Nationwide multi-institutional retrospective analysis of high-dose-rate brachytherapy combined with external beam radiotherapy for localized prostate cancer: An Asian Prostate HDR-BT Consortium

Significance of androgen-deprivation therapy for intermediate- and high-risk prostate cancer treated with high-dose radiotherapy: A literature review

The real-world benefits of adding androgen-deprivation therapy (ADT) and its optimal duration when combined with current standard high-dose radiation therapy (RT) remain unknown. We aimed to assess the efficacy of and toxicities associated with ADT in the setting of combination with high-dose RT for intermediate-risk (IR) and high-risk (HR) prostate cancer (PCa). This article is a modified and detailed version of the commentary on Clinical Question 8 described in the Japanese Clinical Practice Guidelines for Prostate Cancer (ver. 2023). A qualitative systematic review was performed according to the Minds Guide. All relevant published studies between September 2010 and August 2020, which assessed the outcomes of IR or HR PCa treated with high-dose RT, were screened using two databases (PubMed and ICHUSHI). A total of 41 studies were included in this systematic review, mostly consisting of retrospective studies (N = 34). The evidence basically supports the benefit of adding ADT to high-dose RT to improve tumor control. Regarding IR populations, many studies suggested the existence of a subgroup for which adding ADT had no impact on either overall survival or the BF-free duration. On the other hand, regarding HR populations, several studies suggested the positive impact of adding ADT for ≥1 year on overall survival. Adding ADT increases not only the risk of sexual dysfunction but also that of cardiovascular toxicities or bone fracture. Although the benefit of adding ADT was basically suggested for both IR and HR populations, further investigations are warranted to identify subgroups of patients for whom ADT has no benefit, as well as the appropriate duration of ADT for those who do derive benefit.

Long-term outcomes of high-dose-rate brachytherapy and external beam radiotherapy without hormone therapy for high-risk localized prostate cancer

PURPOSE

Until March 2018, patients with high-risk localized prostate cancer had been administered high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) without additional hormone therapy (HT) at our institution. In this study, we aimed to evaluate long-term outcomes of this treatment.

MATERIALS AND METHODS

Patients with prostate cancer who received HDR-BT and EBRT between April 1997 and March 2021 and who were followed up for at least 6 months were included in the study. High-risk groups were classified into five levels according to the National Comprehensive Cancer Network guidelines. The EBRT and HDR-BT doses were 39-45 Gy/13-25 fractions. and 16.5-22 Gy/2-4 fractions, respectively. None of the patients received HT during initial treatment. The Kaplan-Meier method was used to estimate biochemical freedom from failure (bFFF), cause-specific survival (CSS), and overall survival (OS) rates. Biochemical failure was also determined.

RESULTS

Seventy-two patients were enrolled in the study, with a median follow-up of 91.9 months. The median age and initial prostate-specific antigen (iPSA) level were 71 years and 10.95 ng/mL, respectively. The median biologically effective dose for HDR-BT plus EBRT was 270.3 Gy. The 5- and 7-year bFFF, CSS, and OS rates were 85.2 and 74.2%, 100 and 100%, and 95.7 and 91.9%, respectively. Only the iPSA ≤ 20 group was associated with the higher bFFF rate. The 7-year bFFF rates in the groups with iPSA ≤ 20 and iPSA > 20 were 86.6 and 48.6%, respectively.

CONCLUSION

HDR-BT plus EBRT without HT might be an alternative treatment option for patients with high-risk localized prostate cancer and iPSA levels ≤ 20. Further studies are required to validate the efficacy of this treatment strategy.

The influence of Gleason score ≤ 6 histology on the outcome of high-risk localized prostate cancer after modern radiotherapy

We aimed to retrospectively review outcomes in patients with high-risk prostate cancer and a Gleason score ≤ 6 following modern radiotherapy. We analyzed the outcomes of 1374 patients who had undergone modern radiotherapy, comprising a high-risk low grade [HRLG] group (Gleason score ≤ 6; n = 94) and a high-risk high grade [HRHG] group (Gleason score ≥ 7, n = 1125). We included 955 patients who received brachytherapy with or without external beam radio-therapy (EBRT) and 264 who received modern EBRT (intensity-modulated radiotherapy [IMRT] or stereotactic body radiotherapy [SBRT]). At a median follow-up of 60 (2-177) months, actuarial 5-year biochemical failure-free survival rates were 97.8 and 91.8% (p = 0.017), respectively. The frequency of clinical failure in the HRLG group was less than that in the HRHG group (0% vs 5.4%, p = 0.012). The HRLG group had a better 5-year distant metastasis-free survival than the HRHG group (100% vs 96.0%, p = 0.035). As the HRLG group exhibited no clinical failure and better outcomes than the HRHG group, the HRLG group might potentially be classified as a lower-risk group.

Impact of prostate position-based image-guidance in intensity-modulated radiation therapy for localized prostate cancer

BACKGROUND/PURPOSE

The long-term clinical impact of prostate position-based image-guided radiotherapy (IGRT) for localized prostate cancer remains unclear.

