Comparative Toxicities and Cost of Intensity-Modulated Radiotherapy, Proton Radiation, and Stereotactic Body Radiotherapy Among Younger Men With Prostate Cancer

Bowel Disorder Incidence and Rectal Spacer Use in Patients With Prostate Cancer Undergoing Radiotherapy

Importance

The polyethylene glycol-based hydrogel spacer (PHS) system temporarily separates the rectum from the prostate in patients undergoing radiotherapy (RT) for prostate cancer (PCa).

Objective

To compare incidence of bowel disorders and related procedures in patients receiving RT with and without PHS.

Design, Setting, and Participants

This retrospective cohort study used 4 datasets: Medicare 5% Standard Analytic Files, Medicare 100% Standard Analytic Files, Merative MarketScan Commercial Database, and Premier Healthcare Database. Participants included adult patients with PCa undergoing RT from 2015 to 2021.

Exposure

Placement of PHS.

Main Outcomes

All-cause bowel disorders and related procedures, identified from diagnosis and procedure codes. Results were compared with age-matched male general population without PCa or RT.

Results

Of 261 906 patients with PCa included in the study, 25 167 (9.6%) received PHS (mean [SD] age, 70.7 [6.5] years) and 236 739 did not (mean [SD] age, 71.1 [7.5] years). One year prior to RT, patients who received PHS had a lower mean (SD) Charlson Comorbidity Index score than those who did not (2.48 [1.08] vs 3.14 [1.95]; P < .001). Stereotactic RT was more common in patients who received PHS (2743 [10.9%] vs 8810 [3.7%]; P < .001), while intensity-modulated RT was less common (12 755 [50.7%] vs 142 402 [60.2%]; P < .001). After 4 years post RT, patients who received PHS had a 25% lower hazard of bowel disorders (hazard ratio [HR], 0.75 [95% CI, 0.72-0.78]; P < .001) and a 46% lower hazard of related procedures (HR, 0.54 [95% CI, 0.47-0.62]; P < .001) than patients who did not receive PHS. Patients without PHS had higher hazard compared with an age-matched general population (disorders: 17.1% [95% CI, 17.3%-17.6%] vs 10.3% [95% CI, 10.1%-10.5%]; HR, 1.35 [95% CI, 1.32-1.37]; P < .001; procedures: 2.0% [95% CI, 1.9%-2.1%] vs 0.7% [95% CI, 0.7%-0.8%]; HR, 1.92 [95% CI, 1.79-2.06]; P < .001), while patients who received PHS did not (disorders: 12.4% vs 10.3%; HR, 1.00 [95% CI, 0.98-1.05]; P = .82; procedures: 1.1% [95% CI, 1.0%-1.3%] vs 0.7% [95% CI, 0.7%-0.8%]; HR, 1.11 [95% CI, 0.96-1.29]; P = .15). Common procedures included colonoscopy, sigmoidoscopy, and rectal resection.

Conclusions and Relevance

In this cohort study of patients with PCa receiving RT, those receiving a PHS had a significantly lower incidence of all-cause bowel disorders and related procedures compared with patients who did not receive a PHS over the 4-year follow-up. The incidence among patients with PHS was similar to the general population. These findings are consistent with prior phase 3 trial results, where patients receiving PHS experienced no decline in bowel quality of life.

Safety and early outcomes of proton therapy and low-dose rate brachytherapy boost for patients with prostate cancer

PURPOSE

Brachytherapy boost improves biochemical control for patients with prostate cancer. Here, we report the safety and early efficacy of proton therapy (PT) with a low-dose-rate (LDR) brachytherapy boost.

METHODS

This retrospective study included patients with intermediate- or high-risk prostate cancer treated with PT followed by LDR boost, with or without androgen deprivation therapy (ADT), from 2010 through 2023. Patient, disease, and treatment characteristics, gastrointestinal (GI) and genitourinary (GU) toxicity, and efficacy outcomes are reported.

