High-dose intensity modulated radiation therapy for prostate cancer: early toxicity and biochemical outcome in 772 patients

Comparison of commercial atlas-based automatic segmentation software for prostate radiotherapy treatment planning

This study aims to assess the accuracy of automatic atlas-based contours for various key anatomical structures in prostate radiotherapy treatment planning. The evaluated structures include the bladder, rectum, prostate, seminal vesicles, femoral heads and penile bulb. CT images from 20 patients who underwent intensity-modulated radiotherapy were randomly chosen to create an atlas library. Atlas contours of the seven anatomical structures were generated using four software packages: ABAS, Eclipse, MIM, and RayStation. These contours were then compared to manual delineations performed by oncologists, which served as the ground truth. Evaluation metrics such as dice similarity coefficient (DSC), mean distance to agreement (MDA), and volume ratio (VR) were calculated to assess the accuracy of the contours. Additionally, the time taken by each software to generate the atlas contour was recorded. The mean DSC values for the bladder exhibited strong agreement (>0.8) with manual delineations for all software except for Eclipse and RayStation. Similarly, the femoral heads showed significant similarity between the atlas contours and ground truth across all software, with mean DSC values exceeding 0.9 and MDA values close to zero. On the other hand, the penile bulb displayed only moderate agreement with the ground truth, with mean DSC values ranging from 0.5 to 0.7 for all software. A similar trend was observed in the prostate atlas contours, except for MIM, which achieved a mean DSC of over 0.8. For the rectum, both ABAS and MIM atlases demonstrated strong agreement with the ground truth, resulting in mean DSC values of more than 0.8. Overall, MIM and ABAS outperformed Eclipse and RayStation in both DSC and MDA. These results indicate that the atlas-based segmentation employed in this study produces acceptable contours for the anatomical structures of interest in prostate radiotherapy treatment planning.

Two-fractionated stereotactic magnetic resonance-guided adaptive radiation therapy for patients with prostate cancer (SMART PRO trial): protocol for a confirmatory clinical trial

INTRODUCTION

In an MRI-guided linear accelerator (MR-LINAC) system, the planned doses for organs at risk and for tumours are assessed by MR imaging and re-contouring at every treatment. This allows treatment to be safer and more precise by ensuring that it is suitable for the state of the patient's organs on that day, as well as by allowing images to be acquired during radiation therapy to prevent radiation while organs are in motion.Here, we will conduct a confirmatory study of two-fractionated stereotactic magnetic resonance-guided adaptive radiation therapy for patients with localised prostate cancer.

METHODS AND ANALYSIS

This will be a single-arm study to demonstrate the safety and efficacy of ultra-hypofractionated radiation (26 Gy/2 Fr) using an MR-LINAC system in patients with very low-intermediate risk prostate cancer.The primary endpoint will be the incidence of grade ≥2 acute urinary tract adverse events occurring within 90 days of the start of radiation therapy.The sample size has been determined to be 58.

ETHICS AND DISSEMINATION

This study is performed in accordance with Ethical Guidelines for Medical and Health Research Involving Human Subjects, published by Japan's Ministry of Education, Science and Technology and the Ministry of Health, Labour and Welfare and the modified act on the Protection of Personal Information as well as the Declaration of Helsinki. This study was approved by the institutional ethics committee of the National Cancer Center on 20 November 2021.The findings of this trial will be submitted to an international peer-reviewed journal and the key findings will be presented at an international scientific conference.Authorship will be ascribed in accordance with the International Committee of Medical Journal Editors guidance.

TRIAL REGISTRATION NUMBER

UMIN000049746.

A Phase 1 Trial of Salvage Stereotactic Body Radiation Therapy for Radiorecurrent Prostate Cancer After Brachytherapy

PURPOSE

NCT03253744 is a phase 1 trial with the primary objective to identify the maximum tolerated dose (MTD) of salvage stereotactic body radiation therapy (SBRT) in patients with local prostate cancer recurrence after brachytherapy. Additional objectives included biochemical control and imaging response.

METHODS AND MATERIALS

This trial was initially designed to test 3 therapeutic dose levels (DLs): 40 Gy (DL1), 42.5 Gy (DL2), and 45 Gy (DL3) in 5 fractions. Intensity modulation was used to deliver the prescription dose to the magnetic resonance imaging and prostate-specific membrane antigen-based positron emission tomography imaging-defined gross tumor volume while simultaneously delivering 30 Gy to an elective volume defined by the prostate gland. This phase 1 trial followed a 3+3 design with a 3-patient expansion at the MTD. Toxicities were scored until trial completion at 2 years post-SBRT using Common Terminology Criteria for Adverse Events version 5.0. Escalation was halted if 2 dose limiting toxicities occurred, defined as any persistent (>4 days) grade 3 toxicity occurring within the first 3 weeks after SBRT or any grade ≥3 genitourinary (GU) or grade 4 gastrointestinal toxicity thereafter.

RESULTS

Between August 2018 and January 2023, 9 patients underwent salvage SBRT and were observed for a median of 22 months (Q1-Q3, 20-43 months). No grade 3 to 5 adverse events related to study treatment were observed; thus, no dose limiting toxicities occurred during the observation period. Escalation was halted by amendment given excellent biochemical control in DL1 and DL2 in the setting of a high incidence of clinically significant late grade 2 GU toxicity. Therefore, the MTD was considered 42.5 Gy in 5 fractions (DL2). One- and 2-year biochemical progression-free survival were 100% and 86%, representing a single patient in the trial cohort with biochemical failure (prostate-specific antigen [PSA] nadir + 2.0) at 20 months posttreatment.

CONCLUSIONS

The MTD of salvage SBRT for the treatment of intraprostatic radiorecurrence after brachytherapy was 42.5 Gy in 5 fractions producing an 86% 2-year biochemical progression-free survival rate, with 1 poststudy failure at 20 months. The most frequent clinically significant toxicity was late grade 2 GU toxicity.

Conditional Risk and Predictive Factors Associated With Late Toxicity in Patients With Prostate Cancer Treated With External Beam Radiation Therapy Alone in the Randomized Trial RTOG 0126

PURPOSE

The objective of this study was to characterize the conditional risk of developing grade 2+ urinary or gastrointestinal (GI) toxicity for patients treated with external beam radiation therapy in Radiation Therapy Oncology Group 0126. A secondary objective was to analyze baseline patient and treatment characteristics and determine their relevance in predicting toxicity both at the time of trial enrollment and at later points of follow-up.

METHODS AND MATERIALS

One thousand five hundred thirty-two patients with localized prostate cancer were enrolled between March 2002 and August 2008, of whom 1499 were eligible and included in data analysis with a median follow-up of 8.4 years (range, 0.02-13 years). Patients were treated with either 3-dimensional conformal radiation therapy or intensity-modulated radiation therapy according to institutional practice without the addition of androgen deprivation and randomized to receive either standard-dose radiation therapy of 70.2 Gy or dose-escalated radiation therapy of 79.2 Gy of radiation therapy to the prostate only with standard fractionation. Univariate and multivariate analyses were performed to determine whether initial factors were predictive of late toxicity at the time of treatment and at later time points.

RESULTS

As patients proceed further from completion of radiation therapy without the development of toxicity, the subsequent risk of both grade 2+ genitourinary (GU) and GI toxicity decreases with time. At the time of enrollment, the risk of developing grade 2+ toxicity over the next 5 years was 9.57% and 17.89%, respectively. After 5 years of toxicity-free survival, the risk of developing grade 2+ GU or GI toxicity in the subsequent 5 years was 3.02% and 1.54%, respectively. Baseline treatment and patient-related factors predicted late toxicity both at trial enrollment and after 2 years of toxicity-free survivorship. Baseline urinary dysfunction and dose-escalated radiation therapy were associated with increased late GU toxicity. Acute GI toxicity and dose-escalated radiation therapy were associated with increased risk of late GI toxicity. Treatment with intensity-modulated radiation therapy was associated with reduced risk of either toxicity.

CONCLUSIONS

The conditional risk of grade 2+ toxicities decreases as patients proceed further from treatment, with most toxicities occurring in the first few years after treatment completion. Baseline patient and treatment characteristics remain relevant at both enrollment and later time points.

