Prostate brachytherapy: comparison of dose distribution with different 125I source designs

PURPOSE

To evaluate the interchangeability of various commercially available iodine 125 ((125)I) sources and to assess the dosimetric effect of a change in source.

MATERIALS AND METHODS

A modified peripherally loading prostate brachytherapy plan to deliver 145 Gy was devised by using a model (125)I source, which until recently was the only available (125)I source. A dose-volume histogram was generated. By using the available radial dose functions and anisotropy distributions for eight other currently commercially available sources, the same implant placement was planned and dose-volume histogram distributions tabulated. This exercise was performed for 15-, 45-, and 60-cm(3) glands. No implants were placed, and no physical radiation measurements were made. Dose calculations were theoretic: They were generated by using a widely available treatment planning system.

RESULTS

There was little difference in dose distribution to the volume receiving 100% of the prescribed dose (<6%); only one source showed a difference greater than 2%. Large differences, up to -40% to +60%, were seen in the volume of tissue encompassed within internal high-dose regions receiving 150% or 200% of the prescribed dose. These findings held true, irrespective of gland size, within a clinically relevant range (15-60 cm(3)) and for a uniformly loaded radionuclide distribution.

CONCLUSION

Reviewing only peripheral dose at or near the prescription dose of 145 Gy revealed little difference in doses for various source designs. Marked differences in high-dose regions were seen and may affect the dose received by internal sites. Effects of these changes on cure and/or complications remain speculative.

Pretreatment nomogram for predicting freedom from recurrence after permanent prostate brachytherapy in prostate cancer

OBJECTIVES

To develop a prognostic nomogram to predict the freedom from recurrence for patients treated with permanent prostate brachytherapy for localized prostate cancer.

METHODS

We performed a retrospective analysis of 920 patients treated with permanent prostate brachytherapy between 1992 and 2000. The clinical parameters included clinical stage, biopsy Gleason sum, pretreatment prostate-specific antigen (PSA) value, and administration of external beam radiation. Patients who received neoadjuvant androgen deprivation therapy were excluded. Failure was defined as any post-treatment administration of androgen deprivation, clinical relapse, or biochemical failure, defined as three PSA rises. Patients with fewer than three PSA rises were censored at the time of the first PSA rise. Data from two outside institutions served as validation.

RESULTS

A nomogram that predicts the probability of remaining free from biochemical recurrence for 5 years after brachytherapy without adjuvant hormonal therapy was developed using Cox proportional hazards regression analysis. External validation revealed a concordance index of 0.61 to 0.64, and calibration of the nomogram suggested confidence limits of +5% to -30%.

CONCLUSIONS

The pretreatment nomogram we developed may be useful to physicians and patients in estimating the probability of successful treatment 5 years after brachytherapy for clinically localized prostate cancer.

The evolving role of prostate brachytherapy

BACKGROUND

The publication of several large studies with long-term results on the use of prostate brachytherapy has resulted in increased use of this option for patients with localized prostate cancer.

METHODS

A historical review of brachytherapy as an approach to prostate cancer management is provided, as well as a general summary of the implant technique and the results to date according to patient risk. The effects of combination therapies for specific patient groups are also reviewed.

RESULTS

A recent 12-year follow-up reported no failures after 10 years, and 75% of recurrences occurred with-in the first 5 years. Patients at low risk for failure based on stage, grade, and prostate-specific antigen (PSA) parameters are likely to have disease confined to the prostate. Those with more advanced disease are likely to have a lower probability of cure with brachytherapy as monotherapy. Complications involve primarily the urinary tract. Ideal candidates have a PSA of =10, Gleason score of =7, and low-volume/low-stage disease (stage T1c or T2a). Patients with more-advanced disease are candidates for brachytherapy combined with external-beam radiation therapy (EBRT). For high-risk men with multiple adverse prognostic features, consideration should be given to clinical trials investigating innovative treatment combinations (eg, the addition of androgen blockade, and EBRT).

CONCLUSIONS

The rarity of failures after 5 years and the absence of recurrence after 10 years suggest a that brachytherapy for localized prostate cancer can provide durable disease control. Future improvements in pathologic tools may lead to selection of patients more likely to respond well to brachytherapy.

Failure free survival following brachytherapy alone for prostate cancer: comparison with external beam radiotherapy

BACKGROUND AND PURPOSE

To compare failure free survival (FFS) for brachytherapy (BT) alone and external beam radiotherapy (EBXRT) alone.

MATERIALS AND METHODS

Between 12/88 and 12/95, 1527 and 695 T(1) or T(2) Nx-No Mo prostate cancer patients (from the Arizona Oncology Services database) were treated with either EBXRT or BT, respectively. The median age was 74 years. Median follow-up for EBXRT and BT patients was 41.3 and 51.3 months, respectively.