RESULTS

Ninety-nine patients received PT and LDR boost; median age at diagnosis was 68 years (interquartile range [IQR] 61-72). Most patients (n = 77) were White, 12 were African American, 5 Asian, and 3 Hispanic. Thirty-five patients had intermediate-risk (4 favorable and 31 unfavorable), 56 had high-risk, and 8 had very high-risk disease. Median PT dose was 44 Gy(RBE) (range 40-50.4) and median LDR dose was 90Gy (range 90-110). Pd-103 seed strands were used for 95 patients and I-125 for 4; 90 had MRI-assisted radiosurgery brachytherapy; 91 received ADT; and 21 had a rectal spacer. At a median follow-up time of 45 months, 5-year biochemical recurrence-free survival was 98%. There was no local recurrence, distant metastasis, or cancer death. Four patients had acute urinary retention after brachytherapy procedure. Eleven patients (11%) had late grade 2 GU toxicity, and 3 (3%) had late grade 2 GI toxicity. One patient had grade 3 urethral stricture requiring dilatation and transurethral resection.

CONCLUSIONS

At 45 months' follow-up time, treatment with PT and LDR boost led to high control rates and low toxicity for men with prostate cancer.

Health Disparities and Inequities in the Utilization of Proton Therapy for Prostate Cancer

Our study sought to review and summarize the reported health disparities and inequities in the utilization of proton beam therapy (PBT) for prostate cancer. We queried the PubMed search engine through 12/2023 for original publications examining disparate utilization of PBT for prostate cancer. The query terms included the following: prostate cancer AND proton AND (disparities OR IMRT OR race OR insurance OR socioeconomic OR inequities)". Studies were included if they involved United States patients, examined PBT in prostate cancer, and addressed health inequities. From this query, 22 studies met the inclusion criteria, comprising 13 population-based analyses, 5 single-institutional analyses, 3 cost/modeling investigations, and 1 survey-based study. The analyses revealed that in addition to age-related and insurance-related disparities, race and socioeconomic status played significant roles in the receipt of PBT. The likelihood of receiving PBT was lower for non-White patients in population-based and single-institution analyses. Socioeconomic metrics, such as higher median income and higher education level, portended an increased likelihood of receiving PBT. Conclusively, substantial age-based, racial, socioeconomic/insurance-related, and facility-associated disparities and inequities existed for PBT utilization in prostate cancer. The identification of these disparities provides a framework to better address these as the utility of PBT continues to expand across the US and globally.

Impact of Rectal Spacer on Toxicity Reduction in Men Treated With Proton Versus Photon Therapy

Purpose

Rectal toxicity after prostate cancer (PCa) radiation therapy (RT) may be greater with protons compared with photon intensity-modulated RT, perhaps due to lateral penumbra and end-of-range uncertainty. Rectal spacers (RSs) have been shown to mitigate RT-associated acute/late rectal toxicity in men treated with photons. The relative benefit of RS in men treated with protons versus photons is unknown. We hypothesize that RS will confer greater bowel toxicity benefits in PCa treated with protons versus photons.

Materials and Methods

We conducted a single institution, retrospective review of men receiving photon intensity-modulated RT or pencil-beam scanning proton RT for localized PCa. Four cohorts were compared: photon with or without RS, and proton with or without RS. Acute (<3 months), late (≥3 months), and most recent toxicity were compared among the 4 cohorts. The cumulative incidence of physician-reported grade 1 to 2 gastrointestinal (GI) toxicity (common terminology criteria for adverse events V5.0) was compared using χ2 or Fisher exact test. Patient-reported toxicity was evaluated using the International Prostate Expanded Prostate Composite Index-Clinical Practice and compared using linear mixed modeling.

Results

In total, 164 patients were eligible for analysis: 38 photons without RS, 50 photons with RS, 26 protons without RS, and 50 protons with RS. The median follow-up was 17.6 months. In proton patients, acute (6.12% vs 30.77%, P = .009) and most recent (4.26% vs 26.09%, P = .01) G1-2 GI toxicity was lower with versus without RS. In photon patients, there were no significant differences in toxicity with versus without RS. No significant differences in patient-reported outcomes were observed with versus without RS in photon or proton groups.

