Nelson N. Stone

A Dose–Response Study for I-125 Prostate Implants

PURPOSE No dose-response study has ever been performed for I-125 prostate implants using modern techniques of implant evaluation and modern treatment outcome end points. The amount of activity per volume implanted was increased over time based on review of postimplant dosimetry. This resulted in different delivered dose levels. This study explores the relationship between dose, biochemical failure, and biopsy results. MATERIALS AND METHODS 134 patients with T1-T2 prostate cancer were implanted with I-125 radioactive seeds and followed from 12 to 74 months (median: 32) postimplant. No patient received external beam irradiation or hormonal therapy. All patients implanted with I-125 had Gleason scores < or =6. One month postimplant, a CT-based three-dimensional dosimetric evaluation was performed on all patients. Using TG43 guidelines, dose-volume histograms were calculated. The dose delivered to the gland was defined as the D90 (dose delivered to 90% of prostate tissue as defined by CT). The D90s ranged from 26.8 to 256.3 Gy (median: 140.8 Gy). Biochemical failure was defined as two consecutive rises in prostate specific antigen (PSA) or a nadir level above 1.0 ng/ml. Posttreatment prostate biopsies (six to eight core samples) were routinely performed at 2 years postimplant. RESULTS Improvements in freedom from biochemical failure (FFBF) rates were seen with increasing D90 levels. The 4-year FFBF rates for patients with D90 values < 100 Gy, 100-119.9 Gy, 120-13.9 Gy, 140-159.9 Gy, and > or =160 Gy were 53, 82, 80, 95, and 89%, respectively (p = 0.02). Patients receiving a D90 < 140 Gy (65 patients) were similar with respect to presenting disease prognostic factors to those receiving a D90 > or =140 Gy (69 patients). Patients receiving a D90 < 140 Gy had a 4-year FFBF rate of 68% compared to a rate of 92% for those receiving a D90 > or =140 Gy (p = 0.02). Two-year posttreatment biopsies were negative in 70% (33 of 47) of patients with a D90 < 140 Gy compared to a rate of 83% (24 of 29) in patients with a D90 > or =140 Gy (p = 0.2). A multivariate analysis using dose, PSA, score, and stage revealed that dose was the most significant predictor of biochemical failure (p = 0.001). This dose response was more pronounced in patients presenting with PSA levels > 10 ng/ml. In these patients, the 4-year FFBF rates were 51 and 100% for the low and high dose groups, respectively (p = 0.009) and the negative biopsy rates were 64% (14 of 22) and 100% (8 of 8), respectively (p = 0.05). In patients with presenting PSA <10 ng/ml, the 4-year FFBF rates were 82 and 88% for the low and high dose groups, respectively (p = 0.29). CONCLUSION A dose response was observed at a level of 140 Gy. Adequate I-125 implants should deliver a dose of 140-160 Gy using TG43 guidelines.

Re: Insulin-Like Growth Factor-I (IGF-I) and IGF Binding Protein-3 as Predictors of Advanced-Stage Prostate Cancer

A recent study (1) suggested that elevated plasma levels of insulin-like growth factor-I (IGF-I) were a predictor of advanced-stage prostate cancer. We have studied IGF-I in prostate cancer and have found no relationship to disease stage. We studied IGF-I in a group of 126 men with prostate cancer and benign prostatic hypertrophy (BPH). Participants in our study were found through urology and radiation oncology clinics, and all eligible patients were asked to take part. All cancer patients had initially been diagnosed on the basis of levels of prostate-specific antigen (PSA) or abnormal physical examination. All men with BPH had had negative prostate biopsy examinations. Histologic confirmation of cancer diagnosis was also obtained for all subjects. All participants gave written informed consent. All staging of cancer cases was clinical, because almost all of the patients were to receive I seed implant therapy. Serum IGF-I was measured by use of the Nichols Advantage, an automated chemiluminescent immunoassay analyzer (Nichols Institute Diagnostics, San Juan Capistrano, CA). There was no statistically significant difference in the IGF-I levels in men with BPH compared with those in men with prostate cancer, nor was there statistically significant variation of IGF-I level among men with stages T1, T2, or T3 prostate cancer (P .323, one-way analysis of variance; Fig. 1). Multivariable linear regression revealed no statistically significant effect of PSA level, Gleason score, or T stage on IGF-I level (P .277) in men with prostate cancer. Shariat et al. (2) have shown that systemic levels of IGF-I are not associated with metastasis, established markers of biologically aggressive disease, or disease progression in patients with clinically localized prostate cancer. Our results agree with those of Shariat et al. and suggest that serum IGF-I levels are not related to advanced-stage prostate cancer.

