Late toxicity and biochemical recurrence after external-beam radiotherapy combined with permanent-source prostate brachytherapy: analysis of Radiation Therapy Oncology Group study 0019

Salvage Low Dose Rate Prostate Brachytherapy: Clinical Outcomes of a Phase II Trial for Local Recurrence after External Beam Radiotherapy (NRG Oncology/xxxx)

PURPOSE

We report efficacy of a prospective Phase II trial (YYYY) of salvage low dose rate (LDR) prostate brachytherapy (BT) for local failure (LF) after prior external beam radiotherapy (EBRT) with minimum 5- years' follow up.

MATERIALS/METHODS

Eligible patients had low/intermediate risk prostate cancer (PCa) prior to EBRT and biopsy-proven LF > 30 months after EBRT, with PSA < 10 ng/mL and no regional/distant disease. The primary endpoint, late GI/GU Adverse Events (AEs) (CTCAE V3.0 ≥ Grade 3) was 14%. With minimum 5-year follow up after salvage BT, secondary clinical outcomes including disease-free (DFS; includes death from any cause), disease-specific (DSS), and overall survival (OS) were estimated using the Kaplan-Meier method and modelled using Cox proportional hazards regression. Local tumor progression (LF), distant and biochemical failure (DF/BF) were estimated using cumulative incidence. Time to LF, DF and BF were modeled by cause-specific Cox proportional hazards regression.

RESULTS

From 05/2007 -01/2014, 20 centers registered 100 patients (92 analyzable). Median follow up is 6.7 years (range: 0.3-11.2); median age 70 years (range: 55-82); median prior EBRT dose 74 Gy (IQR: 70-76) at a median of 85 months prior(IQR: 60-119). Androgen deprivation was combined with salvage BT in 16%. 10-year OS is 70% (95% confidence interval [CI]: 58 -83). 19 patients died (5 PCa, 10 other, 4 unknown). 10-year failure rates are local 5% (95% CI:1-11), distant 19% (95% CI:10-29) and biochemical 46% (95% CI:34-57). DFS is 61% at 5 years; 33% at 10 years. No baseline characteristic was significantly associated with any clinical outcome.

CONCLUSION

This is the first prospective multicenter trial reporting outcomes of salvage LDR BT for LF after EBRT. Five-year freedom from BF is 68%, comparable to other salvage modalities. Although further LF is rare (5%), BF climbs to 46% by10-years.

Long-term oncological and functional follow-up in low-dose-rate brachytherapy for prostate cancer: results from the prospective nationwide Swiss registry

OBJECTIVE

To evaluate the long-term oncological, functional and toxicity outcomes of low-dose-rate brachytherapy (LDR-BT) in relation to risk factors and radiation dose in a prospective multicentre cohort.

PATIENTS AND METHODS

Data of patients from 12 Swiss centres undergoing LDR-BT from September 2004 to March 2018 were prospectively collected. Patients with a follow-up of ≥3 months were analysed. Functional and oncological outcomes were assessed at ~6 weeks, 6 and 12 months after implantation and annually thereafter. LDR-BT was performed with ¹²⁵ I seeds. Dosimetry was done 6 weeks after implantation based on the European Society for Radiotherapy and Oncology recommendations. The Kaplan-Meier method was used for biochemical recurrence-free survival (BRFS). A prostate-specific antigen (PSA) rise above the PSA nadir + 2 was defined as biochemical failure. Functional outcomes were assessed by urodynamic measurement parameters and questionnaires.

RESULTS

Of 1580 patients in the database, 1291 (81.7%) were evaluable for therapy outcome. The median (range) follow-up was 37.1 (3.0-141.6) months. Better BRFS was found for Gleason score ≤3+4 (P = 0.03, log-rank test) and initial PSA level of <10 ng/mL (P < 0.001). D'Amico Risk groups were significantly associated with BRFS (P < 0.001), with a hazard ratio of 2.38 for intermediate- and high-risk patients vs low-risk patients. The radiation dose covering 90% of the prostate volume (D90) after 6 weeks was significantly lower in patients with recurrence. Functional outcomes returned close to baseline levels after 2-3 years. A major limitation of these findings is a substantial loss to follow-up.

CONCLUSION

Our results are in line with other studies showing that LDR-BT is associated with good oncological outcomes together with good functional results.

A Brief Review of Low-Dose Rate (LDR) and High-Dose Rate (HDR) Brachytherapy Boost for High-Risk Prostate

For patients with unfavorable or high-risk prostate cancer, dose escalated radiation therapy leads to improved progression free survival but attempts to deliver increased dose by external beam radiation therapy (EBRT) alone can be limited by late toxicities to nearby genitourinary and gastrointestinal organs at risk. Brachytherapy is a method to deliver dose escalation in conjunction with EBRT with a potentially improved late toxicity profile and improved prostate cancer related outcomes. At least three randomized controlled trials have demonstrated improved biochemical control with the addition of either low-dose rate (LDR) or high-dose rate (HDR) brachytherapy to EBRT, although only ASCENDE-RT compared brachytherapy to dose-escalated EBRT but did report an over 50% improvement in biochemical failure with a LDR boost. Multiple single institution and comparative research series also support the use of a brachytherapy boost in the DE-EBRT era and demonstrate excellent prostate cancer specific outcomes. Despite improved oncologic outcomes with a brachytherapy boost in the high-risk setting, the utilization of both LDR, and HDR brachytherapy use is declining. The acute genitourinary toxicities when brachytherapy boost is combined with EBRT, particularly a LDR boost, are of concern in comparison to EBRT alone. HDR brachytherapy boost has many physical properties inherent to its rapid delivery of a large dose which may reduce acute toxicities and also appeal to the radiobiology of prostate cancer. We herein review the evidence for use of either LDR or HDR brachytherapy boost for high-risk prostate cancer and summarize comparisons between the two treatment modalities.

