Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial

Multicenter Trial of Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer: Survival and Toxicity Endpoints

PURPOSE

The radiobiology of prostate cancer may favor the extreme hypofractionation inherent in stereotactic body radiation therapy (SBRT); however, data from a large multicenter study are lacking. We therefore examined the hypothesis that dose-escalated SBRT can be safely administered across multiple institutions, with favorable 5-year disease-free survival (DFS) rates compared with historical controls.

METHODS AND MATERIALS

Twenty-one centers enrolled 309 patients with prostate adenocarcinoma: 172 with low-risk (LR) and 137 with intermediate-risk (IR) disease. All were treated with a non-coplanar robotic SBRT platform using real-time tracking of implanted fiducials. The prostate was prescribed 40 Gy in 5 fractions of 8 Gy. We assessed toxicities using Common Terminology Criteria for Adverse Events (CTCAE) version 3 and biochemical failure using the "nadir + 2" definition. The study population yielded 90% power to identify excessive (>10%) rates of grade ≥3 genitourinary (GU) or gastrointestinal toxicities and, in the LR group, 80% power to show superiority in DFS over a 93% historical comparison rate.

RESULTS

At a median follow-up of 61 months, 2 LR patients (1.2%) and 2 IR patients (1.5%) experienced grade 3 GU toxicities, far below the 10% toxicity rate deemed excessive (upper limits of 95% confidence interval, 3.5% and 4.3%, respectively). No grade 4 or 5 toxicities occurred. All grade 3 toxicities were GU, occurring 11 to 51 months after treatment. For the entire group, the actuarial 5-year overall survival rate was 95.6% and the DFS rate was 97.1%. The 5-year DFS rate was 97.3% for LR patients (superior to the 93% DFS rate for historical controls; P = .0008; lower limit of 95% confidence interval, 94.6%) and 97.1% for IR patients.

CONCLUSIONS

Dose-escalated prostate SBRT was administered with minimal toxicity in this multi-institutional study. Relapse rates compared favorably with historical controls. SBRT is a suitable option for LR and IR prostate cancer.

PROstate Multicentre External beam radioTHErapy Using a Stereotactic boost: the PROMETHEUS study protocol

Background

High Dose Rate Brachytherapy (HDRB) boost is a well-established treatment for prostate cancer (PC). We describe the PROstate Multicentre External beam radioTHErapy Using Stereotactic boost (PROMETHEUS) study. Non-surgical stereotactic techniques are used to deliver similar doses to HDRB boost regimens with a dose escalation sub-study.

Methods

Eligible patients have intermediate or high risk PC. PROMETHEUS explores the safety, efficacy and feasibility of multiple Australian centres cooperating in the delivery of Prostate Stereotactic Body Radiotherapy (SBRT) technology. A SBRT boost component Target Dose (TD) of 19Gy in two fractions is to be delivered, followed by a subsequent EBRT component of 46Gy in 23 fractions. Once accrual triggers have been met, SBRT doses can be escalated in 1 Gy increments to a maximum of 22Gy in two fractions. Patient safety will also be measured with the rate of both acute and late moderate to severe Gastro-Intestinal (GI) and Genito-Urinary (GU) Common Terminology Criteria for Adverse Events (CTCAE) toxicities as well as patient reported quality of life. Efficacy will be assessed via biochemical control after 3 years.

Discussion

PROMETHEUS aims to generate evidence for a non-surgical possible future alternative to HDRB boost regimens, and introduce advanced radiotherapy techniques across multiple Australian cancer centres.

Trial registration

The study was retrospectively registered on the ANZCTR (Australian New Zealand Clinical Trials Registry) with trial ID: ACTRN12615000223538.

Dose painting of prostate cancer based on Gleason score correlations with apparent diffusion coefficients

BACKGROUND

Gleason scores for prostate cancer correlates with an increased recurrence risk after radiotherapy (RT). Furthermore, higher Gleason scores correlates with decreasing apparent diffusion coefficient (ADC) data from diffusion weighted MRI (DWI-MRI). Based on these observations, we present a formalism for dose painting prescriptions of prostate volumes based on ADC images mapped to Gleason score driven dose-responses.

METHODS

The Gleason score driven dose-responses were derived from a learning data set consisting of pre-RT biopsy data and post-RT outcomes for 122 patients treated with a homogeneous dose to the prostate. For a test data set of 18 prostate cancer patients with pre-RT ADC images, we mapped the ADC data to the Gleason driven dose-responses by using probability distributions constructed from published Gleason score correlations with ADC data. We used the Gleason driven dose-responses to optimize dose painting prescriptions that maximize the tumor control probability (TCP) with equal average dose as for the learning sets homogeneous treatment dose.

RESULTS

The dose painting prescriptions increased the estimated TCP compared to the homogeneous dose by 0-51% for the learning set and by 4-30% for the test set. The potential for individual TCP gains with dose painting correlated with increasing Gleason score spread and larger prostate volumes. The TCP gains were also found to be larger for patients with a low expected TCP for the homogeneous dose prescription.

CONCLUSIONS

We have from retrospective treatment data demonstrated a formalism that yield ADC driven dose painting prescriptions for prostate volumes that potentially can yield significant TCP increases without increasing dose burdens as compared to a homogeneous treatment dose. This motivates further development of the approach to consider more accurate ADC to Gleason mappings, issues with delivery robustness of heterogeneous dose distributions, and patient selection criteria for design of clinical trials.

Prognostic impact of nodal relapse in definitive prostate-only irradiation

BACKGROUND

Whole pelvic irradiation in prostate cancer patients might prevent metastatic spread of cancer cells through lymphatic drainages in patients eligible for definitive radiotherapy, but its use has declined in the last decades in favor of prostate-only irradiation (POI). The aim of our study is to assess the incidence of pelvic lymph nodal relapse and outcome in prostate cancer patients receiving POI.

MATERIALS AND METHODS

Data from 207 consecutive patients were collected. Clinical and treatment variables were collected. Biochemical relapse-free survival (BRFS), pelvic nodal relapse-free survival (PNRFS), distant metastasis-free survival (DMFS), disease-specific survival (DSS) and overall survival (OS) were calculated; analysis of prognostic variables was performed.

RESULTS

Five-year BRFS, PNRFS, DMFS, DSS and OS were, respectively, 90, 98, 96, 97 and 91%. On multivariate analysis, independent negative predictors of BRFS were Gleason score ≥ 7 (HR: 3.25) and PSA nadir ≥ 0.08 (HR: 4.86). Pelvic nodal relapse was not correlated to impaired outcome.

CONCLUSIONS

Lymph nodal pelvic relapse occurs in 2% of patients at 5 years and does not correlate with impaired outcome, suggesting the lack of theoretical benefit of a prophylactic nodal irradiation. Tumor biology and response to treatment are the main determinants of outcome.

Image-guided radiotherapy reduces the risk of under-dosing high-risk prostate cancer extra-capsular disease and improves biochemical control

BACKGROUND

To determine if reduced dose delivery uncertainty is associated with daily image-guidance (IG) and Prostate Specific Antigen Relapse Free Survival (PRFS) in intensity-modulated radiotherapy (IMRT) of high-risk prostate cancer (PCa).

METHODS

Planning data for consecutive PCa patients treated with IMRT (n = 67) and IG-IMRT (n = 35) was retrieved. Using computer simulations of setup errors, we estimated the patient-specific uncertainty in accumulated treatment dose distributions for the prostate and for posterolateral aspects of the gland that are at highest risk for extra-capsular disease. Multivariate Cox regression for PRFS considering Gleason score, T-stage, pre-treatment PSA, number of elevated clinical risk factors (T2c+, GS7+ and PSA10+), nomogram-predicted risk of extra-capsular disease (ECD), and dose metrics was performed.

RESULTS

For IMRT vs. IG-IMRT, plan dosimetry values were similar, but simulations revealed uncertainty in delivered dose external to the prostate was significantly different, due to positioning uncertainties. A patient-specific interaction term of the risk of ECD and risk of low dose to the ECD (p = 0.005), and the number of elevated clinical risk factors (p = 0.008), correlate with reduced PRFS.

CONCLUSIONS

Improvements in PSA outcomes for high-risk PCa using IG-IMRT vs. IMRT without IG may be due to improved dosimetry for ECD.

A biological modelling based comparison of radiotherapy plan robustness using photons vs protons for focal prostate boosting

BACKGROUND AND PURPOSE

Focal tumour boosting is currently explored in radiotherapy of prostate cancer to increase tumour control. In this study we applied dose response models for both tumour control and normal tissue complications to explore the benefit of proton therapy (PT) combined with focal tumour boosting, also when accounting for inter-fractional motion.