Conclusion

The rectal spacer was associated with lower G1-2 acute and most recent GI toxicity in men treated with protons; this difference was not observed in men treated with photons. While this study is limited by sample size, a relatively greater benefit of RS with proton versus photon therapy was observed.

A Historical Survey of Key Epidemiological Studies of Ionizing Radiation Exposure

In this article we review the history of key epidemiological studies of populations exposed to ionizing radiation. We highlight historical and recent findings regarding radiation-associated risks for incidence and mortality of cancer and non-cancer outcomes with emphasis on study design and methods of exposure assessment and dose estimation along with brief consideration of sources of bias for a few of the more important studies. We examine the findings from the epidemiological studies of the Japanese atomic bomb survivors, persons exposed to radiation for diagnostic or therapeutic purposes, those exposed to environmental sources including Chornobyl and other reactor accidents, and occupationally exposed cohorts. We also summarize results of pooled studies. These summaries are necessarily brief, but we provide references to more detailed information. We discuss possible future directions of study, to include assessment of susceptible populations, and possible new populations, data sources, study designs and methods of analysis.

Intrafractional motion and dosimetric analysis in prostate stereotactic body radiation therapy with auto beam hold technique

Objective: To summarize our institutional prostate stereotactic body radiation therapy (SBRT) experience using auto beam hold (ABH) technique for intrafractional prostate motion and assess ABH tolerance of 10-millimeter (mm) diameter.Approach: Thirty-two patients (160 fractions) treated using ABH technique between 01/2018 and 03/2021 were analyzed. During treatment, kV images were acquired every 20-degree gantry rotation to visualize 3-4 gold fiducials within prostate to track target motion. If the fiducial center fell outside the tolerance circle (diameter = 10 mm), beam was automatically turned off for reimaging and repositioning. Number of beam holds and couch translational movement magnitudes were recorded. Dosimetric differences from intrafractional motion were calculated by shifting planned isocenter.Main Results: Couch movement magnitude (mean ± SD) in vertical, longitudinal and lateral directions were -0.7 ± 2.5, 1.4 ± 2.9 and -0.1 ± 0.9 mm, respectively. For most fractions (77.5%), no correction was necessary. Number of fractions requiring one, two, or three corrections were 15.6%, 5.6% and 1.3%, respectively. Of the 49 corrections, couch shifts greater than 3 mm were seen primarily in the vertical (31%) and longitudinal (39%) directions; corresponding couch shifts greater than 5 mm occurred in 2% and 6% of cases. Dosimetrically, 100% coverage decreased less than 2% for clinical target volume (CTV) (-1 ± 2%) and less than 10% for PTV (-10 ± 6%). Dose to bladder, bowel and urethra tended to increase (Bladder: ΔD10%:184 ± 466 cGy, ΔD40%:139 ± 241 cGy, Bowel: ΔD1 cm3:54 ± 129 cGy; ΔD5 cm3:44 ± 116 cGy, Urethra: ΔD0.03 cm3:1 ± 1%). Doses to the rectum tended to decrease (Rectum: ΔD1 cm3:-206 ± 564 cGy, ΔD10%:-97 ± 426 cGy; ΔD20%:-50 ± 251 cGy).Significance: With the transition from conventionally fractionated intensity modulated radiation therapy to SBRT for localized prostate cancer treatment, it is imperative to ensure that dose delivery is spatially accurate for appropriate coverage to target volumes and limiting dose to surrounding organs. Intrafractional motion monitoring can be achieved using triggered imaging to image fiducial markers and ABH to allow for reimaging and repositioning for excessive motion.

Sexual Structure Sparing for Prostate Cancer Radiotherapy: A Systematic Review

CONTEXT

Erectile dysfunction represents a major side effect of prostate cancer (PCa) treatment, negatively impacting men's quality of life. While radiation therapy (RT) advances have enabled the mitigation of both genitourinary and gastrointestinal toxicities, no significant improvement has been showed in sexual quality of life over time.

OBJECTIVE

The primary aim of this review was to assess sexual structures' dose-volume parameters associated with the onset of erectile dysfunction.

EVIDENCE ACQUISITION

We searched the PubMed database and ClinicalTrials.gov until January 4, 2023. Studies reporting the impact of the dose delivered to sexual structures on sexual function or the feasibility of innovative sexual structure-sparing approaches were deemed eligible.