MATERIALS AND METHODS

We retrospectively compared clinical outcomes following intensity-modulated radiation therapy (IMRT) with cone-beam computed tomography-based prostate position-based IGRT (P-IGRT) or without P-IGRT (non-P-IGRT). From June 2011, we applied P-IGRT in IMRT for intermediate-risk (IR) prostate cancer (PCa) (D'Amico risk classification) (76 Gy in 38 fractions, with smaller margins). Clinical outcomes of patients who received P-IGRT between June 2011 and June 2019 were retrospectively compared with those of patients with IR PCa who received IMRT without P-IGRT between October 2002 and May 2011 in our institution (74 Gy in 37 fractions).

RESULTS

A total of 222 consecutive patients were analyzed: 114 in the P-IGRT cohort and 108 in the non-P-IGRT cohort. The median follow-up period after IMRT was 7.1 years for the P-IGRT cohort and 10.8 years for the non-P-IGRT cohort. The biochemical failure-free rate was significantly better in the P-IGRT cohort (94.9% for the P-IGRT cohort vs 82.7% for the non-P-IGRT cohort at 10 years, p = 0.041). The rate of rectal bleeding which needs intervention including the use of suppositories was significantly lower in the P-IGRT cohort (p < 0.001).

CONCLUSIONS

The use of P-IGRT with higher doses and smaller margins was correlated with significantly better biochemical control, and a lower incidence of rectal bleeding in IMRT for intermediate-risk prostate cancer. The enhanced accuracy using P-IGRT has the potential to independently improve disease control and reduce late rectal bleeding.

Prognostic significance of surgery and radiotherapy in elderly patients with localized prostate cancer: establishing and time-based external validation a nomogram from SEER-based study

OBJECTIVE

Prostate cancer (PC) is a significant disease affecting men's health worldwide. More than 60% of patients over 65 years old and more than 80% are diagnosed with localized PC. The current choice of treatment modalities for localized PC and whether overtreatment is controversial. Therefore, we wanted to construct a nomogram to predict the risk factors associated with cancer-specific survival (CSS) and overall survival (OS) in elderly patients with localized PC while assessing the survival differences in surgery and radiotherapy for elderly patients with localized PC.

METHODS

Data of patients with localized PC over 65 years were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox regression models were used to determine independent risk factors for CSS and OS. Nomograms predicting CSS and OS were built using multivariate Cox regression models. The consistency index (C-index), the area under the subject operating characteristic curve (AUC), and the calibration curve were used to test the accuracy and discrimination of the prediction model. Decision curve analysis (DCA) was used to test the potential clinical value of this model.

RESULTS

A total of 90,434 patients over 65 years and diagnosed with localized PC from 2010 to 2018 were included in the study. All patients were randomly assigned to the training set (n = 63,328) and the validation set (n = 27,106). Univariate and multivariate Cox regression model analysis showed that age, race, marriage, T stage, surgical, radiotherapy, prostate-specific antigen (PSA), and Gleason score (GS) were independent risk factors for predicting CSS in elderly patients with localized PC. Age, race, marriage, surgery, radiotherapy, PSA, and GS were independent risk factors for predicting OS in elderly patients with localized PC. The c-index of the training and validation sets for the predicted CSS is 0.802(95%CI:0.788-0.816) and 0.798(95%CI:0.776-0.820, respectively). The c-index of the training and validation sets for predicting OS is 0.712(95%:0.704-0.720) and 0.724(95%:0.714-0.734). It shows that the nomograms have excellent discriminatory ability. The AUC and the calibration curves also show good accuracy and discriminability.

CONCLUSION

We have developed new nomograms to predict CSS and OS in elderly patients with localized PC. After internal validation and external temporal validation with reasonable accuracy, reliability and potential clinical value, the model can be used for clinically assisted decision-making.

Rectal ulcer associated with lenvatinib 15 years after definitive radiotherapy for prostate cancer: A case report

Lenvatinib is a multi-kinase inhibitor that blocks vascular endothelial growth factor, fibroblast growth factor and platelet-derived growth factor receptors. The present study describes a case of rectal ulceration triggered by lenvatinib treatment for hepatocellular carcinoma 15 years after definitive radiotherapy for prostate cancer. A 58-year-old man underwent definitive external beam radiotherapy and high-dose-rate brachytherapy for prostate cancer. A total of 15 years after radiotherapy for prostate cancer, the patient was diagnosed with hepatocellular carcinoma with multiple metastases. Treatment with 12 mg/day lenvatinib was commenced. A total of 4 months after starting lenvatinib therapy, the patient experienced persistent anal pain with a deep ulceration of the anterior wall of the lower rectum. As the pain did not improve, the patient chose to undergo a colostomy, resulting in the resolution of the anorectal pain. To the best of our knowledge, the present case report is the first to report on lenvatinib-induced rectal ulcers after radiotherapy.

Patients with PSA below 0.2 ng/mL at 8 years post high-dose-rate brachytherapy have an extremely low risk of subsequent recurrence

OBJECTIVES

We have analyzed the long-term follow-up data of patients with prostate cancer (PCa) who underwent high-dose-rate brachytherapy (HDR-BT) and external beam radiotherapy (EBRT) combined with long-term androgen deprivation therapy (ADT). The objective was to determine the optimal time for cessation of PSA monitoring after HDR-BT.

