Posttreatment biopsy results following interstitial brachytherapy in early-stage prostate cancer

Development and internal validation of multivariable prediction models for biochemical failure after MRI-guided focal salvage high-dose-rate brachytherapy for radiorecurrent prostate cancer

Background and purpose

Magnetic resonance-guided focal salvage high-dose-rate brachytherapy (FS-HDR-BT) for radiorecurrent prostate cancer (PCa) shows low toxicity rates. However, biochemical failure (BF) after treatment occurs frequently. We developed two prediction models for BF (Phoenix definition) with the aim of enhancing patient counselling before FS-HDR-BT and during follow-up.

Materials and methods

A prospective cohort of 150 radiorecurrent PCa patients treated with FS-HDR-BT between 2013 and 2020 was used for model development and internal validation. Multivariable Cox Proportional Hazards regression was applied. For model 1, only pre-salvage variables were included as candidate predictors. For model 2, additional (post-)salvage characteristics were tested. After calibration, nomograms and webtools were constructed. Finally, three risk groups were identified.

Results

Sixty-one patients (41%) experienced BF. At baseline (model 1), age, gross tumour volume, pre-salvage PSA, and pre-salvage PSA doubling time (PSADT) were predictive of BF. During follow-up (model 2), age, pre-salvage PSA and PSADT, seminal vesicle involvement, post-salvage time to PSA nadir, and percentage PSA reduction were predictive of BF. The adjusted C-statistics were 0.73 (95% CI: 0.66-0.81) and 0.84 (95% CI: 0.78-0.90), respectively, with acceptable calibration. Estimated 2-year biochemical disease-free survival for the low-, intermediate-, and high-risk groups were 84%, 70%, and 31% (model 1), and 100%, 71%, and 5% (model 2).

Conclusion

Two models are provided for prediction of BF in patients with radiorecurrent PCa treated with FS-HDR-BT. Based on pre- and post-salvage characteristics, we are able to identify patients with a high risk of BF. These findings can aid patient counselling for FS-HDR-BT.

Diffusion weighted and dynamic contrast enhanced MRI as an imaging biomarker for stereotactic ablative body radiotherapy (SABR) of primary renal cell carcinoma

Purpose

To explore the utility of diffusion and perfusion changes in primary renal cell carcinoma (RCC) after stereotactic ablative body radiotherapy (SABR) as an early biomarker of treatment response, using diffusion weighted (DWI) and dynamic contrast enhanced (DCE) MRI.

Methods

Patients enrolled in a prospective pilot clinical trial received SABR for primary RCC, and had DWI and DCE MRI scheduled at baseline, 14 days and 70 days after SABR. Tumours <5cm diameter received a single fraction of 26 Gy and larger tumours received three fractions of 14 Gy. Apparent diffusion coefficient (ADC) maps were computed from DWI data and parametric and pharmacokinetic maps were fitted to the DCE data. Tumour volumes were contoured and statistics extracted. Spearman’s rank correlation coefficients were computed between MRI parameter changes versus the percentage tumour volume change from CT at 6, 12 and 24 months and the last follow-up relative to baseline CT.

Results

Twelve patients were eligible for DWI analysis, and a subset of ten patients for DCE MRI analysis. DCE MRI from the second follow-up MRI scan showed correlations between the change in percentage voxels with washout contrast enhancement behaviour and the change in tumour volume (ρ = 0.84, p = 0.004 at 12 month CT, ρ = 0.81, p = 0.02 at 24 month CT, and ρ = 0.89, p = 0.001 at last follow-up CT). The change in mean initial rate of enhancement and mean Ktrans at the second follow-up MRI scan were positively correlated with percent tumour volume change at the 12 month CT onwards (ρ = 0.65, p = 0.05 and ρ = 0.66, p = 0.04 at 12 month CT respectively). Changes in ADC kurtosis from histogram analysis at the first follow-up MRI scan also showed positive correlations with the percentage tumour volume change (ρ = 0.66, p = 0.02 at 12 month CT, ρ = 0.69, p = 0.02 at last follow-up CT), but these results are possibly confounded by inflammation.

Conclusion

DWI and DCE MRI parameters show potential as early response biomarkers after SABR for primary RCC. Further prospective validation using larger patient cohorts is warranted.

Preliminary safety and efficacy results with robotic high-intensity focused ultrasound : A single center Indian experience

Background:

There are no Indian data of high-intensity focused ultrasound (HIFU). Being an alternative, still experimental modality, reporting short-term safety outcome is paramount.

Aims:

This study was aimed at to assess the safety and short-term outcome in patients with prostate cancer treated by HIFU.

Settings and Design:

A retrospective study of case records of 30 patients undergoing HIFU between January 2008 to September 2010 was designed and conducted.

Materials and Methods:

The procedural safety was analyzed at 3 months. Follow-up consisted of 3 monthly prostate-specific antigen (PSA) levels and transrectal biopsy if indicated. All the patients had a minimum follow-up of 6 months.

Results:

A mean prostate volume of 26.9 ± 8.5 cm³ was treated in a mean time of 115 ± 37.4 min. There was no intraoperative complication. The postoperative pain visual analogue score at day 0 was 2.1 ± 1.9 and at day 1 was 0.4 ± 0.8 on a scale of 1-10. Mean duration of perurethral catheter removal was 3.9 days. The complications after treatment were: LUTS in seven patients, stress incontinence in two, stricture in two, and symptomatic urinary tract infection in five. Average follow-up duration was 10.4 months (range, 6-20 months). Mean time to obtain PSA nadir was 6 ± 3 months with a median PSA nadir value of 0.3 ng/ml. Two patients had positive prostatic biopsy in the localized (high risk) group.

Conclusions:

HIFU was safe in carcinoma prostate patients. The short-term results were efficacious in localized disease. The low complication rates and favorable functional outcome support the planning of further larger studies.

Low-dose rate brachytherapy for men with localized prostate cancer

BACKGROUND

Localized prostate cancer is a slow growing tumor for many years for the majority of affected men. Low-dose rate brachytherapy (LDR-BT) is short-distance radiotherapy using low-energy radioactive sources. LDR-BT has been recommended for men with low risk localized prostate cancer.

OBJECTIVES

To assess the benefit and harm of LDR-BT compared to radical prostatectomy (RP), external beam radiotherapy (EBRT), and no primary therapy (NPT) in men with localized prostatic cancer.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1950), and EMBASE (from 1980) were searched in June 2010 as well as online trials registers and reference lists of reviews.

SELECTION CRITERIA

Randomized, controlled trials comparing LDR-BT versus RP, EBRT, and NPT in men with clinically localized prostate cancer.

DATA COLLECTION AND ANALYSIS

Data on study methods, participants, treatment regimens, observation period and outcomes were recorded by two reviewers independently.

MAIN RESULTS

We identified only one RCT (N = 200; mean follow up 68 months). This trial compared LDR-BT and RP. The risk of bias was deemed high. Primary outcomes (overall survival, cause-specific mortality, or metastatic-free survival) were not reported. Biochemical recurrence-free survival at 5 years follow up was not significantly different between LDR-BT (78/85 (91.8%)) and RP (81/89 (91.0%)); P = 0.875; relative risk 0.92 (95% CI: 0.35 to 2.42).For severe adverse events reported at 6 months follow up, results favored LDR-BT for urinary incontinence (LDR-BT 0/85 (0.0%) versus RP 16/89 (18.0%); P < 0.001; relative risk 0) and favored RP for urinary irritation (LDR-BT 68/85 (80.0%) versus RP 4/89 (4.5%); P < 0.001; relative risk 17.80, 95% CI 6.79 to 46.66). The occurrence of urinary stricture did not significantly differ between the treatment groups (LDR-BT 2/85 (2.4%) versus RP 6/89 (6.7%); P = 0.221; relative risk 0.35, 95% CI: 0.07 to 1.68). Long-term information was not available.We did not identify significant differences of mean scores between treatment groups for patient-reported outcomes function and bother as well as generic health-related quality of life.

AUTHORS' CONCLUSIONS

Low-dose rate brachytherapy did not reduce biochemical recurrence-free survival versus radical prostatectomy at 5 years. For short-term severe adverse events, low-dose rate brachytherapy was significantly more favorable for urinary incontinence, but radical prostatectomy was significantly more favorable for urinary irritation. Evidence is based on one RCT with high risk of bias.

Post-treatment prostate biopsies in the era of three-dimensional conformal radiotherapy: what can they teach us?

BACKGROUND

The ability to discriminate between therapeutic success and failure after radiotherapy (RT) for prostate cancer (PCa) remains a clinical challenge. Post-treatment biopsies would seem ideal for evaluating innovations such as dose escalation protocols or combination treatments involving brachytherapy or hormones.