The evolution of brachytherapy for prostate cancer

Brachytherapy (BT), using low-dose-rate (LDR) permanent seed implantation or high-dose-rate (HDR) temporary source implantation, is an acceptable treatment option for select patients with prostate cancer of any risk group. The benefits of HDR-BT over LDR-BT include the ability to use the same source for other cancers, lower operator dependence, and - typically - fewer acute irritative symptoms. By contrast, the benefits of LDR-BT include more favourable scheduling logistics, lower initial capital equipment costs, no need for a shielded room, completion in a single implant, and more robust data from clinical trials. Prospective reports comparing HDR-BT and LDR-BT to each other or to other treatment options (such as external beam radiotherapy (EBRT) or surgery) suggest similar outcomes. The 5-year freedom from biochemical failure rates for patients with low-risk, intermediate-risk, and high-risk disease are >85%, 69-97%, and 63-80%, respectively. Brachytherapy with EBRT (versus brachytherapy alone) is an appropriate approach in select patients with intermediate-risk and high-risk disease. The 10-year rates of overall survival, distant metastasis, and cancer-specific mortality are >85%, <10%, and <5%, respectively. Grade 3-4 toxicities associated with HDR-BT and LDR-BT are rare, at <4% in most series, and quality of life is improved in patients who receive brachytherapy compared with those who undergo surgery.

Comparative study of late rectal toxicity in prostate cancer patients treated with low-dose-rate brachytherapy: With or without supplemental external beam radiotherapy

PURPOSE

Supplemental external beam radiation therapy (sEBRT) is often prescribed in men undergoing low-dose-rate (LDR) brachytherapy. A population of patients was analyzed to assess the effect of sEBRT on late rectal toxicity. It was hypothesized that sEBRT + LDR would be associated with a higher risk of late rectal toxicity.

METHODS AND MATERIALS

This retrospective cohort study examined LDR brachytherapy patients, treated with or without sEBRT, with a minimum of 5-year followup. Longitudinal assessments were evaluated using the computerized patient record system. The Kaplan-Meier method was used for analysis.

RESULTS

Median followup was 7.5 years for 245 patients from 2004 to 2007. sEBRT was administered to 33.5%. Followup beyond 5 years was available for 89%. Overall rates of Grade ≥2 and ≥3 rectal toxicities were 6.9% and 2.9%, respectively. The risk of Grade ≥2 rectal toxicity was 2.8-fold higher for patients receiving sEBRT (95% confidence interval: 1.1-7.2; p = 0.02). The risk of Grade ≥3 rectal toxicity was 11.9-fold higher for patients who received sEBRT (1.5-97.4, 95% confidence interval; p = 0.003). Six of seven patients with a Grade ≥3 rectal toxicity received sEBRT, including one who required an abdominoperineal resection. Median post-LDR D90, V150, V200, and R100 values were 103.3%, 59.4%, 30.1%, and 0.5 cc.

CONCLUSIONS

In a cohort of LDR brachytherapy patients with high rates of followup, sEBRT + LDR was associated with significantly higher risk of Grade ≥2 and ≥3 late rectal toxicity. This analysis supports previous findings and maintains concern about the supplemental use of external beam radiation therapy with LDR brachytherapy while its benefit for tumor control has yet to be prospectively validated.

Significant association of brachytherapy boost with reduced prostate cancer-specific mortality in contemporary patients with localized, unfavorable-risk prostate cancer

PURPOSE

A randomized trial recently found that adding brachytherapy (BT) boost to external beam radiation therapy (EBRT) improves biochemical recurrence-free survival but not prostate cancer-specific mortality (PCSM). We investigated the relationship between BT boost and PCSM in a modern cohort from a large population-based database.

METHODS AND MATERIALS

We conducted an analysis of patients in Surveillance, Epidemiology, and End Results diagnosed with intermediate- or high-risk prostate cancer in 2004-2011, treated with EBRT only or EBRT + BT. The cumulative incidence of PCSM was evaluated in the presence of other-cause mortality as a competing risk. Propensity score matching and multivariable Fine and Gray proportional hazard models were used to evaluate the association of combined modality RT on PCSM.

RESULTS

A total of 52,535 patients were identified, of which 19.6% were treated with EBRT + BT. One-third of cases were high-risk. On multivariable analysis, the adjusted hazard ratio (AHR) of PCSM for EBRT + BT vs. EBRT alone was 0.69 (95% confidence interval [CI], 0.55-0.87, p = 0.002), and the adjusted incidence of PCSM was 1.8% vs. 2.7% at 8 years, respectively. In subgroup analyses, the AHR for PCSM was also significantly reduced with EBRT + BT for high-risk disease (AHR 0.70; 95% CI, 0.52-0.94, p = 0.02; adjusted incidence of PCSM at 8 years, 5.4% vs. 7.6%), but not for intermediate-risk disease.

CONCLUSIONS

BT boost was associated with a moderate reduction to PCSM in men with localized unfavorable-risk prostate cancer. Those most likely to benefit are younger patients with high-risk disease.