Radiobiological Meta-Analysis of the Response of Prostate Cancer to Different Fractionations: Evaluation of the Linear-Quadratic Response at Large Doses and the Effect of Risk and ADT

The purpose of this work was to investigate the response of prostate cancer to different radiotherapy schedules, including hypofractionation, to evaluate potential departures from the linear-quadratic (LQ) response, to obtain the best-fitting parameters for low-(LR), intermediate-(IR), and high-risk (HR) prostate cancer and to investigate the effect of ADT on the radiobiological response. We constructed a dataset of the dose-response containing 87 entries/16,536 patients (35/5181 LR, 32/8146 IR, 20/3209 HR), with doses per fraction ranging from 1.8 to 10 Gy. These data were fit to tumour control probability models based on the LQ model, linear-quadratic-linear (LQL) model, and a modification of the LQ (LQmod) model accounting for increasing radiosensitivity at large doses. Fits were performed with the maximum likelihood expectation methodology, and the Akaike information criterion (AIC) was used to compare the models. The AIC showed that the LQ model was superior to the LQL and LQmod models for all risks, except for IR, where the LQL model outperformed the other models. The analysis showed a low α/β for all risks: 2.0 Gy for LR (95% confidence interval: 1.7-2.3), 3.4 Gy for IR (3.0-4.0), and 2.8 Gy for HR (1.4-4.2). The best fits did not show proliferation for LR and showed moderate proliferation for IR/HR. The addition of ADT was consistent with a suppression of proliferation. In conclusion, the LQ model described the response of prostate cancer better than the alternative models. Only for IR, the LQL model outperformed the LQ model, pointing out a possible saturation of radiation damage with increasing dose. This study confirmed a low α/β for all risks.

Argon plasma coagulation therapy in hemorrhagic radiation proctitis following pelvic radiation in gynecological malignancies

Introduction

Chronic radiation proctitis is a common chronic complication of malignant pelvic diseases after pelvic radiation therapy. Although, the incidence has decreased after advent of intensity-modulated radiotherapy due to better control of radiation dose to rectum. In the era of conventional two-field radiotherapy to pelvis, this was a common complication usually presenting after 1-2 years of treatment completion. Rectal bleeding caused by radiation proctitis is difficult to manage. Argon plasma coagulation (APC) is an electrocoagulation technique that appears to be an effective and low-cost alternative to the use of lasers in gastrointestinal endoscopy. The aim of this study was to evaluate the efficacy of APC, as well as patients' tolerance of the procedure, in the treatment of bleeding radiation-induced proctitis.

Materials and Methods

Between January 2015 and August 2017, 29 patients of cancer cervix treated with definite radiotherapy both external and brachytherapy who suffered from rectal bleeding due to radiation proctitis were included for treatment with argon plasma laser (APC). Twenty-three patients suffered from anemia, 16 of whom required blood transfusion. APC was performed, applying the no-touch spotting technique at an electrical power of 40 Watt and an argon gas flow of 1.5-2.0 l/min. Pulse duration was <0.5 s. Treatment sessions were carried out at intervals of 3 weeks. Subjects received 2-4 treatment sessions.

Results

Twenty-eight out of 29 patients were accessible for effects and results. APC led to persistent clinical and endoscopic remission of rectal bleeding after a median of three sessions. No adverse effects were encountered after initial treatment. All the patients were in complete remission.

Conclusions

APC is an effective, safe, and well-tolerated treatment for rectal bleeding caused by chronic radiation proctitis. It should be considered as a first-line therapy for radiation proctitis.

An 8-week exercise study to improve cancer treatment related fatigue and QOL among African American breast cancer patients undergoing radiation treatment: A pilot randomized clinical trial

BACKGROUND

Cancer treatment related fatigue (CTRF) is one of the most debilitating side effects of adjuvant radiation therapy (RT). Several studies have found that physical activity (PA) may be an effective intervention to decrease fatigue and enhance QOL in cancer survivors. The primary objective of the PEDLAR study is to test the feasibility of an easily administered 8-week structured moderate-intensity PA intervention, delivered concurrently with RT, in reducing CTRF and improving health-related QOL among African-American breast cancer patients. This study is also designed to provide pilot data on the acceptability and adherence of PA interventions in African-American women with breast cancer.

METHODS

It is a prospective, 2-arm, 8-week feasibility trial. Participants are randomized to either a structured, moderate-intensity aerobic training exercise regimen concurrent with radiotherapy or a control group.

RESULTS

Participants in intervention group reported high satisfaction with exercise and adherence was >75% for exercise sessions.

CONCLUSIONS

African-American breast cancer patients in a moderate-intensity 75 min/wk aerobic exercise intervention had marginally lower fatigue at 8-wk follow-up compared to baseline. The control group participants had marginally higher fatigue at 8-wk follow-up compared to baseline. Participants in the intervention group reported slightly better quality of life at 8-wk follow-up compared to baseline (P = 0.06).

A Retrospective Single-Arm Cohort Study in a Single Center of Radiofrequency Ablation in Treatment of Chronic Radiation Proctitis

BACKGROUND

Chronic radiation proctitis (CRP) may develop in patients within months to years after undergoing pelvic radiotherapy. Numerous treatment modalities are available to achieve hemostasis in CRP, but the optimal treatment remains controversial. We report our clinical experience and long-term outcomes using radiofrequency ablation (RFA) in patients with CRP.

METHODS

We retrospectively reviewed patients who underwent RFA for CRP at Kaohsiung Chang Gung Memorial Hospital between October 2015 and March 2021. The patient characteristics, endoscopic findings, and clinical outcomes were collected and analyzed.

RESULTS

35 total patients were enrolled in the study. The mean age was 70.5 ± 12.4 years. All patients sustained repeated rectal bleeding before RFA, and 15 of 35 patients needed blood transfusion. Bleeding cessation was achieved in all patients. Mean follow-up time was 18.6 months (ranging from 2 to 52 months). The hemoglobin (Hb) levels at 6 months after RFA revealed significant improvement from 11.0 ± 2.3 to 11.8 ± 1.9 g/dL (p = 0.048). The rectal telangiectasia density (RTD) scores also showed significant improvement from 2.96 ± 0.2 to 0.85 ± 0.7 (p < 0.0001). In conclusion, RFA treatment is safe and effective in controlling rectal bleeding in CRP without serious complications and can be considered as a first-line or alternative endoscopic treatment for patients with CRP.

Prostate Cancer Treatment-Related Toxicity: Comparison between 3D-Conformal Radiation Therapy (3D-CRT) and Volumetric Modulated Arc Therapy (VMAT) Techniques

Objective: This paper illustrates the results of a mono-institutional registry trial, aimed to test whether gastrointestinal (GI) and genitourinary (GU) toxicity rates were lower in localized prostate cancer patients treated with image-guided volumetric modulated arc therapy (IG-VMAT) compared to those treated with IG-3D conformal radiation therapy (IG-3DCRT). Materials and Methods: Histologically proven prostate cancer patients with organ-confined disease, treated between October 2008 and September 2014 with moderately hypofractionated radiotherapy, were reviewed. Fiducial markers were placed in the prostate gland by transrectal ultrasound guide. The prescribed total dose was 70 Gy in 28 fractions. The mean and median dose volume constraints for bladder and rectum as well as total volume of treatment were analyzed as potentially prognostic factors influencing toxicity. The Kaplan−Meier method was applied to calculate survival. Results: Overall, 83 consecutive patients were included. Forty-two (50.6%) patients were treated with 3D-CRT and 41 (49.4%) with the VMAT technique. The median follow-up for toxicity was 77.26 months for the whole cohort. The VMAT allowed for a dose reduction to the rectum and bladder for the large majority of the considered parameters; nonetheless, the only parameter correlated with a clinical outcome was a rectal dose limit V66 > 8.5% for late GI toxicity G ≥ 2 (p = 0.045). Rates of G ≥ 2 toxicities were low among the whole cohort of these patients treated with IGRT. The analysis for rectum dose volume histograms (DVHs) showed that a severe (grade ≥ 2) late GI toxicity was related with the rectal dose limit V66 > 8.5% (p = 0.045). Conclusions: This study shows that moderate hypofractionation is feasible and safe in patients with intermediate and high-risk prostate cancer. Daily IGRT may decrease acute and late toxicity to organs at risk and improve clinical benefit and disease control rate, cutting down the risk of PTV geographical missing. The adoption of VMAT allows for promising results in terms of OAR sparing and a reduction in toxicity that, also given the small sample, did not reach statistical significance.