EVIDENCE SYNTHESIS

Sexual-sparing strategies have involved four sexual organs. The mean penile bulb doses exceeding 20 Gy are predictive of erectile dysfunction in modern PCa RT trial. Maintaining a D100% of ≤36 Gy on the internal pudendal arteries showed preservation of erectile function in 88% of patients at 5 yr. Neurovascular bundle sparing appears feasible with magnetic resonance-guided radiation therapy, yet its clinical impact remains unanswered. Doses delivered to the testicles during PCa RT usually remain <2 Gy and generate a decrease in testosterone levels ranging from -4.6% to -17%, unlikely to have any clinical impact.

CONCLUSIONS

Current data highlight the technical feasibility of sexual sparing for PCa RT. The proportion of erectile dysfunction attributable to the dose delivered to sexual structures is still largely unknown. While the ability to maintain sexual function over time is impacted by factors such as age or comorbidities, only selected patients are likely to benefit from sexual-sparing RT.

PATIENT SUMMARY

Technical advances in radiation therapy (RT) made it possible to significantly lower the dose delivered to sexual structures. While sexual function is known to decline with age, the preservation of sexual structures for prostate cancer RT is likely to be beneficial only in selected patients.

Acute toxicity in patients with high-risk prostate cancer treated with stereotactic body radiation, with irradiation to the prostate and pelvic nodes

PURPOSE

Stereotactic body radiation therapy has been used for prostate cancer. However, the bulk of published studies on stereotactic body radiation therapy for prostate cancer has involved the irradiation of the prostate alone, without irradiation of the pelvic lymph nodes. We report our preliminary experience with this approach.

MATERIAL AND METHODS

The files of patients with biopsy-proven prostate cancer treated with stereotactic body radiation therapy in our institution were reviewed. Stereotactic body radiation was delivered with intensity modulated-volumetric arctherapy with daily image-guidance. The prostate planning target volume included the prostate plus a margin of 5mm in all directions. The pelvic planning target volume included pelvic nodes plus an expansion of 6 to 7mm in all directions. The prostate planning target volume received a total dose of 36.25Gy delivered in five fractions on alternate days. The nodal planning target volume received a dose of 25Gy in the same five fractions. Patients were followed during treatment, after 1, and 3 months and every 6 months thereafter. Gastrointestinal and genitourinary toxicity was prospectively graded according to Common Terminology Criteria for Adverse Events.

RESULTS

Among the 188 patients, 80 received stereotactic body radiation to the prostate and the pelvic nodes, while 108 received stereotactic body radiation to the prostate target only. Grade 2 acute gastrointestinal toxicity was 4% in both groups, and grade 2 acute genitourinary toxicity was 27% and 20% (P=0.9) for prostate only versus prostate and pelvis respectively. There was no grade 3 or higher acute gastrointestinal or genitourinary toxicity.

CONCLUSION

Stereotactic body radiation therapy in five fractions including the prostate and pelvic nodes, in patients with high-risk prostate cancer, has been feasible and safe in terms of acute toxicity.

Revolutionizing localized prostate cancer treatment: Stereotactic radiotherapy "Moroccan experience"

INTRODUCTION

Prostate cancer is the most common urological cancer, and its incidence  is increasing. Radical prostatectomy and radiotherapy are theprimary treatments for localized forms. Stereotactic Body RadioTherapy (SBRT), a new and innovative therapy, has been validated for some cancer localizations but not yet for localized prostate cancer. Our study aims to report the efficacy and tolerance results of SBRT for localized prostate cancer.

MATERIALS AND METHODS

This is a retrospective study of 27 patients with localized prostate cancer (CaP) who were treated with SBRT in our department from 2017 to 2021 using transponders for tumor tracking. The dose was 36.25 Gy delivered in five fractions of 7.25 Gy. The delineation and doses of organs at risk were determined based on the recommendations of the SFRO and the TG101 report of medical physics. All patients were treated using a latest-generation linear accelerator (True Beam STXÒ).