MATERIALS AND METHODS

CT scans of seven patients fused with MRI-based index volumes were used. Two volumetric modulated arc therapy (VMAT) plans were created for each patient; one with conventional dose (77 Gy) to the entire prostate, and one with an additional integrated boost (total dose of 95 Gy) to the index lesion. Two corresponding intensity modulated PT (IMPT) plans were created using two lateral opposing spot scanning beams. All plans were evaluated using an MRI-based tumour control probability (TCP) model and normal tissue complication probability (NTCP) models for the rectum and bladder. Plan robustness was evaluated using dose re-calculations on repeat cone-beam CTs.

RESULTS

Across all plans, median TCP increased from 86% (range: 59-98%) without boost to 97% (range: 96-99%) with boost. IMPT plans had lower rectum NTCPs (e.g. 3% vs. 4% for boost plans) but higher bladder NTCPs (20% vs. 18% for boost plans), yet only the bladder NTCPs remained different in the cone beam CT-based re-calculations.

CONCLUSIONS

Focal tumour boosting can be delivered with either VMAT or protons, and increases the predicted TCP. The small benefit of IMPT when assessing the planned dose distributions was lost when accounting for inter-fractional motion.

Saudi Oncology Society and Saudi Urology Association combined clinical management guidelines for prostate cancer 2017

This is an update to the previously published Saudi guidelines for the evaluation and medical and surgical management of patients diagnosed with prostate cancer. Prostate cancer is categorized according to the stage of the disease using the tumor node metastasis staging system 7th edition. The guidelines are presented with supporting evidence levels based on a comprehensive literature review, several internationally recognized guidelines, and the collective expertise of the guidelines committee members (authors) who were selected by the Saudi Oncology Society and Saudi Urological Association. Local factors, such as availability, logistic feasibility, and familiarity of various treatment modalities, have been taken into consideration. These guidelines should serve as a roadmap for the urologists, oncologists, general physicians, support groups, and health-care policymakers in the management of patients diagnosed with adenocarcinoma of the prostate.

Prostate irradiation with focal dose escalation to the intraprostatic dominant nodule: a systematic review

Radiation therapy (RT) is a curative treatment option for localized prostate cancer. Prostate irradiation with focal dose escalation to the intraprostatic dominant nodule (IDN) is an emerging treatment option that involves the prophylactic irradiation of the whole prostate while increasing RT doses to the visible prostatic tumor. Because of the lack of large multicentre trials, a systematic review was performed in an attempt to get an overview on the feasibility and efficacy of focal dose escalation to the IDN.

A bibliographic search for articles in English, which were listed in MEDLINE from 2000 to 2016 to identify publications on RT with focal directed boost to the IDN, was performed. The review was completed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Twenty-two articles describing 1,378 patients treated with RT using focal boost were identified and fulfilled the selection criteria. Intensity-modulated radiation therapy (IMRT) was used in 720 patients (52.3%), volumetric modulated arc therapy was used in 45 patients (3.3%), stereotactic body radiation therapy (SBRT) in 113 patients (8.2%), and low–dose rate and high–dose rate brachytherapy (BT) were used in 305 patients (22.1%) and 195 patients (14.1%), respectively. Use of androgen deprivation therapy varied substantially among series. Biochemical disease-free survival at 5 years was reported for a cohort of 812 (58.9%) patients. The combined median biochemical disease-free survival for this group of patients was 85% (range: 78.8–100%; 95% confidence interval: 77.1–82.7%).

The average occurrence of grade III or worse gastrointestinal and genitourinary late toxicity was, respectively, 2.5% and 3.1% for intensity-modulated RT boost, 10% and 6% for stereotactic body RT, 6% and 2% for low–dose rate BT, and 4% and 4.3% for high–dose rate BT.

This review shows encouraging results for focal dose escalation to the IDN with acceptable short- to medium-term side effects and biochemical disease control rates. However, owing to the heterogeneity of patient population and the short follow-up, the results should be interpreted with caution. Considering that the clinical endpoint in the studies was biochemical recurrence, the use and duration of androgen deprivation therapy administration should be carefully considered before driving definitive conclusions. Randomized trials with long-term follow-up are needed before this technique can be generally recommended.

Influence of inhomogeneous radiosensitivity distributions and intrafractional organ movement on the tumour control probability of focused IMRT in prostate cancer

PURPOSE

To evaluate the influence of radioresistance and intrafractional movement on the tumour control probability (TCP) in IMRT prostate treatments using simultaneous integrated boosts to PSMA-PET/CT-delineated GTVs.

MATERIALS AND METHODS

13 patients had PSMA-PET/CT prior to prostatectomy and histopathological examination. Two GTVs were available: GTV-PET and GTV-histo, which is the true cancer volume. Focused IMRT plans delivering 77 Gy in 35 fractions to the prostate and 95 Gy to PTV-PET were produced. For random portions of the true cancer volume, α and α/β were uniformly changed to represent different radiosensitivity reductions. TCP was calculated (linear quadratic model) for the true cancer volume with and without simulated intrafractional movement.

RESULTS

Intrafractional movement increased the TCP by up to 10.2% in individual cases and 1.2% averaged over all cases for medium radiosensitivity levels. At lower levels of radiosensitivity, movement decreased the TCP. Radiosensitivity reductions of 10-20% led to TCP reductions of 1-24% and 10-68% for 1% and 5% affected cancer volume, respectively. There is no linear correlation but a sudden breakdown of TCPs within a small range of radiosensitivity levels.

CONCLUSION

TCP drops significantly within a narrow range of radiosensitivity levels. Intrafractional movement can increase TCP when the boost volume is surrounded by a sufficiently high dose plateau.

Moderate hypofractionated radiotherapy is more effective and safe for localized prostate cancer patients: a meta-analysis

To compare the efficacy and safety of moderate hypofractionated radiotherapy (H-RT) with those of conventional radiotherapy (C-RT) in patients with localized prostate cancer, we conducted extensive literature searches of The Web of Science, Embase, Pubmed and Cochrane Library databases. We identified nine studies with 5969 patients for a meta-analysis. We calculated pooled risk ratios (RRs) and the 95% confidence intervals (CIs) for multiple parameters and performed statistical analysis using RevMan 5.3 software. Our analysis showed that the H-RT group obtained greater improvements in the 5-year biochemical or clinical failure-free survival (RR = 1.04, 95% CI:1.01–1.08; P = 0.01) and 5-year disease-free survival(RR = 1.04, 95% CI: 1.01–1.07, P = 0.02)than the C-RT group. However, the 5-year overall survival rates were comparable in the two groups (RR = 1.02, 95% CI: 0.99–1.04; P = 0.18). Comparison of multiple secondary parameters, including grade 2-4 acute/late gastrointestinal toxicity, grade 2–4 acute/late genitourinary toxicity, biochemical failure, local failure, distant failure and prostate cancer-specific mortality between the H-RT and the C-RT groups showed no statistical differences. This meta-analysis thus indicates that in patients with localized prostate cancer, moderate H-RT exerts a great beneficial effect on the primary parameters than C-RT without enhancing adverse events.

The relationship between local recurrences and distant metastases in prostate cancer: can 11C-choline PET/CT contribute to understand the link?

PURPOSE

Previous studies in prostate cancer (PCa) patients tried to correlate the onset of local recurrence (LR) with the development of distant metastases and formulated, based on theoretical and experimental data, hypotheses linking the two events. We aimed to address this issue with ¹¹C-choline positron emission tomography/computed tomography (PET/CT).

METHODS

This retrospective study included 491 PCa patients previously treated with radical prostatectomy who had undergone ¹¹C-choline PET/CT owing to biochemical failure. Further inclusion criteria were availability of clinical and pathological variables for survival analysis. Statistical significance was taken at P < 0.05.

RESULTS

Seventy-two patients (14.7%) had evidence of LR at ¹¹C-choline PET/CT. The frequency of LR increased from 13.8% in the interval 0-4 years after prostatectomy, to 23.9% in the 12-16-year interval (P = 0.080). On the contrary, the frequency of lymph node metastases (overall rate in the 0-16 years interval after prostatectomy: 26.3%) and of bone metastases (overall rate: 13.8%) decreased significantly over time. Kaplan-Meier curves showed no significant group difference in the rates of lymph node or bone metastases between patients with LR and patients without LR. LR significantly predicted PCa-specific survival at univariate analysis, but the statistical significance was lost at multivariate analysis.

CONCLUSION

We found no differences in the rates of lymph node and bone metastases between patients with and without LR. An inverse time-dependent trend was observed in the frequency of LR on one side and of lymph node and bone metastases on the other side. These findings were discussed in relation to previous theories linking LR to distant metastases and our study design.