Urinary and Rectal Toxicity Profiles After Permanent Iodine-125 Implant Brachytherapy in Japanese Men: Nationwide J-POPS Multi-institutional Prospective Cohort Study

PURPOSE

To assess, in a nationwide multi-institutional cohort study begun in 2005 and in which 6927 subjects were enrolled by 2010, the urinary and rectal toxicity profiles of subjects who enrolled during the first 2 years, and evaluate the toxicity profiles for permanent seed implantation (PI) and a combination therapy with PI and external beam radiation therapy (EBRT).

METHODS AND MATERIALS

Baseline data for 2339 subjects out of 2354 patients were available for the analyses. Toxicities were evaluated using the National Cancer Institute's Common Terminology Criteria for Adverse Events, and the International Prostate Symptom Scores were recorded prospectively until 36 months after radiation therapy.

RESULTS

Grade 2+ acute urinary toxicities developed in 7.36% (172 of 2337) and grade 2+ acute rectal toxicities developed in 1.03% (24 of 2336) of the patients. Grade 2+ late urinary and rectal toxicities developed in 5.75% (133 of 2312) and 1.86% (43 of 2312) of the patients, respectively. A higher incidence of grade 2+ acute urinary toxicity occurred in the PI group than in the EBRT group (8.49% vs 3.66%; P<.01). Acute rectal toxicity outcomes were similar between the treatment groups. The 3-year cumulative incidence rates for grade 2+ late urinary toxicities were 6.04% versus 4.82% for the PI and the EBRT groups, respectively, with no significant differences between the treatment groups. The 3-year cumulative incidence rates for grade 2+ late rectal toxicities were 0.90% versus 5.01% (P<.01) for the PI and the EBRT groups, respectively. The mean of the postimplant International Prostate Symptom Score peaked at 3 months, but it decreased to a range that was within 2 points of the baseline score, which was observed in 1625 subjects (69.47%) at the 1-year follow-up assessment.

CONCLUSIONS

The acute urinary toxicities observed were acceptable given the frequency and retention, and the late rectal toxicities were more favorable than those of other studies.

Influence of zonal dosimetry on prostate brachytherapy outcomes

Purpose

To examine the influence of zone-specific dosimetry on outcomes during permanent prostate implantation (PI), where the peripheral zone (PZ) and transitional zone (TZ) may receive varying radiation doses.

Material and methods

Four hundred and sixteen patients treated with I-125 PI (target dose: 144 Gy) between 1996 and 2003 were included in this Institutional Review Board (IRB) approved, retrospective analysis. Whole prostate (WP), TZ, and PZ were contoured, and zone-specific D₉₀ and V₁₀₀ were computed. Their influence on biochemical failure (BF) was evaluated using Cox proportional hazards analysis.

Results

The median age and initial prostate-specific antigen (PSA) was 68 years and 6.1 ng/ml, respectively, and the median follow-up time was 8.8 years. There were 329 subjects with Gleason score (GS) 6 disease (79.1%), and 82 subjects had GS 7 disease (19.7%). Androgen deprivation therapy (ADT) was used in 20.4% of patients. Median D₉₀ and V_100% in the WP, PZ, and TZ were 141.2 Gy, 156.1 Gy, and 134.5 Gy; and 88.8%, 93.3%, and 84.2%, respectively. Ten-year rates for biochemical recurrence-free survival, distant metastasis-free survival, and prostate cancer-specific mortality were 82.4%, 92.4%, and 0.97% respectively. Only initial PSA, GS7+ disease, ADT, and PSA frequency were significant on multivariate analysis. Ten-year rates of grade 3 or higher GU and GI toxicity was 10.9% and 1.8%, respectively. TZ V₂₀₀ and TZ V₃₀₀ were significantly associated with late genitourinary toxicity.

Conclusions

The TZ received significantly lower doses of radiation compared to the PZ. On multivariate analysis, no dosimetric parameter was associated with efficacy. Higher TZ doses may be associated with higher late GU toxicity without improving efficacy.

Spacer application for prostate cancer radiation therapy

Definitive radiotherapy is a well-recognized treatment option for localized prostate cancer. Rectum toxicity is the dose-limiting toxicity. Dose-volume correlations have been reported in many studies. The application of a spacer to increase the distance between the prostate and anterior rectal wall is an innovative technique, considerably reducing the dose to the rectum. Hyaluronic acid, human collagen, an inflatable balloon or hydrogel are potential materials to create the desired effect. The number of clinical studies is rapidly increasing. Well-tolerated injection or implantation techniques and low rectal treatment-related toxicity have been demonstrated in prospective studies. Long-term clinical results and the results of randomized studies are needed to better define the beneficial effect for the patient.

Progress and controversies: Radiation therapy for prostate cancer

Radiation therapy remains a standard treatment option for men with localized prostate cancer. Alone or in combination with androgen-deprivation therapy, it represents a curative treatment and has been shown to prolong survival in selected populations. In this article, the authors review recent advances in prostate radiation-treatment techniques, photon versus proton radiation, modification of treatment fractionation, and brachytherapy-all focusing on disease control and the impact on morbidity. Also discussed are refinements in the risk stratification of men with prostate cancer and how these are better for matching patients to appropriate treatment, particularly around combined androgen-deprivation therapy. Many of these advances have cost and treatment burden implications, which have significant repercussions given the prevalence of prostate cancer. The discussion includes approaches to improve value and future directions for research.