OBJECTIVE

Correlate post-treatment biopsy results with prostate-specific antigen (PSA) and clinical outcome in PCa patients treated with three-dimensional conformal radiotherapy (3DCRT) in a dose-escalation study.

DESIGN, SETTING, AND PARTICIPANTS

This study included 160 patients with clinical stage T1c to T3b PCa treated between 1995 and 2005 in Hospital Universitario la Princesa with 3DCRT who consented to and underwent a transrectal ultrasound (TRUS)-guided prostate biopsy 24-36 mo after RT. The median follow-up was 78 mo (range 27-171 mo).

INTERVENTION

The median radiation dose was 74 gray (Gy; range 66.0-84.1). Risk-adapted short-term androgen deprivation (STAD) and long-term androgen deprivation (LTAD) were associated in 25 and 106 patients, respectively. Right and left systematic biopsies were carried out by the same urologist and were examined by a genitourinary pathologist.

MEASUREMENTS

Biochemical disease-free survival (bDFS) according to American Society for Therapeutic Radiology and Oncology (ASTRO) 1997 and Phoenix definition criteria as well as histologic control using post-treatment prostate biopsies.

RESULTS

Twenty-one percent of patients (34 of 160) had post-treatment-positive biopsies (PB). The 5-yr bDFS according to the Phoenix definition was 87%, 65%, and 92% for the whole series (PB and negative biopsies [NB] patients, respectively [p<0.001]). Multivariate analysis showed that biopsy status at 24-36 mo was an independent predictor of bDFS (p<0.0005) and of clinical failure-free survival (p=0.043).

CONCLUSION

The results of the present study show a strong correlation between a post-treatment PB and the 5-yr probability of bDFS, confirming that PSA control can be an adequate surrogate for local control, as assessed by post-treatment biopsies.

Isotope and Patient Age Predict for PSA Spikes After Permanent Prostate Brachytherapy

PURPOSE

To evaluate prostate-specific antigen (PSA) spikes after permanent prostate brachytherapy in low-risk patients.

METHODS AND MATERIALS

The study population consisted of 164 prostate cancer patients who were part of a prospective randomized trial comparing (103)Pd and (125)I for low-risk disease. Of the 164 patients, 61 (37.2%) received short-course androgen deprivation therapy. The median follow-up was 5.4 years. On average, 11.1 post-treatment PSA measurements were obtained per patient. Biochemical disease-free survival was defined as a PSA level of < or =0.40 ng/mL after nadir. A PSA spike was defined as an increase of > or =0.2 ng/mL, followed by a durable decline to prespike levels. Multiple parameters were evaluated as predictors for a PSA spike.

RESULTS

Of the 164 patients, 44 (26.9%) developed a PSA spike. Of the 46 hormone-naive (125)I patients and 57 hormone-naive (103)Pd patients, 21 (45.7%) and 8 (14.0%) developed a PSA spike. In the hormone-naive patients, the mean time between implantation and the spike was 22.6 months and 18.7 months for (125)I and (103)Pd, respectively. In patients receiving neoadjuvant androgen deprivation therapy, the incidence of spikes was comparable between isotopes ((125)I 28.1% and (103)Pd 20.7%). The incidence of spikes was substantially different in patients <65 years vs. > or =65 years old (38.5% vs. 16.3%). On multivariate Cox regression analysis, patient age (p < 0.001) and isotope (p = 0.002) were significant predictors for spike.

CONCLUSION

In low-risk prostate cancer, PSA spikes are most common in patients implanted with (125)I and/or <65 years of age. Differences in isotope-related spikes are most pronounced in hormone-naive patients.

Patterns of Local Failure Following Prostate Brachytherapy

PURPOSE

We describe biopsy results in patients with prostate cancer treated with brachytherapy.

MATERIALS AND METHODS

A total of 1,562 men with localized prostate cancer were treated with permanent prostate brachytherapy, of whom 508 agreed to ultrasound guided biopsies 2 years after the completion of all therapy. Median followup was 6.7 years (range 2 to 14.6) and median prostate specific antigen was 7.4 ng/ml (range 0.3 to 300). Disease was categorized as Gleason score less than 7 in 74.8% of patients, stage T2a or less in 64.2%, low risk in 43.1%, intermediate risk in 24.2% and high risk in 32.7%. Of the 508 men 315 (62%) received (125)I, 110 (21.7%) received (103)Pd and 83 (16.3%) received (103)Pd and external beam radiotherapy. A total of 237 men (46.7%) received a short course of hormonal therapy (3 to 9 months). Subsequent biopsies were performed after 2 years if initial biopsy was positive or prostate specific antigen increased. Post-implantation dosimetry results were grouped into low, normal and high dose. Associations were tested by chi-square analysis. Survival functions were calculated with Kaplan-Meier analysis and Cox regression.

RESULTS

A total of 643 biopsies were performed in 508 men between 2 and 11 years after implantation. Of the 508 men 39 (7.7%) had a final positive biopsy. Positive biopsy was associated with high prostate specific antigen (p=0.035), stage (p=0.003), risk (p=0.024), no hormonal therapy (p=0.002) and low dose (p<0.0001). On multivariate analysis only dose and hormonal therapy were significant (p<0.0001 and p=0.004, respectively). Of the patients 80% were free of PSA failure at 10 years if final biopsy was negative compared to 27.3% with a positive biopsy (p<0.0001). Death from prostate cancer was associated with a positive biopsy (OR 18.5, 95% CI 2.3-143, p<0.0001). Of the 52 men with a positive biopsy at year 2, 23 (44.2%) had negative results on subsequent biopsy, while 10 of the 456 (2.2%) with negative 2-year biopsies showed positive results. Positive biopsy occurred in the prostate only in 31 of 39 men (79.5%), in the prostate and seminal vesicles in 3 (7.7%), and in the seminal vesicles only in 5 (12.8%).

CONCLUSIONS

Patients undergoing prostate brachytherapy must receive an adequate radiation dose to eradicate local disease. Hormonal therapy may benefit local control in patients with intermediate to high risk disease. Extraprostatic biopsies should be performed in patients with local failure who are considering salvage therapy to rule out seminal vesicle involvement.

Cryoablation as Primary Treatment for Localized Prostate Cancer Followed by Penile Rehabilitation

OBJECTIVES

To determine the medium term efficacy and morbidity of patients who underwent cryoablation as primary therapy for localized prostate cancer followed by a penile rehabilitation regimen.

METHODS

Patients were treated with whole gland cryoablation. Those potent at intervention were encouraged to use a vacuum erection device regularly after treatment. Incontinence was defined as any leakage of urine. Potency was defined as the ability to achieve an erection sufficient to complete intercourse with or without oral pharmaceutical agents. Biochemical failure was defined as three successive rises in prostate-specific antigen, with a final value greater than 1.0 ng/mL.

RESULTS

A total of 416 consecutive patients were treated. The mean patient age was 69.4 years, mean prostate-specific antigen level was 8.7 ng/mL, median Gleason score was 6, and median stage was T1c. The mean follow-up of the entire population was 20.4 +/- 14.7 months. Of those continent before treatment, 4.0% were incontinent at 6 months but only 2 (0.6%) used any absorbent pads. Kaplan-Meier analysis demonstrated progressive recovery of sexual function of preoperatively potent men, with 41.4% +/- 4.3% and 51.3% +/- 5.9% potent 1 and 4 years after treatment, respectively. No patients had rectal fistula. The actuarial probability of remaining biochemically disease free at 4 years was 79.6% +/- 2.4%, with a mean time to failure of 4.2 months. After therapy, 168 patients underwent biopsy; 17 had positive findings (10.1%). The positive biopsy rate for the entire population was 4.1% (17 of 416).

CONCLUSIONS

The results of our study have indicated that cryoablation as a primary treatment of localized prostate cancer is effective with acceptable morbidity. The use of a penile rehabilitation regimen after treatment appeared to substantially increase postcryoablation potency.

Short-term outcome after high-intensity focused ultrasound in the treatment of patients with high-risk prostate cancer

OBJECTIVE

To assess the short-term outcome in patients with high-risk prostate cancer treated by transrectal high-intensity focused ultrasound (HIFU).

PATIENTS AND METHODS

From April 2003 to November 2004, 30 patients with high-risk prostate cancer were enrolled in this prospective study; all had transurethral resection of the prostate before transrectal HIFU treatment, using the Ablatherm device (EDAP, Lyon, France) during the same session, associated with hormonal therapy with luteinizing hormone-releasing hormone analogues. After the procedure, all the patients were evaluated every 3 months by physical examination, prostate-specific antigen (PSA) assay and a continence questionnaire. The follow-up schedule also included a transperineal prostate biopsy 6 months after the treatment. All the patients had a minimum follow-up of 12 months.