Conformal Radiotherapy of Clinically Localized Prostate Cancer: Analysis of Rectal and Urinary Toxicity and Correlation with Dose-Volume Parameters

Aims and background

Rectal and urinary toxicities are the principal limiting factors in delivering a high target dose to patients affected by prostate cancer. The verification of such toxicity is an important step before starting a dose-escalation program. The present observational study reports on the acute and late rectal and urinary toxicity in relation with dose-volume parameters in 104 patients with localized prostate cancer treated with 3-dimensional conformal radiation therapy.

Methods and study design

One hundred and four patients with stage T1b-T3b prostate cancer were treated with three-dimensional conformal radiation therapy to a total dose of 74 Gy, 2 Gy per fraction. Rigid dose constraints were applied for rectum and bladder. Acute and late rectal and urinary toxicities were analyzed also in relation to dose-volume histograms. Biochemical relapse-free survival was defined according to the American Society of Therapeutic Radiation Oncology (ASTRO) criteria and to the RTOG-ASTRO Phoenix Consensus Conference Recommendations using the Kaplan-Meier method.

Results

No grade 3 toxicity was observed. Acute and late grade 2 toxicity rates were 5.8% and 9.0% for rectum and 12.5% and 2.0% for bladder, respectively. Rectal V70 influenced the occurrence of late grade 2 toxicity. A relationship between acute and late urinary toxicity was also found. After a median follow-up of 30 months (range, 20–50), the actuarial overall and biochemical relapse-free survival rates were 84% and 77%, respectively, with a significant difference between low-intermediate and high-risk patients.

Conclusions

Conformal radiotherapy to the dose of 74 Gy was administered with good compliance. The incidence of acute and late toxicity was relatively low in accord with our dose constraints. Rectal V70 proved to be a reliable prognosticator of late toxicity. Overall survival and biochemical relapse-free survival rates were more favorable for low and intermediate-risk and significantly less favorable for high-risk patients.

Three-Dimensional Conformal External Beam Radiotherapy versus the Combination of External Radiotherapy with High-Dose Rate Brachytherapy in Localized Carcinoma of the Prostate: Comparison of Acute Toxicity

Aims and background

Radiotherapy represents one of the basic therapeutic methods in treatment of localized carcinoma of the prostate. Optimal irradiation dose is the cornerstone of a successful treatment. Along with local control of the disease and overall survival of the patient, possible acute and long-term side effects need to be monitored very closely.

Methods

A non-randomized prospective study comparing the acute genitourinary and gastrointestinal toxicity in patients irradiated for localized carcinoma of the prostate. Fifty-seven patients were treated with three-dimensional conformal external beam radiotherapy alone, and in the second treatment arm a combination of external beam radiotherapy and high-dose rate brachytherapy was employed in 40 patients.

Results

Three-dimensional conformai external beam radiotherapy. Acute G1 genitourinary toxicity was recorded in 35.1% of patients, G2 in 22.8%, and G2-3 in one patient (1.7%). Acute gastrointestinal toxicity was experienced by 54.4% of patients, G1 in 28.1%, G2 in 17.5%, and G3 in 8.8%. Three-dimensional conformal external beam radiotherapy + brachytherapy. Acute G1 genitourinary toxicity was recorded in 37.5% and grade 2 in 15% of the patients. Only G1 acute gastrointestinal toxicity was recorded in 40% of the patients.

Conclusions

Acute G1 genitourinary toxicity was experienced by a similar percentage of patients in both treatment arms. Acute G2 genitourinary toxicity was more frequent in the three-dimensional conformal radiotherapy arm. Higher acute genitourinary toxicity, G3 or G4, was recorded only in one patient per treatment arm. Acute gastrointestinal toxicity was more frequent in the three-dimensional conformal radiotherapy arm. Higher acute gastrointestinal toxicity, G2 and G3, was only observed in the three-dimensional conformal radiotherapy arm. The acute toxicity observed was of a low grade. The combination of external beam radiotherapy with brachytherapy resulted in a lower incidence of gastrointestinal toxicity than external beam radiotherapy alone.

Hypofractionated Intensity-Modulated Simultaneous Integrated Boost and Image-Guided Radiotherapy in the Treatment of High-Risk Prostate Cancer Patients: A Preliminary Report on Acute Toxicity

Aims and background

To evaluate acute toxicity of hypofractionated intensity-modulated radiotherapy with simultaneous integrated boost and image-guided radiotherapy in the treatment of high-risk prostate cancer patients.

Methods

Between November 2009 and March 2012, 59 patients with high-risk prostate cancer were enrolled. The eclipse inverse planning system (Varian) was used to calculate an IMRT plan with simultaneous integrated boost, delivering 68.75 Gy (2.75 Gy per fraction) to the prostate, 55 Gy (2.2 Gy per fraction) to the seminal vesicles and positive nodes, and 45 Gy (1.8 Gy per fraction) to the pelvis, 4 fractions per week, 25 fractions. Prior to each treatment, patients underwent a kilo-voltage cone-beam CT performing an image-guided radiation therapy (IGRT). All patients were submitted to neoadjuvant, concomitant and adjuvant hormone therapy.

Results

The median follow-up for all patients was 13 months (range, 3–28). At the last follow-up, no grade 3 or 4 side effect was observed. Toxicity occurred as follows during the treatment: grade 1 and 2 gastrointestinal toxicity 5.2% and 6.9%, respectively; grade 1 and 2 genitourinary toxicity 24.1% and 1.7%, respectively. Only 1.7% of the patients developed grade 3 genitourinary toxicity. No grade 3 gastrointestinal toxicity was observed.

Conclusions

The present study demonstrated that 4/w hypofractionated intensity-modulated radiotherapy with simultaneous integrated boost and image-guided radiotherapy in patients with high-risk prostate cancer is feasible and safe. Low acute toxicity rates were verified. Longer follow-up is needed to evaluate the outcomes in terms of late toxicity and survival.

Comparison of interfractional setup reproducibility between two types of patient immobilization devices in image-guided radiation therapy for prostate cancer

Purpose:

The aim of this study is to compare the interfractional setup reproducibility of two types of patient immobilization devices for prostate cancer receiving image-guided radiation therapy (IGRT).

Materials and Methods:

The MOLDCARE (MC) involves hydraulic fixation, whereas the BlueBAG (BB) and Vac-Lock (VL) involve vacuum fixation. For 72 patients, each immobilization device was individually customized during computed tomography (CT) simulation. Before the treatment, bony registration was performed using orthogonal kV images and digitally reconstructed radiographs. The shift of the treatment couch was recorded as a benchmark in the first session. In subsequent sessions, the shifts from the benchmark were measured and analyzed. Soft-tissue registration was performed weekly by cone-beam CT and CT images, and the shifts were measured and analyzed.

Results:

In the superior-inferior and left-right directions, there were nearly no changes in the overall mean among the immobilization devices. In the anterior-posterior (AP) direction, the overall mean for the MC, BB, and VL were 0.34 ± 1.33, −0.47 ± 1.27, and −1.82 ± 1.65 mm, respectively. The mean shifts along the AP direction were approximately 1 mm more in patients immobilized on the BB and 2.5 mm more in those on the VL, compared to those on the MC, after the twentieth treatment. No significant changes were observed among the patients immobilized on those devices, respectively, in soft-tissue registration.

Conclusion:

It can be concluded that the settling of the vacuum fixation was caused by air leakage in the latter-half treatment, and the immobilization device type has no effect on the treatment-position reproducibility in IGRT.

Saudi Oncology Society and Saudi Urology Association combined clinical management guidelines for prostate cancer 2017

This is an update to the previously published Saudi guidelines for the evaluation and medical and surgical management of patients diagnosed with prostate cancer. Prostate cancer is categorized according to the stage of the disease using the tumor node metastasis staging system 7^th edition. The guidelines are presented with supporting evidence levels based on a comprehensive literature review, several internationally recognized guidelines, and the collective expertise of the guidelines committee members (authors) who were selected by the Saudi Oncology Society and Saudi Urological Association. Local factors, such as availability, logistic feasibility, and familiarity of various treatment modalities, have been taken into consideration. These guidelines should serve as a roadmap for the urologists, oncologists, general physicians, support groups, and health-care policymakers in the management of patients diagnosed with adenocarcinoma of the prostate.

Association between measures of treatment quality and disease progression in prostate cancer radiotherapy: An exploratory analysis from the TROG 03.04 RADAR trial

INTRODUCTION

Quality assurance methods are incorporated into multicentre radiotherapy clinical trials for ensuring consistent application of trial protocol and quantifying treatment uncertainties. The study's purpose was to determine whether post-treatment disease progression is associated with measures of the quality of radiotherapy treatment.