IDENTIFICATION OF PATIENTS AT INCREASED RISK FOR PROLONGED URINARY RETENTION FOLLOWING RADIOACTIVE SEED IMPLANTATION OF THE PROSTATE

PURPOSE Urinary retention is a frequently reported complication following radioactive seed implantation of the prostate. If retention is refractory, a post-implant transurethral prostatic resection may ultimately be required to relieve obstruction, leading to an increased risk of urinary incontinence. In this series the incidence of prolonged urinary retention was determined, and the effect of pretreatment and treatment related factors was analyzed to identify high risk patients. MATERIALS AND METHODS A total of 251 patients with organ confined prostate carcinoma underwent transperineal prostate seed implantation. Of the patients 114 were implanted with 103palladium (103Pd) and 137 with 125iodine seeds. Of the patients who were implanted with 103Pd 90 received 3 months of neoadjuvant hormonal therapy. All patients had International Prostate Symptom Scores (I-PSS) recorded before implantation to assess the degree of urinary symptoms. In the patients receiving neoadjuvant hormones prostate volumes and I-PSS were recorded before initiation of hormone treatment and 3 months later at the time of implant. RESULTS Urinary retention developed in 14 patients requiring catheterization for more than 48 hours. Median time to onset was 1 day after implant. Of these patients 6 ultimately required transurethral prostatic resection to relieve urinary obstruction. No patient had urinary incontinence following implantation or transurethral prostatic resection. Multivariate analysis revealed that pretreatment I-PSS, and combined treatment with hormonal therapy and 103Pd predicted for the development of retention. Patients with I-PSS 20 or greater had a 29% risk, I-PSS 10 to 19, 11% risk and I-PSS less than 10, 2% risk of retention. Neither patient age, clinical stage, prostate specific antigen, Gleason score, use of 125I nor prostate volume was significant. A subgroup analysis of patients receiving hormonal therapy and 103Pd revealed that those with persistent urinary symptoms (I-PSS 10 or greater) following 3 months of hormonal therapy had the greatest risk of prolonged retention (37%). CONCLUSIONS The overall risk of prolonged urinary retention following prostate implantation was low in our series. Using the I-PSS questionnaire, high risk patients can be identified before treatment. Patients with significant pretreatment urinary symptoms or persistent urinary symptoms following 3 months of hormonal therapy and then implantation with 103Pd have the greatest risk.

American Brachytherapy Society consensus guidelines for transrectal ultrasound-guided permanent prostate brachytherapy

PURPOSE To provide updated American Brachytherapy Society (ABS) guidelines for transrectal ultrasound-guided transperineal interstitial permanent prostate brachytherapy (PPB). METHODS AND MATERIALS The ABS formed a committee of brachytherapists and researchers experienced in the clinical practice of PPB to formulate updated guidelines for this technique. Sources of input for these guidelines included prior published guidelines, clinical trials, published literature, and experience of the committee. The recommendations of the committee were reviewed and approved by the Board of Directors of the ABS. RESULTS Patients with high probability of organ-confined disease or limited extraprostatic extension are considered appropriate candidates for PPB monotherapy. Low-risk patients may be treated with PPB alone without the need for supplemental external beam radiotherapy. High-risk patients should receive supplemental external beam radiotherapy if PPB is used. Intermediate-risk patients should be considered on an individual case basis. Intermediate-risk patients with favorable features may appropriately be treated with PPB monotherapy but results from confirmatory clinical trials are pending. Computed tomography-based postimplant dosimetry performed within 60 days of the implant is considered essential for maintenance of a satisfactory quality assurance program. Postimplant computed tomography-magnetic resonance image fusion is viewed as useful, but not mandatory. CONCLUSIONS Updated guidelines for patient selection, workup, treatment, postimplant dosimetry, and followup are provided. These recommendations are intended to be advisory in nature with the ultimate responsibility for the care of the patients resting with the treating physicians.

