Long-term results of conformal radiotherapy for prostate cancer: impact of dose escalation on biochemical tumor control and distant metastases-free survival outcomes

Prostate cancer therapy outcome prediction: are miRNAs a suitable guide for therapeutic decisions?

BACKGROUND

Radical prostatectomy, radiotherapy, chemotherapy, and androgen-deprivation therapy are among the most common treatment options for different forms of prostate cancer (PCa). However, making therapeutic decisions is difficult due to the lack of reliable prediction markers indicating therapy outcomes in clinical practice. The involvement of miRNAs in all mechanisms of the PCa development and their easy detection characterize them as attractive PCa biomarkers. Although there are extensive data on the role of miRNAs in PCa therapy resistance and sensitivity development, the issues of whether they could be used as a guide for therapy choice and, if so, how we can progress toward this goal, remain unclear. Thus, generalizable reviews and studies which summarize, compare, and analyze data on miRNA involvement in responses to different types of PCa therapies are required.

OBJECTIVES

Data on the involvement of miRNAs in therapy responses, on the role of cross-miRNA expression in different therapies, and on miRNA targets were analyzed in order to determine the miRNA-related factors which can lend perspective to the future development of personalized predictors of PCa sensitivity/resistance to therapies.

MATERIALS AND METHODS

The data available on the miRNAs associated with different PCa therapies (resistance and sensitivity therapies) are summarized and analyzed in this study, including analyses using bioinformatics resources. Special attention was dedicated to the mechanisms of the development of therapy resistance.

RESULTS AND DISCUSSION

A comprehensive combined analysis of the current data revealed a panel of miRNAs that were shown to be most closely associated with the PCa therapy response and were found to regulate the genes involved in PCa development via cell proliferation regulation, epithelial-mesenchymal transition (EMT), apoptosis, cell-cycle progression, angiogenesis, metastasis and invasion regulation, androgen-independent development, and colony formation.

CONCLUSION

The selected miRNA-based panel has the potential to be a guide for therapeutic decision making in the effective treatment of PCa.

Towards optimal heterogeneous prostate radiotherapy dose prescriptions based on patient-specific or population-based biological features

BACKGROUND

Escalation of prescribed dose in prostate cancer (PCa) radiotherapy enables improvement in tumor control at the expense of increased toxicity. Opportunities for reduction of treatment toxicity may emerge if more efficient dose escalation can be achieved by redistributing the prescribed dose distribution according to the known heterogeneous, spatially-varying characteristics of the disease.

PURPOSE

To examine the potential benefits, limitations and characteristics of heterogeneous boost dose redistribution in PCa radiotherapy based on patient-specific and population-based spatial maps of tumor biological features.

METHOD

High-resolution prostate histology images, from a cohort of 63 patients, annotated with tumor location and grade, provided patient-specific "maps" and a population-based "atlas" of cell density and tumor probability. Dose prescriptions were derived for each patient based on a heterogeneous redistribution of the boost dose to the intraprostatic lesions, with the prescription maximizing patient tumor control probability (TCP). The impact on TCP was assessed under scenarios where the distribution of population-based biological data was ignored, partially included, or fully included in prescription generation. Heterogeneous dose prescriptions were generated for three combinations of maps and atlas, and for conventional fractionation (CF), extreme hypo-fractionation (EH), moderate hypo-fractionation (MH), and whole Pelvic RT + SBRT Boost (WPRT + SBRT). The predicted efficacy of the heterogeneous prescriptions was compared with equivalent homogeneous dose prescriptions.

RESULTS

TCPs for heterogeneous dose prescriptions were generally higher than those for homogeneous dose prescriptions. TCP escalation by heterogeneous dose prescription was the largest for CF. When only using population-based atlas data, the generated heterogeneous dose prescriptions of 55 to 58 patients (out of 63) had a higher TCP than for the corresponding homogeneous dose prescriptions. The TCPs of the heterogeneous dose prescriptions generated with the population-based atlas and tumor probability maps did not differ significantly from those using patient-specific biological information. The generated heterogeneous dose prescriptions achieved significantly higher TCP than homogeneous dose prescriptions in the posterior section of the prostate.

CONCLUSION

Heterogeneous dose prescriptions generated via biologically-optimized dose redistribution can produce higher TCP than the homogeneous dose prescriptions for the majority of the patients in the studied cohort. For scenarios where patient-specific biological information was unavailable or partially available, the generated heterogeneous dose prescriptions can still achieve TCP improvement relative to homogeneous dose prescriptions.

Age 70 +/- 5 Years and Cancer-Specific Outcomes After Treatment of Localized Prostate Cancer: A Systematic Review

A secondary analysis of 2 randomized Radiation Therapy Oncology Group trials demonstrated that age ≥70 years was a favorable prognostic factor among men treated with external beam radiation therapy (EBRT). In contrast, several series based on men undergoing radical prostatectomy (RP) suggested that older age was an unfavorable prognostic factor. Our study was initiated to determine whether these observations reflect a true but paradoxical underlying age-related treatment-dependent biological phenomenon. We conducted a systematic review (PubMed, January 1, 1999-January 30, 2023) evaluating the effect of age on cancer-specific outcomes after definitive local treatment with either RP or EBRT. Our main objective was to assess possible interactions between age (using a cutoff of 70 +/- 5 years) and treatment type, with regard to adverse cancer-specific outcomes (eg, pathology, biochemical failure, distant metastasis, or prostate cancer-specific survival). Forty-five studies were selected for inclusion in this systematic review, including 30 and 15 studies with patients treated with RP and EBRT, respectively. Among patients treated with RP, 10 (50%) of these studies suggested that older age was associated with worse outcome(s) after RP. None suggested that age was a favorable prognostic factor after RP. Among the EBRT-based studies, 8 (53%) suggested that older age was associated with better outcomes, with an additional 3 studies (21%) trending to support a better outcome. None of these studies involving EBRT suggested that older age was an adverse prognostic factor. This systematic review suggests that age using a categorical cutoff of 70 +/- 5 years may be an adverse prognostic factor for men undergoing RP but a favorable prognostic factor for men treated with EBRT. Further research is needed to validate these findings.

Initial Quality of Life and Toxicity Analysis of a Randomized Phase 3 Study of Moderately Hypofractionated Radiation Therapy With or Without Androgen Suppression for Intermediate-Risk Adenocarcinoma of the Prostate: PCG GU003

Purpose

Our objective was to report the quality of life (QoL) analysis and toxicity in patients with intermediate-risk prostate cancer treated with or without androgen deprivation therapy (ADT) in Proton Collaborative Group (PCG) GU003.

Methods and Materials

Between 2012 and 2019, patients with intermediate-risk prostate cancer were enrolled. Patients were randomized to receive moderately hypofractionated proton beam therapy (PBT) to 70 Gy relative biologic effectiveness in 28 fractions to the prostate with or without 6 months of ADT. Expanded Prostate Cancer Index Composite, Short-Form 12, and the American Urological Association Symptom Index instruments were given at baseline and 3, 6, 12, 18, and 24 months after PBT. Toxicities were assessed according to Common Terminology Criteria for Adverse Events (version 4).

Results

One hundred ten patients were randomized to PBT either with 6 months of ADT (n = 55) or without ADT (n = 55). The median follow-up was 32.4 months (range, 5.5-84.6). On average, 101 out of 110 (92%) patients filled out baseline QoL and patient-reported outcome surveys. The compliance was 84%, 82%, 64%, and 42% at 3, 6, 12, and 24 months, respectively. Baseline median American Urological Association Symptom Index was comparable between arms (6 [11%] ADT vs 5 [9%] no ADT, P = .359). Acute and late grade 2+ genitourinary and gastrointestinal toxicity were similar between arms. The ADT arm experienced a QoL decline of mean scores in the sexual (-16.1, P < .001) and hormonal (-6.3, P < .001) domains, with the largest time-specific hormonal differences at 3 (-13.8, P < .001) and 6 (-11.2, P < .001) months. The hormonal QoL domain returned to baseline 6 months after therapy. There was a trend to baseline in sexual function 6 months after completion of ADT.

Conclusions

After 6 months of ADT, sexual and hormonal domains returned to baseline 6 months after completion of treatment for men with intermediate-risk prostate cancer.

Dose-escalated radiotherapy for clinically localized and locally advanced prostate cancer

BACKGROUND

Treatments for clinically localized prostate cancer include radical prostatectomy, external beam radiation therapy, brachytherapy, active surveillance, hormonal therapy, and watchful waiting. For external beam radiation therapy, oncological outcomes may be expected to improve as the dose of radiotherapy (RT) increases. However, radiation-mediated side effects on surrounding critical organs may also increase.

OBJECTIVES

To assess the effects of dose-escalated RT in comparison with conventional dose RT for curative treatment of clinically localized and locally advanced prostate cancer.