METHODS

The TROG 03.04 RADAR trial tested the impact of androgen deprivation on prostate cancer patients receiving dose-escalated external beam radiation therapy. The trial incorporated a plan-review process and Level III dosimetric intercomparison at each centre, from which variables suggestive of treatment quality were collected. Kaplan-Meier statistics and Fine and Gray competing risk modelling were employed to test for associations between quality-related variables and the participant outcome local composite progression.

RESULTS

Increased 'dose-difference' at the prostatic apex and at the anterior rectal wall, between planned and measured dose, was associated with reduced progression. Participants whose treatment plans included clinical target volume (CTV) to planning target volume (PTV) margins exceeding protocol requirements also experienced reduced progression. Other quality-related variables, including total accrual from participating centres, measures of target coverage and other variations from protocol, were not significantly associated with progression.

CONCLUSIONS

This analysis has revealed the association of several treatment quality factors with disease progression. Increased dose and dose margin coverage in the prostate region can reduce disease progression. Extensive and rigorous monitoring has helped to maximise treatment quality, reducing the incidence of quality-indicator outliers, and thus reduce the chance of observing significant associations with progression rates.

Dose escalation of external beam radiotherapy for high-risk prostate cancer-Impact of multiple high-risk factor

Objective

To retrospectively investigate the treatment outcomes of external beam radiotherapy with androgen deprivation therapy (ADT) in high-risk prostate cancer in three radiotherapy dose groups.

Methods

Between 1998 and 2013, patients with high-risk prostate cancer underwent three-dimensional conformal radiotherapy or intensity-modulated radiotherapy of 66 Gy, 72 Gy, or 78 Gy with ADT. Prostate-specific antigen (PSA) relapse was defined using the Phoenix definition. PSA relapse-free survival (PRFS) was evaluated in each radiotherapy dose group. Moreover, high-risk patients were divided into H-1 (patients with multiple high-risk factors) and H-2 (patients with a single high-risk factor) as risk subgroups.

Results

Two hundred and eighty-nine patients with a median follow-up period of 77.3 months were analyzed in this study. The median duration of ADT was 10.1 months. Age, Gleason score, T stage, and radiotherapy dose influenced PRFS with statistical significance both in univariate and multivariate analyses. The 4-year PRFS rates in Group-66 Gy, Group-72 Gy and Group-78 Gy were 72.7%, 81.6% and 90.3%, respectively. PRFS rates in the H-1 subgroup differed with statistical significance with an increasing radiotherapy dose having a more favorable PRFS, while PRFS rates in H-2 subgroup did not differ with increase in radiotherapy dose.

Conclusion

Dose escalation for high-risk prostate cancer in combination with ADT improved PRFS. PRFS for patients in the H-1 subgroup was poor, but dose escalation in those patients was beneficial, while dose escalation in the H-2 subgroup was not proven to be effective for improving PRFS.

Intraprostatic Fiducials Compared with Bony Anatomy and Skin Marks for Image-Guided Radiation Therapy of Prostate Cancer

Purpose

Prostate motion occurs during radiotherapy for localized prostate cancer. We evaluated the input of intraprostatic fiducials for image-guided radiation therapy and compared it with bony anatomy and skin marks.

Methods

Eleven patients were implanted with three fiducial markers in the prostate. Daily sets of orthogonal kV-kV images were compared with digitally reconstructed radiography. Data were recorded for skin marks, bony anatomy, and fiducial markers. The variations were analyzed along three principal axes (left-right: LR, superoinferior: SI, and anteroposterior: AP).

Results

A total of 2,417 measures were recorded over 38 fractions of radiotherapy (76 Gy). Fiducial marker movements from bony anatomy were ≤ 5 mm for 84.2% (confidence interval: CI 95%±1.5), 91.3% (CI 95%±1.1), and 99.5% (CI 95%±0.4) of the measures along the AP, SI, and LR axes, respectively. Ninety-five percent of the shifts between a fiducial marker and the bony anatomy were < 8 mm in the AP and SI axes, and < 3 mm in the LR axis. Fiducial marker movements from skin marks were ≤ 5 mm for 64.8% (CI 95%±1.9), 79.2% (CI 95%±1.6), and 87.2% (CI 95%±1.3) of the measures along the AP, SI, and LR axes, respectively. Bony anatomy movements from skin marks were ≤ 5 mm for 84% (CI 95%±1.4), 92% (CI 95%±1.1), and 87% (CI 95%±1.3) of the measurements along the AP, SI, and LR axes, respectively.

Conclusion

Using fiducial markers provides better accuracy of repositioning of the prostate than using bony anatomy and skin marks for image-guided radiotherapy of prostate cancer.

PAFR selectively mediates radioresistance and irradiation-induced autophagy suppression in prostate cancer cells

Platelet-activating factor receptor (PAFR) promotes tumorigenesis, angiogenesis and metastasis. Here, we defined the PAFR as a yielding new inhibiting target to selectively enhance the sensitivity of prostate cancer (PCa) cells to radiation. The selective responding to PAFR inhibiter may be caused by the differential expression pattern of PAFR in PCa cells. In this study, we also determined PAFR as a molecular basis by which the radiation induces autophagy suppression independent of activating mTOR pathway. PAFR can bind to the autophagy-indispensable protein Beclin 1, leading to the disability in its serine phosphorylation. The PAFR antagonist Ginkgolide B (GB) can sensitize radiotherapy by disrupting the formation of PAFR/Beclin 1 complex in PC3 and LNCaP cells, which have elevated PAFR expression after radiation exposure. Most importantly, GB efficiently radiosensitized PC3 and LNCaP tumor xenografts in vivo, and significantly reduced tumor burden. Overall, our results elucidated a significant role of GB in selectively improving the outcomes of PCa receiving radiation therapy.

National Population-Based Study Comparing Treatment-Related Toxicity in Men Who Received Intensity Modulated Versus 3-Dimensional Conformal Radical Radiation Therapy for Prostate Cancer

PURPOSE

To compare, in a national population-based study, severe genitourinary (GU) and gastrointestinal (GI) toxicity in patients with prostate cancer who were treated with radical intensity modulated radiation therapy (IMRT) or 3-dimensional conformal radiation therapy (3D-CRT).

METHODS AND MATERIALS

Patients treated with IMRT (n=6933) or 3D-CRT (n=16,289) between January 1, 2010 and December 31, 2013 in the English National Health Service were identified using cancer registry data, the National Radiotherapy Dataset, and Hospital Episodes Statistics, the administrative database of care episodes in National Health Service hospitals. We developed a coding system that identifies severe toxicity (at least grade 3 according to the National Cancer Institute Common Terminology Criteria for Adverse Events scoring system) according to the presence of a procedure and a corresponding diagnostic code in patients' Hospital Episodes Statistics records after radiation therapy. A competing risks regression analysis was used to estimate hazard ratios (HRs), comparing the incidence of severe GI and GU complications after IMRT and 3D-CRT, adjusting for patient, disease, and treatment characteristics.

RESULTS

The use of IMRT, as opposed to 3D-CRT, increased from 3.1% in 2010 to 64.7% in 2013. Patients who received IMRT were less likely than those receiving 3D-CRT to experience severe GI toxicity (4.9 vs 6.5 per 100 person-years; adjusted HR 0.66; 95% confidence interval 0.61-0.72) but had similar levels of GU toxicity (2.3 vs 2.4 per 100 person-years; adjusted HR 0.94; 95% confidence interval 0.84-1.06).

CONCLUSIONS

Prostate cancer patients who received radical radiation therapy using IMRT were less likely to experience severe GI toxicity, and they had similar GU toxicity compared with those who received 3D-CRT. These findings in an unselected "real-world" population support the use of IMRT, but further cost-effectiveness studies are urgently required.

Investigating the role of the IGF axis as a predictor of biochemical recurrence in prostate cancer patients post-surgery

BACKGROUND

Between 20% and 35% of prostate cancer (PCa) patients who undergo treatment with curative intent (ie, surgery or radiation therapy) for localized disease will experience biochemical recurrence (BCR). Alterations in the insulin-like growth factor (IGF) axis and PTEN expression have been implicated in the development and progression of several human tumors including PCa. We examined the expression of the insulin receptor (INSR), IGF-1 receptor (IGF-1R), PTEN, and AKT in radical prostatectomy tissue of patients who developed BCR post-surgery.

METHODS

Tissue microarrays (TMA) of 130 patients post-radical prostatectomy (65 = BCR, 65 = non-BCR) were stained by immunohistochemistry for INSR, IGF-1R, PTEN, and AKT using optimized antibody protocols. INSR, IGF1-R, PTEN, and AKT expression between benign and cancerous tissue, and different Gleason grades was assessed. Kaplan-Meier survival curves were used to examine the relationship between proteins expression and BCR.