Combining theoretical potential and advanced technology in high-dose rate brachytherapy boost therapy for prostate cancer

External beam radiation therapy (EBRT) combined with brachytherapy (BT) is an attractive treatment option for select patients with clinically localized prostate cancer. Either low- or high-dose rate BT may be combined with EBRT ('LDR-BT boost,' 'HDR-BT boost,' respectively). HDR-BT boost has potential theoretical benefits over LDR-BT boost or external beam radiation therapy monotherapy in terms of radiobiology, radiophysics and patient convenience. Based on prospective studies in this review, freedom from biochemical failure (FFBF) rates at 5 years for low-, intermediate- and high-risk patients have generally been 85-100%, 68-97%, 63-85%, respectively; late Radiotherapy and Oncology Group Grades 3 and 4 genitourinary and gastrointestinal toxicities are seen in <8% of patients. HDR-BT boost is now a relatively well-established treatment modality for certain intermediate-risk and high-risk prostate cancer patients, though limitations exist in drawing conclusions from the currently published studies.

Future directions from past experience: a century of prostate radiotherapy

Prostate cancer is the most commonly diagnosed noncutaneous malignancy in men, yet 100 years ago it was considered a rare disease. Over the past century, radiation therapy has evolved from a radium source placed in the urethra to today's advanced proton therapy delivered by only a few specialized centers. As techniques in radiation have evolved, the treatment of localized prostate cancer has become one of the most debated topics in oncology. Today, patients with prostate cancer must often make a difficult decision between multiple treatment modalities, each with the risk of permanent sequelae, without robust randomized data to compare every treatment option. Meanwhile, opinions of urologists and radiation oncologists about the risks and benefits involved with each modality vary widely. Further complicating the issue is rapidly advancing technology which often outpaces clinical data. This article represents a complete description of the evolution of prostate cancer radiation therapy with the goal of illuminating the historical basis for current challenges facing oncologists and their patients.

Gastrointestinal radiation injury: Prevention and treatment

With the recent advances in detection and treatment of cancer, there is an increasing emphasis on the efficacy and safety aspects of cancer therapy. Radiation therapy is a common treatment for a wide variety of cancers, either alone or in combination with other treatments. Ionising radiation injury to the gastrointestinal tract is a frequent side effect of radiation therapy and a considerable proportion of patients suffer acute or chronic gastrointestinal symptoms as a result. These side effects often cause morbidity and may in some cases lower the efficacy of radiotherapy treatment. Radiation injury to the gastrointestinal tract can be minimised by either of two strategies: technical strategies which aim to physically shift radiation dose away from the normal intestinal tissues, and biological strategies which aim to modulate the normal tissue response to ionising radiation or to increase its resistance to it. Although considerable improvement in the safety of radiotherapy treatment has been achieved through the use of modern optimised planning and delivery techniques, biological techniques may offer additional further promise. Different agents have been used to prevent or minimize the severity of gastrointestinal injury induced by ionising radiation exposure, including biological, chemical and pharmacological agents. In this review we aim to discuss various technical strategies to prevent gastrointestinal injury during cancer radiotherapy, examine the different therapeutic options for acute and chronic gastrointestinal radiation injury and outline some examples of research directions and considerations for prevention at a pre-clinical level.

Neoadjuvant chemoradiation followed by interstitial prostate brachytherapy for synchronous prostate and rectal cancer

PURPOSE

To describe outcomes with the use of neoadjuvant pelvic chemoradiation followed by prostate interstitial brachytherapy for the treatment of synchronous prostate and rectal cancers.

METHODS AND MATERIALS

An Internal Review Board approved retrospective review was undertaken of 4 patients with synchronous prostate and rectal cancer treated between 2006 and 2008. Patients underwent pelvic chemoradiation followed by prostate brachytherapy, then low anterior resection of the rectum with diverting loop ileostomy and adjuvant chemotherapy. Follow-up evaluation included imaging and laboratory analysis of cancer markers in addition to routine interval history and physical examination.

RESULTS

At 38-62 months postdiagnosis (24-53 months post-treatment), 6 of 8 cancers remained without evidence of relapse. One patient had rising carcinoembryonic antigen levels but no clinically evident rectal cancer relapse; another developed bony metastasis of his high-risk prostate cancer. Three patients experienced grade 1-2 treatment-related toxicity; one patient had grade 3 gastrointestinal toxicity from radiation and surgery, which precluded his receiving adjuvant chemotherapy and ileostomy reversal.

CONCLUSIONS

Chemoradiation followed by prostate brachytherapy, surgery, and adjuvant chemotherapy may be utilized to manage patients with synchronous prostate and rectal cancers.

Role of isotope selection in long-term outcomes in patients with intermediate-risk prostate cancer treated with a combination of external beam radiotherapy and low-dose-rate interstitial brachytherapy

OBJECTIVE

To examine the rates of long-term biochemical recurrence-free survival (BRFS) with respect to isotope in intermediate-risk prostate cancer treated with external beam radiotherapy (EBRT) and brachytherapy.

METHODS

A total of 242 consecutive patients with intermediate-risk prostate cancer were treated with iodine-125 ((125)I) or palladium-103 ((103)Pd) implants after EBRT (range 45.0-50.4 Gy) from 1996 to 2002. Of the 242 patients, 119 (49.2%) were treated with (125)I and 123 (50.8%) with (103)Pd. Multivariate Cox regression analysis was used to analyze BRFS, defined according to the Phoenix definition (prostate-specific antigen nadir plus 2 ng/mL) with respect to Gleason score, stage, pretreatment prostate-specific antigen level, and source selection. Late genitourinary/gastrointestinal toxicities were assessed using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale.