METHODS

We included 309 patients with clinical stage T1c-T4 N0-1 M0 PCa who received HDR-BT and EBRT combined with long-term ADT between 2005 and 2018. We stratified the patients based on their prostate-specific antigen (PSA) levels and identified the factors associated with biochemical recurrence (BCR) and clinical progression (CP).

RESULTS

The median follow-up duration was 98 months (range: 31-207 months). Among the 306 patients, 76 developed BCR and 47 developed CP subsequently. We found that the PSA levels at 3, 5, and 8 years significantly correlated with the oncological outcomes of brachytherapy. No patient with a PSA level ≤ 0.2 ng/mL at 8 years later developed BCR or CP.

CONCLUSION

Our long-term data suggest that in the presence of a PSA level ≤ 0.2 ng/mL at 8 years later, PSA monitoring may be safely discontinued due to the extremely low risk of subsequent oncological events. The data presented in this study will assist clinicians in determining the optimal management strategy for patients with PCa following HDR-BT and EBRT combined with long-term ADT.

Comparison of toxicities between ultrahypofractionated radiotherapy versus brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer

To compare gastrointestinal (GI) and genitourinary (GU) toxicities in patients with localized prostate cancer treated with ultrahypofractionated radiotherapy (UHF) or brachytherapy [BT; low dose rate, LDR or high dose rate (HDR) with or without external beam radiotherapy (EBRT)]. We compared 253 UHF and 1664 BT ± EBRT groups. The main outcomes were the incidence and severity of acute and late GU and GI toxicities. The secondary endpoint was biochemical control rate. Cumulative late actuarial GU toxicity did not differ for grade ≥ 2 (8.6% at 5-years in UHF and 13.3% in BT ± EBRT, hazard ratio [HR], 0.7066; 95% CI, 0.4093–1.22, p = 0.2127). Actuarial grade ≥ 2 late GI toxicity was higher in UHF (5.8% at 5-years, HR: 3.619; 95% CI, 1.774–7.383, p < 0.001) than in BT ± EBRT (1.1%). In detailed subgroup analyses, the high-dose UHF group (H-UHF) using BED ≥ 226 Gy_1.5, showed higher GI toxicity profiles than the other subgroups (HDR + EBRT, LDR + EBRT, and LDR monotherapy, and L-UHF BED < 226 Gy_1.5) with equivalent GU toxicity to other modalities. With a median follow-up period of 32 months and 75 months, the actuarial biochemical control rates were equivalent between the UHF and BT ± EBRT groups. UHF showed equivalent efficacy, higher GI and equivalent GU accumulated toxicity to BT ± EBRT, and the toxicity of UHF was largely dependent on the UHF schedule.

Conventional dose versus dose escalated radiotherapy including high-dose-rate brachytherapy boost for patients with Gleason score 9-10 clinical localized prostate cancer

As several recent researches focus on the importance of Gleason 9-10, we examine the role of radiotherapy dose escalation in those patients. We analyzed 476 patients with Gleason score 9-10 prostate cancer treated with radiotherapy. Of them, 127 patients were treated with conventional-dose external beam radiotherapy (Conv RT) and 349 patients were treated with high-dose radiotherapy (HDRT; 249 patients received high-dose-rate brachytherapy boost + external beam radiotherapy [HDR boost] and 100 patients received intensity-modulated radiotherapy [IMRT]). We compared these treatment groups using multi-institutional retrospective data. The patients had a median follow-up period of 66.3 months. HDRT showed superior biochemical disease-free survival (bDFS) rate (85.2%; HDR boost 84.7% and IMRT 86.6%) to Conv RT (71.1%, p < 0.0001) at 5 years, with a hazard ratio of 0.448. There were borderline difference in prostate cancer-specific mortality (PCSM; 4.3% and 2.75%, p = 0.0581), and distant metastasis-free survival (DMFS; 94.4% and 89.6%, p = 0.0916) rates at 5-years between Conv RT and HDRT group. Dose escalated radiotherapy showed better bDFS, borderline improvement in PCSM, and equivocal outcome in DMFS in with clinically localized Gleason 9-10 prostate cancer.

High rate of local control and cure at 10 years after treatment of prostate cancer with external beam radiotherapy and high-dose-rate brachytherapy: a single centre experience

BACKGROUND AND PURPOSE

To analyse the cumulative incidence of any failure (AF), prostate cancer-specific failure (PCSF), any death (AD), prostate cancer-specific death (PCSD), and local control in 2387 men with prostate cancer (PC), consecutively treated with combined high-dose-rate brachytherapy (HDRBT) and external beam radiotherapy (EBRT) from 1998 to 2010.

MATERIAL AND METHODS

A retrospective, single-institution study of men with localised PC. The mean age was 66 years and 54.7% had high-risk PC according to the Cambridge prognostic group (CPG) classification. The treatment was delivered as EBRT (2 Gy × 25) and HDRBT (10 Gy × 2) with combined androgen blockade (CAB). The median follow-up was 10.2 years.