RESULTS

Overall FFS at 5 years for EBXRT and BT were 69 and 71%, respectively (P=0.91). No significant difference in FFS at 5 years was observed between EBXRT and BT for either T(1) (78 vs. 83%, P=0.47) or T(2) (67 vs. 67%, P=0.89) tumours. Superior outcomes for Gleason 8-10 lesions treated with EBXRT vs. BT (5 years FFS 52 vs. 28%, P=0.04) were observed; outcomes for lower grade lesions when analysed by Gleason score alone did not significantly differ according to treatment received. Patients with initial PSA values 10-20 ng/dl had an improved FFS with EBXRT vs. BT (70 vs. 53%, P=0.001); outcomes for patients with initial PSA ranges 0-4 ng/dl, >4-10 ng/dl and >20 ng/dl did not differ significantly with treatment received.

CONCLUSIONS

EBXRT and BT appear to be equally efficacious for low-risk patients having T(1)/T(2) disease with Gleason scores <6 and PSA <10 ng/dl. Patients with Gleason scores 8-10 or PSA >10 ng/dl-<20 ng/dl) appear to fare worse with BT alone compared with EBXRT. Neither EBXRT nor BT were particularly effective for patients with a presenting PSA >20 ng/dl.

Real-time optimized intraoperative dosimetry for prostate brachytherapy: a pilot study

PURPOSE

To assess the feasibility of real-time intraoperative treatment planning for permanent prostate brachytherapy analyzing the impact on operative time and adequacy of postimplant dosimetry.

METHODS AND MATERIALS

Seventeen consecutive patients undergoing permanent brachytherapy for prostate cancer had real-time intraoperative computer-based and optimized treatment planning. The first 8 patients were implanted using a plan generated before the surgery and served to assure the team qualitatively that this could be performed without greatly increasing intraoperative time. They served as control group for expected achieved dosimetry results reviewing the D90, V100, V150 parameters from the dose-volume histograms. The next 9 patients were implanted according to the real-time plan. The times needed to carry out various steps of the procedure were recorded. The achieved dosimetry was then compared to the control group to assure that accuracy was unchanged.

RESULTS

The median operative time for patients undergoing intraoperative dosimetry was 57 min. Of this, 21 min were devoted to anesthesia and nursing functions. Postoperative dosimetry showed a median achieved V100 (volume of prostate receiving 100% of prescribed dose) of 97% for the control group. For the real-time dosimetry group, the median V100 was similar at 94%. The V150 (volume receiving 150%) is 49% for both groups. The D90 (dose received by 90% of the target) was normalized for easy comparison and was consistently slightly greater than the prescription dose.

CONCLUSION

Treatment planning for permanent brachytherapy of prostate cancer has historically been performed as a computer-generated and optimized plan run weeks in advance of an implant, or according to a set pattern using an intraoperative nomogram. These data show that planning can now be optimized intraoperatively using widely available software without compromising the operative time or implant quality.

Failure-free survival following brachytherapy alone or external beam irradiation alone for T1-2 prostate tumors in 2222 patients: results from a single practice

PURPOSE

To evaluate failure-free survival (FFS) for brachytherapy (BT) alone compared to external beam radiotherapy (EBRT) alone for Stage T1-2 Nx-No Mo patients over the same time period by a single community-based practice in the prostate-specific antigen (PSA) era.

MATERIALS AND METHODS

The database of Arizona Oncology Services (a multiphysician radiation oncology practice in the Phoenix metropolitan area) was reviewed for patients meeting the following criteria: (1) T1 or T2 Nx-No Mo prostate cancer; (2) no prior or concurrent therapy including hormones; (3) treatment period 12/88-12/95; and (4) treatment with either EBRT alone or BT alone ((125)I or (103)Pd). This yielded 1527 EBRT and 695 BT patients; no patients meeting the above criteria were excluded from analysis. Median follow-up for EBRT patients was 41.3 months and, for BT patients, 51.3 months. Patients were not randomized to either therapy but rather received EBRT or BT based upon patient, treating, and/or referring physician preference. PSA failure was defined according to the ASTRO consensus guidelines. The median patient age was 74 years for both groups.

RESULTS

Failure-free survival at 5 years for EBRT and BT are 69% and 71%, respectively (p = 0.91). For T stage, no significant difference in FFS at 5 years is observed between EBRT and BT for either T1 (78% vs. 83%, p = 0.47) or T2 (67% vs. 67%, p = 0.89) tumors. Analysis by Gleason score shows superior outcomes for Gleason 8-10 lesions treated with EBRT vs. BT (5-year FFS 52% vs. 28%, p = 0.04); outcomes for lower grade lesions (Gleason 4-6) when analyzed by Gleason score alone do not significantly differ according to treatment received. Patients with initial PSA values of 10-20 ng/dL have an improved FFS with EBRT vs. BT at 5 years (70% vs. 53%, p = 0.001); outcomes for patients with initial PSA ranges of 0-4 ng/dL, of > 4-10 ng/dL, and > 20 ng/dL did not differ significantly by treatment received. FFS was also determined for presenting Gleason score/PSA combinations; all Gleason combinations in the initial PSA range >10-20 ng/dL had superior outcomes with EBRT compared to BT, and this reached statistical significance for Gleason scores of 2-4 (72% vs. 58%, p = 0.026), Gleason 7 (67% vs. 28%, p = 0.002), and Gleason 8-10 (63% vs. 23%, p = 0.05).