A modified technique allowing interactive ultrasound-guided three-dimensional transperineal prostate implantation

PURPOSE Ultrasound-guided transperineal prostate implantation is a new technique for performing permanent isotope implants of the prostate. The details of the technique are presented to demonstrate its ability to place radioactive seeds three-dimensionally within the prostate gland to achieve uniform dose distribution without the need for complicated preplanning. METHODS AND MATERIALS An accurate measurement of the prostate volume is made using biplanar transrectal ultrasound. The total activity to be implanted is derived from a look-up table based on prostate volume. The basic plan is to implant 60-70% of the total activity in the periphery of the gland and the remaining activity in the interior of the gland. The ultrasound transducer provides visualization of the prostate through transverse, longitudinal and oblique cuts and allows for accurate placement of implant needles, approximately 1 cm apart. In addition, these needles can be moved through the prostate under constant visualization, thus allowing for precise seed placement. RESULTS The setup of the transrectal ultrasound device as well as prostate volume measurements are performed in 10 to 15 min. The actual placement of the needles and seed implantation takes 1 to 1.5 h to perform. Postimplantation dosimetric evaluation is performed using orthogonal x-ray films and 3 mm thick CT slices taken at 3 mm intervals. This evaluation has confirmed accurate seed placement within the prostate gland. CONCLUSION Interactive ultrasound guided transperineal prostate implantation is a fast and accurate method of performing permanent radioactive isotope prostate implants.

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.

Defining the risk of developing Grade 2 proctitis following 125I prostate brachytherapy using a rectal dose–volume histogram analysis

OBJECTIVE To determine the rectal tolerance for developing Grade 2 radiation proctitis after 125I prostate implantation based on the rectal dose-volume histogram. METHODS AND MATERIALS Two hundred twelve patients with T1-T2 prostate cancer underwent 125I implantation without external beam irradiation. One month after the procedure, all patients underwent CT-based postimplant dosimetry (3-mm abutting slices). The rectal volumes, defined by an inner and outer wall, were determined from 9 mm above the seminal vesicles to 9 mm below the prostate apex. All doses were calculated by TG43 formalism. The prostate prescription dose was 160 Gy. A dose response analysis was undertaken for volumes of rectal tissue receiving a given dose. Dose levels examined were 80 Gy, 100 Gy, 120 Gy, 140 Gy, 160 Gy, 180 Gy, 200 Gy, 220 Gy, and 240 Gy. Grade 2 proctitis was defined as rectal bleeding occurring at least once a week for a minimum period of one month. The risk of proctitis was calculated using actuarial methods. For each dose level, a critical volume cutpoint was chosen to define a low and high volume group of patients. The cutpoint was determined based on two goals: minimizing thep value and finding a < or =5% risk of proctitis in the low volume group. Patients were followed from 12 to 61 months (median: 28 months) after implantation. RESULTS Twenty-two patients developed Grade 2 proctitis: 14% within the first year, 72% between the first and second year, and 14% during the third year after the implant date. After the third year postimplantation, no cases of proctitis were reported. Proctitis was found to be significantly volume dependent for a given dose. The prescription dose (160 Gy) delivered to < or =1.3 cc of rectal tissue resulted in a 5% rate of proctitis at 5 years vs. 18% for volumes >1.3 cc (p = 0.001). Similar results were found for all doses examined. As the rectal volume receiving the prescription dose (160 Gy) increased, so did the proctitis rate: 0% for < or =0.8 cc, 7% for >0.8-1.3 cc, 8% for >1.3-1.8 cc, 24% for >1.8-2.3 cc, and 25.5% for >2.3cc (p = 0.002). CONCLUSIONS Rectal dose-volume histogram analysis is a practical and predictive method of assessing the risk of developing Grade 2 proctitis after 125I prostate implantation. Delivered dose should be kept below defined rectal volume thresholds to minimize this risk. This information can allow one to decrease rectal morbidity by modifying prostate implant technique.