RESULTS

INSR (P < 0.001), IGF-1R (P < 0.001), and AKT (P < 0.05) expression was significantly increased and PTEN (P < 0.001) was significantly decreased in cancerous versus benign tissue. There was no significant difference in INSR, IGF-1R, or AKT expression in the cancerous tissue of non-BCR versus BCR patients (P = 0.149, P = 0.990, P = 0.399, respectively). There was a significant decrease in PTEN expression in the malignant tissue of BCR versus non-BCR patients (P = 0.011). Combinational analysis of the tissue proteins identified a combination of decreased PTEN and increased AKT or increased INSR was associated with worst outcome. We found that in each case, our hypothesized worst group was most likely to experience BCR and this was significant for combinations of PTEN+INSR and PTEN+AKT but not PTEN+IGF-1R (P = 0.023, P = 0.028, P = 0.078, respectively).

CONCLUSIONS

Low PTEN is associated with BCR and this association is strongly modified by high INSR and high AKT expression. Measurement of these proteins could help inform appropriate patient selection for postoperative adjuvant therapy and prevent BCR.

The Role of External-Beam Radiation Therapy in the Treatment of Clinically Localized Prostate Cancer

Background

The treatment of clinically localized prostate cancer is controversial. Options include radical prostatectomy, external-beam radiation therapy (EBRT), brachytherapy, cryotherapy, and watchful waiting.

Methods

The author reviews EBRT as treatment for clinically localized prostate cancer, with particular emphasis on the technological advances that have allowed dose escalation and fewer therapy-related side effects.

Results

Technological advances in the last two decades have significantly improved the delivery of EBRT to the prostate. This has resulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest improvements in biochemical outcome. An alternative approach of combining androgen suppression therapy and EBRT has also been successful in improving clinical outcomes. However, establishing the optimal therapy for prostate cancer remains controversial.

Conclusions

Recent progress has led to improvements in clinical outcomes in patients treated with EBRT for prostate cancer. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.

Hypo-fractionated SBRT for localized prostate cancer: a German bi-center single treatment group feasibility trial

BACKGROUND

For prostate cancer treatment, treatment options with minimal side effects are desired. External beam radiation therapy (EBRT) is non-invasive, standard of care and delivered in either conventional fractionation over 8 weeks or with moderate hypo-fractionation over about 5 weeks. Recent advances in radiotherapy technology have made extreme hypo-fractionated stereotactic body radiation therapy (SBRT) of prostate cancer feasible, which has not yet been introduced as a standard treatment method in Germany. Initial results from other countries are promising, but long-term results are not yet available. The aim of this study is to investigate feasibility and effectiveness of SBRT for prostate cancer in Germany.

METHODS/DESIGN

This German bi-center single group trial (HYPOSTAT) is designed to evaluate feasibility and effectiveness, as measured by toxicity and PSA-response, respectively, of an extreme hypo-fractionated SBRT regimen with five fractions of 7 Gy in treatment of localized low and intermediate risk prostate cancer. The target volume includes the prostate with or without the base of seminal vesicles depending on risk stratification and uncertainty margins that are kept at 3-5 mm. SBRT treatment is delivered with the robotic CyberKnife system, which was recently introduced in Germany. Acute and late toxicity after one year will be evaluated according to Common Terminology Criteria for Adverse Events (CTCAE v. 4.0), Radiation Therapy Oncology Group (RTOG) and International Prostate Symptom Score (IPSS) Scores. The quality of life will be assessed before and after treatment with the EORTC QLQ C30 questionnaire. Hypothesizing that the proportion of patients with grade 2 side effects or higher is less or equal than 2.8%, thus markedly lower than the standard EBRT percentage (17.5%), the recruitment target is 85 patients.

DISCUSSION

The HYPOSTAT trial aims at demonstrating short term feasibility of extreme hypo-fractioned SBRT for the treatment of prostate cancer and might be used as the pilot study for a multi-center multi-platform or for randomized-controlled trials comparing conventional radiotherapy with SBRT for localized prostate cancer in the future. The study concept of patient enrollment, follow up and evaluation by multiple public university clinics and actual patient treatment in dedicated private radiosurgery practices with high-tech radiation equipment is unique for clinical trials.

STUDY STATUS

The study is ongoing and currently recruiting patients.

TRIAL REGISTRATION

Registration number: NCT02635256 ( clinicaltrials.gov ). Registered 8 December 2015.

A retrospective study of late adverse events in proton beam therapy for prostate cancer

The efficacy and safety of proton beam therapy (PBT) were retrospectively evaluated in 111 consecutive patients with prostate cancer who underwent definitive PBT between 2008 and 2012. Following exclusion of 18 patients due to treatment suspension, loss to follow-up, and histology, the analysis included 93 patients with a median age of 68 years (range, 49–81 years). A total of 7, 32 and 54 prostate cancer patients were classified as low-, intermediate- and high-risk, respectively, as follows: High-risk, T≥3a or prostate-specific antigen (PSA) ≥20 ng/ml or Gleason Score ≥8; low-risk, T ≤2b and PSA≤10 ng/ml and Gleason Score=6; intermediate-risk, all other combinations. The median initial prostate-specific antigen (PSA) level was 9.75 ng/ml (range, 1.4–100 ng/ml) and the median Gleason score was 7 (range, 6–10). Patients with low-risk disease received 74 GyE (relative biological effectiveness=1.1) in 37 fractions, and those at intermediate or higher risk received 78 GyE in 39 fractions. Complete androgen blockade (CAB) therapy was performed from 6 months prior to PBT for patients with intermediate- or high-risk disease. CAB was continued during PBT and then terminated at the end of PBT for intermediate-risk patients. Patients at high risk continued CAB for 3 years. No combination therapy was used for low-risk patients. All the patients were followed up for >2 years after PBT, and all but one were PSA failure-free. The Common Terminology Criteria for Adverse Events v.4.0 was used to evaluate late adverse events. One patient developed grade 3 non-infectious cystitis and hematuria. Grade 2 urinary frequency was observed in 1 patient, and grade 2 rectal bleeding occurred in 4 patients. Of the 4 patients with grade 2 rectal bleeding, 2 received anticoagulant therapy, but none had diabetes mellitus or another high-risk comorbidity. The median time to occurrence of an adverse event of grade ≥2 was 14 months (range, 3–41 months). Therefore, the present retrospective study revealed that PBT at 78 GyE/39 Fr was well-tolerated and achieved good tumor control in patients with prostate cancer.

Influence of concentration, nanoparticle size, beam energy, and material on dose enhancement in radiation therapy

The purpose of this study was to analyse the effects of the type, concentration, and nanoparticle diameter of dose enhancement materials on the dose enhancement of low- and high-energy megavoltage (MV) X-rays acquired from a medical linear accelerator using Monte Carlo simulation. Monte Carlo simulation was performed with the Monte Carlo N-Particle Transport (MCNPX) code, using the energy spectrum of the linear accelerator and a mathematical Snyder head phantom. A 5-cm-diameter virtual tumour was defined in the centre of the phantom. Gold, gadolinium, iodine and iron oxide were used as dose enhancement materials. Varying concentrations (7, 18 and 30 mg/g) of nanoparticles of different diameters (25, 50, 75, 100 and 125 nm) were applied, and the dose enhancement was comparatively evaluated for 4, 6, 10 and 15 MV X-rays, and a 60Co source. Higher dose enhancement factors (DEFs) were observed when the incident energy was low. Moreover, the dose enhancement effects were greatest with gold nanoparticles, followed by gadolinium, iodine, and iron oxide nanoparticles; the DEFs were 1.011-1.047 (gold), 1.005-1.030 (gadolinium), 1.002-1.028 (iodine) and 1.002-1.014 (iron oxide). The dose enhancement effects increased with increasing nanoparticle diameter and concentration. However, the concentration of the material had a greater impact than the diameter of the nanoparticles. As the concentration and diameter of nanoparticles increased, the DEF also increased. The 4 and 6 MV X-rays demonstrated higher dose enhancement compared with the 10 and 15 MV X-rays.

Moderate Hypofractionation in High-Risk, Organ-Confined Prostate Cancer: Final Results of a Phase III Randomized Trial

Purpose

To report the final results on treatment outcomes of a randomized trial comparing conventional and hypofractionated radiotherapy in high-risk, organ-confined prostate cancer (PCa).