CONCLUSION

In our patient population, either EBRT or BT appear equally efficacious for patients with T1/T2 disease with Gleason scores </= 6 or PSA </= 10 ng/dL. Patients with presenting Gleason scores of 8-10 or PSA > 10 ng/dL (but </= 20 ng/dL) appear to fare significantly worse with BT alone compared to EBRT alone. Neither EBRT nor BT alone was particularly effective for patients with a presenting PSA > 20 ng/dL, as would be anticipated from the significant risks of occult distant metastasis in this group. To our knowledge, this is the first report comparing the outcome of EBRT and BT treatment in patients treated concurrently by a single group, and these results, achieved in a community-based practice, compare favorably to data from academic centers regarding external beam, brachytherapy, or surgical outcomes and should be generalizable to the community at large.

Therapeutic Strategies for Localized Prostate Cancer II: Perineal Prostatectomy, X-Rays, Protons, Neutrons, and Combination Brachytherapy

Application of improved imaging, diagnostic, and computer techniques is beginning to have an impact on the management of localized prostate cancer. It is possible to perform a range of surgical and radiation procedures with less morbidity than in the past. The changes in therapy for patients with localized disease derive from better knowledge of anatomy for invasive procedures and optimization of virtual planning for noninvasive methods. Perineal prostatectomy and combinations of beam and seed radiation offer both patient and physician reasonable therapeutic options.

Permanent brachytherapy as salvage treatment for recurrent prostate cancer

OBJECTIVES

To determine the prostate-specific antigen (PSA)-based freedom from second failure, survival, and morbidity of permanent brachytherapy as salvage treatment for men for whom primary external beam irradiation of prostate cancer failed.

METHODS

A retrospective review was performed on 17 consecutive men seen and treated with permanent brachytherapy for recurrent adenocarcinoma of the prostate from February 1989 to May 1994. Patients had been treated with a median of 63.3 Gy and presented with progressive local disease 23 to 146 months later (median 54). After a staging evaluation documenting no distant disease, all received permanent implantation of iodine-125 for 120 Gy (15 patients) or palladium-103 for 90 Gy (2 patients) using a transperineal ultrasound-guided technique. All doses were calculated before TG-43. Progression after brachytherapy was defined according to the ASTRO Consensus Conference definition. All results are reported as Kaplan-Meier actuarial 5-year results.

RESULTS

The 5-year actuarial freedom from second relapse was 53%. Both PSA and Gleason score appear to be prognostic factors, although both failed to reach statistical significance. Patients with a PSA 10 ng/mL or less at the time of salvage therapy had a freedom from second relapse rate of 67% compared with 25% for men with a PSA greater than 10 ng/mL (P = 0. 15). Those with low-grade tumor at the time of salvage therapy had an 83% freedom from second relapse rate compared with 30% for those with high-grade cancer (P = 0. 12). With 93% alive at 5 years, no significant difference was seen in survival on the basis of these prognostic groups. Acute and transient toxicity were readily managed and indistinguishable from that reported for previously unirradiated patients. Long-term complications were limited to a 24% risk of incontinence at 5 years.

CONCLUSIONS

Ultrasound-guided transperineal brachytherapy is an effective second-line therapy for patients for whom external beam irradiation has failed. Early intervention may be valuable when the PSA is less than 10 ng/mL. The risk of incontinence is significant, and patients must be individually counseled.

Biochemical disease-free survival following 125I prostate implantation

PURPOSE

To assess the 5-year clinical and biochemical results of ultrasound-guided permanent 125I brachytherapy in early adenocarcinoma of the prostate. Biochemical disease-free survival (BDFS) is reported, using PSA follow-up and is compared to the surgical and radiation therapy literature.

METHODS AND MATERIALS

From December 1988 through December 1993, ultrasound-guided brachytherapy was preplanned with 125I and delivered 160 Gy as the sole treatment in 499 patients. All were clinically staged as T1 or T2 node-negative adenocarcinoma of the prostate. Within the first year, 10 patients were lost to follow-up and have been excluded from further study. The remaining 489 patients form the basis of this report. Clinical status and prostate specific antigen (PSA) values were systematically recorded before and after treatment.