SEARCH METHODS

We performed a comprehensive search using multiple databases including trial registries and other sources of grey literature, up until 20 July 2022. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included parallel-arm randomized controlled trials (RCTs) of definitive RT in men with clinically localized and locally advanced prostate adenocarcinoma. RT was dose-escalated RT (equivalent dose in 2 Gy [EQD2] ≥ 74 Gy, lesser than 2.5 Gy per fraction) versus conventional RT (EQD2 < 74 Gy, 1.8 Gy or 2.0 Gy per fraction). Two review authors independently classified studies for inclusion or exclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data from the included studies. We performed statistical analyses by using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We used GRADE guidance to rate the certainty of the evidence of RCTs.

MAIN RESULTS

We included nine studies with 5437 men in an analysis comparing dose-escalated RT versus conventional dose RT for the treatment of prostate cancer. The mean participant age ranged from 67 to 71 years. Almost all men had localized prostate cancer (cT1-3N0M0). Primary outcomes Dose-escalated RT probably results in little to no difference in time to death from prostate cancer (hazard ratio [HR] 0.83, 95% CI 0.66 to 1.04; I2 = 0%; 8 studies; 5231 participants; moderate-certainty evidence). Assuming a risk of death from prostate cancer of 4 per 1000 at 10 years in the conventional dose RT group, this corresponds to 1 fewer men per 1000 (1 fewer to 0 more) dying of prostate cancer in the dose-escalated RT group. Dose-escalated RT probably results in little to no difference in severe RT toxicity of grade 3 or higher late gastrointestinal (GI) toxicity (RR 1.72, 95% CI 1.32 to 2.25; I2 = 0%; 8 studies; 4992 participants; moderate-certainty evidence); 23 more men per 1000 (10 more to 40 more) in the dose-escalated RT group assuming severe late GI toxicity as 32 per 1000 in the conventional dose RT group. Dose-escalated RT probably results in little to no difference in severe late genitourinary (GU) toxicity (RR 1.25, 95% CI 0.95 to 1.63; I2 = 0%; 8 studies; 4962 participants; moderate-certainty evidence); 9 more men per 1000 (2 fewer to 23 more) in the dose-escalated RT group assuming severe late GU toxicity as 37 per 1000 in the conventional dose RT group. Secondary outcomes Dose-escalated RT probably results in little to no difference in time to death from any cause (HR 0.98, 95% CI 0.89 to 1.09; I2 = 0%; 9 studies; 5437 participants; moderate-certainty evidence). Assuming a risk of death from any cause of 101 per 1000 at 10 years in the conventional dose RT group, this corresponds to 2 fewer men per 1000 (11 fewer to 9 more) in the dose-escalated RT group dying of any cause. Dose-escalated RT probably results in little to no difference in time to distant metastasis (HR 0.83, 95% CI 0.57 to 1.22; I2 = 45%; 7 studies; 3499 participants; moderate-certainty evidence). Assuming a risk of distant metastasis of 29 per 1000 in the conventional dose RT group at 10 years, this corresponds to 5 fewer men per 1000 (12 fewer to 6 more) in the dose-escalated RT group developing distant metastases. Dose-escalated RT may increase overall late GI toxicity (RR 1.27, 95% CI 1.04 to 1.55; I2 = 85%; 7 studies; 4328 participants; low-certainty evidence); 92 more men per 1000 (14 more to 188 more) in the dose-escalated RT group assuming overall late GI toxicity as 342 per 1000 in the conventional dose RT group. However, dose-escalated RT may result in little to no difference in overall late GU toxicity (RR 1.12, 95% CI 0.97 to 1.29; I2 = 51%; 7 studies; 4298 participants; low-certainty evidence); 34 more men per 1000 (9 fewer to 82 more) in the dose-escalated RT group assuming overall late GU toxicity as 283 per 1000 in the conventional dose RT group. Based on long-term follow-up (up to 36 months), dose-escalated RT may result or probably results in little to no difference in the quality of life using 36-Item Short Form Survey; physical health (MD -3.9, 95% CI -12.78 to 4.98; 1 study; 300 participants; moderate-certainty evidence) and mental health (MD -3.6, 95% CI -83.85 to 76.65; 1 study; 300 participants; low-certainty evidence), respectively.

AUTHORS' CONCLUSIONS

Compared to conventional dose RT, dose-escalated RT probably results in little to no difference in time to death from prostate cancer, time to death from any cause, time to distant metastasis, and RT toxicities (except overall late GI toxicity). While dose-escalated RT may increase overall late GI toxicity, it may result, or probably results, in little to no difference in physical and mental quality of life, respectively.

Risk factors for rectal bleeding after volumetric-modulated arc radiotherapy of prostate cancer

Background

It is crucially important to understand the risk factors for rectal bleeding after volumetric-modulated arc radiotherapy (VMAT) for prostate cancer to prevent subsequent rectal bleeding. We assayed clinical and dosimetric data to investigate the risk factors for rectal bleeding after VMAT of prostate cancer.

Materials and methods

This study included 149 patients with prostate cancer who received VMAT from February, 2012 to June, 2020. Irradiated total doses were 78 Gy/39 fractions in 33 patients (22.1%), 76 Gy/38 fractions in 89 (59.7%), 74 Gy/37 fractions in 4 (2.7%), and 72 Gy/36 fractions in 23 (15.4%). We investigated multiple clinical and dosimetric factors with reference to rectal bleeding.

Results

The median observation period was 38 months. Fourteen patients (9.4%) experienced rectal bleeding: five (3.4%) were classified as Grade 2, and nine (6.0%) as Grade 1. There were significant differences between Grade ≥ 1 and Grade 0 patients in the overlap region of the planning target volume (PTV) and the rectum, the rectal V30-75, and the mean rectal dose (p < 0.05). There were significant differences between Grade 2 and Grade 0-1 patients in rectal V30-65 and mean rectal dose (p < 0.05).

Conclusions

Rectal bleeding occurred, but its grades and rate of occurrence were permissible. Higher rectal doses were shown to be related to rectal bleeding, and reduction of low/intermediate and mean rectal doses will be important for preventing rectal bleeding.

Comparative evaluation of hypofractionated radiotherapy versus conventionally fractionated radiotherapy for patients with intermediate and high risk prostate cancer

Background

The purpose of this study was to comparatively evaluate an efficacy and toxicity profile of hypofractionated radiotherapy (67.5 Gy in 25 fractions) to conventionally fractionated radiotherapy (78 Gy in 39 fractions) in prostate cancer patients with intermediate and high-risk disease.

Materials and methods

From January 2015 to December 2018, 168 patients were randomized to hypofractionated radiation treatment and conventional fractionated radiation treatment schedules of volumetric modulated arc therapy (VMAT) to the prostate and seminal vesicles. All the patients also received androgen deprivation therapy (ADT) and radiation therapy started after ADT.

Results

The median (range) follow-up was 51 (31-63) and 53 (33-64) months in the hypofractionated and conventionally fractionated regimes, respectively. The 3-year biochemical no evidence of disease (bNED) rates were 86.9% and 73.8% in the hypofractionated and conventionally fractionated groups, respectively (p = 0.032, significant). The 3-year bNED rates in patients at a high risk [i.e., pretreatment prostate-specific antigen (PSA) > 20 ng/mL, Gleason score ≥ 8, or T ≥ 2 c], were 87.9% and 73.5% (p = 0.007, significant) in the hypofractionated and conventionally fractionated radiotherapy groups, respectively. No statistically significant difference was found for late toxicity between the two groups, with 3-year grade 2 gastrointestinal toxicity rates of 19% and 16.7% and 3-year grade 2 genitourinary toxicity rates of 15.5% and 11.9% in the hypofractionated and conventionally fractionated radiotherapy groups, respectively.

Conclusion

Hypofractionated schedule is superior to the conventional fractionation schedule of radiation treatment in terms of bNED in intermediate and high grade prostate cancer patients. Also, the late toxicity is found to be equivalent between the two treatment groups.

Rectal retractor in prostate radiotherapy: pros and cons

Dose escalation in prostate radiotherapy (RT) have led to improved biochemical controls and reduced the risk of distant metastases. Over the past three decades, despite technological advancements in RT planning and delivery, the rectum is a dose-limiting structure in prostate RT owing to the close anatomical proximity of the anterior rectal wall (ARW) to the prostate gland. RT-induced rectal toxicities remain a clinical challenge, limiting the prescribed dose during prostate RT. To address the spatial proximity challenge by physically increasing the distance between the posterior aspect of the prostate and the ARW, several physical devices such as endorectal balloons (ERBs), rectal hydrogel spacers, and rectal retractor (RR) have been developed. Previously, various aspects of ERBs and rectal hydrogel spacers have extensively been discussed. Over recent years, given the interest in the application of RR in prostate external beam radiotherapy (EBRT), this editorial will discuss opportunities and challenges of using RR during prostate EBRT and provide information regarding which aspects of this device need attention.