RESULTS

The cumulative incidence of PCSD at 10 years was 5% [CI 95% 0.04-0.06]. The 10 years PCSD per risk group were: low (L) 0.4%, intermediate favourable (IF) 1%, intermediate unfavourable (IU) 4.3%, high-risk favourable (HF) 5.8%, and high-risk unfavourable (HU) 13.9%. The PCSF rate at 10 years was 16.5% [CI 95% 0.15-0.18]. The PCSF per risk group at 10 years were: L 2.5%, IF 5.5%, IU 15.9%, HF 15.6%, and HU 38.99%. PCSF occurred in 399 men, of whom 15% were found to have local failure. The estimated frequency of local failure in the entire cohort was 1.2%.

CONCLUSIONS

HDRBT combined with EBRT is an effective treatment with long-term overall survival and excellent local control for patients with PC. The low rate of local recurrence among men with relapse suggests that these patients were micro metastasised at time of treatment, which calls for improved methods to detect disseminated disease.

The effectiveness of high-dose-rate brachytherapy with external beam radiotherapy for clinically locally advanced and node-positive prostate cancer: long-term results of a retrospective study

BACKGROUND

No standard treatment exists for locally advanced prostate cancer (PC). This study evaluated the long-term treatment outcomes and toxicity in patients with clinically locally advanced and/or lymph node (LN)-positive PC who underwent high-dose-rate brachytherapy (HDR-BT) with external beam radiotherapy (EBRT).

METHODS

The treatment outcomes and toxicities of 152 patients with PC who underwent HDR-BT with EBRT and had at least 2 years of observation were examined. The treatment dose was 19- and 13-Gy HDR-BT in two and single fractions, respectively, both combined with external irradiation of 46 Gy in 23 fractions. Long-term androgen deprivation therapy (ADT) for patients harboring very high-risk tumors was used in combination.

RESULTS

The median observation period was 59.7 (24.4-182.1) months. The 5-year prostate cancer-specific and recurrence-free (RFS) survival rates were 99.0% and 91.8%, respectively, with only two PC mortalities. When 5-year RFS was examined for each parameter, RFS was significantly lower in pre-radiotherapy (pre-RT) prostate-specific antigen (PSA) > 0.5 ng/mL (77.1%; p = 0.008), and presence of LN metastasis (68.1%; p = 0.017). Multivariable analysis demonstrated that pre-RT PSA (HR, 4.68; 95% CI, 1.39-15.67; p = 0.012) and presence of LN metastasis (HR, 4.70; 95% CI, 1.24-17.74; p = 0.022) were independent recurrence predictors. The 5-year cumulative incidence rate of grade ≥ 2 toxicities in genitourinary and gastrointestinal tracts were 15.4% and 1.3%, respectively.

CONCLUSIONS

HDR-BT combined with EBRT and long-term ADT shows promising disease control and tolerant toxicities for clinically locally advanced and LN-positive PC.

High-dose-rate brachytherapy for prostate cancer: Rationale, current applications, and clinical outcome

Background

High‐dose‐rate brachytherapy (HDR BRT) has been enjoying rapid acceptance as a treatment modality offered to selected prostate cancer patients devoid of risk group, employed either in monotherapy setting or combined with external beam radiation therapy (EBRT) and is currently one of the most active clinical research areas.

Recent findings

This review encompasses all the current evidence to support the use of HDR BRT in various clinical scenario and shines light to the HDR BRT rationale, as an ultimately conformal dose delivery method enabling safe dose escalation to the prostate.

Conclusion

Valid long‐term data, both in regard to the oncologic outcomes and toxicity profile, support the current clinical indication spectrum of HDR BRT. At the same time, this serves as solid, rigid ground for emerging therapeutic applications, allowing the technique to remain in the spotlight alongside stereotactic radiosurgery.

A comparative study of high-dose-rate brachytherapy boost combined with external beam radiation therapy versus external beam radiation therapy alone for high-risk prostate cancer

We aimed to compare the outcomes of high-dose-rate brachytherapy (HDR-BT) boost and external beam radiation therapy (EBRT) alone for high-risk prostate cancer. This was a single-center, retrospective and observational study. Consecutive patients who underwent initial radical treatment by HDR-BT boost or EBRT alone from June 2009 to May 2016 at the Niigata University Medical and Dental Hospital, Japan were included. A total of 96 patients underwent HDR-BT boost, and 61 underwent EBRT alone. The prescription dose of HDR-BT boost was set to 18 Gy twice a day with EBRT 39 Gy/13 fractions. The dose for EBRT alone was mostly 70 Gy/28 fractions. The high-risk group received >6 months of prior androgen deprivation therapy. Overall survival, biochemical-free survival, local control and distant metastasis-free survival rates at 5 years were analyzed. The incidence of urological and gastrointestinal late adverse events of Grade 2 and above was also summarized. In the National Comprehensive Cancer Network (NCCN) high-risk calssification, HDR-BT boost had a significantly higher biochemical-free survival rate at 5 years (98.9% versus 90.7%, P = 0.04). Urethral strictures were more common in the HDR-BT boost group. We will continuously observe the progress of the study patients and determine the longer term results.