Patients and Methods

This single-institution, randomized clinical trial, conducted from January 2003 to December 2007, enrolled 168 patients with high-risk PCa who were randomly assigned in a 1:1 ratio to conventional (80 Gy in 40 fractions in 8 weeks) or hypofractionated radiotherapy (62 Gy in 20 fractions in 5 weeks) to prostate and seminal vesicles. The primary outcome measure was late toxicity. Additional outcomes were freedom from biochemical failure (FFBF), prostate cancer–specific survival (PCaSS), and overall survival (OS), evaluated on an intention-to-treat basis.

Results

A total of 85 patients were assigned to conventional and 83 to hypofractionated radiotherapy. At a median follow-up of 9 years (interquartile range, 7.5 to 10.1 years), no differences was observed in physician-assessed late gastro intestinal and genitourinary toxicity greater than or equal to grade 2 ( P = .68 and .57, respectively) were found between the two arms. The 10-year FFBF rate was 72% in the hypofractionation group and 65% in the conventional fractionation group ( P = .148). Ten-year OS rates were 75% in the hypofractionation group and 64% in the conventional group, respectively ( P = .22). The same features for 10-year PCaSS were 95% and 88%, respectively ( P = .066). Hypofractionation, pretreatment prostate-specific antigen level, Gleason score, and clinical tumor stage for FFBF, and hypofractionation and Gleason score for PCaSS were significant prognostic variables on the multivariate analysis.

Conclusion

Long-term findings showed that hypofractionated radiotherapy failed the intent of either reducing physician-assessed late toxicity or maintaining the same efficacy. A postrandomization analysis, however, revealed that hypofractionation was a significant prognostic factor for FFBF and PCaSS, when adjusted for clinical prognostic variables.

Dose escalation with an IMRT technique in 15 to 28 fractions is better tolerated than standard doses of 3DCRT for LAPC

Purpose

To review acute and late toxicities after chemoradiation for locally advanced pancreatic ductal adenocarcinoma in patients who were treated with escalated dose radiation (EDR).

Methods and materials

Maximum Common Terminology Criteria for Adverse Events Version 4.0 acute toxicities (AT) during radiation and within 60 days after radiation were recorded for both acute gastrointestinal toxicity and overall toxicity (OT). Late toxicities were also recorded. EDR was generally delivered with daily image guidance and breath-hold techniques using intensity modulated radiation therapy (IMRT) planning. These were compared with patients who received standard dose radiation (SDR) delivered as 50.4 Gy in 28 fractions using 3-dimensional chemoradiation therapy planning.

Results

A total of 59 of 154 patients (39%) received EDR with biologically equivalent doses >70 Gy. The most frequent schedules were 63 Gy in 28 fractions (19 of 154 patients), 67.5 Gy in 15 fractions (10 of 154 patients), and 70 Gy in 28 fractions (15 of 154 patients). No grade 4 or grade 5 OT or late toxicities were reported. Rates of grade 3 acute gastrointestinal toxicity were significantly lower in patients who received EDR compared with SDR (1% vs 14%; P < .001). Similarly, rates of grade 3 OT were also lower for EDR compared with SDR (4% vs 16%; P = .004). The proportion of patients who experienced no AT was higher in the EDR group than the SDR group (36% vs 15%; P = .001). For EDR patients treated with IMRT, a lower risk of AT was associated with a later treatment year (P = .007), nonpancreatic head tumor location (P = .01), breath-hold (P = .002), 4-dimensional computed tomography (P = .003), computed tomography on rails (P = .002), and lower stomach V40 (P = .03). With a median time of 12 months (range, 1-79 months) from the start of radiation therapy to the last known follow-up in the EDR group, 51 of 59 patients (86%) had no late toxicity. Six of 59 EDR patients (10%) had either strictures or gastrointestinal bleeding that required intervention. No significant predictors of late toxicity were identified.

Conclusion

Overall acute and late toxicity rates were low with EDR using an IMRT technique with image guidance and respiratory gating.

Randomized Trial of a Hypofractionated Radiation Regimen for the Treatment of Localized Prostate Cancer

Purpose Men with localized prostate cancer often are treated with external radiotherapy (RT) over 8 to 9 weeks. Hypofractionated RT is given over a shorter time with larger doses per treatment than standard RT. We hypothesized that hypofractionation versus conventional fractionation is similar in efficacy without increased toxicity. Patients and Methods We conducted a multicenter randomized noninferiority trial in intermediate-risk prostate cancer (T1 to 2a, Gleason score ≤ 6, and prostate-specific antigen [PSA] 10.1 to 20 ng/mL; T2b to 2c, Gleason ≤ 6, and PSA ≤ 20 ng/mL; or T1 to 2, Gleason = 7, and PSA ≤ 20 ng/mL). Patients were allocated to conventional RT of 78 Gy in 39 fractions over 8 weeks or to hypofractionated RT of 60 Gy in 20 fractions over 4 weeks. Androgen deprivation was not permitted with therapy. The primary outcome was biochemical-clinical failure (BCF) defined by any of the following: PSA failure (nadir + 2), hormonal intervention, clinical local or distant failure, or death as a result of prostate cancer. The noninferiority margin was 7.5% (hazard ratio, < 1.32). Results Median follow-up was 6.0 years. One hundred nine of 608 patients in the hypofractionated arm versus 117 of 598 in the standard arm experienced BCF. Most of the events were PSA failures. The 5-year BCF disease-free survival was 85% in both arms (hazard ratio [short v standard], 0.96; 90% CI, 0.77 to 1.2). Ten deaths as a result of prostate cancer occurred in the short arm and 12 in the standard arm. No significant differences were detected between arms for grade ≥ 3 late genitourinary and GI toxicity. Conclusion The hypofractionated RT regimen used in this trial was not inferior to conventional RT and was not associated with increased late toxicity. Hypofractionated RT is more convenient for patients and should be considered for intermediate-risk prostate cancer.

Initial experience with intra-fraction motion monitoring using Calypso guided volumetric modulated arc therapy for definitive prostate cancer treatment

INTRODUCTION

Accurate delivery of radiation while reducing dose to organs at risk is essential in prostate treatment. The Calypso motion management system detects and corrects both inter- and intra-fraction motion which offers potential benefits over standard alignment to fiducial markers. The aims of this study were to implement Calypso with Dynamic Edge™ gating and to assess both the motion seen, and interventions required.

METHODS

An implementation group was formed which assessed changes needed to standard workflows. Three patients had Calypso beacons inserted into their prostate. All patients were treated using volumetric modulated arc therapy to a dose of 80 Gy in 40 fractions. Standard inter-fraction motion correction using either kilovoltage (kV) orthogonal paired imaging or cone beam computed tomography (CBCT) image-guided radiotherapy techniques, were used along with the Calypso system to compare accuracy. A gating threshold of >0.5 cm was used during treatment. Workflow variations along with inter- and intra-fraction motion and interventions required were assessed.

RESULTS

A total of 116 fractions were treated using Calypso with Dynamic Edge™ gating. There was a strong concordance between aligning beacons using kV orthogonal imaging or CBCT and Calypso (mean variation ≤0.06 cm). The mean intra-fraction motion detected was ≤0.2 cm in all directions with the largest motion recorded being 2.2 cm in the left direction while the treatment beam was off. Prostate rotation was largest in the pitch direction and 28 fractions exceeded the 10° tolerance. A total of 78 couch shift corrections of ≥0.3 cm were required, usually following standard imaging, and before treatment starting. Three gating events due to intra-fraction motion occurred during treatment.

CONCLUSIONS

Intra-fraction motion monitoring with Calypso was successfully implemented. Greatest movement was seen between time of standard imaging and treatment starting with more than half the treatments requiring a ≥0.3 cm adjustment. This would not have been detected without intra-fraction monitoring.

Local tumor control and DNA-PK activity of peripheral blood lymphocytes in prostate cancer patients receiving radiotherapy

Repair of DNA damage is critical for genomic stability, and DNA-dependent protein kinase (DNA-PK) has an important role in repairing double-strand breaks. We examined whether the DNA-PK activity of peripheral blood lymphocytes (PBLs) was related to biochemical (prostate-specific antigen: PSA) relapse and radiation toxicity in prostate cancer patients who have received radiotherapy. A total of 69 patients with localized adenocarcinoma of the prostate participated in this study. Peripheral blood was collected 2 years or later after radiotherapy and centrifuged, then DNA-PK activity was measured by a filter binding assay. The high DNA-PK activity group had a significantly higher PSA relapse-free survival rate than the low DNA-PK activity group. The 10-year PSA relapse-free survival was 87.0% in the high DNA-PK activity group, whereas it was 52.7% in the low DNA-PK activity group. Multivariate analysis showed the Gleason score and the level of DNA-PK activity were significant predictors of PSA relapse after radiotherapy. In addition, the low DNA-PK activity group tended to have a higher incidence of Grade 1-2 urinary toxicity than the high DNA-PK activity group. Prostate cancer patients with low DNA-PK activity had a higher rate of PSA relapse and a higher incidence of urinary toxicity. DNA-PK activity in PBLs might be a useful marker for predicting PSA relapse and urinary toxicity, possibly contributing to personalized treatment of prostate cancer.