The Microbeam Insert at the White Beam Beamline P61A at the Synchrotron PETRA III/DESY: A New Tool for High Dose Rate Irradiation Research

Simple Summary

The excellent preservation of normal tissue function after high dose rate radiotherapy has been shown in pre-clinical studies. Normal tissue in the tumor environment is well preserved even after target doses of several hundred Gy while reliably destroying the tumor cells. These results have triggered the establishment of appropriate research structures at the synchrotron PETRA III on the DESY campus in Hamburg, Germany. Dose rates of hundreds of Gy/s can be achieved, compared to 6–20 Gy/min in clinical radiotherapy. We describe the design, development, key parameters, and first use of a mobile insert for high dose rate radiotherapy research, a new research instrument at P61A, the first polychromatic beamline of PETRA III. The data obtained at the end station P61A will support the international interdisciplinary effort to improve radiotherapy concepts for patients with malignant tumors that are considered radioresistant with the currently established clinical radiotherapy techniques.

Abstract

High dose rate radiotherapies such as FLASH and microbeam radiotherapy (MRT) both have developed to the stage of first veterinary studies within the last decade. With the development of a new research tool for high dose rate radiotherapy at the end station P61A of the synchrotron beamline P61 on the DESY campus in Hamburg, we increased the research capacity in this field to speed up the translation of the radiotherapy techniques which are still experimental, from bench to bedside. At P61, dose rates of several hundred Gy/s can be delivered. Compared to dedicated biomedical beamlines, the beam width available for MRT experiments is a very restrictive factor. We developed two model systems specifically to suit these specific technical parameters and tested them in a first set of experiments.

High levels of health-related quality of life five years after curative treatment of prostate cancer with HDR-brachytherapy and external beam radiation

BACKGROUND AND PURPOSE

The aim of this cross-sectional study was to investigate long-term health-related quality of life (HRQoL) in men with prostate cancer treated 2002-2008 with external beam radiotherapy (EBRT) combined with high dose-rate brachytherapy (HDRBT), Cohort A, and to compare these data with age-adjusted normative data. In addition, differences in HRQoL following adjustments of the brachytherapy technique in 2001 were investigated by comparing Cohort A with men treated at the same clinic from 1998-2000, Cohort B.

METHODS AND MATERIAL

Cohort A: 1495 men treated with EBRT 2 Gy to 50 Gy and 2 fractions of 10 Gy HDRBT at a single centre, 2002-2008, still alive at five years. As part of routine follow-up, the patients responded to the EORTC QLQ-C30 and PR-25 questionnaires. Cohort B: HRQoL data was retrieved from an earlier study from the original article.

RESULTS

In Cohort A, 1046 (70%) men completed the questionnaires at five years, median age 66 years. In general, HRQoL mean scores were high and similar to Swedish age-matched normative data. Concerning disease-specific HRQoL, low levels of bowel and urinary problems were reported, in contrast to a substantial effect on sexual functioning. 'No' or 'A little' problems with faecal incontinence and urinary incontinence were reported by 98% and 93% of patients, respectively. The corresponding figure for sexual functioning was 39%. A difference in the frequency of nocturia in favour of Cohort A was the only statistically significant difference between Cohort A and B found in general and disease-specific HRQOL (p = 0.03), despite modifications in the brachytherapy procedure introduced in 2001.

CONCLUSION

Long-term general HRQoL was rated high and comparable to an aged-matched reference population five years after treatment with combined radiotherapy. Disease-specific HRQoL was still affected, foremost in the sexual domain.

External beam radiation therapy treatment factors prognostic of biochemical failure free survival: a multi-institutional retrospective study for prostate cancer

BACKGROUND AND PURPOSE

The goal of this work is to identify specific treatment planning and delivery features that are prognostic of biochemical failure-free survival (BFFS) for prostate cancer patients treated with external beam radiotherapy (EBRT).

MATERIALS AND METHODS

This study reviewed patients diagnosed with localized prostate adenocarcinoma between 2005 and 2016, and treated with EBRT on a Varian linear accelerator at one of the four cancer centers in Alberta, Canada. BFFS was calculated using the Kaplan-Meier estimator. Patient demographics, tumor characteristics, and EBRT treatment planning and delivery factors, were collected for each patient. The patient cohort was split into a training dataset with patients from two centers and a validation dataset with patients from another two centers. A random survival forest was used to identify features associated with BFFS.

RESULTS

This study included 2827 patients with a median follow-up of 6.4 years. The BFFS for this cohort collectively was 84.9% at 5 years and 69.3% at 10 years. 2519 patients from two centers were used for model training and 308 patients from two different centers were used for model validation. The prognostic features were Gleason score, prostate-specific antigen (PSA) at diagnosis, clinical T stage, CTV D99, pelvic irradiation, IGRT frequency, and PTV V98. Variables including bladder volume, dose calculation algorithm, PTV D99, age at diagnosis, hip prosthesis, number of malignancies, fiducial marker usage, PTV volume, RT modality, PTV HI, rectal volume, hormone treatment, PTV D1cc, equivalent PTV margin, IGRT type, and EQD2_1.5 were unlikely to be prognostic. A random survival forest using only the seven prognostic variables was built. The Harrell's concordance index for the model was 0.65 for the whole training dataset, 0.62 for out-of-bag samples of the training dataset, and 0.62 for the validation dataset.

CONCLUSION

EBRT features prognostic of BFFS were identified and a random survival forest was developed for predicting prostate cancer patients' BFFS after EBRT.

Variability of α/β ratios for prostate cancer with the fractionation schedule: caution against using the linear-quadratic model for hypofractionated radiotherapy

BACKGROUND

Prostate cancer (PCa) is known to be suitable for hypofractionated radiotherapy due to the very low α/β ratio (about 1.5-3 Gy). However, several randomized controlled trials have not shown the superiority of hypofractionated radiotherapy over conventionally fractionated radiotherapy. Besides, in vivo and in vitro experimental results show that the linear-quadratic (LQ) model may not be appropriate for hypofractionated radiotherapy, and we guess it may be due to the influence of fractionation schedules on the α/β ratio. Therefore, this study attempted to estimate the α/β ratio in different fractionation schedules and evaluate the applicability of the LQ model in hypofractionated radiotherapy.

METHODS

The maximum likelihood principle in mathematical statistics was used to fit the parameters: α and β values in the tumor control probability (TCP) formula derived from the LQ model. In addition, the fitting results were substituted into the original TCP formula to calculate 5-year biochemical relapse-free survival for further verification.

RESULTS

Information necessary for fitting could be extracted from a total of 23,281 PCa patients. A total of 16,442 PCa patients were grouped according to fractionation schedules. We found that, for patients who received conventionally fractionated radiotherapy, moderately hypofractionated radiotherapy, and stereotactic body radiotherapy, the average α/β ratios were 1.78 Gy (95% CI 1.59-1.98), 3.46 Gy (95% CI 3.27-3.65), and 4.24 Gy (95% CI 4.10-4.39), respectively. Hence, the calculated α/β ratios for PCa tended to become higher when the dose per fraction increased. Among all PCa patients, 14,641 could be grouped according to the risks of PCa in patients receiving radiotherapy with different fractionation schedules. The results showed that as the risk increased, the k (natural logarithm of an effective target cell number) and α values decreased, indicating that the number of effective target cells decreased and the radioresistance increased.

CONCLUSIONS

The LQ model appeared to be inappropriate for high doses per fraction owing to α/β ratios tending to become higher when the dose per fraction increased. Therefore, to convert the conventionally fractionated radiation doses to equivalent high doses per fraction using the standard LQ model, a higher α/β ratio should be used for calculation.

Radiation therapy for prostate cancer: What's the best in 2021

Radiotherapy is highly involved in the management of prostate cancer. Its features and potential applications experienced a radical evolution over last decades, as they are associated to the continuous evolution of available technology and current oncological innovations. Some application of radiotherapy like brachytherapy have been recently enriched by innovative features and multidisciplinary dedications. In this report we aim to put some questions regarding the following issues regarding multiple aspects of modern application of radiation oncology: the current application of radiation oncology; the modern role of stereotactic body radiotherapy (SBRT) for both the management of primary lesions and for lymph-nodal recurrence; the management of the oligometastatic presentations; the role of brachytherapy; the aid played by the application of the organ at risk spacer (spacer OAR), fiducial markers, electromagnetic tracking systems and on-line Magnetic Resonance guided radiotherapy (MRgRT), and the role of the new opportunity represented by radiomic analysis.