Radiotherapy for Clinically Localized T3b or T4 Very-High-Risk Prostate Cancer-Role of Dose Escalation Using High-Dose-Rate Brachytherapy Boost or High Dose Intensity Modulated Radiotherapy

Simple Summary

Recently, high-risk prostate cancer was subdivided to a very-high-risk group considered to have the worst prognosis, including clinical stage T3b–T4, primary Gleason pattern 5, or more than four biopsy cores with Gleason score 8–10. Among these, T3b–T4 stage is a special interest in radiotherapy because of their wider target volume outside the prostate. We examined this subgroup and found that dose escalation in radiotherapy both with brachytherapy or intensity modulated radiotherapy (IMRT) improved biochemical free survival rate but not in prostate cancer specific survival rate and overall survival rate.

Abstract

To examine the efficacy of dose escalating radiotherapy into patients with cT3b or T4 localized prostate cancer, we compared Group A (86 conventional dose external beam radiotherapy: EBRT group, treated with 70–72 Gy) and group B (39 high dose EBRT group (HDEBRT group, 74–80 Gy) and 124 high-dose-rate brachytherapy (HDR) + EBRT (HDR boost)) using multi-institutional retrospective data. The actuarial 5-year biochemical disease-free survival (bDFS) rate, prostate cancer specific survival rate (PSS), and overall survival rate (OS) were 75.8%, 96.8%, and 93.5%. Group B showed superior 5-year bDFS rate (81.2%) as compared to the group A (66.5%) (p < 0.0001) with a hazard ratio of 0.397. Equivocal 5-year PSS (98.3% and 94.8% in group B and group A) and OS (both 93.7%) were found between those groups. Accumulated late grade ≥ 2 toxicities in gastrointestinal and genitourinary tracts were similar among those three groups. Therefore, both HDEBRT and HDR boost could be good options for improving the bDFS rate in cT3–T4 localized prostate cancer without affecting PSS and OS.

High-dose-rate brachytherapy with external beam radiotherapy versus low-dose-rate brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer

To compare the outcomes of localized prostate cancer treatment with high-dose-rate brachytherapy (HDR-BT) and low-dose-rate brachytherapy (LDR-BT), we examined 924 patients treated with HDR-BT + external beam radiotherapy (EBRT) and 500 patients treated with LDR-BT ± EBRT using multi-institutional retrospective data. The HDR-BT treated advanced disease with more hormonal therapy than LDR-BT. To reduce background selection bias, we performed inverse probability of treatment weighting (IPTW) analysis using propensity scores and excluded patients with T3b-4 disease/ initial prostate-specific antigen (PSA) levels > 50 ng/ml. The actuarial 5-year biochemical control rates (5y-bNED) were 96.3% and 95.7% in the HDR-BT and LDR-BT groups, respectively. The corresponding values were 100% and 96.5% in the low-risk group; 97.4% and 97.1% in the intermediate-risk group (97.2% and 97% in the higher titer group and 97.5% and 94.6% in the lower titer group, respectively); and 95.7% and 94.9% in the selected high-risk group, respectively. IPTW correction indicated no significant difference among the groups. The 5y-bNED in the HDR-BT + EBRT, LDR-BT + EBRT, and LDR-BT alone groups were 96.3%, 95.5%, and 97%, respectively (P = 0.3011). The corresponding values were 97.4%, 94.7%, and 96.6% (P = 0.1004) in the intermediate-risk group (97.5%, 100%, and 94.5% in the lower titer group [P = 0.122] and 97.2%, 96.2%, and 100% [P = 0.664] in the higher titer group, respectively) and 95.7%, 95.5%, and 100% (P = 0.859) in the high-risk group, respectively. The HDR-BT group showed a lower incidence of acute grade ≥ 2 genitourinary toxicities; the incidence of other early and late grade ≥ 2 toxicities were similar between the HDR-BT and LDR-BT groups. Acute genitourinary toxicity predicted the occurrence of late genitourinary toxicity. EBRT increased the risk of grade ≥ 2 gastrointestinal toxicity. HDR-BT + EBRT is a good alternative to LDR-BT ± EBRT for low-, intermediate-, and selected high-risk patients.

Radiotherapy for elder patients aged ≥80 with clinically localized prostate cancer - Brachytherapy enhanced late GU toxicity especially in elderly

Background and purpose

Elongation of life expectancy had led to marked increase in number of elderly patients with localized prostate cancer. However, the standard treatment for such patients is not well determined because of a high prevalence of comorbidities and slow growth of prostate cancer. The aim of this study is to examine the feasibility of radiotherapy for elderly patients aged ≥80 years.

Materials and methods

We compared 96 patients aged ≥80 years and 2333 younger patients (aged 60-79 years) using multi-institutional data included cT1-T4N0M0 prostate cancer treated with 902 external beam radiotherapy (EBRT) and 1527 brachytherapy (BT).

Results

The 5-year biochemical failure-free survival rate was similar between elderly ≥80 years and younger control (91.3% vs. 85.9%, p = 0.6171) (100%, 92.9%, 82.4% and 96.3%, 93.7%, 89% for low, intermediate and high risk group), and for the prostate cancer-specific survival rate (100% and 99.3%, p = 0.6171). The accumulated incidence of late gastrointestinal (GI) at 5 years was also similar between elderly and younger patients (3.5% vs. 2.5%, p = 0.6857). Brachytherapy improved biochemical control rate and reduced GI toxicity compared with EBRT, however, enhanced late genitourinary (GU) toxicity, especially in elderly patients. Elderly received brachytherapy showed highest rate of late GU toxicity grade ≥2 of 22.1% than the younger counterparts of 12.7% at 5 years, whereas younger patients treated with EBRT had 2.4% and elderly EBRT had 2.7% (p < 0.0001).