Cone-beam CT delta-radiomics to predict genitourinary toxicities and international prostate symptom of prostate cancer patients: a pilot study

For prostate cancer (PCa) patients treated with definitive radiotherapy (RT), acute and late RT-related genitourinary (GU) toxicities adversely impact disease-specific quality of life. Early warning of potential RT toxicities can prompt interventions that may prevent or mitigate future adverse events. During intensity modulated RT (IMRT) of PCa, daily cone-beam computed tomography (CBCT) images are used to improve treatment accuracy through image guidance. This work investigated the performance of CBCT-based delta-radiomic features (DRF) models to predict acute and sub-acute International Prostate Symptom Scores (IPSS) and Common Terminology Criteria for Adverse Events (CTCAE) version 5 GU toxicity grades for 50 PCa patients treated with definitive RT. Delta-radiomics models were built using logistic regression, random forest for feature selection, and a 1000 iteration bootstrapping leave one analysis for cross validation. To our knowledge, no prior studies of PCa have used DRF models based on daily CBCT images. AUC of 0.83 for IPSS and greater than 0.7 for CTCAE grades were achieved as early as week 1 of treatment. DRF extracted from CBCT images showed promise for the development of models predictive of RT outcomes. Future studies will include using artificial intelligence and machine learning to expand CBCT sample sizes available for radiomics analysis.

Urethra Sparing With Target Motion Mitigation in Dose-Escalated Extreme Hypofractionated Prostate Cancer Radiotherapy: 7-Year Results From a Phase II Study

Purpose

To explore whether the rectal distension-mediated technique, harnessing human physiology to achieve intrafractional prostate motion mitigation, enables urethra sparing by inverse dose painting, thus promoting dose escalation with extreme hypofractionated stereotactic ablative radiotherapy (SABR) in prostate cancer.

Materials and Methods

Between June 2013 and December 2018, 444 patients received 5 × 9 Gy SABR over 5 consecutive days. Rectal distension-mediated SABR was employed via insertion of a 150-cm³ air-inflated endorectal balloon. A Foley catheter loaded with 3 beacon transponders was used for urethra visualization and online tracking. MRI-based planning using Volumetric Modulated Arc Therapy - Image Guided Radiotherapy (VMAT-IGRT) with inverse dose painting was employed in delivering the planning target volume (PTV) dose and in sculpting exposure of organs at risk (OARs). A 2-mm margin was used for PTV expansion, reduced to 0 mm at the interface with critical OARs. All plans fulfilled D_mean ≥45 Gy. Target motion ≥2 mm/5 s motions mandated treatment interruption and target realignment prior to completion of the planned dose delivery.

Results

Patient compliance to the rectal distension-mediated immobilization protocol was excellent, achieving reproducible daily prostate localization at a patient-specific retropubic niche. Online tracking recorded ≤1-mm intrafractional target deviations in 95% of treatment sessions, while target realignment in ≥2-mm deviations enabled treatment completion as scheduled in all cases. The cumulative incidence rates of late grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxicities were 5.3% and 1.1%, respectively. The favorable toxicity profile was corroborated by patient-reported quality of life (QOL) outcomes. Median prostate-specific antigen (PSA) nadir by 5 years was 0.19 ng/ml. The cumulative incidence rate of biochemical failure using the Phoenix definition was 2%, 16.6%, and 27.2% for the combined low/favorable–intermediate, unfavorable intermediate, and high-risk categories, respectively. Patients with a PSA failure underwent a ⁶⁸Ga-labeled prostate-specific membrane antigen (⁶⁸Ga-PSMA) scan showing a 20.2% cumulative incidence of intraprostatic relapses in biopsy International Society of Urological Pathology (ISUP) grade ≥3.

Conclusion

The rectal distension-mediated technique is feasible and well tolerated. Dose escalation to 45 Gy with urethra-sparing results in excellent toxicity profiles and PSA relapse rates similar to those reported by other dose-escalated regimens. The existence of intraprostatic recurrences in patients with high-risk features confirms the notion of a high α/β ratio in these phenotypes resulting in diminished effectiveness with hypofractionated dose escalation.

Brachytherapy focal dose escalation using ultrasound based tissue characterization by patients with non-metastatic prostate cancer: Five-year results from single-center phase 2 trial

PURPOSE

This prospective trial investigates side effects and efficacy of focal dose escalation with brachytherapy for patients with prostate cancer.

METHODS AND MATERIALS

In the Phase II, monocentric prospective trial 101 patients with low-/intermediate- and high-risk prostate cancer were enrolled between 2011 and 2013. Patients received either PDR-/HDR-brachytherapy alone with 86-90 Gy (EQD2, α/β = 3 Gy) or PDR-/HDR-brachytherapy as boost after external beam radiation therapy up to a total dose of 91-96 Gy (EQD2, α/β = 3 Gy). Taking place brachytherapy all patients received the simultaneous integrated focal boost to the intra-prostatic tumor lesions visible in computer-aided ultrasonography (HistoScanning™) - up to a total dose of 108-119 Gy (EQD2, α/β = 3 Gy). The primary endpoint was toxicity. Secondary endpoints were cumulative freedom from local recurrence, PSA-free survival, distant metastases-free survival, and overall survival. This trial is registered with ClinicalTrials.gov, number NCT01409876.

RESULTS

Median follow-up was 65 months. Late toxicity was generally low with only four patients scoring urinary grade 3 toxicity (4/101, 4%). Occurrence of any grade of late rectal toxicities was very low. We did not register any grade ≥2 of late rectal toxicities. The cumulative 5 years local recurrence rate (LRR) for all patients was 1%. Five years- biochemical disease-free survival estimates according Kaplan-Meier were 98,1% and 81,3% for low-/intermediate-risk and high-risk patients, respectively. Five years metastases-free survival estimates according Kaplan-Meier were 98,0% and 83,3% for all patients, low-/intermediate-risk and high-risk patients, respectively.

CONCLUSIONS

The 5 years-results from this Phase II Trial show that focal dose escalation with computer-aided ultrasonography and brachytherapy for patients with non-metastatic prostate cancer is safe and effective.

Intensity-Modulated Radiotherapy with Regional Hyperthermia for High-Risk Localized Prostate Carcinoma

Background: The purpose of this study was to evaluate the efficacy and toxicity of adding regional hyperthermia to intensity-modulated radiotherapy (IMRT) plus neoadjuvant androgen deprivation therapy (ADT) for high-risk localized prostate carcinoma. Methods: Data from 121 consecutive patients with high-risk prostate carcinoma who were treated with IMRT were retrospectively analyzed. The total planned dose of IMRT was 76 Gy in 38 fractions for all patients; hyperthermia was used in 70 of 121 patients. Intra-rectal temperatures at the prostate level were measured to evaluate thermal dose. Results: Median number of heating sessions was five and the median total thermal dose of CEM43T90 was 7.5 min. Median follow-up duration was 64 months. Addition of hyperthermia to IMRT predicted better clinical relapse-free survival. Higher thermal dose with CEM43T90 (>7 min) predicted improved biochemical disease-free survival. The occurrence of acute and delayed toxicity ≥Grade 2 was not significantly different between patients with or without hyperthermia. Conclusions: IMRT plus regional hyperthermia represents a promising approach with acceptable toxicity for high-risk localized prostate carcinoma. Further studies are needed to verify the efficacy of this combined treatment.

Locally Advanced Rectal Cancer: What We Learned in the Last Two Decades and the Future Perspectives

The advancement in surgical techniques, optimization of systemic chemoradiotherapy, and development of refined diagnostic and imaging modalities have brought a phenomenal shift in the treatment of the locally advanced rectal cancer. Although each therapeutic option has shown substantial progress in their field, it is finding their ideal amalgamation which has baffled the clinician and researchers alike. In the effort to identifying the perfect salutary treatment plan, we have even shifted our attention from the trimodal approach to non-operative "watchful waiting" to more recent individualized care. In this article, we acknowledge the scientific progress in the management of locally advanced rectal cancer and compare the opportunities as well as the obstacles while implementing them clinically. We also explore the current challenges and controversies surrounding the multidisciplinary approach and highlight the new trends and recent advances with an ultimate goal to improve the patients' quality of life.

Comparison of atlas-based auto-segmentation accuracy for radiotherapy in prostate cancer

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Auto-contouring accuracy and contouring time were evaluated using two procedures.

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Dice coefficient was better for the multiple atlases procedure than for one atlas.

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Contouring time of the multiple atlases procedure is clinically acceptable.

Atlas-based auto-segmentation (ABS) procedure used in radiotherapy can be classified into two groups, one using one atlas per patient (sSM) and the other using multiple atlases (sMM). This study evaluated auto-contouring accuracy and contouring time in patients with prostate cancer using the two procedures. The Dice similarity coefficient of sMM was significantly better than that of sSM (prostate [median, 0.81 (range, 0.66–0.91) vs. 0.64 (0.27–0.71), p < 0.01], seminal vesicles [0.49 (0.31–0.80) vs. 0.18 (0.01–0.60), p < 0.05], and rectum [0.81 (0.37–0.91) vs. 0.57 (0.31–0.77), p < 0.01]). The median contouring times were 2.6 (sMM) and 1.3 min (sSM).