RESULTS

The HIFU treatment took a median (interquartile range, IQR) of 140 (100-160) min. No complications were reported during treatment. The mean (IQR) hospitalization was 2.2 (1-4) days, and the suprapubic drainage tube was removed after 12 (7-18) days. The complications after treatment were: urinary tract infections in five patients (16%), stenosis of the intraprostatic and membranous urethra in three (10%), and secondary infravesical obstruction in four (13%). At 12 months after the procedure, 28 patients (93%) were continent. Seven of the 30 men (23%) had a positive prostate biopsy. At the 1-year follow-up only three of the 30 patients with high-risk prostate cancer had a PSA level of >0.3 ng/mL.

CONCLUSIONS

HIFU is a modern, minimally invasive therapy for prostate cancer, often used in selected patients with localized disease. The present results show that HIFU was also feasible in patients with high-risk prostate cancer. The low complication rates and favourable functional outcome support the planning of further larger studies in such patients. The oncological efficacy of HIFU should be assessed in further studies with a longer follow-up.

Percentage of positive biopsies associated with freedom from biochemical recurrence after low-dose-rate prostate brachytherapy alone for clinically localized prostate cancer

OBJECTIVES

To examine the relationship between the percentage of positive biopsies (PPBs) and freedom from biochemical recurrence (FFBR) in men treated with low-dose-rate prostate brachytherapy (LDRPB) alone. The PPBs has been associated with FFBR in men treated with radical prostatectomy and external beam radiotherapy for prostate cancer.

METHODS

This report concerns 108 men treated with LDRPB alone between November 1997 and December 1999. All patients had clinically localized prostate cancer confirmed by biopsy. All men were treated with iodine-125 to 144 Gy. FFBR was estimated using the product-limit method. Putative covariates for FFBR, including T stage, Gleason score, pretreatment prostate-specific antigen level, minimal dose received by 90% of the target volume, and PPBs, were examined using the proportional hazards regression model.

RESULTS

The median follow-up was 61 months. Of the 108 men, 13 developed evidence of biochemical relapse at a median of 25 months. The 5-year estimate of FFBR was 87% (95% confidence interval 81% to 93%) for the entire cohort. On univariate analysis, prostate-specific antigen, T stage, minimal dose received by 90% of the target volume, and PPBs were associated with FFBR. In the multivariate model, the PPBs was the only variable that predicted for FFBR (P = 0.002). The 5-year estimate of FFBR was 95% for patients with less than 50% PPB disease versus 63% in patients with more than 50% PPB disease (P < 0.0001).

CONCLUSIONS

The PPBs is an important independent predictor of FFBR after LDRPB alone. The FFBR after LDRPB in the group of patients with more than 50% PPBs was poor.

Recommendations of the American Association of Physicists in Medicine regarding the impact of implementing the 2004 task group 43 report on dose specification for 103Pd and 125I interstitial brachytherapy

In March 2004, the recommendations of the American Association of Physicists in Medicine (AAPM) on the interstitial brachytherapy dosimetry using 125I and 103Pd were reported in Medical Physics [TG-43 Update: Rivard et al., 31, 633-674 (2004)]. These recommendations include some minor changes in the dose-calculation formalism and a major update of the dosimetry parameters for eight widely used interstitial brachytherapy sources. A full implementation of these recommendations could result in unintended changes in delivered dose without corresponding revisions in the prescribed dose. Because most published clinical experience with permanent brachytherapy is based upon two widely used source models, the 125I Model 6711 and 103Pd Model 200 sources, in this report we present an analysis of the dosimetric impact of the 2004 TG-43 dosimetry parameters on the history of dose delivery for these two source models. Our analysis indicates that the currently recommended prescribed dose of 125 Gy for Model 200 103Pd implants planned using previously recommended dosimetry parameters [AAPM 103Pd dose prescription: Williamson et al., Med. Phys. 27, 634-642 (2000)] results in a delivered dose of 120 Gy according to dose calculations based on the 2004 TG-43 update. Further, delivered doses prior to October 1997 varied from 113 to 119 Gy for a prescribed dose of 115 Gy compared to 124 Gy estimated by the AAPM 2000 report. For 125I implants using Model 6711 seeds, there are no significant changes (less than 2%). Practicing physicians should take these results into account when selecting the clinically appropriate prescribed dose for 103Pd interstitial implant patients following implementation of the 2004 TG-43 update dose-calculation recommendations. The AAPM recommends that the radiation oncology community review this report and consider whether the currently recommended dose level (125 Gy) needs to be revised.

70 Gy or more: which dose for which prostate cancer?

INTRODUCTION

Radical prostatectomy and radiotherapy are currently accepted treatment modalities for localized prostate cancer. Regarding radiotherapy, current evidence suggests that favorable treatment outcome critically depends on adequate radiation doses. However, the exact role of dose in relation to the individual risk profile is complex. In order to evaluate available data on radiation dose response relationships, in prostate cancer, a thorough and critical literature analysis was performed.

MATERIAL AND METHODS

Studies on dose response relationships from randomized trials, dose escalation trials, retrospective subgroup analyses and pooled data were identified by Pubmed and ISI web of sciences searches and were critically reviewed.

RESULTS AND CONCLUSION

All available data suggest a clear dose response relationship for radiotherapy for localized prostate cancer. In low risk cases, most studies suggest that doses of 70-72 Gy are adequate. Dose escalations up to 78-80 Gy seem to be beneficial for intermediate risk patients. Due to confounding variables, the dose response curves for high-risk patients are less steep. The integration of dose escalation into a more comprehensive treatment protocol is difficult, since trials on the relative impact of either hormonal ablation or inclusion of adjuvant nodal regions on dose escalation are missing.

Posttreatment Complications of Early-Stage Prostate Cancer Patients

PURPOSE

The purpose of this study was to compare treatment complications for early-stage prostate cancer managed by either brachytherapy or three-dimensional conformal radiotherapy (3D-CRT).

MATERIALS AND METHODS

[corrected] Records were reviewed for 86 men treated with transperineal interstitial permanent prostate brachytherapy and for 76 men treated with dose-escalated (75.6-Gy) six-field 3DCRT between 1998 and 2000. Median ages were 65 and 66 years, respectively; median Gleason scores were 6 and 7; baseline prostate-specific antigen levels were 6.1 and 9.0 ng/mL; and the follow-up period was 42 months. In the urinary domain, patients who underwent brachytherapy recorded an International Prostate Symptom Score prospectively at baseline, as well as 3 months and every 6 months following, whereas patients who underwent 3D-CRT were assigned a Radiation Therapy Oncology Group (RTOG) late toxicity score at similar time intervals. In the bowel domain, RTOG late toxicity score was used for both groups, and physician-dictated notes were used to assess sexual function. All patients who underwent brachytherapy were prescribed tamsulosin (Flomax) to manage urinary symptoms for a minimum of 3 months after treatment.

RESULTS

With respect to urinary symptoms, a direct comparison cannot be made between the International Prostate Symptom Score and the RTOG late toxicity score. Nonetheless, it was evident that patients who underwent brachytherapy had more severe urinary sequelae in the months after implantation. Tamsulosin was still being used by 78% of patients at 6 months, decreasing to 55% at 1 year and 27% at 2 years. Intermittent self-catheterization was required at 6 months after treatment by 5% of patients who underwent brachytherapy, and a transurethral resection of the prostate was performed in one of these patients at 12 months. In patients who underwent 3D-CRT, 14% used tamsulosin at some point in the follow-up period and none required catheterization or transurethral resection of the prostate. In the bowel domain, 20% of patients who underwent brachytherapy experienced grade 1 gastrointestinal toxicity, most within the first 12 months of follow-up, compared with 30% grade 1 or 2 gastrointestinal scores in the 3D-CRT group (peaking in the second year after treatment). In the sexual domain, 9% of patients who underwent brachytherapy who were previously potent reported a loss of potency by 18 months, compared with 53% of patients who underwent 3D-CRT. Without the help of sildenafil (Viagra), these figures rose to 24% and 58%.

CONCLUSIONS

3D-CRT is associated with fewer urinary symptoms, whereas brachytherapy has a more favorable toxicity profile for bowel and sexual function. In the absence of a randomized clinical trial, such a comparison can be helpful both in counseling patients as to what to expect from either treatment and in facilitating their treatment decision process.

Undetectable prostate specific antigen at 6-12 months

BACKGROUND

The concept of a prostate-specific antigen (PSA) "nadir" has been used as a predictive marker for treatment success in patients treated with radiotherapy for localized prostate carcinoma. However, this approach is not applicable in patients who are concomitantly treated with short-term hormonal therapies. To address this, the authors sought to develop a new predictive marker in such patients after prostate brachytherapy (BT).