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.

The Journey of Radiotherapy Dose Escalation in High Risk Prostate Cancer; Conventional Dose Escalation to Stereotactic Body Radiotherapy (SBRT) Boost Treatments

High risk prostate cancer (HR-PrCa) is a subset of localized PrCa with significant potential for morbidity and mortality associated with disease recurrence and metastasis. Radiotherapy combined with Androgen Deprivation Therapy has been the standard of care for many years in HR-PrCa. In recent years, dose escalation, hypo-fractionation and high precision delivery with immobilization and image-guidance have substantially changed the face of modern PrCa radiotherapy, improving treatment convenience and outcomes. Ultra-hypo-fractionated radiotherapy delivered with high precision in the form of stereotactic body radiation therapy (SBRT) combines delivery of high biologically equivalent dose radiotherapy with the convenience of a shorter treatment schedule, as well as the promise of similar efficacy and reduced toxicity compared to conventional radiotherapy. However, rigorous investigation of SBRT in HR-PrCa remains limited. Here, we review the changes in HR-PrCa radiotherapy through dose escalation, hypo- and ultra-hypo-fractionated radiotherapy boost treatments, and the radiobiological basis of these treatments. We focus on completed and on-going trials in this disease utilizing SBRT as a sole radiation modality or as boost therapy following pelvic radiation.

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.

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.

Multi-institutional retrospective analysis of ultrahypofractionated radiotherapy for Japanese prostate cancer patients

To report outcomes and risk factors of ultrahypofractionated (UHF) radiotherapy for Japanese prostate cancer patients. This multi-institutional retrospective analysis comprised 259 patients with localized prostate cancer from 6 hospitals. A total dose of 35–36 Gy in 4–5 fractions was prescribed for sequential or alternate-day administration. Biochemical failure was defined according to the Phoenix ASTRO consensus. Toxicities were assessed using National Cancer Institute Common Toxicity Criteria version 4. Tumor control and toxicity rates were analyzed by competing risk frames. Median follow-up duration was 32 months (range 22–97 months). 2- and 3-year biochemical control rates were 97.7% and 96.4%, respectively. Initial prostate-specific antigen (p < 0.01) and neoadjuvant androgen deprivation therapy (p < 0.05) were identified as risk factors for biochemical recurrence. 2- and 3-year cumulative ≥ Grade 2 late genitourinary (GU) toxicities were 5.8% and 7.4%, respectively. Corresponding rates of gastrointestinal (GI) toxicities were 3.9% and 4.5%, respectively. Grade 3 rates were lower than 1% for both GU and GI toxicities. No grade 4 or higher toxicities were encountered. Biologically effective dose was identified as a risk factor for ≥ Grade 2 late GU and GI toxicities (p < 0.05). UHF radiotherapy offered effective, safe treatment for Japanese prostate cancer with short-term follow-up. Our result suggest higher prescribed doses are related to higher toxicity rates.

Clinicoradiological Profile and Treatment Outcomes in Prostate Cancer at a Tertiary Care Cancer Center in India

Introduction: Prostate cancer is the most common solid cancer in men and is responsible for 11% of all cancer-related deaths. There are limited data available regarding clinicoradiological (prostate-specific membrane antigen [PSMA]-positron emission tomography [PET]/computed tomography [CT], magnetic resonance imaging, and bone scan) characteristics, treatment outcomes, and correlation of clinicoradiological characteristics with treatment outcomes of prostate cancer patients from India, especially in the era of PSMA-PET/CT scan. Methodology: This was a single center, retrospective, observational study, conducted for 6 months. We retrospectively collected the data of 332 prostate cancer patients treated between January 2015 and December 2017 at our institute. Results: Three hundred and thirty-two patients were enrolled and were divided into three groups depending on the stage and treatment modality, i.e., Group A, B, and C containing 205, 47, and 80 patients, respectively. The median age was 67 years, and the median prostate-specific antigen (PSA) was 19.3 ng/ml. Lower urinary tract symptoms (83.4%) and bone pain (8.1%) were the common presenting symptoms. PSMA-PET/CT scan revealed regional lymph node metastasis in 56.5% patients, bone metastasis in 35.7%, and visceral metastasis in 11.5% patients, respectively. In patients treated with curative intent, radical prostatectomy was performed in 61.74% of patients, whereas radiation therapy was performed in 47 (14.15%) patients. Among those treated with palliative intent, androgen deprivation therapy (ADT) alone (40) was the most preferred therapy followed by the combination of ADT with docetaxel (28) or abiraterone (12). Significantly (P = 0.006), a greater number of patients who were treated with ADT alone progressed to castration-resistant prostate cancer (CRPC) compared to those on combination ADT with either abiraterone or docetaxel. No significant difference was seen in the disease progression when treatment arm containing ADT with docetaxel was compared to ADT with abiraterone. Conclusion: Patients with metastatic disease had a higher median PSA level and also had a higher likelihood of having Gleason score 8–10. Among patients who were treated with palliative intent for metastatic disease, disease progression to CRPC state was significantly higher in those treated with ADT alone compared to those treated with either ADT + docetaxel or ADT + abiraterone.

Dosimetric and clinical outcomes of SpaceOAR in men undergoing external beam radiation therapy for localized prostate cancer: A systematic review

SpaceOAR, an absorbable polyethylene glycol hydrogel, increases the space between the prostate and rectum to reduce the radiation received by the rectum during prostate cancer radiation therapy. The objective of this systematic review was to evaluate controlled studies on the dosimetric and clinical outcomes of SpaceOAR in men undergoing external beam radiation therapy for localized prostate cancer. Eight studies were included in the review. All of the studies showed SpaceOAR to reduce the radiation dose volume to the rectum over numerous dosimetry levels. Of the four studies that assessed toxicity, one reported SpaceOAR to significantly decrease acute Grade 1 diarrhoea and two reported SpaceOAR to significantly decrease late Grade 1 and Grade ≥2 rectal toxicities. Two studies assessed cumulative incidence of toxicity at 3 years in which one reported SpaceOAR to significantly decrease urinary incontinence and Grade ≥1 and Grade ≥2 rectal toxicities, and the other reported SpaceOAR to significantly decrease Grade 1 diarrhoea and Grade 2 proctitis. Moreover, one study reported that fewer SpaceOAR patients experienced 10-point declines in bowel quality of life at 3 years, but another study reported no significant difference in 10-point declines in bowel quality of life between the SpaceOAR and control groups at 5 years. With the current research available, SpaceOAR may be beneficial to those who did not meet the standard rectal dose-volume criteria, have higher risk factors of developing rectal toxicities post-radiation, or wish to decrease the length and costs of radiotherapy by increasing the dose of radiation per fraction.

Feeding the Controversy: When Pelvic Irradiation Improves Outcomes in High-Risk and Very High-Risk Prostate Cancer

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Single dose high-dose-rate brachytherapy with focal dose escalation for prostate cancer: Mature results of a phase 2 clinical trial

AIM

The dominant intraprostatic lesion (DIL) is the commonest site of relapse after single dose high-dose-rate brachytherapy (HDR-BT) for localised prostate cancer. This study investigated toxicity and clinical outcomes of focal dose escalation to the DIL with dose de-escalation to the remaining prostate.

MATERIALS/METHODS

Between November 2012 and July 2016, 50 patients with localised prostate adenocarcinoma received single fraction HDR-BT. 21 Gy was prescribed to the DIL, with two de-escalation prescription schedules for the remaining prostate. Primary outcomes included biochemical no evidence of disease (bNED), local recurrence free survival (LRFS), and metastasis free survival (MFS). Secondary outcomes included late genitourinary, gastrointestinal and sexual toxicity. Kaplan-Meier analyses with log rank tests were used to estimate bNED, LRFS and MFS.

RESULTS

With a median follow up of 70.6 months, 15 patients developed biochemical failure, including 8 in the group that received minor dose de-escalation to the non-DIL prostate (group 1) and 7 in the group that received moderate de-escalation (group 2). Five-year bNED was 88% in group 1 and 76% in group 2 (p = 0.05). Overall 4-year and 5-year FFLF in group 1 was 100% and 96% and in group 2 92% and 84%. These differences were statistically significant (p = 0.03). No acute ≥G3 genitourinary or ≥G2 gastrointestinal toxicity was reported. The median IIEF decreased in the first 6 months improving to a peak median score of 20 at 54 months.

CONCLUSION

Focal boost to the DIL did not improve biochemical or local control after single-fraction HDR monotherapy compared to what would be expected from 19 Gy single fraction treatment to the whole gland.

Defining the index lesion for potential salvage partial or hemi-gland ablation after radiation therapy for localized prostate cancer

BACKGROUND

Salvage partial gland ablation (sPGA) has been proposed to treat some localized radiorecurrent prostate cancer. The role of prostate biopsy and magnetic resonance imaging (MRI) characteristics to identify patients eligible for sPGA is unknown.

