Three-dimensional computed tomography-guided monotherapeutic pararectal brachytherapy of prostate cancer with seminal vesicle invasion

Examination of dosimetry accuracy as a function of seed detection rate in permanent prostate brachytherapy

The variation of permanent prostate brachytherapy dosimetry as a function of seed detection rates was investigated for I125 implants with seed activities commonly employed in contemporary practice. Post-implant imaging and radiation dosimetry data from nine patients who underwent PPB served as the basis of this simulation study. One-thousand random configurations of detected seeds were generated for each patient dataset using various seed detection levels from 30% to 99%. Dose parameters, including D90, were computed for each configuration and compared with the actual dosimetry data. A total of 108 000 complete sets of post-PPB dose volume statistics were computed. The results demonstrated that although the average D90 differed from the true value by less than 5% when 70% or more seeds were identified, the D90 of an individual case could deviate up to 13%. The 95% confidence interval (CI) of estimated D90 values differ by less than 5% from the actual value when 95% or more seeds are detected, or approximately a 7 Gy difference in the D90 value for a prescription dose of 144 Gy. Estimated target volume dose parameters tended to decrease with reduced seed detection rates. The most variable dose parameter was the prostate V100 in absolute scale while the urethral V100 was most variable in a relative sense. Based on this comprehensive simulation study, it is suggested that 95% or more seeds need to be localized in order to provide an accurate estimation of dose parameters for contemporary iodine 125 permanent prostate brachytherapy.

3D conformal HDR brachytherapy and external beam irradiation combined with temporary androgen deprivation in the treatment of localized prostate cancer

PURPOSE

To evaluate treatment outcome of 3D conformal high dose rate (HDR) brachytherapy and external beam irradiation (EBRT) combined with temporary androgen deprivation for patients with localized prostate cancer.

PATIENTS AND METHODS

Between January 1997 and September 1999 we treated 102 patients with stage T1-3 N0 M0 prostate cancer. Stage T1-2 was found in 71, T3 in 31 patients. Median pretreatment PSA level was 15.3 ng/ml. After ultrasound-guided transrectal implantation of four afterloading needles, CT based 3D brachytherapy planning was performed. All patients received four HDR implants using a reference dose per implant of 5 or 7Gy. Time between each implant was 14 days. After brachytherapy EBRT followed up to 39.6 or 45.0 Gy. All patients received temporary androgen deprivation, starting 2-19 months before brachytherapy, ending 3 months after EBRT.

RESULTS

Median follow-up was 2.6 years (range 2.0-4.1 years). Actuarial biochemical control rate was 87% at 2 years and 82% at 3 years. In 14 patients we noted biochemical failure, in five patients clinical failure. Overall survival was 90%, disease specific survival 98.0% at 3 years. Acute grade 3 toxicity occurred in 4%, late grade 3 toxicity in 5%. One patient developed a prostatourethral-rectal fistula as late grade 4 toxicity. The conformal quality of 300 HDR implants was analyzed using dose volume histograms.

CONCLUSIONS

3D conformal HDR brachytherapy and EBRT combined with temporary androgen deprivation is an effective treatment modality for prostate cancer with minimal associated toxicity and encouraging biochemical control rates after a median follow-up of 2.6 years.

Measurement of the ultrasound backscatter signal from three seed types as a function of incidence angle: application to permanent prostate brachytherapy

PURPOSE

To measure the relative ultrasound backscatter of different seed types as a function of seed orientation and to evaluate the corresponding images of these seeds.

METHODS AND MATERIALS

Three seed types were evaluated: OncoSeed (standard), EchoSeed (corrugated), and RAPID Strand(RS). Ultrasound images for angles of incidence varying from 90 degrees (perpendicular) to 20 degrees at 5MHz and 7.5MHz were produced by raster scanning the seeds in a degassed water bath. Seed images were visually inspected and analyzed using the integrated-optical-density (IOD) method.

RESULTS

Corrugated seeds appear as contiguous objects over the range of frequencies and orientations examined, whereas standard seeds appear as contiguous objects from 90 degrees to 80 degrees only. The ranges and means of the backscattered IOD ratio of the seeds from 85 degrees to 20 degrees were: (corrugated vs. standard) 1.48 to 3.72 (2.32 +/- 0.62) for 5 MHz and 1.26 to 3.77 (2.19 +/- 0.84) for 7.5 MHz and (corrugated vs. RS) 1.21 to 9.53 (2.98 +/- 2.48) for 5 MHz and 1.008 to 10.86 (2.79 +/- 3.08) for 7.5 MHz. Backscattered signal increase ranged from 1.66 dB to 20.7 dB for the corrugated seed as compared to the other seeds.

CONCLUSIONS

Corrugated seeds produce greater backscatter signal and a more readily identifiable seed image over a large range of seed orientation as compared with standard brachytherapy seeds.