METHODS

Between March 1997 and November 2002, 194 men with clinical Stage T1A-T3N0M0 prostate carcinoma (according to the 1992 International Union Against Cancer/American Joint Committee on Cancer TNM classification system) were treated with interstitial palladium (103Pd3) BT and androgen ablation therapy with or without external beam radiotherapy (EBRT). Based on tumor characteristics, 127 patients received an antiandrogen, finasteride, and BT whereas 67 received an antiandrogen, leuprolide, and EBRT followed by a BT boost. Hormonal therapy was initiated 2-3 months before any radiotherapy for a total duration of 8-9 months. Follow-up included physical examination and determining the PSA level at 3-month intervals. Postoperative serum testosterone was evaluated in preoperatively potent patients with erectile dysfunction > 6 months after therapy. A PSA level < or = 0.06 ng/mL or < or = 0.20 ng/mL detected during a 6-12-month window after the implant were evaluated as predictors of biochemically disease-free survival (DFS), defined as the time to a PSA level > or = 1.0 ng/mL.

RESULTS

Of the 194 patients, 163 were available for analysis. The median length of follow-up was 48 months. In those patients with a PSA level < or = 0.20 ng/mL at 6-12 months, the DFS at 48 months after the implant was 96% (95% confidence interval [95% CI], 91-99%) compared with the remainder of the patients, whose DFS decreased to 80% (95% CI, 65-89%) (P < 0.001). When a PSA level < or = 0.06 ng/mL was used as an indicator, the 48-month DFS was 99% (95% CI, 91-100%) compared with that for patients with a PSA level > 0.06 ng/mL, in whom the DFS was 85% (95% CI, 74-92%) (P = 0.004). Furthermore, because testosterone levels may occasionally remain low after the cessation of luteinizing hormone-releasing hormone agonist therapy and result in erectile dysfunction and an artificially low PSA level, the authors reviewed the serum testosterone levels in 23 patients who were so treated and were experiencing erectile dysfunction. None had PSA values below the lower limit of normal.

CONCLUSIONS

A PSA level < or = 0.20 ng/mL or < or = 0.06 ng/mL measured at 6-12 months after BT appears to be a useful predictive marker for detecting early success in patients with prostate carcinoma who are treated with neoadjuvant androgen ablation and BT. These markers may be used to identify those patients who are at an increased risk of biochemical failure and may be useful in stratifying patients for closer follow-up, long-term adjuvant therapies, or clinical trials. A longer follow-up period will be needed to verify whether these are predictive of long-term cancer control.

Clinical correlates to PSA spikes and positive repeat biopsies after prostate brachytherapy

OBJECTIVES

To make some preliminary observations regarding the biochemical characteristics of the doubly confusing picture of prostate-specific antigen (PSA) spikes and histologically positive biopsies after prostate brachytherapy.

METHODS

All patients reported here had a pretreatment PSA level of less than 10 ng/mL and Gleason score of 4 to 6. Transperineal iodine-125 implants (without supplemental beam radiotherapy) were performed as previously described. After implantation, patients were followed up routinely, with repeat PSA measurements and physical examinations every 4 to 6 months. The timing of the postimplant PSA measurements was at the discretion of the patients and their doctors. No patient received preimplant or postimplant hormonal therapy. Repeat biopsies were performed from 13 to 31 months (median 22) after implant.

RESULTS

Patients' prespike nadir ranged from 0.9 to 1.7 ng/mL (median 1.2). The time from the implant to the start of the spike ranged from 9 to 24 months (median 13). The time from implant to the spike peak ranged from 12 to 30 months (median 22). The peak spike height ranged from 2.6 to 8.4 ng/mL (median 3.1). Patients' last PSA value ranged from 0.1 to 0.5 ng/mL (median 0.2).

CONCLUSIONS

Transient PSA rises can occur even in the presence of a persistently positive biopsy, and patients and physicians should not feel compelled to rush ahead with salvage therapy. On the basis of the patient data reported here, it appears that a spike up to 10 ng/mL is still consistent with cancer eradication.

Atypia in nonneoplastic prostate glands after radiotherapy for prostate cancer: duration of atypia and relation to type of radiotherapy

It is unknown how long postradiation atypia of benign prostate glands persists and whether the type of radiation is a factor. Forty-four cases consisting of 37 needle biopsies and 7 transurethral resections of the prostate seen in consultation (January 1997 to September 2000) were studied. In two men (5%), the cases were initially sent without a history of radiotherapy. Thirteen patients had minimal cancer (one core) with the remaining showing no residual tumor. Twenty patients were treated with interstitial radiotherapy (brachytherapy) (IRT), 17 with external beam radiation (XRT), and 7 with a combination of both (CT). The time interval between the treatment and tissue sampling ranged from 8 to 72 months (mean 3 months). Slides were reviewed blindly to the type of radiation and the time interval. Radiation-induced atypia in nonneoplastic glands, stromal fibrosis, and vascular changes was scored separately 0-3, with 0 showing no radiation injury and grade 3 showing prominent nuclear atypia, stromal fibrosis, and vascular hyalinization. We derived a combined score for the epithelial atypia from 0 to 300 (% of glands x grade) for each biopsy. For each case, an overall grade from 0 to 3 was given separately for the stromal and vascular changes. Cases were divided into three groups based on time between treatment and biopsy: <24 months (n = 14), between 24 and 48 months (n = 19), and >48 months (n = 11). Because the scores for epithelial atypia with IRT and CT were the same, we combined them into one group. There was more atypia in cases treated with IRT/CT (mean score 190) than XRT (mean score 105) (p <0.00001). There was also a greater degree of stromal fibrosis with IRT/CT than XRT (p <0.04). There was no correlation between the type of treatment and the effect on vessels. There was no change over time in epithelial atypia in men treated with IRT/CT. With XRT, there was less epithelial atypia in cases biopsied >48 months after treatment (mean score 57) compared with those with a shorter interval between biopsy and treatment (mean score 132) (p = 0.02). Radiation atypia in benign prostate glands may persist for a long time after the initial treatment, resulting in a significant pitfall in evaluating prostate biopsies. Prominent radiation effect (100% of the glands showing grade 2 and 3 atypia) was detected up to 72 months in one of the patients treated with IRT. In some cases, the clinician may not be aware of a prior remote history of radiation or does not relay this history to the pathologist. The pathologist must recognize radiation atypia without relying on the clinician to provide this history. The type of radiation therapy (IRT/CT vs XRT) is a major factor in the degree and duration of postradiation epithelial atypia.

Prostate-specific antigen (PSA) velocity and benign prostate hypertrophy predict for PSA spikes following prostate brachytherapy

PURPOSE

To evaluate if variants of serum PSA or benign prostatic hypertrophy correlate with the development of a PSA spike following permanent prostate brachytherapy.

METHODS AND MATERIALS

Two-hundred-eighteen hormone-naïve patients with clinical T1b-T3a (1997 AJCC) prostate cancer who were treated with brachytherapy between August 1995 and November 1999, with or without supplemental external beam radiation therapy, and who remained free of biochemical failure were analyzed. The median follow-up was 46 months. A PSA spike was defined as a rise > or =0.2 ng/mL followed by a durable decline. Biochemical disease-free survival was defined by the ASTRO Consensus Definition with the additional constraint that the most recent PSA be < or =1.0 ng/mL. In addition, none of the patients possessed equivocal biochemical results (1 or 2 consecutive PSA rises or a declining PSA >1.0 ng/mL). In addition to previously reported clinical, treatment, and dosimetric parameters evaluated for spike, PSA density, transition zone (TZ) PSA density, percent free PSA, PSA velocity, PSA doubling time, TZ volume, and transition zone index (TZI) were included. The PSA kinetics of 18 hormone naïve patients who were implanted during the same time period and subsequently failed were also evaluated.

RESULTS

Fifty-two (23.9%) developed a PSA spike. Of the demographic and preimplant clinical parameters, patient age, TZ volume, TZI, TZ PSA density, and 125I were statistically significant predictors for a PSA spike. Of the postimplant parameters, V200, follow-up, first postimplant PSA, and most recent PSA predicted for a PSA spike. In multivariate Cox regression analysis, PSA nadir, TZI, follow-up, age, months to PSA nadir and preimplant PSA velocity were significant predictors for spike. However, when variables only determinable after a PSA spike were included in the multivariate analysis, TZI, age, PSA velocity, and first postimplant PSA were predictors for a spike. Using categorical cutpoints of TZI >0.25, age at implant <62 years, and first postimplant PSA >1.0 ng/mL in the regression analysis, a positive likelihood ratio for a PSA spike of >1.8 was noted for each variable. Patients with PSA progression displayed significantly different PSA kinetics than those with a spike.