Patient reported toxicity and quality of life after hypofractionated high-dose intensity-modulated radiotherapy for intermediate- and high risk prostate cancer

Background and purpose

For irradiation of localized prostate-cancer, moderately-hypofractionated regimens with a variety of dose per fraction are used. We adopted a regimen of 70 Gy in 28 fractions of 2.5 Gy, using state of the art radiotherapy (RT) and closely monitored the efficacy, toxicity and health-related quality of life (HRQoL) in a large cohort, using patient-reported outcomes.

Materials and methods

Between 2008 and 2016, 462 patients with intermediate- to high-risk localized prostate cancer were treated with RT, 28 fractions of 2.5 Gy, using IMRT/VMAT, an online fiducial-maker based correction protocol and a daily inserted endorectal balloon. Overall freedom from failure (no biochemical or clinical recurrence) , as well as self-reported genitourinary (GU) and gastrointestinal (GI) related toxicity and HRQoL are reported.

Results

Overall freedom from failure rates at 3 and 5 years were 92.0% (89.1–94.9%) and 83.5% (78.6–88.4%), respectively. Prevalence rates of grade ≥ 2 GU/GI-toxicity were 16.3%/6.3% and 22,1%/3.2% after 3 and 5 years respectively. The 5-year actuarial incidences of grade ≥ 2 GU/GI-toxicity were 43.5%/18.5%. HRQoL worsened during RT and gradually recovered thereafter, In accordance with the prevalence rates.

Conclusion

Treatment of intermediate- or high-risk localized prostate cancer with RT to 70 Gy in 28 fractions with IMRT/VMAT, using fiducial markers and an endorectal balloon leads to good long-term tumor control rates and acceptable patient reported toxicity rates. Furthermore, patient-reported outcomes, including HRQoL, are essential for a good comparison between different studies. Finally, prevalence rates show a better correlation with HRQoL than actuarial incidence rates do and might therefore better represent the burden of toxicity.

Technical Note: Three-dimensional QA of simultaneous integrated boost radiotherapy treatments by a dose-volume histogram methodology and its comparison with 3D gamma results

PURPOSE

Intensity-modulated radiotherapy with simultaneous integrated boost (SIB) presents several attractive advantages to be employed in clinical practice. Its secure application demands a rigorous quality assurance (QA) procedure, ideal for three-dimensional (3D) dose distribution measurements. Thus, a gel dosimetry methodology to evaluate the dose delivery of SIB treatments is presented and compared to conventional gamma evaluation.

METHODS

MAGIC-f gel dosimeter with magnetic resonance images for dose reading were used following its standard procedures. Four SIB QA plans created in gel dosimeter phantoms were used. The gel measured and treatment planning system (TPS) calculated doses were compared using 3D gamma analyses (3%/3mm/15% threshold). Two structures were artificially on the TPS dose distribution expected on the phantom by converting the 1.7 and 2.0 Gy isodose levels into structures to represent the treatment. The gel and TPS dose-volume histogram (DVH) were compared based on five dose points: D95%, D90%, D50%, D10%, and D5%.

RESULTS

Approvals of 93%, 96%, 98%, and 92% were achieved in the 3D gamma analyses for the plans QA 1, 2, 3, and 4. In the DVH analyses, QA plan 1 measured and expected curves showed a good agreement. QA plan 2 showed deviations in the highest doses for both structures with a maximum deviation (Δ_máx ) of 8.0%. QA plans 3 and 4 showed the highest dose variation between the gel and TPS in the smaller doses of the DVH (Δ_máx of 7.2% and -8.9%, respectively). For QA plan 4, the curves of the 1.7 Gy structure presented a good agreement, but deviations in the smaller dose region of the DVH occurred for the 2 Gy structure (Δ_máx of 7.7%).

CONCLUSIONS

A methodology for 3D dose evaluation of complex SIB treatments was proposed. It provided an important overview of the dose distributions. Their results significantly complemented the usual gamma analysis results.

Rolling out RapidPlan: What we've learnt

INTRODUCTION

RapidPlan (RP), a knowledge-based planning system, aims to consistently improve plan quality and efficiency in radiotherapy. During the early stages of implementation, some of the challenges include knowing how to optimally train a model and how to integrate RP into a department. We discuss our experience with the implementation of RP into our institution.

METHODS

We reviewed all patients planned using RP over a 7-month period following inception in our department. Our primary outcome was clinically acceptable plans (used for treatment) with secondary outcomes including model performance and a comparison of efficiency and plan quality between RP and manual planning (MP).

RESULTS

Between November 2017 and May 2018, 496 patients were simulated, of which 217 (43.8%) had an available model. RP successfully created a clinically acceptable plan in 87.2% of eligible patients. The individual success of the 24 models ranged from 50% to 100%, with more than 90% success in 15 (62.5%) of the models. In 40% of plans, success was achieved on the 1st optimisation. The overall planning time with RP was reduced by up to 95% compared with MP times. The quality of the RP plans was at least equivalent to historical MP plans in terms of target coverage and organ at risk constraints.

CONCLUSION

While initially time-consuming and resource-intensive to implement, plans optimised with RP demonstrate clinically acceptable plan quality, while significantly improving the efficiency of a department, suggesting RP and its application is a highly effective tool in clinical practice.

Multi-atlas-based auto-segmentation for prostatic urethra using novel prediction of deformable image registration accuracy

PURPOSE

Accurate identification of the prostatic urethra and bladder can help determine dosing and evaluate urinary toxicity during intensity-modulated radiation therapy (IMRT) planning in patients with localized prostate cancer. However, it is challenging to locate the prostatic urethra in planning computed tomography (pCT). In the present study, we developed a multiatlas-based auto-segmentation method for prostatic urethra identification using deformable image registration accuracy prediction with machine learning (ML) and assessed its feasibility.

METHODS

We examined 120 patients with prostate cancer treated with IMRT. All patients underwent temporary urinary catheter placement for identification and contouring of the prostatic urethra in pCT images (ground truth). Our method comprises the following three steps: (a) select four atlas datasets from the atlas datasets using the deformable image registration (DIR) accuracy prediction model, (b) deform them by structure-based DIR, (3) and propagate urethra contour using displacement vector field calculated by the DIR. In (a), for identifying suitable datasets, we used the trained support vector machine regression (SVR) model and five feature descriptors (e.g., prostate volume) to increase DIR accuracy. This method was trained/validated using 100 patients and performance was evaluated within an independent test set of 20 patients. Fivefold cross-validation was used to optimize the hype parameters of the DIR accuracy prediction model. We assessed the accuracy of our method by comparing it with those of two others: Acostas method-based patient selection (previous study method, by Acosta et al.), and the Waterman's method (defines the prostatic urethra based on the center of the prostate, by Waterman et al.). We used the centerlines distance (CLD) between the ground truth and the predicted prostatic urethra as the evaluation index.

RESULTS

The CLD in the entire prostatic urethra was 2.09 ± 0.89 mm (our proposed method), 2.77 ± 0.99 mm (Acosta et al., P = 0.022), and 3.47 ± 1.19 mm (Waterman et al., P < 0.001); our proposed method showed the highest accuracy. In segmented CLD, CLD in the top 1/3 segment was highly improved from that of Waterman et.al. and was slightly improved from that of Acosta et.al., with results of 2.49 ± 1.78 mm (our proposed method), 2.95 ± 1.75 mm (Acosta et al., P = 0.42), and 5.76 ± 3.09 mm (Waterman et al., P < 0.001).

CONCLUSIONS

We developed a DIR accuracy prediction model-based multiatlas-based auto-segmentation method for prostatic urethra identification. Our method identified prostatic urethra with mean error of 2.09 mm, likely due to combined effects of SVR model employment in patient selection, modified atlas dataset characteristics and DIR algorithm. Our method has potential utility in prostate cancer IMRT and can replace use of temporary indwelling urinary catheters.

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.

Impact of diabetes on gastrointestinal and urinary toxicity after radiotherapy for gynecologic malignancy

Objective

Although diabetes is a common co-morbidity in patients with gynecologic cancer, information about its impact on radiation toxicity in patients with gynecologic cancer treated with external pelvic irradiation is scarce. We aimed to investigate the relation of diabetes with acute toxicity in patients with gynecologic tumors who underwent pelvic +/- paraaortic radiotherapy.

Materials and Methods

One hundred twenty-nine patients with endometrium or cervix carcinoma were enrolled in the study. Demographic features, presence of diabetes, incidence and severity of upper gastrointestinal (UGIS), lower gastrointestinal (LGIS), and urinary symptoms were recorded from files. Correlation and logistic regression analysis was used to determine the impact of diabetes, age, chemotherapy, paraaortic irradiation on toxicities, and a prediction model was developed.