Salvage reimplantation in patient with local recurrent prostate carcinoma after brachytherapy with three dimensional computed tomography-guided permanent pararectal implant

Thirty-one [31] patients with local recurrent or residual adenocarcinoma of the prostate, with no evidence of distant metastases, were treated with second permanent implant using a stereotactic three dimensional system and posterior pararectal CT-guided method. All patients had extensive under local anesthesia or IV sedation pararectal CT-guided biopsy of the prostate and seminal vesicles. All patients except one had 3 month neoadjuvant androgen ablation prior to salvage reimplantation. Twenty [20] of these patients had local recurrence in the prostate and eleven [11] patients had seminal vesicle invasion which was not diagnosed nor treated with the initial brachytherapy. In addition, the patients had PSA failure or local palpable disease, "cold spots" with CT imaging or areas of dosage less than 80% of the prescribed dose with DVH (dose volume histogram). Initial prescribed dose was 120 Gy with (103)Pd loose seeds in 26 patients and 144 Gy with (125)I loose seeds in 5 patients. For the reimplant the dosage in the recurrent site was 100-144 Gy with (125)I seeds in strand in 24 patients (77%) and 100-120 Gy with (103)Pd loose seeds in 7 patients (23%). The preference of (125)I seeds in the second treatment was because only (125)I in strand was available at the time of the reimplant. Eleven [11] patients had second implant twelve to twenty-four months after the initial implant and 20 patients had after twenty-five to eighty-seven months and median follow-up was thirty months. A high level of biochemical control (87%) was achieved in all of these patients who are recognized as high risk due to local recurrence. Four [4] patients experienced grade 2 or 3 GI or GU complications and two [2] patients experienced grade 4 GI complications. Patients with local recurrent prostate cancer following initial brachytherapy including those with seminal vesicle invasion can be successfully treated with pararectal stereotactic CT-guided reimplantation. Assessment of seminal vesicle status is an essential part of staging for local recurrence.

High and intermediate risk prostate cancer treated with three-dimensional computed tomography-guided brachytherapy: 2-8-year follow-up

PURPOSE

To report post-brachytherapy results in high and intermediate risk patients of prostatic adenocarcinoma.

METHODS AND MATERIALS

From June 1994 to June 2000, 356 consecutive high and intermediate risk patients were treated with three-dimensional computed tomography-guided stereotactic pararectal brachytherapy. The age was 42-90 years (median, 68 years), the initial prostate volume was 14-180 cm3 (median, 59 cm3), and initial PSA was 1.7-143 ng/ml (median, 10.5 ng/ml). Three hundred forty-eight patients were available for follow-up for 2-8 years (median, 4.5 years). Two hundred eighty patients had one or more high risk factors (PSA >20 ng/ml, Gleason>7, Stage T2b, T3a, or T3b). Sixty-eight patients had only one intermediate risk factor (PSA 10-20 ng/ml or Gleason=7). Patients with both intermediate risks were considered high risk. The high-risk group was further stratified into subgroups with similar risk profile. A dose of 144 Gy with 125I or 120 Gy with 103Pd was achieved in 90-100% of the target. Thirty (30) patients (9%) had prior transurethral resection and 229 (64%) were treated with 3 months neoadjuvant androgen ablation.

RESULTS

Biochemical disease-free survival was 92% of 280 high risk patients and 96% of 68 intermediate risk patients. Seven patients (2%) required catheterization during the first year for urinary retention, nine patients (3%) required TUR 1-3 years post-implant, three patients (1%) developed grade 1 or 2 incontinence after a second TUR, and four patients (1%) developed grade 3 rectal complications.

CONCLUSION

This method produces a high level of biochemical control 2-8 years (median 4.5 years). Morbidity is acceptable regardless of risk profile or initial prostate volume.

Prostate cancer with large glands treated with 3-dimensional computerized tomography guided pararectal brachytherapy: up to 8 years of followup

PURPOSE

We report post-brachytherapy results in patients with cancer in a large prostate.

MATERIALS AND METHODS

From June 1, 1994 to June 30, 2000, 331 consecutive patients with a large prostate of 50 to 180 cm.3 (median 69) were treated with 3-dimensional computerized tomography guided brachytherapy. Patient age was 42 to 90 years (median 69). Of these patients 327 were available for followup for 2 to 8 years (median 4.5). Patients were stratified according to risk profile. The high risk group had 1 or more high risk factors (prostate specific antigen [PSA] greater than 20 ng./ml., Gleason greater than 7, stage T2b, T3a or T3b) or 2 intermediate risk factors (PSA 10 to 20 ng./ml. and Gleason 7). The high risk group was further stratified into subgroups with a similar risk profile. The intermediate risk group had only 1 high risk factor (PSA 10 to 20 ng./ml. or Gleason 7). The low risk group had PSA less than 10 ng./ml., Gleason less than 7 and stage T1a, b, c or T2a. A dose of 144 Gy. with 125I or 120 Gy. with 103Pd was achieved in 90% to 100% of the target. A total of 31 patients (9%) had previously undergone transurethral resection and 198 (60%) were treated with 3 months of neoadjuvant androgen ablation.