OBJECTIVE

To evaluate the ability of MRI and prostate biopsy characteristics to identify an index lesion suitable for sPGA and validate this selection using detailed tumor maps created from whole-mount slides from salvage radical prostatectomy (sRP) specimens.

DESIGN, SETTING, AND PARTICIPANTS

Men who underwent sRP for recurrent prostate cancer following primary radiotherapy with external beam radiotherapy (EBRT) and/or brachytherapy between 2000 and 2014 at a single high-volume cancer center were eligible. Those with tumor maps, MRI and biopsy data were included in analysis.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Primary outcome was the ability of clinicopathologic and imaging criteria to identify patients who may be eligible for sPGA based on detailed tumor map from whole-mount sRP slides.

RESULTS AND LIMITATIONS

Of 216 men who underwent sRP following whole gland radiotherapy, tumor maps, MRI, and biopsy data were available for 77. Of these, 15 (19%) were determined to be eligible for sPGA based on biopsy-proven unilateral disease in contiguous sextant segments, a dominant lesion on MRI concordant with biopsy location or no focal region of interest, and no imaging evidence of extraprostatic disease. Review of tumor maps identified 6 additional men who would have met criteria for sPGA, resulting in sensitivity of 71% (95% C.I. 48%-89%) and specificity of 100% (lower bound of 95% C.I. 94%). None of the 15 men who met the criteria for sPGA on clinical data were identified incorrectly on tumor maps to require full gland surgery (upper bound of 95% C.I. 22%). Median tumor volume of the index lesion was 0.4 cc and recurrent cancer was noted in the apex, mid-gland, and base in 81%, 100%, and 29% of men.

CONCLUSIONS

In men with recurrent prostate cancer after radiotherapy, biopsy findings and MRI can be used to select index lesions potentially amenable for sPGA and can guide patient evaluation for inclusion in clinical trials of sPGA following radiation failure. Larger, prospective studies are required to evaluate both the role of MRI and clinical criteria in guiding focal salvage therapy and the effectiveness of this modality for radiorecurrent prostate cancer.

miRNAs and radiotherapy response in prostate cancer

BACKGROUND

Gaining insight into microRNAs (miRNAs) and genes that regulate the therapeutic response of cancer diseases in general and prostate cancer (PCa) in particular is an important issue in current molecular biomedicine and allows the discovery of predictive miRNA targets.

OBJECTIVES

The aim of this study was to analyze the available data on the influence of radiotherapy (RT) on miRNA expression and on miRNA involved in radiotherapy response in PCa.

MATERIALS AND METHODS

The data used in this review were extracted from research papers and the DIANA, STRING, and other databases with a special focus on the mechanisms of radiotherapy PCa response and the miRNA involved and associated genes.

RESULTS AND DISCUSSION

A search for miRNA prognostic and therapeutic effectiveness markers should rely on both the data of recent experimental studies on the influence of RT on miRNA expression and miRNAs involved in regulation of radiosensitivity in PCa and on bioinformatics resources. miRNA panels and genes targeted by them and involved in radioresponse regulation highlighted by meta-analysis and cross-analysis of the data in the present review have.

CONCLUSION

Selected miRNA and gene panel has good potential as prognostic and radiotherapy effectiveness markers for PCa and, moreover, as radiotherapy effectiveness markers in other types of cancer, as the proposed model is not specific to PCa, which opens up opportunities for the development of a universal diagnostic system (or several intersecting systems) for oncology radiotherapy in general.

Management of Isolated Local Failures Following Stereotactic Body Radiation Therapy for Low to Intermediate Risk Prostate Cancer

Background: Stereotactic body radiation therapy (SBRT) is a safe and effective treatment option for patients with low to intermediate risk prostate cancer (1). SBRT results in very low PSA nadirs secondary to the delivery of high biologically effective doses. Studies reporting on the diagnosis, confirmation, and management of salvageable isolated local failures (ILF) are limited. This study aims to determine the incidence and management approach of ILF after SBRT in a large single institution cohort. Method: All patients with low or intermediate risk localized prostate cancer treated with SBRT at Georgetown University Hospital were eligible for this study. Treatment was delivered using robotic SBRT with doses of 35-36.25 Gy in five fractions. ILF were diagnosed using multiparametric MRI and/or biopsy prompted by rising PSA levels after achieving long-term nadir. Patient's characteristics were extracted from a prospective institutional quality of life trial (IRB 2009-510). Type of salvage therapy and post-salvage PSA were determined on subsequent follow-up and chart review. Results: Between December 2008 to August 2018, 998 men with low to intermediate risk prostate cancer were eligible for inclusion in this analysis. Twenty-four patients (low risk, n = 5; intermediate risk, n = 19) were found to have ILF within the prostate on either MRI (n = 19) and/or biopsy (n = 20). Median pre-treatment PSA was 7.55 ng/ml. Median time to diagnosis of ILF was 72 months (24-110 months) with median PSA at the time of ILF of 2.8 ng/ml (0.7-33 ng/ml). Median PSA doubling time was 17 months (5-47 months). Thirteen patients with biopsy proven ILF proceeded with salvage therapy (cryotherapy n = 12, HIFU n = 1). Of 12 patients who underwent cryotherapy, 7 had a post-treatment PSA of <0.1 ng/ml. One patient experienced a urethral-cutaneous fistula (grade 3 toxicity). Conclusion: The incidence of isolated local recurrence is rare in our cohort. Diagnosis and management of isolated local failures post-SBRT continues to evolve. Our report highlights the importance of early utilization of MRI and confirmatory biopsy at relatively low PSA levels and long PSA doubling time (1). Additionally, undetectable PSA levels after salvage therapy supports the role of early treatment in ILF (1). Further research is needed to determine appropriate patient selection and salvage modality in this population.

Prostate re-irradiation: current concerns and future perspectives

INTRODUCTION

To date, the optimal management of locally relapsed prostate cancer patients after an initial course of radiotherapy remains a matter of debate. In recent years, local approaches have been proposed as a therapeutic option, which may potentially delay the initiation of hormone therapy. In the case of external beam radiotherapy (EBRT), re-irradiation has been supported by growing evidence in the literature, mostly represented by extreme hypofractionated schedules delivered with stereotactic body radiotherapy (SBRT).

AREAS COVERED

We performed a systematic review of the literature using the PICO methodology to explore the available evidence regarding the use of EBRT in the setting of locally relapsed prostate cancer, both in terms of safety, tolerability and preliminary clinical outcomes.

EXPERT OPINION

Current literature data report the use of EBRT and particularly of SBRT for the safe and feasible re-treatment of locally recurrent prostate cancer after an initial treatment course of radiotherapy. When extreme hypofractionation is adopted, only occasional grade ≥3 late adverse events are reported. Despite the current lack of high-level evidence and the short follow-up, preliminary clinical outcomes are promising and allow clinicians to hypothesize further prospective studies to evaluate SBRT as an alternative to the early initiation of androgen-deprivation therapy.

Margin verification for hypofractionated prostate radiotherapy using a novel dose accumulation workflow and iterative CBCT

PURPOSE

Hypofractionated radiotherapy for prostate cancer reduces the inconvenience of an extended treatment course but the appropriate treatment margin to ensure tumor control while minimizing toxicity is not standardized. Using a novel dose accumulation workflow with iterative CBCT (iCBCT) images, we were able to validate treatment margins.

METHODS

Sixteen patients treated to the prostate on a hypofractionated clinical trial were selected. Prescription dose was 3625 cGy to > 95% of the PTV in 5 fractions with a boost to 4000 cGy to the high risk GTV (if applicable). PTV margin expansion was 5 mm isotropic except 3 mm posterior, no margin for the GTV. Daily iCBCT images were obtained while practicing strict bladder and rectal filling protocols. Using a novel adaptive dose accumulation workflow, synthetic CTs were created and the daily delivered dose was recalculated. The daily dose distributions were accumulated and target coverage and organ dose were assessed.

RESULTS

Although the PTV coverage dropped for the accumulated dose, the prostate coverage was not compromised. The differences in bladder and anorectum dose were not significantly different. Four patients received a boost to the GTV and a significant decrease in coverage was noted in the accumulated dose.

CONCLUSIONS

The novel dose accumulation workflow demonstrated that daily iCBCT images can be used for dose accumulation. We found that our clinical treatment margins resulted in adequate dose to the prostate while sparing OARs. If the goal is to deliver the full dose to an intra-prostatic GTV, a margin may be appropriate.