Results

The median age of 77 patients with endometrium cancer and 52 cervix cancer was 61 (range, 25-92) years, and 28 (21.7%) of them had diabetes. The median pelvic and tumor/tumor bed dose was 5040+247.65 cGy and 5040+222.91 cGy, respectively. Age and Gr 0 UGIS toxicity were significantly related (p=0.047). LGIS Gr 0 toxicity was found to be significantly higher in patients with diabetes (p=0.045). Gr 0 and 2 UGIS toxicities were both found to be significantly correlated with paraaortic irradiation (both p<0.001). Diabetes is also an important determinant on UGIS toxicity in patients who underwent paraaortic irradiation.

Conclusion

The correlation we found between toxicity and diabetes, concurrent chemotherapy or paraaortic radiation necessitates special care and risk stratification for patients with diabetes. Further prospective studies with long follow-up and larger patient groups are warranted.

Pelvic Radiation-Induced Testicular Damage: An Experimental Study at 1 Gray

Therapeutic radiation of the pelvic region has been shown to cause damage to testicular germ cells. In this study we aimed to evaluate the effects of a low therapeutic dose of 1 Gy on the induction of cellular and histological damage in early-stage testicular germ cells and the impact of this radiation on offspring sex ratio. Unirradiated and irradiated male rats were mated with unirradiated female rats. Female rats were followed and the sex of the offspring was determined. The male rats were sacrificed at the end of the second week, and the testicular germ cells were subjected to genetic analysis along with cytological and histopathological examination. Sperm DNA was amplified with primers specific to testis-specific Y-linked protein, rat actin beta and testis-specific X-linked genes. The resulting products were separated by capillary electrophoresis. Histopathological changes were investigated by light microscopy along with the TUNEL assay and immunohistochemical staining for caspase-3. There was no significant difference between the two groups for sex ratio and size of offspring. The number of sperm cells bearing X or Y chromosomes' did not differ significantly between these two groups. However, a 1 Gy dose of radiation caused significant cytopathological and histopathological changes in the testicular tissue. In the irradiated group, edematous regions were evident. The number of caspase-3 positive cells in the germinal epithelium of the seminiferous tubules was also significantly higher in the irradiated group. Our results showed that low-dose radiation induced apoptosis and caused significant cyto- and histopathological changes in the testicular tissue. Further research is required to fully elucidate their contribution to apoptosis and if low-dose radiation may potentially lead to long-term effects in the offspring. These results may also lead us to develop a new technique using the caspase-3 staining to monitor the susceptibility to low dose radiation.

A convolutional neural network approach for IMRT dose distribution prediction in prostate cancer patients

The purpose of the study was to compare a 3D convolutional neural network (CNN) with the conventional machine learning method for predicting intensity-modulated radiation therapy (IMRT) dose distribution using only contours in prostate cancer. In this study, which included 95 IMRT-treated prostate cancer patients with available dose distributions and contours for planning target volume (PTVs) and organs at risk (OARs), a supervised-learning approach was used for training, where the dose for a voxel set in the dataset was defined as the label. The adaptive moment estimation algorithm was employed for optimizing a 3D U-net similar network. Eighty cases were used for the training and validation set in 5-fold cross-validation, and the remaining 15 cases were used as the test set. The predicted dose distributions were compared with the clinical dose distributions, and the model performance was evaluated by comparison with RapidPlan™. Dose-volume histogram (DVH) parameters were calculated for each contour as evaluation indexes. The mean absolute errors (MAE) with one standard deviation (1SD) between the clinical and CNN-predicted doses were 1.10% ± 0.64%, 2.50% ± 1.17%, 2.04% ± 1.40%, and 2.08% ± 1.99% for D2, D98 in PTV-1 and V65 in rectum and V65 in bladder, respectively, whereas the MAEs with 1SD between the clinical and the RapidPlan™-generated doses were 1.01% ± 0.66%, 2.15% ± 1.25%, 5.34% ± 2.13% and 3.04% ± 1.79%, respectively. Our CNN model could predict dose distributions that were superior or comparable with that generated by RapidPlan™, suggesting the potential of CNN in dose distribution prediction.

Technological evolution of radiation treatment: Implications for clinical applications

The contemporary approach to the management of a cancer patient requires an "ab initio" involvement of different medical domains in order to correctly design an individual patient's pathway toward cure. With new therapeutic tools in every medical field developing faster than ever before the patient care outcomes can be achieved if all surgical, drug, and radiation options are considered in the design of the appropriate therapeutic strategy for a given patient. Radiation therapy (RT) is a clinical discipline in which experts from different fields continuously interact in order to manage the multistep process of the radiation treatment. RT is found to be an appropriate intervention for diverse indications in about 50% of cancer patients during the course of their disease. Technologies are essential in dealing with the complexity of RT treatments and for driving the increasingly sophisticated RT approaches becoming available for the treatment of Cancer. High conformal techniques, namely intensity modulated or volumetric modulated arc techniques, ablative techniques (Stereotactic Radiotherapy and Stereotactic Radiosurgery), particle therapy (proton or carbon ion therapy) allow for success in treating irregularly shaped or critically located targets and for the sharpness of the dose fall-off outside the target. The advanced on-board imaging, including real-time position management systems, makes possible image-guided radiation treatment that results in substantial margin reduction and, in select cases, implementation of an adaptive approach. The therapeutic gains of modern RT are also due in part to the enhanced anticancer activity obtained by coadministering RT with chemotherapy, targeted molecules, and currently immune checkpoints inhibitors. These main clinically relevant steps forward in Radiation Oncology represent a change of gear in the field that may have a profound impact on the management of cancer patients.

Can automated treatment plans gain traction in the clinic?

Recently, there has been an increased interest in the feasibility and impact of automation within the field of medical dosimetry. While there have been many commercialized solutions for automatic treatment planning, the use of an application programming interface to achieve complete plan generation for specific treatment sites is a process only recently available for certain commercial vendors. Automatic plan generation for 20 prostate patients was achieved via a stand‐alone automated planning script that accessed a knowledge‐based planning solution. Differences between the auto plans and clinically treated, baseline plans were analyzed and compared. The planning script successfully initialized a treatment plan, accessed the knowledge‐based planning model, optimized the plan, assessed for constraint compliance, and normalized the treatment plan for maximal coverage while meeting constraints. Compared to baseline plans, the auto‐generated plans showed significantly improved rectal sparing with similar coverage for targets and comparable doses to the remaining organs‐at‐risk. Utilization of a script, with its associated time saving and integrated process management, can quickly and automatically generate an acceptable clinical treatment plan for prostate cancer with either improved or similar results compared to a manually created plan.

Penile Reinnervation Surgery: A Comprehensive Review of the Literature

BACKGROUND

Modern approaches to erectile dysfunction (ED) often entail the use of multimodal medical therapy and surgery; however, with recent advances in microsurgery, new options may exist for patients suffering from ED. This comprehensive review of the literature serves to reevaluate anatomical and physiological principles that mediate erection to improve understanding for reconstructive surgeons hoping to offer new interventions.

METHODS

A search strategy for this review was agreed upon by all authors. Articles were divided into 2 categories - primary and secondary. Primary articles were defined as those in which the anatomy of the pelvis and/or perineum was the primary focus of the article, whereas secondary did not directly focus on anatomic considerations. Select historical texts and textbook chapters were also included to provide well established and critical anatomical evidence for this review.

RESULTS

Several approaches may be used to restore nerve function to treat neurogenic and vasculogenic ED. Somatic sensory loss can be treated by either direct neurorrhaphy or neuroplasty in the location of disruption. Microvascular techniques also exist to improve flow or to repair small vessels injured in the pelvis. Classical approaches to impotence include vein stripping to reduce venous outflow or direct vascularization to improve inflow.

CONCLUSIONS

Postradical prostatectomy ED has been demonstrated to improve with microsurgical interventions. In the coming years, innovation will continue and collaboration between plastic surgeons and urologists will allow us to tackle this common and difficult problem.

Dose-Escalated Intensity Modulated Radiation Therapy for Prostate Cancer: 15-Year Outcomes Data

PURPOSE

To report 15-year outcomes for dose-escalated intensity modulated radiation therapy (IMRT) for localized prostate cancer (PC) by evaluating biochemical relapse, distant metastases, cancer-specific survival, and long-term toxicity.

METHODS AND MATERIALS

A database search was conducted for the first cohort of patients treated at this institution with 81 or 86.4 Gy between 1996 and 1998 using IMRT. Toxicity data were scored according to the Common Terminology Criteria for Adverse Events version 3.0. Median follow-up was 11.6 years (range, 5-21 years).