CONCLUSIONS

In multivariate analysis, PSA nadir, TZI, patient age, months to PSA nadir, follow-up, and preimplant PSA velocity were predictive of a PSA spike. However, when only variables identifiable prior to a spike were evaluated, TZI, patient age, preimplant PSA velocity, and first postimplant PSA were the strongest predictors for a PSA spike.

Prostate-specific antigen spikes after permanent prostate brachytherapy

PURPOSE

To evaluate whether any clinical, treatment, or dosimetric parameters correlated with the development of a prostate-specific antigen (PSA) spike after permanent prostate brachytherapy.

METHODS AND MATERIALS

The evaluated population consisted of 218 hormone-naive patients free of biochemical or clinical failure who underwent permanent prostate brachytherapy with or without supplemental external beam radiotherapy for clinical Stage T1b-T3a adenocarcinoma of the prostate gland (1997 AJCC) between August 1995 and November 1999. No patient underwent pre- or postimplant hormonal manipulation, pretreatment seminal vesicle biopsy, or pathologic lymph node staging. In addition, none of the 218 patients possessed equivocal biochemical results (one or two consecutive PSA rises or a declining PSA >1.0 ng/mL). The median patient follow-up was 46.2 months. A PSA spike was defined as a rise of >or=0.2 ng/mL, followed by a durable decline. The clinical parameters evaluated included patient age, clinical T stage, Gleason score, pretreatment PSA level, prostate volume, brachytherapy planning volume, and patient follow-up in months. The evaluated treatment parameters included isotope and use of supplemental external beam radiotherapy. The dosimetric parameters evaluated included the minimal dose received by 90% of the prostate gland (D(90)), the percentage of the prostate volume receiving 100% (V(100)), 150%, and 200% (V(200)) of the prescribed minimal peripheral dose, and the mean, median, maximal, and minimal urethral doses. Biochemical disease-free survival was defined by the American Society for Therapeutic Radiology and Oncology consensus definition with the additional constraint that the most recent PSA level was <or=1.0 ng/mL.

RESULTS

Fifty-two patients (23.9%) developed a PSA spike at a mean and median of 19.5 +/- 9.4 months and 16.3 months (range 6.5-59.9), respectively. The median serum PSA before the PSA spike was 0.50 ng/mL, and the median PSA at the time of the spike was 0.90 ng/mL (range 0.3-3.0). On average, patients experiencing a PSA spike were 3.4 years younger (63.9 vs. 67.3 years, p = 0.002) than patients not experiencing a spike and were more likely to have been implanted with 125I than with 103Pd (32.7% vs. 16.7%, p = 0.006). In addition, the mean first postimplant PSA level was significantly higher in the spike than in the nonspike patients (1.2 vs. 0.7 ng/mL, p <0.001). By 66 months, the mean and median serum PSA levels for the spike and nonspike patients were all <or=0.1 ng/mL. Stratified into three nadir PSA groups, patients with a nadir PSA <or=0.2 ng/mL were significantly less likely to develop a PSA spike than those patients with a PSA nadir >0.2 to <or=0.5 ng/mL or >0.5 to 1.0 ng/mL (20%, 50%, and 80%, respectively, p <0.001). In Cox multivariate regression analysis, patient age, clinical stage, first postimplant PSA level, and V(150) were predictive for the development of a PSA spike. A postimplant dosimetric threshold of either <115% of the minimal peripheral dose for D(90) or <55% of the prostate volume for V(150) was strongly predictive of a spike. When the variables only determinable after the occurrence of the PSA spike were included in the multivariate analysis, V(150), preimplant PSA level, and nadir PSA were the significant predictors.

CONCLUSION

Of the patients, 23.9% developed a PSA spike with a median time to development of 16.3 months and a median prespike and median postspike PSA of 0.50 ng/mL and 0.90 ng/mL, respectively. In multivariate analysis, patient age, clinical stage, first postimplant PSA level, and V(150) were predictive for the development of a PSA spike. At approximately 66 months after implantation, the PSA curves converged for spike and nonspike patients, with a median PSA level <0.1 ng/mL.

Pathologic evidence of dose-response and dose-volume relationships for prostate cancer treated with combined external beam radiotherapy and high-dose-rate brachytherapy

PURPOSE

The clinical significance of postradiotherapy (RT) prostate biopsy characteristics is not well understood relative to the known prognostic factors. We performed a detailed pathologic review of posttreatment biopsy specimens in an attempt to clarify their relationship with clinical outcome and radiation dose.

METHODS AND MATERIALS

Between 1991 and 1998, 78 patients with locally advanced prostate cancer were prospectively treated with external beam RT in combination with high-dose-rate brachytherapy at William Beaumont Hospital and had post-RT biopsy material available for a complete pathologic review. Patients with any of the following characteristics were eligible for study entry: pretreatment prostate-specific antigen level > or =10.0 ng/mL, Gleason score > or =7, or clinical Stage T2b-T3cN0M0. Pelvic external beam RT (46.0 Gy) was supplemented with three (1991-1995) or two (1995-1998) ultrasound-guided transperineal interstitial (192)Ir high-dose-rate implants. The brachytherapy dose was escalated from 5.50 to 10.50 Gy per implant. Post-RT prostate biopsies were performed per protocol at a median interval of 1.5 years after RT. All pre- and post-RT biopsy specimen slides from each case were reviewed by a single pathologist (N.S.G.). The presence and amount of residual cancer, most common RT-effect score, and least amount RT-effect score were analyzed. The median follow-up was 5.7 years. Biochemical failure was defined as three consecutive prostate-specific antigen rises.

RESULTS

Forty patients (51%) had residual cancer in the post-RT biopsies. The 7-year biochemical control rate was 79% for patients with negative biopsies vs. 62% for those with positive biopsies with marked RT damage vs. 33% for those with positive biopsies with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores (p = 0.01), lower total RT dose (p = 0.001), lower dose per implant (p = 0.001), and greater percentage of positive post-RT biopsy cores (p = 0.01) were each associated with biochemical failure (Cox regression, univariate analysis). For patients with <25% positive post-RT biopsy cores, the 7-year biochemical control rate was 81% vs. a 62% biochemical control rate for those with 25-49% positive cores and only 32% for those with > or =50% positive cores (p = 0.01). On Cox multiple regression analysis, only the percentage of positive pre-RT biopsy cores and RT dose remained significantly associated with biochemical failure. Of all the factors analyzed, only the pretreatment cancer volume and lower RT dose were significantly associated with residual cancer and/or residual cancer with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.04). A lower total RT dose was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.02). For patients who received <80 Gy (equivalent in 2-Gy fractions), 73% had positive post-RT biopsies vs. a 56% biopsy positivity rate for those who received 84-90 Gy and only 39% for those who received > or =92 Gy (p = 0.07).

CONCLUSION

Patients with positive post-RT biopsies are more likely to experience biochemical failure, especially when the RT damage is minimal. Patients who have a larger pretreatment tumor volume or receive a lower RT dose are more likely to demonstrate post-RT biopsy positivity and biochemical failure.

The influence of percentage of preradiation needle biopsies with adenocarcinoma and total radiation dose on the pathologic response of unfavorable prostate adenocarcinoma

We studied relationships among clinicopathologic factors in 78 patients with unfavorable prostate adenocarcinoma treated in a dose-escalation radiation therapy (RT) study using pre- and 18-month protocol post-RT biopsy specimens. Pre-RT factors analyzed were serum prostate-specific antigen (PSA) level, Gleason score, and percentage of needle cores with adenocarcinoma; post-RT factors were percentage of needle cores with adenocarcinoma and amount of radiation effect on the adenocarcinoma. Of 78 patients, 42 (54%) had residual adenocarcinoma in the post-RT biopsy specimen. Lower total RT dose and dose per implant and greater serum PSA level were associated with an increasing percentage of needle cores with residual post-RT adenocarcinoma. Lower RT dose, an increasing percentage of pre-RT needle cores with adenocarcinoma, and a greater serum PSA level were associated with an increasing percentage of post-RT needle cores with no to moderate RT effect scores in adenocarcinoma. The mean percentage of pre-RT and post-RT needle cores with adenocarcinoma was greater in patients with post-RT biopsy specimens with no to moderate RT effect. The percentage of pre-RT needle cores with adenocarcinoma (a surrogate marker of adenocarcinoma volume), serum PSA level, and RT dose are the key components in the dose-response relationship. Gleason score and gland volume did not contribute significantly to this relationship.