Brachytherapy improves outcomes in young men (≤60 years) with prostate cancer: A SEER analysis

PURPOSE

The aim of the study was to compare prostate cancer-specific mortality (PCSM) in young men with clinically localized prostate cancer treated by either external beam radiation (EBRT) alone or brachytherapy with or without external beam radiation.

METHODS AND MATERIALS

Utilizing the Surveillance, Epidemiology and End Results database, 15,505 patients ≤60 years of age diagnosed with prostate cancer between 2004 and 2009 and treated with radiation therapy alone were identified. Incidence of PCSM was determined for both groups and compared using competing risk models.

RESULTS

The overall 8-year PCSM for the study population was 1.9% (95% confidence interval [CI]: 1.6-2.2). For patients treated with EBRT or brachytherapy with or without external beam, the 8-year PCSM was found to be 2.8% (CI: 2.2-3.4) and 1.2% (CI: 0.9-1.6), respectively (p < 0.001). Univariable analysis demonstrated that brachytherapy was associated with lower PCSM risk (hazard ratio = 0.40; CI: 0.30-0.54; p < 0.001). High Gleason risk category, black race, higher Tumor (T) stage, and higher grade were all associated with greater mortality risk (p < 0.01). On multivariable analysis, brachytherapy continued to be associated with a significantly lower mortality risk (hazard ratio = 0.65; CI: 0.47-0.89; p = 0.008). Subgroup analyses found that among those with Gleason score ≥8, younger patients had increased risk of PCSM (p = 0.001).

CONCLUSIONS

In men ≤60 years of age with prostate cancer, radiation therapy continues to offer excellent outcomes. After adjusting for relevant variables, the use of brachytherapy was associated with reduced PCSM compared to treatment with EBRT alone.

Optimal planning strategy among various arc arrangements for prostate stereotactic body radiotherapy with volumetric modulated arc therapy technique

BACKGROUND

The aim of this study was to determine the optimal strategy among various arc arrangements in prostate plans of stereotactic body radiotherapy with volumetric modulated arc therapy (SBRT-VMAT).

PATIENTS AND METHODS

To investigate how arc arrangements affect dosimetric and biological metrics, SBRT-VMAT plans for eighteen patients were generated with arrangements of single-full arc (1FA), single-partial arc (1PA), double-full arc (2FA), and double-partial arc (2PA). All plans were calculated by the Acuros XB calculation algorithm. Dosimetric and radiobiological metrics for target volumes and organs at risk (OARs) were evaluated from dosevolume histograms.

RESULTS

All plans were highly conformal (CI<1.05, CN=0.91) and homogeneous (HI=0.09-0.12) for target volumes. For OARs, there was no difference in the bladder dose, while there was a significant difference in the rectum and both femoral head doses. Plans using 1PA and 2PA showed a strong reduction to the mean rectum dose compared to plans using 1FA and 2FA. Contrastively, the D2% and mean dose in both femoral heads were always lower in plans using 1FA and 2FA. The average tumor control probability and normal tissue complication probability were comparable in plans using all arc arrangements.

CONCLUSIONS

The use of 1PA had a more effective delivery time and produced equivalent target coverage with better rectal sparing, although all plans using four arc arrangements showed generally similar for dosimetric and biological metrics. However, the D2% and mean dose in femoral heads increased slightly and remained within the tolerance. Therefore, this study suggests that the use of 1PA is an attractive choice for delivering prostate SBRT-VMAT.

Patient characterization and usage trends of proton beam therapy for localized prostate cancer in the United States: A study of the National Cancer Database

PURPOSE

To evaluate usage trends and identify factors associated with proton beam therapy (PBT) compared to alternative forms of external beam radiation therapy (RT) (EBRT) for localized prostate cancer.

PATIENTS AND METHODS

The National Cancer Database was queried for men with localized (N0, M0) prostate cancer diagnosed between 2004 and 2013, treated with EBRT, with available data on EBRT modality (photon vs. PBT). Binary multiple logistic regression identified variables associated with EBRT modality.

RESULTS

In total, 143,702 patients were evaluated with relatively few men receiving PBT (5,709 [4.0%]). Significant differences in patient and clinical characteristics were identified between those men treated with PBT compared to those treated with photon (odds ratio [OR]; 95% CI). Patients treated with PBT were generally younger (OR = 0.73; CI: 0.67-0.82), National Comprehensive Cancer Network low-risk compared to intermediate (0.71; 0.65-0.78) or high (0.44; 0.38-0.5) risk, white vs. black race (0.66; 0.58-0.77), with less comorbidity (Charlson-Deyo 0 vs. 2+; 0.70; 0.50-0.98), live in higher income counties (1.55; 1.36-1.78), and live in metropolitan areas compared to urban (0.21; 0.18-0.23) or rural (0.14; 0.10-0.19) areas. Most patients treated with PBT travelled more than 100 miles to the treatment facility. Annual PBT utilization significantly increased in both total number and percentage of EBRT over time (2.7%-5.6%; P<0.001). PBT utilization increased mostly in men classified as National Comprehensive Cancer Network low-risk (4%-10.2%).

CONCLUSION

PBT for men with localized prostate cancer significantly increased in the United States from 2004 to 2013. Significant demographic and prognostic differences between those men treated with photons and protons were identified.

Classifying high-risk versus very high-risk prostate cancer: is it relevant to outcomes of conformal radiotherapy and androgen deprivation?

OBJECTIVE

To evaluate outcomes in prostate cancer patients classified as high-risk (HR) or very high-risk (VHR) who were treated with conformal radiation therapy (CRT) and androgen deprivation therapy (ADT).

METHODS

Between 11/2001 and 3/2012, 203 patients with HR disease received CRT to the prostate (78-82 Gy) and pelvic lymph nodes (46-50 Gy) with ADT (6 m-2 years). Median follow-up was 50 months (12 m-142 m). Biochemical failure was defined according to Phoenix definition. Imaging studies were used to identify local, regional or metastatic failure. Four different VHR/HR groupings were formed using the 2014 and revised 2015 NCCN guidelines. Differences were examined using Kaplan Meier (KM) estimates with log rank test and uni- and multivariate Cox regression analysis (MVA).

RESULTS

Failure occurred in 30/203 patients (15%). Median time to failure was 30 m (4 m-76 m). KM estimate of 4 year biochemical disease free survival (b-DFS) for the entire cohort was 87% (95%CI: 82-92%). Four year KM survival estimates for b-DFS, PCSS and OS were comparable for each NCCN subgroup. On univariate analysis, the NCCN subgroups were not predictive of b-DFS at 4 years, however, DMFS was worse for both VHR subgroups (p = .03and .01) respectively. Cox univariate analysis was also significant for: PSA ≥40 ng/ml p = 0.001; clinical stages T2c p = .004, T3b p = .02 and > 4 cores with Gleason score 8-10 p < .03. On MVA, only PSA ≥ 40 ng/ml was predictive for b-DFS or MFS at 4 years (HR: 3.75 and 3.25, p < 0.005).

CONCLUSION

Patients with HR and VHR disease treated with CRT and ADT had good outcomes. Stratification into HR and VHR sub-groups provided no predictive value. Only PSA ≥40 ng/ml predicted poor outcomes on MVA. Distant failure was dominant and local recurrence rare, suggesting that improved systemic treatment rather than intensification of local therapy is needed. Patients with high-risk prostate cancer are most often treated with conformal dose escalated radiation therapy with androgen deprivation. Stratification into high versus very high-risk subgroups using 2014 or revised 2015 National Comprehensive Cancer Network (NCCN) criteria did not impact treatment outcomes. Only Prostate Serum Antigen (PSA) ≥40 ng/ml was predictive of poor prognosis. Distant failure was dominant and local recurrence uncommon which challenges the notion that intensification of local therapy will further improve outcomes in patients with high-risk disease.

Prostate Cancer Radiation Therapy: What Do Clinicians Have to Know?