Conclusion

Elderly patients aged ≥80 years showed equivalent biochemical control, prostate cancer-related survival, and gastrointestinal toxicity profiles to younger patients. Meticulous care should be required for brachytherapy enhanced late GU toxicity, especially in elderly patients aged ≥80 years.

Potential Risk of Other-Cause Mortality Due to Long-Term Androgen Deprivation Therapy in Elderly Patients with Clinically Localized Prostate Cancer Treated with Radiotherapy-A Confirmation Study

Androgen deprivation therapy (ADT) is used to improve overall survival (OS) in prostate cancer treatment; however, we encountered that long-term ADT in elderly patients may be related to high other-cause mortality (OCM). This study aimed to confirm the potential risk associated with long-term ADT in elderly patients using a different large cohort. A comparison analysis was conducted between the ≥2- and <2-year ADT groups using open, large data from 1840 patients with clinically localized prostate cancer treated with radiotherapy (1172 treated with high-dose-rate brachytherapy (HDR) + external beam radiotherapy (EBRT) and 668 treated with external beam radiotherapy). The OCM-free survival (OCMFS), overall survival, and prostate cancer-specific survival rates were measured. The 10-year OCMFS rates in patients aged ≥75 years were 94.6% and 86% in the <2- and ≥2-year ADT groups, respectively, but were 96.3% and 93.5% (p = 0.0006) in their younger counterparts. If dividing into HDR and EBRT groups. This inclination was found in brachytherapy group but not in EBRT group. The overall survival rate was also lower in the elderly patients in the ≥2-year ADT group than in the <2-year ADT group; however, the 10-year prostate cancer-specific survival rate was the same in both groups. Long-term ADT in elderly patients resulted in not only higher OCM rates but also poorer OS rates; therefore, longer-term ADT in elderly patients should be performed with meticulous care.

Modern development of high-dose-rate brachytherapy

Brachytherapy is an invasive therapy with placement of radiation source into or near the tumor. The difference between planning target volume and clinical target volume is minimal, and the dose out of the tumor reduces rapidly due to the inverse-square law. High-dose-rate brachytherapy enables three-dimensional image guidance, and currently, tumor dose as well as doses of the surrounding normal structures can be evaluated accurately. High-dose-rate brachytherapy is the utmost precision radiation therapy even surpassing carbon ion therapy. Biological disadvantages of high-dose rate have been overcome by the fractional irradiation. High-dose-rate brachytherapy is indispensable in the definitive radiation therapy of cervical cancer. Also in prostate cancer and breast cancer, high-dose-rate brachytherapy plays a significant role. Brachytherapy requires techniques and skills of radiation oncologists at the time of invasive placement of the radiation source into the tumor area. Education of young radiation oncologists is most urgent and important.

Building a High-Dose-Rate Prostate Brachytherapy Program With Real-Time Ultrasound-Based Planning: Initial Safety, Quality, and Outcome Results

Purpose

Growing evidence supports the efficacy and safety of high-dose-rate (HDR) brachytherapy as a boost or monotherapy in prostate cancer treatment. We initiated a new HDR prostate brachytherapy practice in April 2014. Here, we report the learning experiences, short-term safety, quality, and outcome.

Methods and Materials

From April 2014 to December 2017, 164 men were treated with HDR brachytherapy with curative intent. Twenty-eight men (17.1%) underwent HDR brachytherapy as monotherapy, receiving 25 to 27 Gy in 2 fractions. Men treated with HDR brachytherapy as a boost received 19 to 21 Gy in 2 fractions. Fifty-two men (31.7%) had high-risk disease. HDR procedure times, dosimetry, and response were recorded and analyzed. Genitourinary (GU) and gastrointestinal (GI) toxicities were recorded according to the toxicity criteria of the Radiation Therapy Oncology Group.

Results

Mean HDR procedure times decreased yearly from 179 minutes in 2014 to 115 minutes in 2017. Median follow-up was 18.6 months (range, 3-55 months). At last review, 79% of patients reported returning to baseline GU status, and 100% of patients noted no change in GI status from their baseline. Four patients experienced acute urinary retention. Treatment planning target volume (PTV) was defined as prostate with margins. Dosimetrically, 97.5% of all HDR implants had PTV D90 ≥100%, 81.5% had PTV V100 ≥95%, 73.6% had maximal urethral doses ≤120%, and 77.5% had rectal 1 mL dose ≤70% (all but one ≤10.8 Gy). The estimated 3-year overall survival was 98.7% (95% confidence interval, 91.4%-99.8%), and disease-free survival was 96.2% (95% confidence interval, 89.5%-98.7%).

Conclusions

The low incidence of GU and GI complications in our cohort demonstrates that a HDR brachytherapy program can be successfully developed as a treatment option for patients with localized prostate cancer.

