risk with prostate specific antigen (PSA) 10 ng./ml. or less, Gleason score 6 or less and clinical stage T2a or less were treated with 125iodine alone, 152 at moderate risk with PSA greater than 10 ng./ml., Gleason score greater than 6 or stage T2b or greater were treated with 125iodine or 103palladium or combined implant alone with 5 months of hormonal therapy, and 40 at high risk with PSA greater than 15 ng./ml., Gleason 8 or greater, clinical stage T2c to T3 or positive seminal vesicle biopsy (20) were treated with combination brachytherapy, external beam irradiation and 9 months of hormonal therapy. Patients with a positive seminal vesicle biopsy (T3c disease) and negative pelvic lymph nodes were included in the high risk group, and the walls of the seminal vesicles were also treated with implantation. Followup was performed every 6 months with digital rectal examination and ultrasound evaluation. Prostate biopsy was routinely recommended 2 years after completion of the radiation. Failure was defined as PSA increase on 2 consecutive determinations above 1 ng./ml. or evidence of local recurrence on digital rectal examination, transrectal ultrasound or biopsy. Kaplan-Meier projections were used to calculate progression-free survival rates.

RESULTS

Of the 109 patients at low risk followed from 1 to 7 years (median 18 months) 91% were free of PSA failure at 4 years. No patient experienced urinary incontinence following implantation, although grade 1 to 2 radiation proctitis occurred in 5 (4.5%). Of the 152 patients at moderate risk 73 received implantation and 79 received implantation combined with hormonal therapy. The 4-year biochemical freedom from failure rate for the hormone group was 85% versus 58% for the no hormone group (p = 0.08). The difference was more significant for those with Gleason score 7 or greater (90 versus 43%, p = 0.01) and for those with PSA greater than 10 ng./ml. (87 versus 59%, p = 0.04). Grade 1 to 2 radiation proctitis occurred in 1 of the 79 patients (1.3%) receiving hormonal therapy and in 3 (4%) treated with implantation only. There were no cases of urinary incontinence. Of the 40 patients at high risk 71% were free of biochemical failure at 3 years. Of the 4 patients with failure (10%) 3 (75%) originally had positive seminal vesicle biopsies. Five patients experienced gastrointestinal complications, although none was grade 3 or 4. The actuarial freedom from grade 2 proctitis was 82%. No patient experienced urinary incontinence. Prostate biopsies were negative in 87% of the low risk, 96.8 (hormone group) versus 68.6% (no hormone group) of the moderate risk (p = 0.0023) and 86% of the high risk patients.

CONCLUSIONS

Brachytherapy appears to offer comparable results to external beam irradiation and radical prostatectomy when patients are stratified by disease extent. Adopting a strategy of implant alone, implant with hormonal therapy or implant with hormonal therapy and external beam irradiation in patients who present with low to high risk features can improve the overall results in the more advanced cases.

American Brachytherapy Society (ABS) recommendations for transperineal permanent brachytherapy of prostate cancer

PURPOSE/OBJECTIVE

To develop and disseminate the American Brachytherapy Society (ABS) recommendations for the clinical quality assurance and guidelines of permanent transperineal prostate brachytherapy with 125I or 103Pd.

METHODS AND MATERIALS

The ABS formed a committee of experts in prostate brachytherapy to develop consensus guidelines through a critical analysis of published data supplemented by their clinical experience. The recommendations of the panels were reviewed and approved by the Board of Directors of the ABS.

RESULTS

Patients with high probability of organ-confined disease are appropriately treated with brachytherapy alone. Brachytherapy candidates with a significant risk of extraprostatic extension should be treated with supplemental external beam radiation therapy (EBRT). Patient selection guidelines were developed. Dosimetric planning of the implant should be carried out for all patients before seed insertion. A modified peripheral loading is preferred. The AAPM TG-43 recommendations requiring a change in prescription dose for 125I sources should be universally implemented. The recommended prescription doses for monotherapy are 145 Gy for 125I and 115-120 Gy for 103Pd. The corresponding boost doses (after 40-50 Gy EBRT) are 100-110 Gy and 80-90 Gy, respectively. Clinical evidence to guide selection of radionuclide (103Pd or 125I) is lacking. Post implant dosimetry and evaluation must be performed on all patients. It is suggested that the dose that covers 90% (D90) and 100% (D100) of the prostate volume and the percentage of the prostate volume receiving the prescribed dose (V100) be obtained from a dose-volume histogram (DVH) and reported.