Stereotactic body radiotherapy for localized prostate cancer - 5-year efficacy results

BACKGROUND

The use of stereotactic body radiotherapy (SBRT) as the primary treatment modality in clinically localized prostate cancer (PCa) is emerging. The aim of the study was to analyze the long-term results of PCa patients treated with SBRT.

METHODS

This non-selected, real-life patient cohort included 213 patients with localized PCa treated with a robotic SBRT device during 2012-2015.

RESULTS

The median follow-up was 64 months (range, 10-85 months), and all risk-groups were represented as 47 (22.1%), 56 (26.3%) and 110 (51.6%) patients were classified into D'Amico risk stratification of low, intermediate and high-risk groups, respectively. Androgen deprivation therapy (ADT) was administered to 64.3% of the patients. At cut-off, the biochemical relapse-free survival (bRFS) was 100, 87.5 and 80.0% for patients at low, intermediate and high-risk (p = 0.004), and 92.5, 84.2 and 66.7% for patients with Gleason score ≤ 6, 7 and ≥ 8, respectively (p = 0.001). The actuarial 5-year overall survival (OS) rates were 97.9, 96.4 and 88.6% in the low, intermediate and high-risk groups, respectively, and at the cut-off, the disease-specific survival (DSS) rate of the whole cohort was high (99.1%), as only two high-risk patients died due to PCa.

CONCLUSION

Our present results of SBRT delivered with CyberKnife produced excellent long-term bRFS, OS and DSS outcomes among patients with localized PCa. We conclude that SBRT provides an efficient and convenient treatment option for patients with localized PCa, irrespective of the risk-group.

Patterns of treatment failure in patients with prostate cancer treated with 76-80 Gy radiotherapy to the prostate and seminal vesicles ± hormonotherapy

PURPOSE

To assess the pattern of treatment failure in patients with prostate cancer (PCa) treated with radiotherapy (76-80 Gy) ± hormone therapy (HT). We also evaluated the influence of treatment failure on survival outcomes.

METHODS

Retrospective study of patients with PCa (n = 302) treated with radiotherapy (RT) ± HT at our centre between November 1999 and July 2007. The mean patient age was 70.2 years (range 51-87). Distribution by NCCN risk group was low (n = 80, 26.5%), intermediate (n = 86, 28.5%), high (n = 77, 25.5%), and very high (n = 49, 16.2%). Most patients (n = 273, 90.4%) received IMRT at a dose of 76-80 Gy. HT was administered in 237 patients (78.5%), in most cases (n = 167, 55.3%) for < 7 months RESULTS: Survival rates at 10 years were: overall survival (OS), 64.3%; biochemical disease-free survival, 83.9%; disease-free survival, 92.5%; and metastasis-free survival (MFS), 94.3%. Biochemical failure (BF) was observed in 55 cases (18.2%), 32 of whom subsequently developed clinical recurrence: metastasis (n = 17, 5.6%), local failure (n = 11, 3.6%), and regional failure (n = 4, 1.3%). The cause of death (n = 159) was intercurrent disease in 115 cases (72.3%), second cancer in 27 (17.0%), and PCa in 17 (10.7%). Biochemical failure-free survival ≤ 24 months was significantly associated with worse OS and MFS (p = 0.0001). Late genitourinary and gastrointestinal toxicity grade ≥ 3 (RTOG) was observed in 18 (6.0%) and 7 (2.3%) patients, respectively.

CONCLUSIONS

The main type of treatment failure after 76-80 Gy of radiotherapy ± HT is local or metastatic. In all cases, biochemical failure occurred prior to treatment failure. BF within 24 months of treatment completion was significantly associated with worse OS and MFS.

Clinical Outcomes of Dose-escalated Radiotherapy for Localised Prostate Cancer: A Single-institution Experience

BACKGROUND/AIM

To report the outcomes of patients with prostate cancer treated with dose-escalated radiotherapy over a 15-year period at our Institution.

PATIENTS AND METHODS

Patients with biopsy-proven cT1-4N0M0 disease who received radical external beam radiotherapy (EBRT) were reviewed. The endpoints were 5-year overall survival (OS), freedom from biochemical failure (FFBF) and late treatment toxicities.

RESULTS

A total of 236 patients were eligible. Median follow-up was 70 months. Low-, intermediate- and high-risk disease was found in 9%; 29% and 62% of patients, respectively. The median radiation dose was 73.8 Gy. Overall 42% of patients had dose escalation to >74 Gy. Five-year OS and FFBF were 95.2%/81.6%/75.4% and 95.0%/98.0%/82.0% for low-/intermediate-/high-risk patients, respectively. Dose escalation to >74 Gy did not improve FFBF (hazard ratio=0.97, 95% confidence intervaI=0.43-2.19, p=0.93) and was associated with a 4.3-fold increase in the odds of grade 3 or more rectal bleeding (p<0.01).

CONCLUSION

Dose escalation to >74 Gy did not improve OS or FFBF but was associated with a higher rate of grade 3 or more rectal haemorrhage.

Dose escalation (81 Gy) with image-guided radiation therapy and volumetric-modulated arc therapy for localized prostate cancer: A retrospective preliminary result

Objectives:

The objective of the study is to report the acute and late toxicity and preliminary results of localized prostate cancer treated with high-dose radiation therapy (RT).

Materials and Methods:

Between March 2010 and October 2018, a total of 53 patients with clinically localized prostate cancer were treated with definitive RT at our institution. All patients were planned to receive a total dose of 81 Gy with the volumetric-modulated arc therapy technique. Patients were stratified by prognostic risk groups based on the National Comprehensive Cancer Network risk classification criteria. Acute and late toxicities were scored by the Radiation Therapy Oncology Group morbidity grading scales. The definition of biochemical failure was using the 2005 ASTRO Phoenix consensus definition. Median follow-up time was 46.5 months (range: 4.7–81.0 months).

Results:

The 3-year biochemical failure-free survival rates for low-, intermediate-, and high-risk group patients were 100%, 87.5%, and 84%, respectively. The 3- and 5-year overall survival rates were 83% and 62%, respectively. Three (5.6%) patients developed Grade II acute gastrointestinal (GI) toxicity. Four (7.5%) patients developed Grade II acute genitourinary (GU) toxicity, and none experienced Grade III or higher acute GI or GU symptoms. One (1.8%) patient developed Grade II or higher late GI toxicity. Six (11.3%) patients experienced Grade II late GU toxicity. No Grade III or higher late GI and GU complications have been observed.

Conclusions:

Data from the current study demonstrated the feasibility of dose escalation with image-guided and volumetric-modulated arc therapy techniques for the treatment of localized prostate cancer. Minimal acute and late toxicities were observed from patients in this study. Long-term prostate-specific antigen controls are comparable to previously published results of high-dose intensity-modulated RT for localized prostate cancer. Based on this favorable outcome, dose escalation (81 Gy) has become the standard treatment for localized prostate cancer at our institution.

[Indications and outlooks of radiohormonal therapy of high-risk prostate cancers]

Prostate cancer is a sensitive adenocarcinoma, in more than 80% of cases, to chemical castration, due to its hormone dependence. Locally advanced and/or high-risk cancer is defined based on clinical stage, initial prostate specific antigen serum concentration value or high Gleason score. Hormone therapy associated with radiation therapy is the standard of management and improves local control, reduces the risk of distant metastasis and improves specific and overall survival. Duration of hormone therapy, dose level of radiation therapy alone or associated with brachytherapy are controversial data in the literature. The therapeutic choice, multidisciplinary, depends on the age and comorbidity of the patient, the prognostic criteria of the pathology and the urinary function of the patient. Current research focuses on optimizing local and distant control of these aggressive forms and incorporates neoadjuvant or adjuvant chemotherapy and also new hormone therapies.

Ultra-hypofractionated radiation therapy for unfavourable intermediate-risk and high-risk prostate cancer is safe and effective: 5-year outcomes of a phase II trial

OBJECTIVES

To report toxicity (primary endpoint) and biochemical disease-free survival (BDFS) outcomes of a phase II trial evaluating ultra-hypofractionated radiation therapy (UHRT), focusing on patients with unfavourable intermediate-risk and high-risk prostate cancer (PCa).

PATIENTS AND METHODS

From 2012 to 2017, 154 patients (92 with unfavourable intermediate-risk or high-risk PCa) were treated with helical TomoTherapy delivering 43.8-45.2 Gy in eight fractions over 3 weeks. Of these, 73% received hormonotherapy (51% neoadjuvant).

RESULTS

The median (range) follow-up was 48 (19-84) months. For the whole series, crude BDFS and 5-year BDFS rates were 97.4% and 94.3%, respectively. The corresponding figures for unfavourable intermediate-risk and high-risk PCa were 96.7% and 90%, respectively. The crude metastasis-free survival rate was 98% for the unfavourable intermediate-risk and high-risk group. For the whole series, the 5-year cumulative urinary/intestinal grade 2+ late toxicity was 17.8/7.4%. No grade 4-5 toxicity was observed. One patient experienced late grade 3 toxicity (urinary).