Analysis of outcomes after non-contour-based dose painting of dominant intra-epithelial lesion in intra-operative low-dose rate brachytherapy

Purpose

To compare the outcomes of patients with intermediate risk prostate cancer (IR-PCa) treated with low-dose rate I-125 seed brachytherapy (LDR-BT) and targeted dose painting of a histologic dominant intra-epithelial lesion (DIL) to those without a DIL.

Methods

455 patients with IR-PCa were treated at a single center with intra-operatively planned LDR-BT, each following the same in-house dose constraints. Patients with a DIL on pathology had hot spots localized to that region but no specific contouring during the procedure.

Results

396 (87%) patients had a DIL. Baseline tumor characteristics and overall prostate dosimetry were similar between patients with and without DIL except the median number of biopsy cores taken: 10 (10–12) vs 12 (10–12) (p = 0.002).

19 (5%) and 18 (5%) of patients with and 1 (2%) and 0 (0%) of those without DIL experienced CTCAE grade 2 and 3 toxicity respectively. Overall, toxicity grade did not significantly correlate with presence of DIL (p = 0.10).

Estimated 7-year freedom from biochemical failure (FFBF) was 84% (95% confidence interval: 79–89) and 70% (54–89) in patients with and without a DIL (log-rank p = 0.315). In DIL patients, cox regression revealed location of DIL (“Base” vs “Apex” HR: 1.03; 1.00–1.06; p = 0.03) and older age (70 vs 60 HR: 1.62; 1.06–2.49; p = 0.03) was associated with poor FFBF.

Conclusions

Targeting DIL through dose painting during intraoperatively planned LDR-BT provided no statistically significant change in FFBF. Patients with DILs in the prostate base had slightly lower FFBF despite DIL boost.

Late toxicity after single dose HDR prostate brachytherapy and EBRT for localized prostate cancer: Clinical and dosimetric predictors in a prospective cohort study

PURPOSE

To describe the genitourinary (GU) and gastrointestinal (GI) late toxicity profile and to analyse the clinical and dosimetry outcomes predictors of the combination of EBRT and high-dose-rate (HDR) prostate brachytherapy (BT) for localized prostate cancer.

MATERIALS AND METHODS

Between January 2012 and May 2017, 210 patients were included in a prospective protocol. Treatment consisted in HDR-BT (15 Gy single fraction) plus 3DCRT (37.5 Gy/15 fractions). Univariate and multivariate logistic regressions were used to analyse the impact of variables on late toxicity.

RESULTS

Median age was 71 (56-82), 12.4% of patients had low, 44.3% intermediate and 41% high-risk prostate cancer. Median prostate volume was 28.4 cc. Median V100, V150, V200 were 98.2%, 27% and 7.4% respectively. Median urethra Dmax, rectum D1cc and D2cc, were 113.5%, 62.2%% and 54.2% respectively. After a median follow-up of 41 months (5-75) late G2 GU and GI late toxicity was observed in 14.8% and 5.2% of patients respectively. Late G3 GU and GI toxicity occurred in 0% and 1% of patients respectively. There were no outcome correlations with late G ≥ 2 GU toxicity on univariate analysis. Previous cardiovascular comorbidity (p = 0.042), and dose to the rectum D2cc (p = 0.016) and D1cc (p = 0.017) were associated with G ≥ 2 GI toxicity. Multivariate analysis showed that rectum D1cc (HR11.56; 95%CI 1.4-92.1; p = 0.021) and prior history of cardiovascular disease (HR3.6; 95%CI 1-12.9; p = 0.045) remained independent predictors of G ≥ 2 GI toxicity.

CONCLUSIONS

There is a low incidence of late GU and GI morbidity using single fraction HDR-BT and hypofractionated EBRT. Previous cardiovascular disease and dose to the rectum were observed to correlate with GI toxicity.

Radical dose escalation by high-dose-rate brachytherapy for localized prostate cancer-Significance of prostate-specific antigen nadir level within 18 months as correlation for long-term biochemical control

PURPOSE

High-dose-rate brachytherapy (HDR-BT) for dose escalation in localized prostate cancer has been established as one standard treatment option. However, long-term results at followup (FU) ≥5 years are usually needed to ensure robustness of reported outcomes. Potential benefit of salvage therapy is, nevertheless, higher when relapse is diagnosed early. This study aimed to solve this dilemma by evaluating the prostate-specific antigen (PSA) nadir for early prediction of long-term biochemical control.

METHODS AND MATERIALS

Combined pelvis-external beam radiation/HDR-BT boost to EQD2 >100 Gy (α/β = 3) was performed in 459 consecutively treated patients. These patients with an FU ≥ 24 months were analyzed and stratified in PSA nadir (nPSA)-groups by PSA nadir within 18 months after radiotherapy (nPSA18). Kaplan-Meier/log-rank tests and Cox-regression models were used to compare the study endpoints.

RESULTS

The mean FU was 77 months. A PSA nadir within 18 months (nPSA18) <0.5 ng/mL was achieved in 222 patients with median time to reach nPSA18 of 7 months. The 5-year American Society of Therapeutic Radiology and Oncology (ASTRO) biochemical control (prostate-specific antigen disease-free survival) for the nPSA18 group <0.5 ng/mL was 89% and for the group ≥ 0.5 ng/mL, it was 78.6% (p = 0.011). nPSA18 was an independent predictor of cancer-specific survival, distant metastasis-free survival, and biochemical control (ASTRO) (p = 0.026, p = 0.020, and p = 0.01, respectively).