LAPAROSCOPIC PELVIC LYMPH NODE DISSECTION FOR PROSTATE CANCER: COMPARISON OF THE EXTENDED AND MODIFIED TECHNIQUES

PURPOSE We compared the results of extended (obturator, hypogastric, common and external iliac nodes) to modified (obturator and hypogastric nodes only) laparoscopic pelvic lymph node dissection in patients with clinically localized prostate cancer. MATERIALS AND METHODS A total of 189 patients with stage T1 to T3 prostate cancer underwent modified (150) or extended (39) laparoscopic pelvic lymph node dissection for pelvic nodal assessment before definitive treatment. RESULTS Twice as many lymph nodes were removed via extended than modified laparoscopic pelvic lymph node dissection (mean 17:8 versus 9.3). The overall positivity rate was 23 of 189 lymph nodes (12.2%), including 14 of 150 (7.3%) for modified and 9 of 39 (23.1%) for extended dissection (p = 0.02). Two patients (22%) who underwent extended dissection had positive lymph nodes in the external iliac area. Patients who presented with the high risk features of prostate specific antigen (PSA) greater than 20 ng./ml., Gleason score 7 or greater, or stage T2b disease or greater had a 26.5% (p = 0.0002), 22% (p = 0.0006) or 16.4% (p = 0.003) likelihood of positive lymph nodes, respectively. For extended versus modified laparoscopic pelvic lymph node dissection node positivity in high risk patients was 27% versus 18.8% (p = 0.4), 30 versus 26.4% (p = 0.8) and 25.4 versus 14.6% (p = 0.17) for Gleason score 7 or greater, PSA greater than 20 ng./ml. and disease stage T2b to T3a, respectively. Patients who underwent the extended procedure had a higher complication rate (35.9 versus 2%, p < 0.0001). No laparotomy was required. CONCLUSIONS Despite yielding a 2-fold higher node count and higher node positivity rate, extended laparoscopic pelvic lymph node dissection offers no advantage over modified laparoscopic pelvic lymph node dissection for diagnosing positive lymph nodes when results are analyzed by prognostic factors. The extended procedure is associated with a much higher complication rate. In patients with the high risk features of PSA greater than 20 ng./ml., Gleason score 7 or greater and stage T2b to T3a disease modified laparoscopic pelvic lymph node dissection can be performed safely and effectively to help identify those who may benefit most from curative therapy.

Penile erectile function after permanent radioactive seed implantation for treatment of prostate cancer.

PURPOSE We assess erectile function after prostate brachytherapy and analyze those factors affecting potency preservation. MATERIALS AND METHODS A total of 416 patients treated from October 1990 to September 1998 with permanent radioactive seed implantation for T1 to T2 prostate cancer had erectile function assessed before and after treatment. Erectile function was assessed using the scoring system of 0-complete inability to have erections, 1-able to have erections but insufficient for intercourse, 2-can have erections sufficient for intercourse but considered suboptimal and 3-has normal erectile function. Implant dose was defined as the D90, which was the dose delivered to 90% of the gland on a dose volume histogram from the 1-month computerized tomography based dosimetric analysis. RESULTS Pretreatment erectile function assessment revealed scores of 0 in 57 (14%), 1 in 46 (11%), 2 in 77 (18%) and 3 in 236 (57%) patients. In 313 patients who were potent with a score 2 or greater before therapy the actuarial freedom from any decrease in erectile function score was 64% and 30% at 3 and 6 years, respectively. The actuarial preservation of potency, with a score 2 or greater, was 79% and 59% at 3 and 6 years, respectively. The 2 factors found to have a significant negative effect on potency in univariate and multivariate analyses were high implant dose (D90 greater than 160 Gy. for I-125 and D90 greater than 100 Gy. for Pd-103) and a pretreatment erectile function score of 2 versus 3. CONCLUSIONS The rate of potency preservation after brachytherapy is high, although a decrease occurs from 3 to 6 years. Pretreatment erectile dysfunction as well as higher implant dose are associated with greater impotency.

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.