RESULTS

At a median follow-up of 10 years, the BRFS rate was 77.3%. A statistically significant difference was found in the 10-year BRFS rate between the (125)I- and (103)Pd-treated groups (82.7% and 70.6%, respectively; P = .001). The addition of hormonal therapy did not improve the 10-year BRFS rate (77.6%) compared with RT alone (77.1%; P = .22). However, a statistically significant difference in the BRFS rate was found with the addition of hormonal therapy to (103)Pd, improving the 10-year BRFS rate for (73.8%) compared with (103)Pd alone (69.1%; P = .008). On multivariate analysis, isotope type ((103)Pd vs (125)I), pretreatment prostate-specific antigen level >10 ng/mL, and greater tumor stage increased the risk of recurrence by 2.6-fold (P = .007), 5.9-fold (P < .0001), and 1.7-fold (P = .14), respectively.

CONCLUSION

(125)I renders a superior rate of BRFS compared with (103)Pd when used with EBRT. Hormonal therapy does not provide additional benefit in patients with intermediate-risk prostate cancer treated with a combination of EBRT and brachytherapy, except for the addition of hormonal therapy to (103)Pd.

External-beam radiation therapy and high-dose rate brachytherapy combined with long-term androgen deprivation therapy in high and very high prostate cancer: preliminary data on clinical outcome

PURPOSE

To determine the feasibility of combined long-term androgen deprivation therapy (ADT) and dose escalation with high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Between 2001 and 2007, 200 patients with high-risk prostate cancer (32.5%) or very high-risk prostate cancer (67.5%) were prospectively enrolled in this Phase II trial. Tumor characteristics included a median pretreatment prostate-specific antigen of 15.2 ng/mL, a clinical stage of T2c, and a Gleason score of 7. Treatment consisted of 54 Gy of external irradiation (three-dimensional conformal radiotherapy [3DCRT]) followed by 19 Gy of HDR brachytherapy in four twice-daily treatments. ADT started 0-3 months before 3DCRT and continued for 2 years.

RESULTS

One hundred and ninety patients (95%) received 2 years of ADT. After a median follow-up of 3.7 years (range, 2-9), late Grade ≥2 urinary toxicity was observed in 18% of the patients and Grade ≥3 was observed in 5%. Prior transurethral resection of the prostate (p = 0.013) and bladder D(50) ≥1.19 Gy (p = 0.014) were associated with increased Grade ≥2 urinary complications; age ≥70 (p = 0.05) was associated with Grade ≥3 urinary complications. Late Grade ≥2 gastrointestinal toxicity was observed in 9% of the patients and Grade ≥3 in 1.5%. CTV size ≥35.8 cc (p = 0.007) and D(100) ≥3.05 Gy (p = 0.01) were significant for increased Grade ≥2 complications. The 5-year and 9-year biochemical relapse-free survival (nadir + 2) rates were 85.1% and 75.7%, respectively. Patients with Gleason score of 7-10 had a decreased biochemical relapse-free survival (p = 0.007).

CONCLUSIONS

Intermediate-term results at the 5-year time point indicate a favorable outcome without an increase in the rate of late complications.

A survey of current clinical practice in permanent and temporary prostate brachytherapy: 2010 update

PURPOSE

To help establish patterns of care and standards of care of interstitial permanent low-dose-rate (LDR) and temporary high-dose-rate brachytherapy for prostate cancer and to compare the results with a similar 1998 American Brachytherapy Society (ABS) survey.

METHODS AND MATERIALS

A comprehensive questionnaire intended to survey specific details of current clinical brachytherapy practice was provided to the participants of the seventh ABS Prostate Brachytherapy School. Responses were tabulated and descriptive statistics are reported.

RESULTS

Sixty-five brachytherapy practitioners responded to the survey. Eighty-nine percent (89%) of respondents performed LDR and 49% perform high-dose-rate brachytherapy. The median number of years of experience for LDR brachytherapists increased from 5 to 10 years over the course of the 12 years since the preceding survey. Compared with the first ABS, a smaller proportion of respondents received formal brachytherapy residency training (43% vs. 56%) or formal "hands-on" brachytherapy training (15% vs. 63%). There has been a marked decline in the utilization of the Mick applicator (Mick Radio-Nuclear Instruments, Inc., Mount Vernon, NY, USA) (60% vs. 28%) and an increase in the use of stranded seeds (40% vs. 11%). Compliance with postimplant dosimetry was higher in the 2010 survey.

CONCLUSION

This survey does suggest an evolution in the practice of LDR brachytherapy since 1998 and aids in identifying aspects that require further progress or investigation. ABS guidelines and other practice recommendations appear to impact the practice of brachytherapy.

Combination external beam radiation and brachytherapy boost with androgen deprivation for treatment of intermediate-risk prostate cancer: long-term results of CALGB 99809

BACKGROUND

Combined transperineal prostate brachytherapy and external beam radiation therapy (EBRT) is widely used for treatment of prostate cancer. Long-term efficacy and toxicity results of a multicenter phase 2 trial assessing combination of EBRT and transperineal prostate brachytherapy boost with androgen deprivation therapy (ADT) for intermediate-risk prostate cancer are presented.