CONCLUSIONS

The present results suggest that the PSA nadir level within 18 months after radiotherapy may serve as an early parameter for long-term biochemical control according to ASTRO definitions following radical dose escalation by HDR-BT for prostate cancer. Excellent outcomes were associated with nPSA18 < 0.5 ng/mL.

High dose-rate brachytherapy in the treatment of prostate cancer

High dose-rate (HDR) brachytherapy involves delivery of a high dose of radiation to the cancer with great sparing of surrounding organs at risk. Prostate cancer is thought to be particularly sensitive to radiation delivered at high dose-rate or at high dose per fraction. The rapid delivery and high conformality of dose results in lower toxicity than that seen with low dose-rate (LDR) implants. HDR combined with external beam radiotherapy results in higher cancer control rate than external beam only, and should be offered to eligible high and intermediate risk patients. While a variety of dose and fractionations have been used, a single 15 Gy HDR combined with 40-50 Gy external beam radiotherapy results in a disease-free survival of over 90% for intermediate risk and 80% for high risk. HDR monotherapy in two or more fractions (e.g., 27 Gy in 2 fractions or 34.5 Gy in 3) is emerging as a viable alternative to LDR brachytherapy for low and low-intermediate risk patients, and has less toxicity. The role of single fraction monotherapy to a dose of 19-20 Gy is evolving, with some conflicting data to date. HDR should also be considered as a salvage approach for recurrent disease following previous external beam radiotherapy. A particular advantage of HDR in this setting is the ease of delivering focal treatments, which combined with modern imaging allows focal dose escalation with minimal toxicity. Trans-rectal ultrasound (TRUS) based planning is replacing CT-based planning as the technique of choice as it minimizes or eliminates the need to move the patient between insertion, planning and treatment delivery, thus ensuring high accuracy and reproducibility of treatment.

Prostate cancer high dose-rate brachytherapy: review of evidence and current perspectives

INTRODUCTION

Patients with intermediate to high risk disease (prostate specific antigen (PSA) ≥ 10, Gleason score ≥ 7, or clinical stage ≥ T2b) suffer from poorer long-term biochemical control (freedom from an increasing prostate specific antigen level) when treated with external beam radiation (EBRT) alone. In order to improve biochemical control while limiting long-term complications, brachytherapy has been incorporated into radiotherapy treatment, either alone or in combination with EBRT.

AREAS COVERED

Current literature regarding the use of high dose-rate (HDR) brachytherapy for localized prostate cancer, including as a boost and monotherapy. The efficacy and toxicities of various approaches are evaluated including comparisons to low dose-rate (LDR) brachytherapy.

EXPERT COMMENTARY

Prostate HDR brachytherapy has higher conformality than EBRT, potentially improving the therapeutic ratio by allowing higher doses per fraction to tumor cells. The improved biochemical control shown in trials have resulted in EBRT plus brachytherapy to be included as a standard treatment option supported by the NCCN and ASCO guidance documents for intermediate to high risk prostate cancer.

High-dose-rate brachytherapy boost for prostate cancer: Comparison of three different fractionation schemes

PURPOSE

Dose escalation for prostate cancer can be achieved with a combination of external beam radiotherapy (EBRT) and brachytherapy (BT) boost to increase local control. For high-dose-rate (HDR)-BT, optimal fractionation remains under debate. The objective was to assess the clinical outcome of three schemes of HDR-BT boost.

METHODS AND MATERIALS

Retrospective single institution data collection was performed. Patients received 46 Gy EBRT then an HDR-BT boost: 3 × 6 Gy, 2 × 9 Gy, or 1 × 14 Gy. HDR needles were placed under general anesthesia with endorectal ultrasonography guidance. CT-scan and treatment were performed postoperatively.

RESULTS

Between 2009 and 2012, 159 patients were included. Nine patients (5.7%) were low, 32 (20.1%) intermediate, and 118 (74.2%) high risk (D'Amico classification) without significant difference between the three BT schemes. With a median followup of 61 months, 5-year biochemical relapse-free survival, 5-year local relapse-free survival, 5-year metastases-free survival, and 5-year overall survival rates were 86.6% (SE 2.7%), 98.3% (SE 1%), 95.3% (SE 1%), and 96.5% (SE 1.5%), respectively, with no significant difference between the BT schemes. The rates of acute ≥ G2 genitourinary and ≥G2 gastrointestinal toxicities were 11.3% and 6.3%, respectively (p = NS). The rates of late genitourinary ≥ G2 and gastrointestinal ≥ G2 toxicities (at last followup) were 9.4% and 0.6% with, respectively, 0.6% and 0% of G4 (p = NS).

CONCLUSIONS

Hypofractionation up to a single-fraction HDR-BT boost for prostate cancer yields similar results in terms of biochemical control and late toxicity compared with two or three-fraction schemes. Single fraction HDR-BT appears acceptable for boosting prostate cancer after definitive EBRT.