Radiotherapy (RT) for prostate cancer (PC) has steadily evolved over the last decades, with improving biochemical disease-free survival. Recently population based research also revealed an association between overall survival and doses ≥ 75.6 Gray (Gy) in men with intermediate- and high-risk PC. Examples of improved RT techniques are image-guided RT, intensity-modulated RT, volumetric modulated arc therapy, and stereotactic ablative body RT, which could facilitate further dose escalation. Brachytherapy is an internal form of RT that also developed substantially. New devices such as rectum spacers and balloons have been developed to spare rectal structures. Newer techniques like protons and carbon ions have the intrinsic characteristics maximising the dose on the tumour while minimising the effect on the surrounding healthy tissue, but clinical data are needed for confirmation in randomised phase III trials. Furthermore, it provides an overview of an important discussion issue in PC treatment between urologists and radiation oncologists: the comparison between radical prostatectomy and RT. Current literature reveals that all possible treatment modalities have the same cure rate, but a different toxicity pattern. We recommend proposing the possible different treatment modalities with their own advantages and side-effects to the individual patient. Clinicians and patients should make treatment decisions together (shared decision-making) while using patient decision aids.

Continued Benefit to Rectal Separation for Prostate Radiation Therapy: Final Results of a Phase III Trial

PURPOSE

SpaceOAR, a Food and Drug Administration-approved hydrogel intended to create a rectal-prostate space, was evaluated in a single-blind phase III trial of image guided intensity modulated radiation therapy. A total of 222 men were randomized 2:1 to the spacer or control group and received 79.2 Gy in 1.8-Gy fractions to the prostate with or without the seminal vesicles. The present study reports the final results with a median follow-up period of 3 years.

METHODS AND MATERIALS

Cumulative (Common Terminology Criteria for Adverse Events, version 4.0) toxicity was evaluated using the log-rank test. Quality of life (QOL) was examined using the Expanded Prostate Cancer Index Composite (EPIC), and the mean changes from baseline in the EPIC domains were tested using repeated measures models. The proportions of men with minimally important differences (MIDs) in each domain were tested using repeated measures logistic models with prespecified thresholds.

RESULTS

The 3-year incidence of grade ≥1 (9.2% vs 2.0%; P=.028) and grade ≥2 (5.7% vs 0%; P=.012) rectal toxicity favored the spacer arm. Grade ≥1 urinary incontinence was also lower in the spacer arm (15% vs 4%; P=.046), with no difference in grade ≥2 urinary toxicity (7% vs 7%; P=0.7). From 6 months onward, bowel QOL consistently favored the spacer group (P=.002), with the difference at 3 years (5.8 points; P<.05) meeting the threshold for a MID. The control group had a 3.9-point greater decline in urinary QOL compared with the spacer group at 3 years (P<.05), but the difference did not meet the MID threshold. At 3 years, more men in the control group than in the spacer group had experienced a MID decline in bowel QOL (41% vs 14%; P=.002) and urinary QOL (30% vs 17%; P=.04). Furthermore, the control group were also more likely to have experienced large declines (twice the MID) in bowel QOL (21% vs 5%; P=.02) and urinary QOL (23% vs 8%; P=.02).

CONCLUSIONS

The benefit of a hydrogel spacer in reducing the rectal dose, toxicity, and QOL declines after image guided intensity modulated radiation therapy for prostate cancer was maintained or increased with a longer follow-up period, providing stronger evidence for the benefit of hydrogel spacer use in prostate radiation therapy.

Infiltrating mast cells increase prostate cancer chemotherapy and radiotherapy resistances via modulation of p38/p53/p21 and ATM signals

Early studies indicated that mast cells in prostate tumor microenvironment might influence prostate cancer (PCa) progression. Their impacts to PCa therapy, however, remained unclear. Here we found PCa could recruit more mast cells than normal prostate epithelial cells then alter PCa chemotherapy and radiotherapy sensitivity, leading to PCa more resistant to these therapies. Mechanism dissection revealed that infiltrated mast cells could increase p21 expression via modulation of p38/p53 signals, and interrupting p38-p53 signals via siRNAs of p53 or p21 could reverse mast cell-induced docetaxel chemotherapy resistance of PCa. Furthermore, recruited mast cells could also increase the phosphorylation of ATM at ser-1981 site, and inhibition of ATM activity could reverse mast cell-induced radiotherapy resistance. The in vivo mouse model with xenografted PCa C4-2 cells co-cultured with mast cells also confirmed that mast cells could increase PCa chemotherapy resistance via activating p38/p53/p21 signaling. Together, our results provide a new mechanism showing infiltrated mast cells could alter PCa chemotherapy and radiotherapy sensitivity via modulating the p38/p53/p21 signaling and phosphorylation of ATM. Targeting this newly identified signaling may help us better suppress PCa chemotherapy and radiotherapy resistance.

Comparison of prostate positioning guided by three-dimensional transperineal ultrasound and cone beam CT

OBJECTIVE

The accuracy of a transperineal three-dimensional ultrasound system (3DUS) was assessed for prostate positioning and compared to fiducial- and bone-based positioning in kV cone beam computed tomography (CBCT) during definitive radiotherapy of prostate cancer.

METHODS

Each of the 7 patients had three fiducial markers implanted into the prostate before treatment. Prostate positioning was simultaneously measured by 3DUS and CBCT before each fraction. In total, 177 pairs of 3DUS and CBCT scans were collected. Bone-match and seed-match were performed for each CBCT. Using seed-match as a reference, the accuracy of 3DUS and bone-match was evaluated. Systematic and random errors as well as optimal setup margins were calculated for 3DUS and bone-match.

RESULTS

The discrepancy between 3DUS and seed-match in CBCT (average ± standard deviation) was 0.0 ± 1.7 mm laterally, 0.2 ± 2.0 mm longitudinally, and 0.3 ± 1.7 mm vertically. Using seed-match as a reference, systematic errors for 3DUS were 1.2 mm, 1.1 mm, and 0.9 mm; and random errors were 1.4 mm, 1.8 mm, and 1.6 mm, on lateral, longitudinal, and vertical axes, respectively. By analogy, the difference of bone-match to seed-match was 0.1 ± 1.1 mm laterally, 1.3 ± 3.8 mm longitudinally, and 1.3 ± 4.5 mm vertically. Systematic errors were 0.5 mm, 2.2 mm, and 2.6 mm; and random errors were 1.0 mm, 3.1 mm, and 3.9 mm on lateral, longitudinal, and vertical axes, respectively. The accuracy of 3DUS was significantly higher than that of bone-match on longitudinal and vertical axes, but not on the lateral axis.

CONCLUSION

Image-guided radiotherapy of prostate cancer based on transperineal 3DUS was feasible, with overall small discrepancy to seed-match in CBCT in this retrospective study. Compared to bone-match, transperineal 3DUS achieved higher accuracy on longitudinal and vertical axes.

The dose-response of salvage radiotherapy following radical prostatectomy: A systematic review and meta-analysis

PURPOSE/OBJECTIVES

To date neither the optimal radiotherapy dose nor the existence of a dose-response has been established for salvage RT (SRT).

MATERIALS/METHODS

A systematic review from 1996 to 2015 and meta-analysis was performed to identify the pathologic, clinical and treatment factors associated with relapse-free survival (RFS) after SRT (uniformly defined as a PSA>0.2ng/mL or rising above post-SRT nadir). A sigmoidal dose-response curve was objectively fitted and a non-parametric statistical test used to determine significance.

RESULTS

71 studies (10,034 patients) satisfied the meta-analysis criteria. SRT dose (p=0.0001), PSA prior to SRT (p=0.0009), ECE+ (p=0.039) and SV+ (p=0.046) had significant associations with RFS. Statistical analyses confirmed the independence of SRT dose-response. Omission of series with ADT did not alter results. Dose-response is well fit by a sigmoidal curve (p=0.0001) with a TCD₅₀ of 65.8Gy, with a dose of 70Gy achieving 58.4% RFS vs. 38.5% for 60Gy. A 2.0% [95% CI 1.1-3.2] improvement in RFS is achieved for each Gy. The SRT dose-response remarkably parallels that for definitive RT of localized disease.

CONCLUSIONS

This study provides level 2a evidence for dose-escalated SRT>70Gy. The presence of an SRT dose-response for microscopic disease supports the hypothesis that prostate cancer is inherently radio-resistant.

The delineation of intraprostatic boost regions for radiotherapy using multimodality imaging

Dose escalation to the prostate improves tumor control but at the expense of increased rectal toxicity. Modern imaging can be used to detect the most common site of recurrence, the intraprostatic lesion (IPL), which has led to the concept of focusing dose escalation to the IPL in order to improve the therapeutic ratio. Imaging must be able to detect lesions with adequate sensitivity and specificity to accurately delineate the IPL. This information must be carefully integrated into the radiotherapy planning process to ensure the dose is targeted to the IPL. This review will consider the role and challenges of multiparametric MRI and PET computed tomography in delineating a tumor boost to be delivered by external beam radiotherapy.