METHODS

Intermediate-risk patients per Memorial Sloan-Kettering Cancer Center/National Comprehensive Cancer Network criteria received 6 months of ADT, and 45 grays (Gy) EBRT to the prostate and seminal vesicles, followed by transperineal prostate brachytherapy with I125 (100 Gy) or Pd103 (90 Gy). Toxicity was graded using the National Cancer Institute Common Toxicity Criteria version 2 and Radiation Therapy Oncology Group late radiation morbidity scoring systems. Disease-free survival (DFS) was defined as time from enrollment to progression (biochemical, local, distant, or prostate cancer death). In addition to the protocol definition of biochemical failure (3 consecutive prostate-specific antigen rises>1.0 ng/mL after 18 months from treatment start), the 1997 American Society for Therapeutic Radiology and Oncology (ASTRO) consensus and Phoenix definitions were also assessed in defining DFS. The Kaplan-Meier method was used to estimate DFS and overall survival.

RESULTS

Sixty-one of 63 enrolled patients were eligible. Median follow-up was 73 months. Late grade 2 and 3 toxicity, excluding sexual dysfunction, occurred in 20% and 3% of patients. Six-year DFS applying the protocol definition, 1997 ASTRO consensus, and Phoenix definitions was 87.1%, 75.1%, and 84.9%. Six deaths occurred; only 1 was attributed to prostate cancer. Six-year overall survival was 96.1%.

CONCLUSIONS

In a cooperative setting, combination of EBRT and transperineal prostate brachytherapy boost plus ADT resulted in excellent DFS with acceptable late toxicity for patients with intermediate-risk prostate cancer.

Phase II trial of combined high-dose-rate brachytherapy and external beam radiotherapy for adenocarcinoma of the prostate: preliminary results of RTOG 0321

PURPOSE

To estimate the rate of late Grade 3 or greater genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) after treatment with external beam radiotherapy and prostate high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Each participating institution submitted computed tomography-based HDR brachytherapy dosimetry data electronically for credentialing and for each study patient. Patients with locally confined Stage T1c-T3b prostate cancer were eligible for the present study. All patients were treated with 45 Gy in 25 fractions using external beam radiotherapy and one HDR implant delivering 19 Gy in two fractions. All AEs were graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Late GU/GI AEs were defined as those occurring >9 months from the start of the protocol treatment, in patients with ≥18 months of potential follow-up.

RESULTS

A total of 129 patients from 14 institutions were enrolled in the present study. Of the 129 patients, 125 were eligible, and AE data were available for 112 patients at analysis. The pretreatment characteristics of the patients were as follows: Stage T1c-T2c, 91%; Stage T3a-T3b, 9%; prostate-specific antigen level ≤10 ng/mL, 70%; prostate-specific antigen level >10 but ≤20 ng/mL, 30%; and Gleason score 2-6, 10%; Gleason score 7, 72%; and Gleason score 8-10, 18%. At a median follow-up of 29.6 months, three acute and four late Grade 3 GU/GI AEs were reported. The estimated rate of late Grade 3-5 GU and GI AEs at 18 months was 2.56%.

CONCLUSION

This is the first prospective, multi-institutional trial of computed tomography-based HDR brachytherapy and external beam radiotherapy. The technique and doses used in the present study resulted in acceptable levels of AEs.

Combination of IG-IMRT and permanent source prostate brachytherapy in patients with organ-confined prostate cancer: GU and GI toxicity and effect on erectile function

PURPOSE

To assess toxicity outcomes of image-guided intensity-modulated radiation therapy (IG-IMRT) combined with permanent prostate seed implant in a cohort of patients with localized prostate cancer.

METHODS AND MATERIALS

A retrospective analysis was performed on 67 patients with the median pretreatment prostate-specific antigen level of 5.4. The Gleason score was less than 7 in 7 patients, 7 in 52 patients, and greater than 7 in 8 patients. The median followup was 28.2 months (range, 12-89.5 months). Treatment consisted of 45 (n=65) or 50.4 Gy (n=2) at 1.8 Gy/fraction of IG-IMRT to the prostate and seminal vesicles. Eight patients had simultaneous irradiation of pelvic lymph nodes to 45 (n=65) or 50.4 Gy (n=2). After IG-IMRT, patients received transperineal prostate implant boost with either (103)Pd (n=65, the prescribed D(90) of 100 Gy) or (125)I (n=2, D(90) of 110 Gy). Eleven patients received androgen deprivation therapy with radiotherapy.

RESULTS

Toxicity higher than Grade 3 was not observed. The combined incidence of acute and late Grade 3 genitourinary toxicity was 6%. The combined incidence of acute and late Grade 3 gastrointestinal toxicity was 3%. At least one episode of gastrointestinal bleeding on followup, which could be attributed to radiation, was recorded in 14.9% of patients. For patients achieving erections before radiation, the 3-year Kaplan-Meier potency preservation rate was 66.5%.

CONCLUSIONS

The early toxicity of the combination of IG-IMRT and low-dose rate brachytherapy boost in this study was favorable.

[Which modality for prostate brachytherapy?]