CONCLUSION

This eight-fraction UHRT regimen can be safely delivered to patients with unfavourable intermediate-risk/high-risk PCa. Its relapse rates are similar to those reported for the combination of external beam radiotherapy plus brachytherapy, however, the observed toxicity profile is milder. The disease survival rates compare favourably with historical controls in some other forms of radiotherapy, with similar side effects. Since the low rate of biochemical/metastasis relapse is encouraging, further research to confirm these results is justified.

[Moderate or extreme hypofractionation and localized prostate cancer: The times are changing]

There are many treatment options for localized prostate cancers, including active surveillance, brachytherapy, external beam radiotherapy, and radical prostatectomy. Quality of life remains a primary objective in the absence of superiority of one strategy over another in terms of specific survival with similar long-term biochemical control rates. Despite a significant decrease in digestive and urinary toxicities thanks to IMRT and IGRT, external radiotherapy remains a treatment that lasts approximately 2 months or 1.5 months, when combined with a brachytherapy boost. Given the specific radiosensitivity of this tumor, several randomized studies have shown that a hypofractionated scheme is not inferior in terms of biochemical control and toxicities, allowing to divide the number of fractions by a factor 2 to 8. Given that SBRT becomes a validated therapeutic option for a selected population of patients with localized prostate cancer, extreme hypofractionation is becoming a strong challenger of conventional external radiotherapy or brachytherapy.

Stereotactic Body Radiation Therapy Boost for Intermediate-Risk Prostate Cancer: A Phase 1 Dose-Escalation Study

PURPOSE

High-dose-rate brachytherapy boost plus external beam radiation therapy is an established option for intermediate-risk prostate cancer (PCa). Stereotactic body radiation therapy (SBRT) boost can potentially mimic high-dose-rate boost and could be a viable alternative. Here we report the long-term outcomes of a phase 1 dose-escalation trial of single-fraction SBRT boost.

METHODS AND MATERIALS

Patients had intermediate-risk PCa and were accrued to 3 different SBRT single-fraction dose-level cohorts (10 Gy, 12.5 Gy, and 15 Gy). All received supplemental radiation therapy afterwards (37.5 Gy in 15 fractions). Three gold fiducials were implanted for image guidance. Patients were simulated and treated with a foley catheter and intrarectal balloon. A T2 magnetic resonance imaging scan was used for contouring, and a cine magnetic resonance imaging scan was used to calculate patient-specific internal target volume margins. Toxicity and quality-of-life data were collected using Common Terminology Criteria for Adverse Events v3.0 and the Expanded Prostate Cancer Index Composite.

RESULTS

30 patients were accrued, 10 in each cohort. Median follow-up was 72 months. 60% had unfavorable intermediate-risk PCa. Two patients in the 15 Gy cohort developed late grade ≥3 gastrointestinal and genitourinary toxicity, with 1 patient suffering from a grade-4 rectal fistula after a rectal ulcer was biopsied repeatedly. Two patients had biochemical failure. Median PSA nadir was 0.4 ng/mL with 10 Gy, 0.09 ng/mL with 12.5 Gy and 0.07 ng/mL with 15 Gy. Median PSA at 4 years as well as proportion achieving a nadir <0.2 ng/mL improved significantly with higher doses. There was no significant change in quality of life from baseline in any of the domains, and the minimal clinically important change was not statistically different between the 3 cohorts.

CONCLUSIONS

Other than a grade 4 toxicity, which may in part be due to repeated biopsies of a rectal ulcer, single-fraction SBRT boost was feasible and well tolerated. Larger studies are warranted to better document the outcomes of such an approach.

[Optimizing local control of high-risk prostate cancers through multimodal treatments]

Prostate cancer is a sensitive adenocarcinoma, in more than 80 % of cases, to chemical castration, due to its hormone dependence. Locally advanced and/or high-risk cancer is defined based on clinical stage, initial PSA value or high Gleason score. Hormone therapy associated with radiation therapy is the standard of management and improves local control, reduces the risk of distant metastasis and improves specific and overall survival. Duration of hormone therapy, dose level of radiation therapy alone or associated with brachytherapy are controversial data in the literature. Radical prostatectomy surgery is a therapeutic option that must be performed with extensive lymph node dissection and is often part of a multimodal care sequence. The therapeutic choice, multidisciplinary, depends on the age and co-morbidity of the patient, the prognostic criteria of the pathology and the urinary function of the patient. Current research focuses on optimizing local and distant control of these aggressive forms and incorporates neo-adjuvant or adjuvant chemotherapy and also new hormone therapies.

Prostate cancer dose-response, fractionation sensitivity and repopulation parameters evaluation from 25 international radiotherapy outcome data sets

OBJECTIVE

This study was undertaken to model the biochemical free survival at 5 years and to evaluate the parameters defining dose-response curve, dose-fractionation radiosensitivity and repopulation.

METHODS

It was carried out a literature search on Pubmed to retrieve data sets of patients treated with external beam radiation therapy of 1.8-4.0 Gy per fraction and overall treatment time of 3 to 10 weeks. 10 groups were identified, based on risk class and androgen deprivation therapy (ADT). Dose-response curve D₅₀ (dose at 50% probability of control) and g₅₀ (steepness), α/β (dose-fractionation radiosensitivity), and repopulation parameters, d_prolif and T_prolif , were calculated. Bootstrap-based cross-validation was performed and median and 95% CI (confidence interval) were evaluated.

RESULTS

25 data sets, including 20,310 patients, were considered. The median (95% CI) D₅₀ and g₅₀ values were 62 (CI 53 - 66) Gy and 1.6 (0.8 - 2.4). ADT patients showed lower values of D₅₀ and g₅₀ (57 ± 5 Gy and 1.1 ± 0.4) compared to no-ADT patients (65 ± 2 Gy and 2.3 ± 0.6), with p < 0.0001 and p = 0.002. If we did not consider any dependence on overall treatment time, the median (95% CI) value of α/β was 1.4 (1.0 - 1.9) Gy with p < 0.0001 for all patients. The median values of d_{proli f} and T_prolif were 0.0 to 0.3 Gy/d and 18-40 days.

CONCLUSION

Dose-response curve resulted dependent on risk class and ADT, with higher steepness for no-ADT patients. Low values of dose-fractionation radiosensitivity were found, supporting the use of moderate hypofractionated radiotherapy in each risk class. A limited dependence on repopulation was observed.

ADVANCES IN KNOWLEDGE

Prostate cancer response to moderate hypofractionated radiotherapy was reliably quantified considering risk class and androgen deprivation therapy.

Two StereoTactic ablative radiotherapy treatments for localized prostate cancer (2STAR): Results from a prospective clinical trial

PURPOSE

Ultrahypofractionation is appealing for prostate cancer (PCa) due to low α/β, and increasing the dose per fraction could improve the therapeutic index. Here we report the outcomes of a phase II prostate SABR trial using two fractions.

METHODS

Patients had low or intermediate risk prostate cancer. Three gold fiducials were implanted for image guidance. The clinical target volume (CTV) included the prostate only, and the planning target volume (PTV) was a 3 mm expansion enabled through the use of a rectal immobilization device. The dose prescribed was 26 Gy in 2 weekly fractions (EQD2 110 Gy_1.4). The primary endpoint was quality of life using EPIC, and minimal clinically important change (MCIC) was defined as an EPIC QOL decrease >0.5 SD.

RESULTS

30 patients were accrued with a median follow-up of 49.3 months. 10% had low-risk, 33% had favourable intermediate-risk and 57% had unfavourable intermediate-risk PCa. Five patients received a short course of ADT. Median nPSA was 0.2 ng/ml. One patient had BF and is being observed. 56.6% of patients had a 4yPSARR. Six (20.7%) patients had a MCIC in the urinary domain, 6 (21.4%) had a MCIC in the bowel domain, and 3 (20%) had a MCIC in the sexual domain.

CONCLUSIONS

Two-fraction SABR in prostate cancer is safe and feasible, with a minimal change in QOL and a low rate of late grade 3-4 toxicity. The PSA kinetics and biochemical control rates are encouraging given that the majority had unfavourable intermediate-risk disease, although longer follow-up is required.

Fiducial markers in prostate cancer image-guided radiotherapy

Background: Image-guided radiotherapy (IGRT) is recommended to reduce the risk of geometrical miss when modern radiotherapy technologies with high grades of conformity are used. The purpose of this study was to evaluate the efficacy of fiducial markers (FMs) for electronic portal imaging in prostate cancer radiotherapy in term of evaluating the complications associated with FMs implantation, quantifying inter-fraction prostate motion, and determination of optimal planning target volume (PTV) margins.