[Clinical and biological surveillance after radiotherapy for localized prostate cancer]

Serum PSA is an excellent marker of disease status after external beam radiotherapy or brachytherapy for patients with prostate carcinoma. A low PSA nadir < or = 1 even < or = 0.5 ng/mL has been shown to be as a surrogate end point for disease control. Three successive increases of this marker after achieving the nadir defines recurrence as recommended by the American Society for Therapeutic Radiology and Oncology. The biochemical relapse or PSA failure after treatment precedes clinical disease relapse by several months. PSA profile or kinetics may have implications for patterns of failure and prognosis. Prostate post-radiotherapy biopsies should not be part of routine follow-up as its interpretation is frequently problematic. Other exams should not be performed unless clinical symptoms are present. Post-radiotherapy relapse treatment has generally no curative intent.

Risk group dependence of dose-response for biopsy outcome after three-dimensional conformal radiation therapy of prostate cancer

BACKGROUND AND PURPOSE

We fit phenomenological tumor control probability (TCP) models to biopsy outcome after three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer patients to quantify the local dose-response of prostate cancer.

MATERIALS AND METHODS

We analyzed the outcome after photon beam 3D-CRT of 103 patients with stage T1c-T3 prostate cancer treated at Memorial Sloan-Kettering Cancer Center (MSKCC) (prescribed target doses between 64.8 and 81Gy) who had a prostate biopsy performed >or=2.5 years after end of treatment. A univariate logistic regression model based on D(mean) (mean dose in the planning target volume of each patient) was fit to the whole data set and separately to subgroups characterized by low and high values of tumor-related prognostic factors T-stage (<T2c vs. >or=T2c), Gleason score (<or=6 vs. >6), and pre-treatment prostate-specific antigen (PSA) (<or=10 ng/ml vs. >10 ng/ml). In addition, we evaluated five different classifications of the patients into three risk groups, based on all possible combinations of two or three prognostic factors, and fit bivariate logistic regression models with D(mean) and the risk group category to all patients. Dose-response curves were characterized by TCD(50), the dose to control 50% of the tumors, and gamma(50), the normalized slope of the dose-response curve at TCD(50).

RESULTS

D(mean) correlates significantly with biopsy outcome in all patient subgroups and larger values of TCD(50) are observed for patients with unfavorable compared to favorable prognostic factors. For example, TCD(50) for high T-stage patients is 7Gy higher than for low T-stage patients. For all evaluated risk group definitions, D(mean) and the risk group category are independent predictors of biopsy outcome in bivariate analysis. The fit values of TCD(50) show a clear separation of 9-10.6Gy between low and high risk patients. The corresponding dose-response curves are steeper (gamma(50)=3.4-5.2) than those obtained when all patients are analyzed together (gamma(50)=2.9).

CONCLUSIONS

Dose-response of prostate cancer, quantified by TCD(50) and gamma(50), varies by prognostic subgroup. Our observations are consistent with the hypothesis that the shallow nature of clinically observed dose-response curves for local control result from a patient population that is a heterogeneous mixture of sub-populations with steeper dose-response curves and varying values of TCD(50). Such results may eventually help to identify patients, based on their individual pre-treatment prognostic factors, that would benefit most from dose-escalation, and to guide dose prescription.

Factors influencing risk of acute urinary retention after TRUS-guided permanent prostate seed implantation

PURPOSE

To look for factors predictive of acute urinary retention (AUR) after permanent seed prostate brachytherapy.

METHODS AND MATERIALS

From March 1999 to February 2001, 150 permanent seed prostate implants were performed at Princess Margaret Hospital (Stage T1c, n = 113; T2a, n = 37; mean prostate-specific antigen level 5.9 ng/mL, prescription dose 145 Gy per Task Group No. 43). alpha-Blockers were used routinely after implantation. Dosimetry was based on the 1-month postimplant CT scan. The International Prostate Symptom Score (IPSS) and catheterization were recorded at 1 month and 3 months and then every 3 months. The following variables were examined: age, baseline IPSS, prior androgen ablation, prostate transrectal ultrasound volume, number of seeds, D(90), V(100), V(200), and urethral dose.

RESULTS

Twenty patients (13%) experienced AUR. No difference was seen in the mean D(90) (149 Gy vs. 152 Gy, p = 0.6), V(100) (90% vs. 91%, p = 0.6), V(200) (23% vs. 25% p = 0.4), IPSS (6.4 vs. 5.9, p = 0.8), or maximal urethral dose (204 Gy vs. 210 Gy, p = 0.5). The prostate volume was significantly larger in men with AUR (39.8 cm(3) vs. 34.3 cm(3), p = 0.003), and the mean number of seeds was higher (112 vs. 103, p = 0.006). Of the 20 patients experiencing AUR, 11 (55%) had received prior antiandrogen therapy to downsize their prostates vs. 35 (27%) of the 130 who did not have AUR (p = 0.02). Multivariate analysis showed prostate volume and prior hormone use to be independent predictors of AUR.

CONCLUSIONS

Implant quality as determined by D(90), V(100), V(200), and urethral dose did not predict AUR. Prostate size was the major determinant of AUR. For any given prostate size, prior androgen ablation increased the risk of AUR. Men with larger prostates should be aware of the increased risk when contemplating brachytherapy.

The utility of transition zone index in predicting acute urinary morbidity after 125I prostate brachytherapy

PURPOSE

Acute urinary morbidity after prostate brachytherapy is common and, although usually self-limited, can be distressing to the patient, especially if acute urinary retention (AUR) develops. We undertook to determine whether prospective measurement of the transition zone index would be predictive of either urinary retention or the severity of urinary symptoms after brachytherapy.

METHODS AND MATERIALS

One hundred men undergoing transperineal interstitial permanent prostate brachytherapy (TIPPB) with 125I underwent transrectal ultrasound before the procedure to measure prostate and transition zone (TZ) volumes. TZ index was calculated as TZ volume divided by total prostate volume. TIPPB was performed between July 2000 and January 2002. Patients were observed for 1, 3, or 6 months with an International Prostate Symptom Score (IPSS) at each visit. alpha-Blockers were prescribed prophylactically in all patients. Postimplant dosimetry was performed at 1 month by using CT/MRI fusion for all patients.

RESULTS

The mean patient age was 65.1 years (range, 46-77 years). There were 59 T1c tumors and 41 T2a tumors. The Gleason score was 6 in 86% of patients, with 3% being Gleason 4 or 5 and 11% Gleason 7. The mean baseline IPSS was 7.4, with the mean at 1 month being 17.3; at 3 months, 14.4; and at 6 months, 11.3. Baseline IPSS was the only factor predictive of IPSS at 1 and 3 months after TIPPB. Neoadjuvant androgen deprivation was used for 26% of men for 2-6 months to reduce prostate size before the procedure. AUR developed in 17%. In univariate analysis, prior hormone therapy (p = 0.002), duration of hormone therapy (p = 0.005), TZ index (p = 0.014), number of seeds implanted (p = 0.016), T stage (p = 0.035), percentage of the prostate volume receiving at least the full prescribed dose (V100, p = 0.036), percentage of the prostate volume receiving > 200% of the prescribed dose (V200, p = 0.037), and prostate volume (p = 0.038) were all predictive of AUR. When the TZ index was divided into quartiles, the risk of AUR was 4%, 16%, 20%, and 28% (p = 0.032). However, in multivariate analysis, TZ index was no longer predictive of AUR.

CONCLUSIONS

Baseline urinary function is the only factor predictive of symptom scores at 1 and 3 months after brachytherapy. TZ index, initial prostate volume, and use of neoadjuvant hormones are interrelated and are all predictive of AUR in univariate analysis, but in multivariate analysis, TZ index is not an independent prognostic factor.

Fitting tumor control probability models to biopsy outcome after three-dimensional conformal radiation therapy of prostate cancer: pitfalls in deducing radiobiologic parameters for tumors from clinical data

PURPOSE

The goal of tumor control probability (TCP) models is to predict local control for inhomogeneous dose distributions. All existing fits of TCP models to clinical data have utilized summaries of dose distributions (e.g., prescription dose). Ideally, model fits should be based on dose distributions in the tumor, but usually only dose-volume histograms (DVH) of the planning target volume (PTV) are available. We fit TCP models to biopsy outcome after three-dimensional conformal radiation therapy of prostate cancer using either a dose distribution summary or the full DVH in the PTV. We discuss differences in the radiobiologic parameters and dose-response curves and demonstrate pitfalls in interpreting the results.