Brachytherapy techniques by permanent implant of radioactive sources or by temporary high-dose-rate (HDR) fractions are nowadays extensively used for the treatment of prostatic carcinoma. Long-term results (at 20 years) concerning large amount of patients have been published by major centers confirming both in terms of efficacy and toxicities that permanent implant of radioactive iodine-125 seeds yields at least the same good results of surgery and of external beam irradiation when proposed to patients affected by low-risk disease. For intermediate to high-risk tumors, HDR temporary implants are proposed as a boost for dose escalation. For both techniques, several topics still need to be clarified dealing with a recent enlargement of indications (HDR alone for low-risk, iodine-125 seeds boost for intermediate-high-risk cancers), or with technical aspects (loose seeds versus linked ones, number of fractions and dose for HDR protocols), while dosimetric issues have only recently been addressed by cooperatives groups. Last but not least, there is a real need to address and clearly characterize the correct definition of biochemical disease control both for iodine permanent implant and for HDR implant. New challenges are facing the prostate-brachytherapy community in the near future: local relapse after external beam radiotherapy are currently managed by several salvage treatments (prostatectomy, cryo, high intensity focused ultrasounds [HIFU]) but the role of reirradiation by brachytherapy is also actively investigated. Focal therapy has gained considerable interest in the last 5 years aiming at treating only the area of cancer foci inside the prostate and preserving nearby healthy tissues. Encouraging results have been obtained with the so-called "minimally invasive" approaches and both permanent seed implantation and HDR brachytherapy techniques may be worthwhile testing in this setting because of their capability of exactly sculpting the dose inside the prostatic gland.

Late rectal toxicity after prostate brachytherapy: influence of supplemental external beam radiation on dose-volume histogram analysis

PURPOSE

To describe the rate of gastrointestinal (GI) toxicity after prostate brachytherapy and describe how external beam radiation therapy (EBRT) may influence the association of rectal dose-volume histogram (DVH) parameters with rectal toxicity.

METHODS AND MATERIALS

One hundred ten patients with prostate cancer were treated with I-125 brachytherapy alone (n=62, 144 Gy) or as a boost (n=48, 108 Gy) after 45-Gy EBRT. CT-based dosimetry was performed a median of 29 days after implantation. GI toxicity was evaluated by Radiation Therapy Oncology Group criteria. Median followup was 41 months.

RESULTS

Eleven patients developed Grade 2+GI toxicity. Men treated with EBRT had an increased risk of GI toxicity, with freedom from Grade 2+ toxicity of 82% vs. 91% for implant alone, but this difference was not statistically significant (p=0.3044). Of the DVH parameters analyzed, only the rectal volume receiving the prescription dose (rV(100)(%)) was associated with late Grade 2+GI toxicity. Men with rV(100%) >or= 0.05 cc had a 4-year freedom from Grade 2+ toxicity of 77% vs. 100% for those with an rV(100%) <0.05 cc (p=0.0248). However, this relationship was only significant for the subset of patients treated with EBRT, where men with rV(100%) >or= 0.05 cc had a 26% risk of Grade 2+ toxicity compared with 0% for rV(100%) <0.05 cc. Additional DVH parameters, including dose to the hottest 0.1 cc (p=0.0199), 1% (p=0.0086), and 3% (p=0.0043), were also associated with GI toxicity but only in men treated with EBRT.

CONCLUSIONS

Supplemental EBRT may lower the threshold for rectal toxicity after prostate brachytherapy. Morbidity can be minimized by observing rectal constraints.

Recent advances in the management of radiation colitis

Radiation colitis, an insidious, progressive disease of increasing frequency, develops 6 mo to 5 years after regional radiotherapy for malignancy, owing to the deleterious effects of the latter on the colon and the small intestine. When dealing with radiation colitis and its complications, the most conservative modality should be employed because the areas of intestinal injury do not tend to heal. Acute radiation colitis is mostly self-limited, and usually, only supportive management is required. Chronic radiation colitis, a poorly predictable progressive disease, is considered as a precancerous lesion; radiation-associated malignancy has a tendency to be diagnosed at an advanced stage and to bear a dismal prognosis. Therefore, management of chronic radiation colitis remains a major challenge owing to the progressive evolution of the disease, including development of fibrosis, endarteritis, edema, fragility, perforation, partial obstruction, and cancer. Patients are commonly managed conservatively. Surgical intervention is difficult to perform because of the extension of fibrosis and alterations in the gut and mesentery, and should be reserved for intestinal obstruction, perforation, fistulas, and severe bleeding. Owing to the difficulty in managing the complications of acute and chronic radiation colitis, particular attention should be focused onto the prevention strategies. Uncovering the fibrosis mechanisms and the molecular events underlying radiation bowel disease could lead to the introduction of new therapeutic and/or preventive approaches. A variety of novel, mostly experimental, agents have been used mainly as a prophylaxis, and improvements have been made in radiotherapy delivery, including techniques to reduce the amount of exposed intestine in the radiation field, as a critical strategy for prevention.

Radiotherapy: long-term effects on gastrointestinal function

PURPOSE OF REVIEW

Radiotherapy frequently results in persistent effects on gastrointestinal function adversely impacting on the quality of life of patients cured of their malignant disease. Long-term effects on gastrointestinal function remain prevalent despite the advent of three-dimensional techniques of radiotherapy because higher radiation doses and more combined modality treatments are prescribed to improve cure rates.