CONCLUSION

Guidelines for appropriate patient selection, dose reporting, and improved quality of permanent prostate brachytherapy are presented. These broad recommendations are intended to be technical and advisory in nature, but the ultimate responsibility for the medical decisions rests with the treating physician. This is a constantly evolving field, and the recommendations are subject to modifications as new data becomes available.

Permanent radioactive seed implantation in the treatment of prostate cancer

Prostate brachytherapy has come a long way in the last 15 years, from an open free-hand technique with which seed placement was often inaccurate to the highly technical and accurate procedure of today. It has become a viable treatment option for low-risk patients along with EBRT and prostatectomy. Its most promising use may be in combination with hormonal therapy and EBRT in moderate- to high-risk patients, for whom it may offer improved outcomes over standard single-modality therapies.

PSA kinetics following I-125 radioactive seed implantation in the treatment of T1-T2 prostate cancer

Although there is renewed interest in prostate brachytherapy, little information is available on the effect of the procedure on prostate-specific antigen (PSA) changes over time. This study describes PSA kinetics after iodine-125 (I-125) transrectal ultrasound-guided transperineal implantation of the prostate. From February 1991-September 1997, 207 patients were treated with an I-125 prostate implant alone for T1-T2 prostate cancer. PSA values were obtained prior to treatment and at 1-73 months (median, 24 months). The change in PSA after implantation of the prostate was measured as a fraction of the pretreatment PSA (PSA at follow-up/pretreatment PSA). PSA failure was defined as two elevations in PSA or PSA > 1 ng/ml. One hundred fifty-five patients had PSA values recorded at the 1-month time period. A PSA value greater than the pretreatment PSA at 1 month was found in 27% (42/155). This had no significant effect on future PSA failure. The median percentage change in PSA after implantation for all patients were as follows: 1 month, 0.73; 3 months, 0.30; 6 months, 0.18; 12 months, 0.12; 18 months, 0.12; 24 months, 0.08; 30 months, 0.07; 36 months, 0.08; 42 months, 0.08; and 48 months, 0.05. The most significant decline occurred in the first 12 months. This was followed by a more gradual decline between 12-24 months. There was little change in PSA values after 24 months. The 1-year PSA value had a significant effect on PSA failure. Patients with a 1-year PSA <1 ng/ml (66) had an actuarial 4-year freedom-from-failure rate of 90%, compared to a rate of 62% for those with values >1 ng/ml (69) (P = 0.002). Twenty-seven patients developed PSA failure. The time to PSA failure ranged from 12-48 months (median, 24 months), but most (20/27) failures occurred after 18 months. We conclude that the greatest decline in PSA after I-125 implantation of the prostate occurs during the first year, and little change occurs after 2 years. A 1-year PSA value > 1 ng/ml is highly predictive of eventual PSA failure, which occurs in most patients after 18 months posttreatment.

Acute urinary morbidity following I-125 interstitial implantation of the prostate gland

The objective of this paper was to evaluate the acute urinary morbidity associated with I-125 interstitial implantation of the prostate gland. From 1991-1995, 117 patients underwent ultrasound (U/S)-guided implantation of the prostate gland. Median dose to 90% of the gland (d90) was 14.68 Gy (range = 1.65-21.75 Gy). The patients' urinary symptoms were recorded pre-implantation and at regular intervals after implantation using the International Prostate Symptom Score (IPSS), a self-assessment questionnaire in which patients scored 7 symptoms: incomplete emptying, frequency, intermittency, urgency, weak stream, straining, and nocturia. Median follow-up was 12 months. The natural history of implant-related urinary symptoms was assessed in this manner. In addition, dosimetric factors including U/S prostate volume, total activity, activity per seed, dose volume histogram (DVH) values for dose to gland, and dose area histogram (DAH) values for dose to urethra and bladder were examined for correlation to the severity of each symptom as well as to total IPSS (sum of the individual symptom scores). Total IPSS peaked at 1 month post-implant and gradually returned to approximately baseline at 24 months. Total IPSS directly correlated with total activity and DVH for the prostate. Total IPSS, however, did not correlate with bladder or urethral DAH. With the exception of frequency, individual symptoms did not correlate with dose to gland, bladder, or urethra. Frequency scores did, however, correlate not only with dose to prostate gland but also dose to urethra. The acute urinary side effects of I-125 prostate implantation are transient and peak at 1 month post-implant. The severity of the urinary irritative symptoms developed are closely related to total dose to the gland. Urethral dose appears to affect frequency most significantly. Urinary symptoms, therefore, may be a limiting factor when considering dose escalation with I-125.