RESULTS

In the study, 301 patients were treated with 81 Gy (n = 269, 89%) or 86.4 Gy (n = 32, 11%). Patients were analyzed by National Comprehensive Cancer Network risk group, with 29% low risk (LR), 49% intermediate risk (IR), and 22% high risk (HR). Late grade 3 gastrointestinal (GI) toxicity was seen in 3 patients (1.0%). No grade 4 GI toxicity events occurred. Median time from radiation therapy to late grade 3 GI toxicity was 2.9 years. One event occurred after 10 years. Late grade 3 and 4 genitourinary (GU) toxicity was seen in 6 (2.0%) and 1 (0.3%) patient, respectively. Median time to late grade 3+ GU toxicity was 5.5 years. Two events occurred after 10 years. In addition, 38 (12.6%) developed second primary malignancies (SPMs), 8 of which were in-field malignancies. Median time from radiation therapy to all SPM and in-field SPM was 10 years. The 15-year relapse-free survival was 76%, 65%, and 55% in the LR, IR, and HR groups, respectively. Distant metastases-free survival was 88%, 75%, and 63% for LR, IR, and HR patients, respectively. PC-specific mortality was 1.9%, 7.1%, and 12.2% for LR, IR, and HR patients.

CONCLUSIONS

This report represents the longest follow-up data set to our knowledge of patients treated with high-dose IMRT for PC. Our findings indicate that it is well tolerated with 1.0% and 2.3% incidence of long-term grade 3+ GI and GU toxicity, respectively. The cohort had excellent PC-specific survival.

Incidence and Morbidity of Radiation-Induced Hemorrhagic Cystitis in Prostate Cancer

OBJECTIVE

To determine if reported incidence rates of hemorrhagic cystitis after radiation therapy for prostate cancer are accurate, to investigate the effect of different radiation modalities on the development of hemorrhagic cystitis and to assess its morbidity and treatment.

MATERIALS AND METHODS

A retrospective chart review was completed of 709 patients at 2 Detroit Medical Center hospitals who underwent radiation therapy for prostate cancer between January 2000 and September 2015. In patients who developed hemorrhagic cystitis, we analyzed the incidence, radiation modality, morbidity, treatment, and complications.

RESULTS

The incidence rate of hemorrhagic cystitis after radiation for prostate cancer was 11.1%. There was no significant difference between external beam and intensity-modulated radiation therapy and the development of hemorrhagic cystitis (P = .18). Patients developed hemorrhagic cystitis an average of 79.1 months (4-230 months) after radiation. The average number of admissions was 2.5 (1-9) with an average length of stay of 7.6 days (1-42 days). Fifty-two percent of patients required blood transfusion with an average of 4.3 units transfused per patient (1-33U). The most common treatment was cystoscopy with fulguration/clot evacuation in 86% of patients. Complications included urinary tract infection, acute kidney injury, urosepsis, and even death.

CONCLUSION

The incidence of hemorrhagic cystitis following radiation therapy for prostate cancer is under-reported in the literature. Hemorrhagic cystitis is associated with high morbidity and complications for patients, requiring multiple hospitalizations, blood transfusions, and procedures. Advances in radiation have not significantly reduced the risk of developing hemorrhagic cystitis.

Late rectal bleeding after volumetric-modulated arc therapy for localised prostatic cancer

Aim

Late adverse effects following radiation therapy for prostate cancer involve the urinary and lower gastrointestinal tracts, with continuous rectal bleeding being the most serious issue. We focused on late adverse effects, particularly rectal bleeding after volumetric-modulated arc therapy (VMAT), for patients with locally advanced prostate cancer.

Materials and Methods

Seventy-three patients with localized prostate cancer were treated with radiation therapy using VMAT with an image-guided radiation therapy system. Patient age at the start of irradiation ranged from 54 to 81 years (median, 71 years). The follow-up period ranged from 23 to 87 months (median, 57 months). The prescribed total irradiation dose was 76 Gy in 38 fractions.

Results

Late rectal bleeding was observed in 14 (19%) patients, with nine (12.3%), four (5.5%), and one (1.4%) being classified as grades 1, 2, and 3, respectively. One grade 3 patient with rectal bleeding had severe diabetes and was administered intravenous warfarin for cardiomyopathy.

Findings

VMAT may provide better accuracy and involve fewer time constraints for patients compared with other intensity-modulated radiation therapy (IMRT) methods. The incidence of late rectal bleeding in VMAT is almost equivalent to that of other IMRT methods.

Interfraction variation and dosimetric changes during image-guided radiation therapy in prostate cancer patients

Purpose

The aim of this study was to identify volume changes and dose variations of rectum and bladder during radiation therapy in prostate cancer (PC) patients.

Materials and Methods

We analyzed 20 patients with PC treated with helical tomotherapy. Daily image guidance was performed. We re-contoured the entire bladder and rectum including its contents as well as the organ walls on megavoltage computed tomography once a week. Dose variations were analyzed by means of Dmedian, Dmean, Dmax, V₁₀ to V₇₅, as well as the organs at risk (OAR) volume. Further, we investigated the correlation between volume changes and changes in Dmean of OAR.

Results

During treatment, the rectal volume ranged from 62% to 223% of its initial volume, the bladder volume from 22% to 375%. The average Dmean ranged from 87% to 118% for the rectum and 58% to 160% for the bladder. The Pearson correlation coefficients between volume changes and corresponding changes in Dmean were -0.82 for the bladder and 0.52 for the rectum. The comparison of the dose wall histogram (DWH) and the dose volume histogram (DVH) showed that the DVH underestimates the percentage of the rectal and bladder volume exposed to the high dose region.

Conclusion

Relevant variations in the volume of OAR and corresponding dose variations can be observed. For the bladder, an increase in the volume generally leads to lower doses; for the rectum, the correlation is weaker. Having demonstrated remarkable differences in the dose distribution of the DWH and the DVH, the use of DWHs should be considered.

MRI Radiomic Analysis of IMRT-Induced Bladder Wall Changes in Prostate Cancer Patients: A Relationship with Radiation Dose and Toxicity

BACKGROUND

The main purpose of this study was to assess the structural changes in the bladder wall of prostate cancer patients treated with intensity-modulated radiation therapy using magnetic resonance imaging texture features analysis and to correlate image texture changes with radiation dose and urinary toxicity.

METHODS

Ethical clearance was granted to enroll 33 patients into this study who were treated with intensity-modulated radiation therapy for prostate cancer. All patients underwent two magnetic resonance imagings before and after radiation therapy (RT). A total of 274 radiomic features were extracted from MR-T2W-weighted images. Wilcoxon singed rank-test was performed to assess significance of the change in mean radiomic features post-RT relative to pre-RT values. The relationship between radiation dose and feature changes was assessed and depicted. Cystitis was recorded as urinary toxicity. Area under receiver operating characteristic curve of a logistic regression-based classifier was used to find correlation between radiomic features with significant changes and radiation toxicity.

RESULTS

Thirty-three bladder walls were analyzed, with 11 patients developing grade ≥2 urinary toxicity. We showed that radiomic features may predict radiation toxicity and features including S5.0SumVarnc, S2.2SumVarnc, S1.0AngScMom, S0.4SumAverg, and S5. _5InvDfMom with area under receiver operating characteristic curve 0.75, 0.69, 0.65, 0.63, and 0.62 had highest correlation with toxicity, respectively. The results showed that most of the radiomic features were changed with radiation dose.

CONCLUSION

Feature changes have a good correlation with radiation dose and radiation-induced urinary toxicity. These radiomic features can be identified as being potentially important imaging biomarkers and also assessing mechanisms of radiation-induced bladder injuries.

Brachytherapy: A critical component of primary radiation therapy for cervical cancer: From the Society of Gynecologic Oncology (SGO) and the American Brachytherapy Society (ABS)

Brachytherapy is well-established as an integral component in the standard of care for treatment of patients receiving primary radiotherapy for cervical cancer. A decline in brachytherapy has been associated with negative impacts on survival in the era of modern EBRT techniques. Conformal external beam therapies such intensity modulated radiation therapy (IMRT) or stereotactic body radiation therapy (SBRT) should not be used as alternatives to brachytherapy in patients undergoing primary curative-intent radiation therapy for cervical cancer. Computed tomography or magnetic resonance image-guided adaptive brachytherapy is evolving as the preferred brachytherapy method. With careful care coordination EBRT and brachytherapy can be successfully delivered at different treatment centers without compromising treatment time and outcome in areas where access to brachytherapy maybe limited.