RESULTS

With a median follow-up of 35 months (3-70), the actuarial clinical local control is 83%. Both stage and grade are shown to predict for this endpoint. Actuarial biochemical disease-free survival (BDFS) is also correlated with stage, grade, and PSA at presentation. Biochemical disease-free survival at 5 years is 94% for T1, 70% for unilateral T2, and 34% for T2c tumors. Grade is also predictive, ranging from 85% in low-grade tumors to 30% in high-grade tumors. In a multivariate analysis, the pretreatment PSA is most highly correlated (p < 0.0001) with BDFS, local control, and clinical disease-free survival. Patients with a normal pretreatment PSA enjoyed 93% BDFS, while those presenting with PSA > 10 had a BDFS of 40%. Complications have been few, with severe urinary urgency or dysuria in 4% and both incontinence and proctitis seen in 1%.

CONCLUSIONS

While biochemical disease-free survival reports in the literature are immature and have short follow-up, our data compares favorably with studies following radical prostatectomy or radiation therapy. Further follow-up of this cohort is required. The complication rate is low and patient acceptance excellent. Permanent implantation of 125I as the sole treatment for early prostate adenocarcinoma is a viable alternative for patients with early-stage and low- to moderate-grade cancers. The PSA provides significant prognostic information and aids in case selection. Better management options are needed for high grade and bilateral tumors.

Guided brachytherapy for treatment of confined prostate cancer

A total of 133 patients underwent transperineal ultrasound-guided iodine 125 seed implantation for Stages A and B prostate cancer with a twenty-seven-month follow-up. There has been no mortality and our morbidity is no more than experienced after transurethral resection of the prostate. By using a Mick applicator our operating time is well under one hour, and our patients go home the same day without a Foley catheter. Our results indicate that patients with PSA values of less than 20 ng/mL (Yang method) and/or Gleason scores of 6 or less are excellent candidates for brachytherapy. By subdividing the percentage of normal PSA values in the follow-up periods according to the patient's original PSA value, further credence is given to the PSA value as a strong aid in staging when the Gleason score is 6 or less. Although the follow-up at twenty-seven months is small, our preliminary results indicate that brachytherapy is a viable option to radical surgery in those patients who are not good candidates for surgery or who prefer nonsurgical treatment.

Pterygia: single-fraction postoperative beta irradiation

A retrospective evaluation was performed with records of 128 patients with 146 eyes that underwent applications of strontium-90 after pterygium excisions performed between 1982 and 1988. With a median follow-up of 13 months, 135 eyes were evaluable. Most pterygia (127 of 135) were treated with a single postoperative application of Sr-90 that delivered 3,000 cGy of beta radiation in one fraction. The actuarial freedom from relapse was 87%; all recurrences occurred within the first 18 months, and 46% of these within the first 3 months. Of the 13 recurrences, 10 have been re-treated with surgery and a second course of beta irradiation with excellent results. All eight eyes for which follow-up was available had no evidence of disease. The ultimate control rate was 96.3% for the series. Correlation of various treatment parameters, including age, bilaterality, prior recurrence, and interval from surgery to irradiation, was performed, and no statistically significant difference was seen. No serious complications have developed. Transient conjunctivitis and photophobia were almost universally seen, with five cases lasting beyond 5 months. The authors conclude that a single application of Sr-90 after surgery is effective and safe in managing pterygia.

Superior sulcus tumors

A retrospective analysis of 35 patients treated for superior sulcus tumors of the lung at UCLA was performed for the years 1960-1983. Follow-up ranged from 19 months to 21 years, with all but one patient followed at least 2 years. The 28 patients with localized disease were treated by megavoltage irradiation with or without surgical resection and had a 5-year survival (product-limit) of 21%. However, the 15 patients receiving combined treatment had a 48% 5-year survival (p = 0.009). An effort was made to identify those factors affecting survival. Patients presenting with no radiographic evidence of nodal enlargement appeared to have a survival advantage with a survival of 31% at 3 years, versus no survivors among those with positive nodes (p = 0.059). Bony erosion contiguous with the primary tumor at presentation was found not to affect the prognosis. Patients with local control of the primary tumor showed a survival of 71% vs 0% for those locally recurring. Those patients receiving at least 55 Gy showed a trend toward increased survival though not with statistical significance. The pattern of failure was evaluable in 25 patients. Local recurrence was observed in 18 patients (72%) with seven (39%) of these manifesting as spinal cord compressions. Distant metastases were seen in 35% of recurrences, and as the sole site of disease in only 10%. Three patients developed brain metastases, all of whom had concomitant local failure. Significant pain relief was achieved in 74% of patients. However, it was transient in 60% of these. We conclude that superior sulcus tumors remain primarily a localized problem, and that aggressive treatment is indicated even with apparently local invasive disease.