METHODS AND MATERIAL

Two mechanistic TCP models were fit with a maximum likelihood technique to biopsy outcome from 103 prostate patients treated at Memorial Sloan-Kettering Cancer Center. Fits were performed separately for different patient subgroups defined by tumor-related prognostic factors. Fits were based both on full DVHs, denoted TCP(DVH(calc)), and, alternatively, assuming a homogeneous PTV dose given by the mean dose (Dmean) of each DVH, denoted TCP(Dmean(calc)). Dose distributions for these patients were very homogeneous with any cold spots located on the periphery of the PTV. These cold spots were uncorrelated with biopsy outcome, likely because the low-dose regions may not contain tumor cells. Therefore, fits of TCP models that are potentially sensitive to cold spots (e.g., TCP(DVH(calc))) likely give biologic parameters that diminish this sensitivity. In light of this, we examined differences in fitted clonogenic cell number, N(C), or density, rho(C), surviving fraction after 2 Gy, SF(2), or radiosensitivity, alpha, and their standard deviations in the population, sigma(SF(2)) and sigma(alpha), resulting from fits based on TCP(DVH(calc)) and TCP(Dmean(calc)). Dose-response curves for homogeneous irradiation (characterized by TCD(50), the dose for a TCP of 50%) and differences in TCP predictions calculated from the DVH using alternatively derived parameters were evaluated.

RESULTS

Fits of TCP(Dmean(calc)) are better (i.e., have larger likelihood) than fits of TCP(DVH(calc)). For TCP(Dmean(calc)) fits, matching values of SF(2) and sigma(SF(2)) (or alpha and sigma(alpha)) exist for all N(C) (rho(C)) above a threshold that give fits of equal quality, with no maximum in likelihood. In contrast, TCP(DVH(calc)) fits have maximum likelihood for high SF(2) (low alpha) values that minimize effects of cold spots. Consequently, small N(C) (rho(C)) values are obtained to match the observed control rate. For example, for patients in low-, intermediate-, and high-risk groups, optimum values of SF(2) and N(C) are 0.771 and 3.3 x 10(3), 0.736 and 2.2 x 10(4), and 0.776 and 1.0 x 10(4), respectively. The TCD(50) of dose-response curves for intermediate-risk patients is 2.6 Gy lower using TCP(DVH(calc)) parameters (TCD(50) = 67.8 Gy) than for TCP(Dmean(calc)) parameters (TCD(50) = 70.4 Gy). TCP predictions calculated from the DVH using risk group-dependent TCP(Dmean(calc)) parameters are up to 53% lower than corresponding calculations with TCP(DVH(calc)) parameters.

CONCLUSION

For our data, TCP parameters derived from DVHs likely do not reflect true radiobiologic parameters in the tumor, but are a consequence of the reduced importance of low-dose regions at the periphery of the PTV. Deriving radiobiologic parameters from TCP(Dmean(calc)) fits is not possible unless one parameter is already known. TCP predictions using TCP(DVH(calc)) and TCP(Dmean(calc)) parameters may differ substantially, requiring consistency in the derivation and application of model parameters. The proper derivation of radiobiologic parameters from clinical data requires both substantial dose inhomogeneities and understanding of how these coincide with tumor location.

Temporary PSA rises and repeat prostate biopsies after brachytherapy

PURPOSE

The long-standing confusion regarding the clinical relevance of postimplant biopsies is complicated by the common occurrence of temporary PSA rises between 1 and 2 years after brachytherapy. We report here 4 patients with temporary, self-limited PSA rises and postimplant biopsies, for whom radical prostatectomy was strongly advised but for whom surgery would probably have been the wrong choice.

MATERIALS AND METHODS

Transperineal I-125 or Pd-103 implants were performed as previously described. After implantation, patients were followed routinely, with repeat PSA and physical examination at approximately every 4 to 6 months. Timing of postimplant PSAs was at the discretion of the patient and his doctors. Postimplant biopsies were performed in all cases out of concern for a persistently elevated serum PSA. Sections of fixed and embedded tissue were stained with standard hematoxylin and eosin.

RESULTS

All 4 patients presented here were advised to have a salvage prostatectomy based primarily on their PSA changes. However, all of the patients have subsequently had a dramatic PSA fall, consistent with long-term cancer control, despite the fact that 3 of the 4 had histologic evidence of persistent cancer on repeat prostate biopsy.

CONCLUSIONS

It is crucial that clinicians be aware of the potential for the doubly confusing situation of temporary PSA rises and apparently positive rebiopsies and the pressure it puts on both patients and their physicians to go ahead with inappropriate salvage therapy.

Radiation therapy for prostate cancer

OBJECTIVES

To review the advances in radiation therapy for prostate cancer and the nursing care of patients with prostate cancer.

DATA SOURCES

Peer-reviewed journal articles, including research studies and review articles.

CONCLUSIONS

Radiation therapy is used to cure early stage prostate cancer, control locally advanced disease, and effectively palliate symptoms of metastasis. The three forms of treatment used include external beam radiation therapy, brachytherapy; and radiopharmaceutical treatments.

IMPLICATIONS FOR NURSING PRACTICE

Nursing care of patients receiving radiation therapy for prostate cancer includes managing the symptoms associated with the disease and treatment, educating patients and families about self-care measures, and providing support throughout the course of the disease.

Radiation for prostate cancer

The balance between tumour control and normal tissue damage with conventional radiotherapy is critical to outcome and morbidity in the treatment of localised prostate cancer. Recent technological advances have allowed a reduction in the amount of normal tissue included in target treatment volumes. This reduces morbidity and allows dose escalation, theoretically increasing the likelihood of tumour control. The methods used to achieve dose escalation are discussed and the available evidence for their safety and efficacy, relative to conventional treatment, is reviewed. Although there are no randomised studies to provide evidence of increased survival, the available evidence supports the hypothesis that dose escalation produces survival rates equivalent to surgical series and provides a realistic choice for patients.

The effect of disease and treatment-related factors on biopsy results after prostate brachytherapy: implications for treatment optimization

BACKGROUND

Posttreatment prostate biopsy is a method of assessing local control after irradiation for prostate carcinoma. An analysis of the effect of disease- and treatment-related factors on biopsy results after prostate brachytherapy was performed to aid in patient selection and treatment optimization.

METHODS

Two hundred sixty-eight patients underwent posttreatment prostate biopsy (6-8 cores) 2 years after brachytherapy alone without external beam irradiation. Follow-up ranged from 24 to 111 months (median, 43 months). Implants were performed using a real-time ultrasound guided technique with the isotopes (125)I in 186 and (103)Pd in 82 patients. Ninety-eight patients underwent hormonal therapy (HT) 3 months before and 2-3 months after implant. Implant dose was defined as the D90 (dose delivered to 90% of the gland from the dose volume histogram generated using 1-month computed tomography-based dosimetry).

RESULTS

Overall, 89% of patients (238 of 268) had negative biopsies. A positive biopsy was a predictor of biochemical failure. Patients with a positive biopsy had a 5-year freedom from biochemical failure of 40% versus 76% for patients with a negative biopsy (P = 0.0003). Univariate and multivariate analysis found that risk group, HT, and implant dose significantly affected biopsy outcome. Patients with low risk features (prostate specific antigen [PSA] </= 10 ng/mL; Gleason score </= 6; and classification T2a or lower) (n = 104) had a negative biopsy rate of 95% versus 85% for those with high risk features (PSA > 10 ng/mL or Gleason score >/= 7 or classification T2b or higher) (n = 164) (P = 0.008). Hormonal therapy was associated with a negative biopsy rate of 98% versus 84% for implant alone (P = 0.003). Patients receiving a high implant dose (D90 >/= 140 grays [Gy] for (125)I or >/= 100 Gy for (103)Pd) (n = 174) had a negative biopsy rate of 95% versus 77% for those receiving a low dose (D90 < 140 Gy for (125)I or < 100 Gy for (103)Pd) (n = 87; P < 0.001).

CONCLUSIONS

Biopsy results support the use of brachytherapy without external beam irradiation for patients with low risk features and highlight the importance of achieving an adequate implant dose.

Analysis of biopsy outcome after three-dimensional conformal radiation therapy of prostate cancer using dose-distribution variables and tumor control probability models

PURPOSE

To investigate tumor control following three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer and to identify dose-distribution variables that correlate with local control assessed through posttreatment prostate biopsies.

METHODS AND MATERIAL

Data from 132 patients, treated at Memorial Sloan-Kettering Cancer Center (MSKCC), who had a prostate biopsy 2.5 years or more after 3D-CRT for T1c-T3 prostate cancer with prescription doses of 64.8-81 Gy were analyzed. Variables derived from the dose distribution in the PTV included: minimum dose (Dmin), maximum dose (Dmax), mean dose (Dmean), dose to n% of the PTV (Dn), where n = 1%,...,99%. The concept of the equivalent uniform dose (EUD) was evaluated for different values of the surviving fraction at 2 Gy (SF(2)). Four tumor control probability (TCP) models (one phenomenologic model using a logistic function and three Poisson cell kill models) were investigated using two sets of input parameters, one for low and one for high T-stage tumors. Application of both sets to all patients was also investigated. In addition, several tumor-related prognostic variables were examined (including T-stage, Gleason score). Univariate and multivariate logistic regression analyses were performed. The ability of the logistic regression models (univariate and multivariate) to predict the biopsy result correctly was tested by performing cross-validation analyses and evaluating the results in terms of receiver operating characteristic (ROC) curves.