A Phase 1 Pilot Study of Preoperative Radiation Therapy for Prostate Cancer: Long-Term Toxicity and Oncologic Outcomes

PURPOSE

Neoadjuvant radiation therapy (RT) improves disease control in various cancers and has become an established oncologic treatment strategy. During 2001 to 2004, we conducted a phase 1 pilot study assessing the role of short-course preoperative RT (PreORT) for men with unfavorable intermediate- and high-risk localized prostate cancer. Herein, we present long-term follow-up toxicity and oncologic outcomes.

METHODS AND MATERIALS

Eligible patients had histologically proven prostate cancer, cT1-T2N0M0 disease, prostate-specific antigen >15 to 35 ng/mL regardless of Gleason score, or prostate-specific antigen 10 to 15 ng/mL with Gleason score ≥7. Patients received 25 Gy in 5 consecutive daily fractions (5 Gy per fraction) to the prostate only, followed by radical prostatectomy within 14 days after RT completion. Primary outcomes were intraoperative morbidity and late genitourinary (GU) and gastrointestinal toxicities.

RESULTS

In total, 15 patients were enrolled; 14 patients completed PreORT followed by radical prostatectomy, which also included bilateral lymph node dissections in 13 cases. Median follow-up was 12.2 years (range, 6.7-16.3). Late GU toxicity was common, with 2 patients (13.3%) experiencing G2 toxicity and 6 patients (40%) G3 toxicity. There were no patients with G4 to G5 late GU toxicity. Late gastrointestinal toxicity was infrequent, with only 1 patient (6.7%) experiencing transient G2 proctitis. At last follow-up, 8 (53.3%) and 6 (40%) patients experienced biochemical and metastatic disease recurrence, respectively.

CONCLUSIONS

The use of PreORT in men with high-risk prostate cancer is associated with unexpected high rates of late GU toxicity. Future studies examining the role of RT preradical prostatectomy must cautiously select RT technique and dose schedule. Importantly, long-term follow-up data are essential to fully determine the therapeutic index of PreORT in the management of localized disease.

A Literature Review of Proton Beam Therapy for Prostate Cancer in Japan

Aim: Patients of proton beam therapy (PBT) for prostate cancer had been continuously growing in number due to its promising characteristics of high dose distribution in the tumor target and a sharp distal fall-off. Considering the large number of proton beam facilities in Japan, the further increase of patients undergoing this treatment is due to the emendations by Japanese National Health Insurance (NHI) and the development of medical equipment and technology, it is necessary to know what kind of research and advancements has been done on proton therapy for prostate cancer in the country. For these reasons, this literature review was conducted. The aim of this review is to identify and discuss research studies of proton beam therapy for prostate cancer in Japan. These include observational, interventional, and secondary data analysis of published articles. Method: A literature review on published works related to proton beam therapy for prostate cancer in Japan was conducted using articles that were gathered in the PubMed database of June 2018. We went through abstracts and manuscripts written in English with the keywords ‘proton beam therapy’, ‘prostate cancer’, and ‘Japan’. Results: A total of 23 articles were included. Fourteen articles were observational studies, most of which focused on the adverse effects of Proton Beam Therapy (PBT). Seven articles were interventional studies related on treatment planning, equipment parts, as well as target positioning. Two were secondary data analysis. The included studies were published in 13 different journals by different institutions using various equipment. Conclusion: Despite the favorable results of proton beam therapy, future research should include more patients and longer follow-up schedules to clarify the definitive role of PBT, yet, up to recent retrospective studies, included in this paper, concluded that PBT can be a suitable treatment option for localized prostate cancer. In addition, interventional studies were conducted by several institutions to further embellish proton therapy.

Machine learning-based radiomic models to predict intensity-modulated radiation therapy response, Gleason score and stage in prostate cancer

OBJECTIVE

To develop different radiomic models based on the magnetic resonance imaging (MRI) radiomic features and machine learning methods to predict early intensity-modulated radiation therapy (IMRT) response, Gleason scores (GS) and prostate cancer (Pca) stages.

METHODS

Thirty-three Pca patients were included. All patients underwent pre- and post-IMRT T2-weighted (T2 W) and apparent diffusing coefficient (ADC) MRI. IMRT response was calculated in terms of changes in the ADC value, and patients were divided as responders and non-responders. A wide range of radiomic features from different feature sets were extracted from all T2 W and ADC images. Univariate radiomic analysis was performed to find highly correlated radiomic features with IMRT response, and a paired t test was used to find significant features between responders and non-responders. To find high predictive radiomic models, tenfold cross-validation as the criterion for feature selection and classification was applied on the pre-, post- and delta IMRT radiomic features, and area under the curve (AUC) of receiver operating characteristics was calculated as model performance value.

RESULTS

Of 33 patients, 15 patients (45%) were found as responders. Univariate analysis showed 20 highly correlated radiomic features with IMRT response (20 ADC and 20 T2). Two and fifteen T2 and ADC radiomic features were found as significant (P-value ≤ 0.05) features between responders and non-responders, respectively. Several cross-combined predictive radiomic models were obtained, and post-T2 radiomic models were found as high predictive models (AUC 0.632) followed by pre-ADC (AUC 0.626) and pre-T2 (AUC 0.61). For GS prediction, T2 W radiomic models were found as more predictive (mean AUC 0.739) rather than ADC models (mean AUC 0.70), while for stage prediction, ADC models had higher prediction performance (mean AUC 0.675).

CONCLUSIONS

Radiomic models developed by MR image features and machine learning approaches are noninvasive and easy methods for personalized prostate cancer diagnosis and therapy.

Management of radiation-induced proctitis

The occurrence of chronic proctitis as a side effect among radiotherapy patients is about 5%. Radiation proctitis and consequent development of chronic proctitis are not associated to each other. However, a lot of samples of proctitis that are limited easily could be treated by typical remedial techniques. Improvements in radiotherapy techniques that make possible the delivery of superior doses of radiation could easily reduce both chronic and acute proctitis. The step-by-step remedial procedure for treatment of this disorder starts with conservative remedial management and includes iron substitution as a second-line therapy. For patients who did not receive initial therapies, sucralfate injection, topical corticosteroids, and antidiarrhea therapy were provided as a means of aggressive care. In cases of continuous rectal bleeding, remedial laser techniques and formaldehyde administration should be attempted before surgical therapy. When surgical therapy is required, a descending or transverse colostomy must be carried out. Advanced methods such as intraperitoneal injections of formalin or novel methods of cold therapy and radiofrequency ablation (RFA) provide a wider remedial field. Exceptionally, unanticipated conclusion of neosquamous wound healing via RFA may have additional preponderances in stopping symptoms and may require better assessment through accurate randomized examination. Since aggressive treatments like coloanal anastomosis and colorectal surgery are correlated with remarkable mortality and morbidity, they must be considered as the final course of remedial treatment.

Dosimetric comparison between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma

Background

This work aims to compare the dosimetric performance of three-dimensional conformal radiotherapy (3D-CRT), a relatively available technique in developing countries, to intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma (NPC).

Materials and Methods

According to the diagnostic stages, 40 NPC patients were divided into two equal groups. Three planning techniques such as 3D-CRT, seven-field IMRT (7F-IMRT) and nine-field IMRT (9F-IMRT) were compared. Dose prescriptions of 70 and 66 Gy were delivered in 35 fractions to gross planning target volume (PTV1) and bilateral retropharyngeal carcinoma (PTV2), respectively.

Results

Stage I dose data for almost all of the three investigated planning techniques obey the international recommendations. The dose delivered to PTV1 and PTV2 for 3D-CRT and 7F-IMRT are statistically similar, whereas 9F-IMRT is significantly better than 3D-CRT. For organs at risk (OARs), the delivered dose is significantly better for 9F-IMRT compared with the other two techniques, whereas 7F-IMRT is significantly better than 3D-CRT.

Conclusions

3D-CRT is an acceptable alternative treatment technique for stage I NPC patients in developing countries suffering from the lack of advanced radiotherapy treatment techniques. 3D-CRT and 7F-IMRT have comparable performance in PTVs, while 9F-IMRT is superior in PTVs and OARs.

Evaluating the potential benefit of reduced planning target volume margins for low and intermediate risk patients with prostate cancer using real-time electromagnetic tracking

Purpose

The aim of this study is to quantify and describe the feasibility, clinical outcomes, and patient-reported outcomes of reduced planning target volume (PTV) margins for prostate cancer treatment using real-time, continuous, intrafraction monitoring with implanted radiation frequency transponder beacons.

Methods and materials

For this prospective, nonrandomized trial, the Calypso localization system was used for intrafraction target localization in 31 patients with a PTV margin reduced to 2 mm in all directions. A total of 1333 fractions were analyzed with respect to movement of the prostate, pauses and interruptions, and dosimetric data. Pre- and posttreatment quality-of-life scores were tracked at baseline, during treatment, and up to 24 months after treatment.