Outpatient ultrasound-guided palladium 103 brachytherapy for localized adenocarcinoma of the prostate: a preliminary report of 434 patients

OBJECTIVES

To assess the effectiveness of palladium 103 (Pd-103) brachytherapy in Stage T1 and T2 adenocarcinoma of the prostate.

METHODS

Charts of 474 patients treated between 1991 and 1996 with transperineal real-time ultrasound-guided Pd-103 implants were reviewed to assess post-treatment prostate-specific antigen (PSA) levels and follow-up biopsy results. Of 474 patients, 434 had sufficient data for this report. The implant technique used allows precise placement of seeds and accurate dose delivery of the entire prostate. Preoperative neoadjuvant leuprolide (Lupron) and flutamide (Eulexin) were given selectively to reduce prostate size greater than 50 cc and for Gleason grade lesions greater than 7.

RESULTS

Of 434 patients, successful cancer control was demonstrated in 81% of patients by a decrease in PSA levels to less than 1.5 ng/mL at 1 year. Biopsies were negative in 88% of patients 1 year after the procedure and in 89% at 2 years. Analysis of the data suggests that patients with pretreatment PSA levels less than 10 ng/mL had the best outcomes. There were no disease-related deaths; the predominant morbidity was short-term bladder and bowel irritation without permanent sequelae. Incontinence occurred in less than 5% of patients who had undergone prior transurethral resection of the prostate. Impotence occurred in less than 15% of patients.

CONCLUSIONS

The technique used in this study proved effective in reducing PSA levels to less than 1.5 ng/mL and in producing negative biopsies 1 and 2 years postoperatively. Results are comparable to external-beam radiation therapy, demonstrating a significant reduction in morbidity.

The effect of prognostic factors on therapeutic outcome following transperineal prostate brachytherapy

The objectives of this study were to examine the effect of both disease and treatment related prognostic factors on biochemical control and post-treatment biopsy. Two-hundred fifty-eight patients underwent interactive ultrasound guided transperineal prostate implantation for T1-T2 prostate cancer using Iodine-125 (139 patients) and Palladium-103 (119 patients) and were followed from 6-67 months (median, 19). Hormonal therapy with 3 months of leuprolide and flutamide prior to implantation and two months given after the implant was used in 96 patients. Pre-treatment prostate-specific antigen (PSA) had the most significant effect on biochemical failure. Freedom from biochemical failure (FFBF) rates at 4 years were 75% for patients with PSA 1.3-10 ng/ml (144), 74% for patients with PSA 10.1-20 ng/ml (73), and 34% for patients with PSA > 20 ng/ml (41) (P = 0.0004). Gleason score also had a significant effect on FFBF rates. Four-year rates were 81%, 65% and 47% for patients with scores of 2-4 (68), 5-6 (130), and > or = 7 respectively (60) (P = 0.01). These two factors were also significant in multivariate analysis (P = 0.002, 0.007, respectively). Gleason score was the only factor to significantly affect post-treatment biopsy results. Patients with scores of 2-6 had 85% (63/ 74) negative 2-year biopsies versus 62% (13/21) for patients with scores > or = 7 (P = 0.02). Low-risk patients (PSA < or = 10 ng/ml, scores < 7 and stage < T2a) had a 4-year FFBF rate of 88% as compared to 60% for high-risk patients (PSA > 10 ng/ml, score > 6 or stage > or = T2b) (P = 0.02) and had a 95% negative biopsy rate versus 76% for high-risk patients (P = 0.06). Low-risk patients demonstrate high FFBF and negative biopsy rates following implantation. Patients presenting with higher risk prognostic factors such as PSA > 20 ng/ml or Gleason scores > or = 7 may require more aggressive treatment regimens.

Interstitial iodine-125 radiation without adjuvant therapy in the treatment of clinically localized prostate carcinoma

BACKGROUND

This study was designed to evaluate the efficacy of iodine-125 interstitial radiation in the treatment of prostate carcinoma classified as T1 or T2.