RESULTS

Biochemical disease-free survival was achieved in 90% of the 182 patients at high risk, 96% of the 52 at intermediate risk and 99% of the 93 at low risk. Seven patients (2%) required catheterization during year 1 for urinary retention, 11 (3%) required transurethral prostate resection 1 to 4 years after implantation, 3 patients (1%) had grade 1 or 2 incontinence after repeat transurethral prostate resection and 4 (1%) had grade 3 or 4 rectal complications.

CONCLUSIONS

The 3-dimensional computerized tomography guided pararectal permanent implant results in a high level of biochemical control with low morbidity at 2 to 8 years in patients with prostate cancer who have a large prostate. There was less favorable biochemical control in patients with PSA greater than 20 ng./ml., Gleason 7 or greater and seminal vesicle invasion.

Treatment of prostate cancer with radiotherapy: should the entire seminal vesicles be included in the clinical target volume?

PURPOSE

When treating high-risk prostate cancer with radiation therapy, inclusion of the seminal vesicles (SVs) within the clinical target volume (CTV) can dramatically increase the volume of radiated normal tissues and hinder dose escalation. Because cancer may involve only the proximal portion of the frequently lengthy SVs, we performed a complete pathology review of prostatectomy specimens to determine the appropriate length of SV to include within the CTV when SV treatment is indicated.

METHODS AND MATERIALS

A detailed pathologic analysis was performed for 344 radical prostatectomy specimens (1987-2000). All slides from each case were reviewed by a single pathologist (N.S.G.). Factors recorded for each case included length of each SV (cm), length of cancer involvement in each SV (cm) measured from the prostate-SV junction, and percentage of SV length involved.

RESULTS

Fifty-one patients (15%) demonstrated SV involvement in 81 SVs (21 unilateral, 30 bilateral SV involvement). The median SV length was 3.5 cm (range: 0.7-8.5 cm). Factors associated with SV involvement included the pretreatment PSA level, biopsy Gleason score, and clinical T classification. The commonly used risk group stratification was very effective at predicting SV positivity. Only 1% of low-risk patients (PSA <10 ng/mL, Gleason <or=6, and clinical stage <or=T2a) demonstrated SV involvement vs. 27% of high-risk patients. Patients with only one high-risk feature still demonstrated a 15% risk of SV involvement, whereas 58% of patients with all three high-risk features had positive SVs. The median length of SV involvement was 1.0 cm (90th percentile: 2.0 cm, range: 0.2-3.8 cm). A median of 25% of each SV was involved with adenocarcinoma (90th percentile: 54%, range: 4%-75%). For the 81 positive SVs, no factor was associated with a greater length or percentage of SV involvement. In the entire population, 7% had SV involvement beyond 1.0 cm. There was an approximate 1% risk of SV involvement beyond 2.0 cm or 60% of the SV. In addition, this risk was less than 4% for all subgroups, including high-risk patients.

CONCLUSIONS

A portion of the SV should be included in the CTV only for higher-risk patients (PSA >or=10 ng/mL, biopsy Gleason >or=7, or clinical T stage >or=T2b). When treating the SV for prostate cancer, only the proximal 2.0-2.5 cm (approximately 60%) of the SV should be included within the CTV.

Multiobjective anatomy-based dose optimization for HDR-brachytherapy with constraint free deterministic algorithms

In high dose rate (HDR) brachytherapy, conventional dose optimization algorithms consider multiple objectives in the form of an aggregate function that transforms the multiobjective problem into a single-objective problem. As a result, there is a loss of information on the available alternative possible solutions. This method assumes that the treatment planner exactly understands the correlation between competing objectives and knows the physical constraints. This knowledge is provided by the Pareto trade-off set obtained by single-objective optimization algorithms with a repeated optimization with different importance vectors. A mapping technique avoids non-feasible solutions with negative dwell weights and allows the use of constraint free gradient-based deterministic algorithms. We compare various such algorithms and methods which could improve their performance. This finally allows us to generate a large number of solutions in a few minutes. We use objectives expressed in terms of dose variances obtained from a few hundred sampling points in the planning target volume (PTV) and in organs at risk (OAR). We compare two- to four-dimensional Pareto fronts obtained with the deterministic algorithms and with a fast-simulated annealing algorithm. For PTV-based objectives, due to the convex objective functions, the obtained solutions are global optimal. If OARs are included, then the solutions found are also global optimal, although local minima may be present as suggested.

Computed tomography-guided salvage brachytherapy of recurrent large nonresectable familial colo-rectal cancer in the pelvis: case report

Here we present the first reported case of three-dimensional CT-guided salvage brachytherapy of recurring colorectal cancer in the pelvis after failed radiation therapy, total colectomy, and chemotherapy. Initial CEA was 67.0 ng/mL and tumor volume 93 cm3 with no metastasis outside the pelvis. A total of 333 seeds of Iodine-125 were delivered to the entire target, with dosage of 150 to 200 Gy as calculated by post-implant CT dosimetry with Varian MMS software. CEA 12 months after implant decreased to 5.7 ng/mL. Clinical and biochemical results are encouraging; however long-term data in a greater universe of patients are required.