Results

The mean time of daily treatment was 10 minutes, with 96.1% of all treatments falling within a 20-minute treatment window standard. On average, beacon motion exceeded 3 mm during active treatment only 1.76% of the time. The average length of treatment interruption was 34.2 seconds, with an average of 1 interruption every 3.39 fractions. The displacement or excursion of the prostate was the greatest in the superior or inferior dimension (0.11 mm and 0.09 mm, respectively) and anterior or posterior dimension (0.07 mm and 0.13 mm, respectively), followed by the left or right dimension (0.05 mm and 0.06 mm, respectively). At 6 months, patients demonstrated a smaller change in Expanded Prostate Cancer Index Composite scores than the ProtecT comparator group (decreased short-term morbidity). However, in the Bowel and Urinary domains at 12 and 24 months, there was no significant difference.

Conclusions

Our data confirm and support that the use of Calypso tracking with intensity modulated radiation therapy reliably provides minimal disruption to daily treatments and overall time of treatment, with the PTV only moving outside of a 3-mm margin < 2% of the time. The use of a 3-mm PTV margin provides adequate dosimetric coverage while minimizing genitourinary and gastrointestinal toxicity.

Dosimetric predictors for acute esophagitis during radiation therapy for lung cancer: Results of a large statewide observational study

PURPOSE

The purpose of this study is to identify dosimetric variables that best predict for acute esophagitis in patients treated for locally advanced non-small cell lung cancer in a prospectively accrued statewide consortium.

METHODS AND MATERIALS

Patients receiving definitive radiation therapy for stage II-III non-small cell lung cancer within the Michigan Radiation Oncology Quality Consortium were included in the analysis. Dose-volume histogram data were analyzed to determine absolute volumes (cc) receiving doses from 10 to 60 Gy (V10, V20, V30, V40, V50, and V60), as well as maximum dose to 2 cc (D2cc), mean dose (MD), and generalized equivalent uniform dose (gEUD). Logistic regression models were used to characterize the risk of toxicity as a function of dose and other covariates. The ability of each variable to predict esophagitis, individually or in a multivariate model, was quantified by receiver operating characteristic analysis.

RESULTS

There were 533 patients who met study criteria and were included; 437 (81.9%) developed any grade of esophagitis. Significant variables on univariate analysis for grade ≥2 esophagitis were concurrent chemotherapy, V20, V30, V40, V50, V60, MD, D2cc, and gEUD. For grade ≥3 esophagitis, the predictive variables were: V30, V40, V50, V60, MD, D2cc, and gEUD. In multivariable modeling, gEUD was the most significant predictor of both grade ≥2 and grade ≥3 esophagitis. When gEUD was excluded from the model, D2cc was selected as the most predictive variable for grade ≥3 esophagitis. For an estimated risk of grade ≥3 esophagitis of 5%, the threshold values for gEUD and D2cc were 59.3 Gy and 68 Gy, respectively.

CONCLUSIONS

In this study, we report the novel finding that gEUD and D2cc, rather than MD, were the most predictive dose metrics for severe esophagitis. To limit the estimated risk of grade ≥3 esophagitis to <5%, thresholds of 59.3 Gy and 68 Gy were identified for gEUD and D2cc, respectively.

Androgen Ablation Therapy Does not Increase the Risk of Late Morbidity following 3D-conformal Radiotherapy of Organ-confined Prostate Cancer: The Experience of the European Institute of Oncology

Aims and Background

Androgen ablation therapy in conjunction with radiotherapy-neoadjuvant and adjuvant – has consistently been shown to be associated with improved biochemical and local control, whereas controversy still remains as regards its benefit in terms of overall survival. The objective of this study is to determine the impact of androgen ablation in combination to 3D-conformal radiotherapy on late treatment-related toxicity.

Methods

236 patients were treated with 3D-conformal radiotherapy to a total dose ranging from 70 and 78.6 Gy. Fifty-six patients did not receive any form of androgen ablation whereas 176 were given at least 3 months of neoadjuvant androgen ablation. Of these, 64 stayed on androgen ablation for a median time of 6 months post-radiotherapy. Acute toxicity was evaluated weekly during the course of treatment. Late toxicity was assessed at 3-months intervals during the follow-up. Toxicity was scored according to the RTOG criteria.

Results

The median follow-up was 24.6 months (range, 12-62). The incidence of late genitourinary toxicity was: 3% G2, 3.5% G3, 0.5% G4. The incidence of late gastrointestinal toxicity was: 12% G2, 2% G3, 1% G4. No association was observed between the use of androgen ablation and late treatment-related toxicity. High-risk patients who continued on androgen ablation long-term were not found to have an increased risk of developing late toxicity with respect to those who never had any form of androgen ablation or those only treated neoadjuvantly.

Conclusions

In our experience, the use of androgen ablation does not impact on late toxicity following high dose 3D-conformal radiotherapy for prostate cancer.

Inter-institutional analysis demonstrates the importance of lower than previously anticipated dose regions to prevent late rectal bleeding following prostate radiotherapy

PURPOSE

To investigate whether inter-institutional cohort analysis uncovers more reliable dose-response relationships exemplified for late rectal bleeding (LRB) following prostate radiotherapy.

MATERIAL AND METHODS

Data from five institutions were used. Rectal dose-volume histograms (DVHs) for 989 patients treated with 3DCRT or IMRT to 70-86.4 Gy@1.8-2.0 Gy/fraction were obtained, and corrected for fractionation effects (α/β = 3 Gy). Cohorts with best-fit Lyman-Kutcher-Burman volume-effect parameter a were pooled after calibration adjustments of the available LRB definitions. In the pooled cohort, dose-response modeling (incorporating rectal dose and geometry, and patient characteristics) was conducted on a training cohort (70%) followed by final testing on the remaining 30%. Multivariate logistic regression was performed to build models with bootstrap stability.

RESULTS

Two cohorts with low bleeding rates (2%) were judged to be inconsistent with the remaining data, and were excluded. In the remaining pooled cohorts (n = 690; LRB rate = 12%), an optimal model was generated for 3DCRT using the minimum rectal dose and the absolute rectal volume receiving less than 55 Gy (AUC = 0.67; p = 0.0002; Hosmer-Lemeshow p-value, pHL = 0.59). The model performed nearly as well in the hold-out testing data (AUC = 0.71; p < 0.0001; pHL = 0.63), indicating a logistically shaped dose-response.

CONCLUSION

We have demonstrated the importance of integrating datasets from multiple institutions, thereby reducing the impact of intra-institutional dose-volume parameters explicitly correlated with prescription dose levels. This uncovered an unexpected emphasis on sparing of the low to intermediate rectal dose range in the etiology of late rectal bleeding following prostate radiotherapy.

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.

Minimal toxicity after proton beam therapy for prostate and pelvic nodal irradiation: results from the proton collaborative group REG001-09 trial

BACKGROUND

Proton beam therapy (PBT) reduces normal organ dose compared to intensity modulated radiation therapy (IMXT) for prostate cancer patients who receive pelvic radiation therapy. It is not known whether this dosimetric advantage results in less gastrointestinal (GI) and genitourinary (GU) toxicity than would be expected from IMXT.

MATERIAL AND METHODS

We evaluated treatment parameters and toxicity outcomes for non-metastatic prostate cancer patients who received pelvic radiation therapy and enrolled on the PCG REG001-09 trial. Patients who received X-ray therapy and/or brachytherapy were excluded. Of 3210 total enrolled prostate cancer patients, 85 received prostate and pelvic radiation therapy exclusively with PBT. Most had clinically and radiographically negative lymph nodes although 6 had pelvic nodal disease and one also had para-aortic involvement. Pelvic radiation therapy was delivered using either 2 fields (opposed laterals) or 3 fields (opposed laterals and a posterior beam). Median pelvic dose was 46.9 GyE (range 39.7-56) in 25 fractions (range 24-30). Median boost dose to the prostate +/- seminal vesicles was 30 GyE (range 20-41.4) in 16 fractions (range 10-24).

RESULTS

Median follow-up was 14.5 months (range 2.8-49.2). Acute grade 1, 2, and 3 GI toxicity rates were 16.4, 2.4, 0%, respectively. Acute grade 1, 2, and 3 GU toxicity rates were 60, 34.1, 0%, respectively.

CONCLUSIONS

Prostate cancer patients who receive pelvic radiation therapy using PBT experience significantly less acute GI toxicity than is expected using IMXT. Further investigation is warranted to confirm whether this favorable acute GI toxicity profile is related to small bowel sparing from PBT.