RESULTS

In univariate analysis, prescription dose (Dprescr), Dmax, Dmean, dose to n% of the PTV with n of 70% or less correlate with outcome (p < 0.01). The area under the ROC curve for Dmean is 0.64. In contrast, Dmin (p = 0.6), D98 (p = 0.2) or D95 (p = 0.1) are not significantly correlated with outcome. The results for EUD depend on the input parameter SF(2): EUD correlates significantly with outcome for SF(2) of 0.4 or more, but not for lower SF(2) values. Using either of the two input parameters sets, all TCP models correlate with outcome (p < 0.05; ROC areas 0.60-0.62). Using T-stage dependent input parameters, the correlation is improved (logistic function: p < 0.01, ROC area 0.67, Poisson models: p < 0.01, ROC areas 0.64-0.66). In comparison, the ROC area is 0.68 for the combination of Dmean and T-stage. After multivariate analysis, a model based on TCP, D20 and Gleason score is the best overall model (ROC area 0.73). However, an alternative model based on Dmean, Gleason score, and T-stage is competitive (ROC area 0.70).

CONCLUSION

Biopsy outcome after 3D-CRT of prostate cancer at MSKCC is not correlated with Dmin in the PTV and appears to be insensitive to cold spots in the dose distribution. This observation likely reflects the fact that much of the PTV, especially at the periphery, may not contain viable tumor cells and that the treatment margins were sufficiently large. Therefore, the predictive power of all variables which are sensitive to cold spots, like TCPs with Poisson models and EUD for low SF(2), is limited because the low dose region may not coincide with the tumor location. Instead, for MSKCC prostate cancer patients with their standardized CTV definition, substantial target motion and small dose inhomogeneities, Dmean (or any variable that downplays the effect of cold spots) is a very good predictor of biopsy outcome. While our findings may indicate a general problem in the application of current TCP models to clinical data, these conclusions should not be extrapolated to other disease sites without careful analysis.

[Prostatic brachytherapy: an alternative therapy. Review of the literature]

Radical prostatectomy remains the 'golden standard' therapy for localized prostate carcinoma for patients with a survival rate of more than ten years. However, because of the complications inherent in this surgical procedure, prostatectomy is presently increasingly challenged by various radiotherapy procedures. In the last decade, more sophisticated conformal therapy techniques have been proposed for prostate cancer patients. In parallel, for highly selected patients, brachytherapy is being promoted by an increasing number of medical centers. In fact, brachytherapy techniques for prostate cancers can be traced back to 1911, but recently developed techniques offer reliability and reproducibility, with satisfactory results in terms of tumor control and reduced toxicity, in selected patients. We present here the different techniques that are available today in prostate cancer brachytherapy.

Needle displacement during HDR brachytherapy in the treatment of prostate cancer

PURPOSE

We used clinical patient data to examine implant displacement between high dose rate (HDR) brachytherapy fractions for prostate cancer to determine its impact on treatment delivery.

MATERIALS AND METHODS

We analyzed the verification films taken prior to each fraction for 96 consecutive patients treated with HDR brachytherapy boosts as part of their radiation therapy for definitive treatment of organ-confined prostate cancer at our institution. Patients were treated with 18-24 Gy in 4 fractions of HDR delivered in 40 hours followed by 36-39.6 Gy external beam radiation to the prostate. We determined the mean and maximum displacement distances of marker seeds placed in the prostate and of the implanted needles between HDR fractions.

RESULTS

Mean and maximum displacement distances between fractions were documented up to 7.6 mm and 28.5 mm, respectively, for the implant needles and 3.6 mm and 11.4 mm, respectively, for the gold marker seeds. All displacement of implant needles occurred in the caudal direction. At least 1 cm caudal displacement of needles occurred prior to 15.5% all fractions. Manual adjustment of needles was required prior to 15% of fractions, and adjustment of the CLP only was required in 24%. Most of the displacement for both the marker seeds and needles occurred between the first and second fractions.

CONCLUSIONS

There is significant caudal displacement of interstitial implant needles between HDR fractions in our prostate cancer patients. Obtaining verification films and making adjustments in the treatment volume prior to each fraction is necessary to avoid significant inaccuracies in treatment delivery.

Palladium-103 brachytherapy for prostate carcinoma

PURPOSE

A report of biochemical outcomes for patients treated with palladium-103 (Pd-103) brachytherapy over a fixed time interval.

METHODS AND MATERIALS

Two hundred thirty patients with clinical stage T1-T2 prostate cancer were treated with Pd-103 brachytherapy and followed with prostate-specific antigen (PSA) determinations. Kaplan-Meier estimates of biochemical failure on the basis of two consecutive elevations of PSA were utilized. Multivariate risk groups were constructed. Aggregate PSA response by time interval was assessed.

RESULTS

The overall biochemical control rate achieved at 9 years was 83.5%. Failures were local 3.0%; distant 6.1%; PSA progression only 4.3%. Significant risk factors contributing to failure were serum PSA greater than 10 ng/ml and Gleason sum of 7 or greater. Five-year biochemical control for those exhibiting neither risk factor was 94%; one risk factor, 82%; both risk factors, 65%. When all 1354 PSA determinations obtained for this cohort were considered, the patients with a proportion of PSAs < or = 0.5 ng/ml continued to increase until at least 48 months post-therapy. These data conformed to a median PSA half-life of 96.2 days.

CONCLUSIONS

Prostate brachytherapy with Pd-103 achieves a high rate of biochemical and clinical control in patients with clinically organ-confined disease. PSA response following brachytherapy with low-dose-rate isotopes is protracted.

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.

Histopathologic effects of three-dimensional conformal external beam radiation therapy on benign and malignant prostate tissues

We reviewed 137 prostate sextant needle biopsies from 137 patients obtained at a median of 35.7 months after three-dimensional conformal external beam radiation therapy (3DCRT). Thirty-one patients (23%) received 3 months of androgen deprivation therapy (ADT) before 3DCRT. We also retrospectively reviewed and assigned a combined Gleason score to the pre-3DCRT needle biopsies (97 patients) or transurethral resection of the prostate gland (1 patient). High-molecular-weight cytokeratin (34betaE12) and prostate-specific antigen (PSA) immunohistochemistry was performed in select cases. After 3DCRT, histopathologic changes in benign prostate gland consisted of glandular atrophy, cytologic atypia, and basal cell prominence. The benign glands showed intensely positive reactions with antibodies to high-molecular-weight cytokeratin (34betaE12) and negative to weakly positive reactions to PSA. Paneth cell-like change was seen in 44 (32%) of the biopsies, mucinous metaplasia in 29 (21%), luminal blue-tinged mucinous secretions in 14 (10%), and squamous metaplasia in 8 (6%). The changes in benign prostate tissues were similar between patients treated with ADT and 3DCRT and those treated with 3DCRT alone. After 3DCRT, we recognized two histologic patterns of prostate cancer: (1) prostate cancer showing radiation therapy (RT)-related changes characterized by PSA-positive/34betaE12-negative poorly formed glands or individual cells with abundant clear to finely granular cytoplasm, and (2) prostate cancer showing no apparent RT effect. High-grade prostatic intraepithelial neoplasia (PIN) was seen in 12 post-3DCRT biopsies (8.8%). The use of neoadjuvant ADT had a significant impact on the results of post-RT biopsy. Of the 31 patients treated with neoadjuvant ADT and 3DCRT, 3 (10%) had post-3DCRT biopsies showing prostate cancer without RT effect compared to 44 of 106 men (41%) treated with 3DCRT alone (p = 0.004). Compared to the Gleason score pre-RT, the Gleason score of cancers showing no RT effect was the same in 25 patients (71%), +/-1 point in 8 patients (23%), and +2 points in 2 patients (6%). The mean combined Gleason score post-RT was slightly, although significantly, higher than that pre-RT (7.29 +/- 0.71 versus 7.00 +/- 0.59, p = 0.01). Serum PSA at the time of post-3DCRT biopsy correlated with biopsy results. Prostate cancer without therapy effect was seen in only one of 43 patients (2%) with a serum PSA level < or = 1 ng/ml compared to 46 of 94 patients (49%) with a PSA level > 1 ng/ml (p = 0.0001). After 3DCRT, benign prostate glands show profound histopathologic changes and may be confused with prostate cancer. The effects of 3DCRT on prostate cancer are variable, with some cases showing profound therapy-related changes and others showing no apparent therapy effect.