RECENT FINDINGS

Chronic elevation of cytokine levels and implication of the cyclooxygenase-2 pathway in radiation bowel injury in animals, and the involvement of the Rho/Rho kinase pathway in the fibrogenic differentiation of smooth muscle cells of patients with late radiation enteritis, suggest a role for inhibition of these pathways. The importance of limiting acute gastrointestinal toxicity by dietary, pharmacological and physical interventions and of optimizing radiotherapy techniques and prescriptions is underscored by increasing evidence that a component of the long-term effects of radiotherapy on gastrointestinal function is a consequence of acute damage.

SUMMARY

Strategies to control acute toxicity are important in reducing the impact of long-term effects of radiotherapy on gastrointestinal function. Further research into genetic profiling to characterize individual risk of radiation bowel damage and the pathways implicated in fibrogenic differentiation is needed to reduce and prevent bowel complications.

Definitive radiotherapy for prostate cancer

The probability of extraprostatic disease may be estimated based on clinical T-stage, pretreatment prostatic-specific antigen, Gleason score, and percent positive core biopsies. Patients with disease confined to the prostate may be treated with either prostatectomy or radiotherapy (RT). Patients with extraprostatic disease without evidence of distant metastases are best managed with RT. RT consisting of either external beam and/or brachytherapy results in a relatively high likelihood of cure, particularly for those with low- and intermediate-risk disease. The impact of elective nodal RT on survival is unclear. Dose escalation results in improved biochemical relapse-free survival compared with standard dose RT. Androgen deprivation therapy likely improves the probability of disease control in patients with high-risk cancers.

Technology Insight: Combined external-beam radiation therapy and brachytherapy in the management of prostate cancer

External-beam radiation therapy (EBRT) combined with brachytherapy is an attractive treatment option for selected patients with clinically localized prostate cancer. This therapeutic strategy offers dosimetric coverage if local-regional microscopic disease is present and provides a highly conformal boost of radiation to the prostate and immediate surrounding tissues. Either low-dose-rate (LDR) permanent brachytherapy or high-dose-rate (HDR) temporary brachytherapy can be combined with EBRT; such combined-modality therapy (CMT) is typically used to treat patients with intermediate-risk to high-risk, clinically localized disease. Controversy persists with regard to indications for CMT, choice of LDR or HDR boost, isotope selection for LDR, and integration of EBRT and brachytherapy. Initial findings from prospective, multicenter trials of CMT support the feasibility of this strategy. Updated results from these trials as well as those of ongoing and new phase III trials should help to define the role of CMT in the management of prostate cancer. In the meantime, long-term expectations for outcomes of CMT are based largely on the experience of single institutions, which demonstrate that CMT with EBRT and either LDR or HDR brachytherapy can provide freedom from disease recurrence with acceptable toxicity.

Combined brachytherapy with external beam radiotherapy for localized prostate cancer: reduced morbidity with an intraoperative brachytherapy planning technique and supplemental intensity-modulated radiation therapy

PURPOSE

To report the acute and late treatment-related toxicities of combined permanent interstitial (125)I implantation delivered via real-time intraoperative planning and supplemental intensity-modulated radiotherapy (IMRT) for patients with clinically localized prostate cancer.

METHODS AND MATERIALS

One hundred twenty-seven patients were treated with a combined modality (CM) regimen consisting of (125)I implantation (110Gy) using a transrectal ultrasound-guided approach followed 2 months later by 50.4Gy of IMRT directed to the prostate and seminal vesicles. Late toxicity was scored according to the NCI Common Terminology Criteria for Adverse Events toxicity scale. The acute and late toxicities were compared to a contemporaneously treated cohort of 216 patients treated with (125)I alone to a prescribed dose of 144Gy.

RESULTS

The incidence of Grade 2 acute rectal and urinary side effects was 1% and 10%, respectively, and 2 patients developed Grade 3 acute urinary toxicities. The 4-year incidence of late Grade 2 gastrointestinal toxicity was 9%, and no Grade 3 or 4 complications have been observed. The 4-year incidence of late Grade 2 gastrourinary toxicities was 15% and 1 patient developed a Grade 3 urethral stricture, which was corrected with urethral dilatation. The percentage of patients who experienced resolution of late rectal and urinary symptoms was 92% and 65%, respectively. Multivariate analysis revealed that in addition to higher baseline International Prostate Symptom Score, those patients treated with implant alone compared to CM were more likely to experience Grade 2 acute urinary symptoms. Increased Grade 2 late rectal toxicities were noted for CM patients (9% vs. 1%; p=0.001) as well as a significant increase for late Grade 2 urinary toxicities (15% vs. 9%; p=0.004).

CONCLUSIONS

Adherence to dose constraints with combination real-time brachytherapy using real-time intraoperative planning and IMRT is associated with a low incidence of acute and late toxicities. Acute urinary side effects were significantly less common for CM patients compared to those treated with implantation alone. Late Grade 2 rectal and urinary toxicities were more common for patients treated with CM compared to implant alone.

Permanent prostate seed brachytherapy: a current perspective on the evolution of the technique and its application

This Review highlights current areas of controversy and development in the field of transperineal permanent prostate seed implantation brachytherapy (PPI), in particular the technological evolution of PPI treatment planning that has led to intra-operative treatment planning and execution, the use of MRI spectroscopy and ultrasonography to target intraprostatic tumor foci, and the introduction of (131)Cs as a new PPI isotope. Here we present a comprehensive review of mature data for PPI monotherapy and PPI combined with supplemental external beam radiation therapy, and a critical discussion of issues pertinent to supplemental EBRT. We also present our current policies in the treatment of prostate cancer at the University of California, San Francisco.