METHODS

One hundred twenty-six consecutive patients with adenocarcinoma of the prostate (T1, 23%; T2, 77%) were treated with iodine-125 radionuclides between January 1, 1988, and December 31, 1990. Four patients died of intercurrent illness within 1 year postimplant, leaving 122 men in the study. The prescribed minimum radiation dose was 160 gray. Median follow-up was 69.3 months. Prebiopsy prostate specific antigen (PSA) values (median, 5.0 ng/mL) were available for all patients. Posttherapy evaluation included clinical, biochemical (PSA), and pathologic (repeat needle biopsy) studies. No patient was surgically staged, and none received androgen deprivation therapy. Morbidity was graded according to the Radiation Therapy Oncology Group grading scale. Statistical appraisal was performed by the Kaplan-Meier method. PSA failure was defined in two ways: (1) PSA progression, i.e., 2 consecutive increases from a nadir value; and (2) failure to attain an arbitrary serum PSA value of 1.0 or 0.5 ng/mL at last follow-up.

RESULTS

The overall 7-year survival was 77%; there were no deaths from prostate carcinoma in this cohort. The 7-year actuarial PSA progression free outcome was 89%, and the PSA < or = 1.0 ng/mL outcome was 87%. When PSA < or = 0.5 ng/mL was selected as an outcome end point, and PSA values in this series of radiation-treated patients were compared with PSA values proposed to indicate disease free survival after radical prostatectomy (PSA < or = 0.3-< or = 0.6 ng/mL), the 7-year actuarial disease free survival was 79%. Morbidity was minimal except in patients who had preimplant or postimplant transurethral prostate resection.

CONCLUSIONS

Outpatient-based iodine-125 prostate brachytherapy for prostate carcinoma classified as T1 or T2 resulted in biochemical outcomes comparable to end points resulting from radical prostatectomy and external beam radiation.

Prostate specific antigen findings and biopsy results following interactive ultrasound guided transperineal brachytherapy for early stage prostate carcinoma

BACKGROUND

Interactive, transrectal, ultrasound-guided transperineal implantation is a new technique for performing permanent brachytherapy implants of the prostate. Prostate specific antigen (PSA) findings, biopsy results, and morbidity are examined to demonstrate its efficacy and safety in treating early stage prostate carcinoma.

METHODS

Ninety-seven patients underwent permanent implants for classifications T1 to T2 adenocarcinoma of the prostate gland with a median follow-up of 18 months (range: 6-51 months). Seventy-nine patients had negative laparoscopic pelvic lymph node dissections prior to implantation. Patients with positive lymph nodes were not implanted. The radioactive isotope used was I-125 in 71 patients and Pd-103 in 26 patients.

RESULTS

PSA failure was defined as two consecutive increases in PSA above the nadir level. The actuarial freedom from PSA failure (FFPF) at 2 years was 76% for the entire group. Stage significantly affected FFPF. Patients classified as T1b to T2a (35) had a FFPF of 91% at 2 years compared with 68.5% for patients classified as T2b to T2c (62) (P = 0.04). The pre-treatment PSA also significantly affected FFPF. Patients with PSA values of < or = 10 ng/mL (44) had a FFPF of 83% at 2 years. A similar rate of 82% was found in patients with PSA values of 10.1 to 20 ng/mL (29). Patients with PSA values > 20 ng/mL (24) had a significantly poorer FFPF at 2 years of 58% (P = 0.02). The PSA values of patients free from a PSA failure (82) ranged from 0.1 to 12.9 ng/mL with a median of 0.8 ng/mL. Transrectal prostate biopsies were performed 18 to 36 months posttreatment in 39 patients. Negative biopsies were found in 74% (29/39) of cases. The procedure was associated with an actuarial preservation of erectile function rate and sexual potency at 2 years of 96% and 79%, respectively. There were no cases of urinary incontinence or radiation cystitis. Associated morbidity included urinary retention requiring catheterization in 4% of the patients, outlet obstruction requiring a transurethral resection of the prostate in 2% and Grade 2 rectal complications in 1%.

CONCLUSIONS

Interactive, ultrasound-guided transperineal brachytherapy results in a low PSA failure rate, high negative biopsy rate, and is associated with low morbidity and preservation of erectile function.