Methods: In this single institution, prospective, consecutive study, 27 patients underwent implantation of three-gold seed FMs into the prostate gland before prostate radiotherapy. Prior to computed tomography planning, all patients were asked to report any complication associated with FMs implantation that have experienced to date. Daily pre-treatment electronic portal images were captured, and prostate position errors were corrected if they were greater than 2 mm along three translational directions. Optimal PTV expansions were computed using van Herk formula [PTV-margin= 2.5Σ + 0.7σ].

Results: FMs implantation was successful with an acceptable toxicity profile in all patients. Without IGRT, margins of 5.4 mm, 5.8 mm and 5.5 mm, in vertical, longitudinal and lateral directions, respectively, are needed for a 95% confidence level of complete clinical target volume (CTV) coverage in each treatment session. The PTV margins of 3.0 mm, 3.3 mm and 4.0 mm in corresponding directions were calculated when FMs based electronic portal imaging was applied.

Conclusion: FMs based electronic portal imaging is an effective tool for prostate cancer IGRT.

A pilot study of patient reported outcomes evaluating treatment related symptoms and quality of life for men receiving high dose rate brachytherapy combined with hypo-fractionated radiotherapy or hypo-fractionated radiotherapy alone for the treatment of localised prostate cancer

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PROMs have an important role to play in clinical practice.

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The radiographer-led collection of multiple PROMs is feasible.

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Monotherapy Group reported higher levels of bowel toxicity than Combination Group.

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RTOG scale was not of sufficient sensitivity and under-reported symptoms.

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A good QoL was maintained throughout treatment for both treatment groups.

Patient Reported Outcome Measures (PROMS) are useful metrics in evidence-based clinical care and translational research. Recording treatment-related symptoms and Quality of Life (QoL) can provide information in counselling patients to aid decision-making. This prospective study tested the feasibility of radiographer-led collection of multiple validated PROMS from Prostate Cancer (PCa) patients comparing High Dose Rate Brachytherapy combined with hypo-fractionated external beam radiotherapy (hEBRT) and hEBRT alone.

From June to August 2017, 20 men with localised PCa (T1-T3aN0M0) consented to participate in the study. Ten patients received combination treatment (37.5 Gray/15 fractions followed by a 15 Gray implant), and ten patients received monotherapy (60 Gray/20 fractions). PROMS were collected at four time-points (1) at baseline, (2) final fraction of hEBRT, (3) 8 weeks after commencing radiotherapy and (4) 12 weeks after commencing radiotherapy. The PROMS used were EPIC-26, IPSS, IIEFF-5 and SF-12. The difference between the two groups were tested using Mann-Whitney U test and Wilcoxon Signed-Rank Test.

All participants completed all PROMS (100% response-rate). The Monotherapy group reported a higher incidence of bowel symptoms compared to the combination group and at Week 12, EPIC-26 bowel summary score demonstrated a statistically significant difference (p = 0.005). The prevalence of erectile dysfunction increased within both groups. Maintenance of QoL was reported throughout treatment.

This small study demonstrated feasibility of radiographer-led PROMS collection by 100% completion rate. Streamlining of these tools into integrated technology applications and real time PROMS measurement has the ability to benefit patients and guide clinicians in adapting therapies based on individual need.

Benefits of Elective Para-Aortic Radiotherapy for pN1 Prostate Cancer Using Arc Therapy (Intensity-Modulated or Volumetric Modulated Arc Therapy): Protocol for a Nonrandomized Phase II Trial

BACKGROUND

In patients with prostate cancer (PCa) with histopathologically proven pelvic lymph node (LN) metastasis (pN1) after extended pelvic lymph node dissection (ePLND), multimodality treatment consisting of treatment of the primary tumor and whole pelvic radiotherapy (WPRT) combined with androgen deprivation therapy (ADT) offers promising results, leading to better cause-specific survival rates compared with ADT alone. However, in case more than one pelvic LN is invaded by the tumor, approximately 40% of the patients relapse biochemically and clinically. Clinical relapse is present in the para-aortic LNs (M1a disease) in up to 77% of the relapsing cases.

OBJECTIVE

We hypothesize that, based on the evidence that positive LNs represent the door to hematogenous dissemination, elective para-aortic irradiation will reduce the development of both retroperitoneal nodal (M1a) and distant metastasis (M1b or M1c disease), postpone the need for palliative ADT, and prolong the time to castration-refractory disease.

METHODS

To test this hypothesis, we will conduct a prospective, nonrandomized phase II trial to study the efficacy of additional elective para-aortic radiotherapy (PART) in pN1 patients compared with those who were historically treated with adjuvant WPRT alone. We aim to include 137 patients with PCa and presence of pN1 disease after ePLND. With this number of patients, an improvement of 15% in the 5-year clinical relapse-free survival can be detected with a power of 80%.

RESULTS

Recruitment of patients for this trial started in 2017 and will be completed approximately by March 2020.

CONCLUSIONS

This is the first phase II trial to investigate the benefits of an elective PART in patients with PCa. The results of this trial will potentially serve as a sound base for a later randomized phase III trial. All participants are given a PART information sheet and required to give written informed consent. Results are expected to be published in a peer-reviewed journal.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03079323; https://clinicaltrials.gov/ct2/show/NCT03079323 (Archived by WebCite at http://www.webcitation.org/73ELimv1d).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/11256.

SABR in High-Risk Prostate Cancer: Outcomes From 2 Prospective Clinical Trials With and Without Elective Nodal Irradiation

PURPOSE

There is limited data on stereotactic ablative radiation therapy (SABR) in high-risk prostate cancer (PCa), especially regarding the role of elective nodal irradiation (ENI). This study compares 2 prospective phase 2 trials using SABR in high-risk PCa, with and without ENI.

METHODS AND MATERIALS

Patients had high-risk PCa. Those in trial 1 received 40 Gy in 5 fractions to the prostate and 30 Gy in 5 fractions to the seminal vesicles. Patients in trial 2 received 40 Gy in 5 fractions to the prostate and 25 Gy in 5 fractions to the pelvis and seminal vesicles. National Cancer Institute Common Terminology Criteria for Adverse Events toxicities were collected. Biochemical failure (BF) was defined as nadir + 2, and the 4-year prostate-specific antigen (PSA) response rate (4yPSARR) was <0.4 ng/mL.

RESULTS

Sixty patients were included (trial 1, n = 30; trial 2, n = 30). Median follow-up was 5.6 years and 4.0 years. The median nadir PSA was 0.02 ng/mL for both trials. Six patients had BF, all from trial 1. The BF rate was 14.6% at 5 years in trial 1 and 0% in trial 2. Sixty-three percent of patients in trial 1 and 93% in trial 2 had a 4yPSARR. Two patients died in trial 1, 1 from metastatic disease. One patient in trial 2 died of other causes. No other patients developed metastatic disease, and 1 patient in trial 1 had castrate resistant PCa. Overall survival at 5 years was 93.2% and 96.7% (P = .86). There was significantly worse late gastrointestinal and sexual toxicity in trial 1, but there was no difference in late genitourinary toxicity.

CONCLUSIONS

SABR in high-risk PCa yields biochemical control rates that may be comparable to that of other radiation therapy modalities. ENI using SABR is feasible and may lead to a significant improvement in biochemical control and in 4yPSARR, without an increase in late gastrointestinal or genitourinary toxicity. Longer follow-up would provide a better assessment of biochemical control. Well-conducted phase 3 trials are needed to fully establish the role of SABR and ENI in high-risk PCa.

Multimodal imaging for radiation therapy planning in patients with primary prostate cancer

Implementation of advanced imaging techniques like multiparametric magnetic resonance imaging (mpMRI) or Positron Emission Tomography (PET) in radiation therapy (RT) planning of patients with primary prostate cancer demands several preconditions: accurate staging of the extraprostatic and intraprostatic tumor mass, robust delineation of the intraprostatic gross tumor volume (GTV) and a reproducible characterization of the prostate cancer's biological properties. In the current review we searched for the currently available imaging techniques and we discussed their ability to fulfill these preconditions. We found that current pretreatment imaging was mainly performed with mpMRI and/or Prostate-specific membrane antigen PET imaging. Both techniques offered an accurate detection of the extraprostatic and intraprostatic tumor burden and had a major impact on RT concepts. However, some studies postulated that mpMRI and PSMA PET had complementary information for intraprostatic GTV detection. Moreover, interobserver differences for intraprostatic tumor delineation based on mpMRI were observed. It is currently unclear whether PET based GTV delineation underlies also interobserver heterogeneity. Further research is warranted to answer whether multimodal imaging is able to visualize biological processes related to prostate cancer pathophysiology and radiation resistance.