RESULTS

Acute toxicities were observed in 33.3% of cases, with 22.2% grade 1 or 2 genitourinary (GU) and no grade 3 while 11.1% gastrointestinal (GI) toxicities were reported as grade 1-2 (7.4%) and one case grade 3 (3.7%). Late grade 1 or 2 GU toxicity was observed in 14.84% of cases, with no reports of late GI toxicity. After a 26-month follow-up period, the biochemical failure-free survival rate was 92.6%.

CONCLUSIONS

The results of our study are consistent with the existing literature and support the safety and effectiveness of SBRT as a treatment option for localized prostate cancer (CaP). In the United States, both ASTRO and the NCCN recognize SBRT as a valid treatment option for localized CaP. Ongoing phase III trials are being conducted to further substantiate these long-term results and to establish SBRT as the future standard of care for localized CaP.

Transcriptional Inflammatory Signature in Healthy Donors and Different Radiotherapy Cancer Patients

Cancer and ionizing radiation exposure are associated with inflammation. To identify a set of radiation-specific signatures of inflammation-associated genes in the blood of partially exposed radiotherapy patients, differential expression of 249 inflammatory genes was analyzed in blood samples from cancer patients and healthy individuals. The gene expression analysis on a cohort of 63 cancer patients (endometrial, head and neck, and prostate cancer) before and during radiotherapy (24 h, 48 h, ~1 week, ~4-8 weeks, and 1 month after the last fraction) identified 31 genes and 15 up- and 16 down-regulated genes. Transcription variability under normal conditions was determined using blood drawn on three separate occasions from four healthy donors. No difference in inflammatory expression between healthy donors and cancer patients could be detected prior to radiotherapy. Remarkably, repeated sampling of healthy donors revealed an individual endogenous inflammatory signature. Next, the potential confounding effect of concomitant inflammation was studied in the blood of seven healthy donors taken before and 24 h after a flu vaccine or ex vivo LPS (lipopolysaccharide) treatment; flu vaccination was not detected at the transcriptional level and LPS did not have any effect on the radiation-induced signature identified. Finally, we identified a radiation-specific signature of 31 genes in the blood of radiotherapy patients that were common for all cancers, regardless of the immune status of patients. Confirmation via MQRT-PCR was obtained for BCL6, MYD88, MYC, IL7, CCR4 and CCR7. This study offers the foundation for future research on biomarkers of radiation exposure, radiation sensitivity, and radiation toxicity for personalized radiotherapy treatment.

Simulating an intra-fraction adaptive workflow to enable PTV margin reduction in MRIgART volumetric modulated arc therapy for prostate SBRT

Purpose

This study simulates a novel prostate SBRT intra-fraction re-optimization workflow in MRIgART to account for prostate intra-fraction motion and evaluates the dosimetric benefit of reducing PTV margins.

Materials and methods

VMAT prostate SBRT treatment plans were created for 10 patients using two different PTV margins, one with a 5 mm margin except 3 mm posteriorly (standard) and another using uniform 2 mm margins (reduced). All plans were prescribed to 36.25 Gy in 5 fractions and adapted onto each daily MRI dataset. An intra-fraction adaptive workflow was simulated for the reduced margin group by synchronizing the radiation delivery with target position from cine MRI imaging. Intra-fraction delivered dose was reconstructed and prostate DVH metrics were evaluated under three conditions for the reduced margin plans: Without motion compensation (no-adapt), with a single adapt prior to treatment (ATP), and lastly for intra-fraction re-optimization during delivery (intra). Bladder and rectum DVH metrics were compared between the standard and reduced margin plans.

Results

As expected, rectum V18 Gy was reduced by 4.4 ± 3.9%, D1cc was reduced by 12.2 ± 6.8% (3.4 ± 2.3 Gy), while bladder reductions were 7.8 ± 5.6% for V18 Gy, and 9.6 ± 7.3% (3.4 ± 2.5 Gy) for D1cc for the reduced margin reference plans compared to the standard PTV margin. For the intrafraction replanning approach, average intra-fraction optimization times were 40.0 ± 2.9 seconds, less than the time to deliver one of the four VMAT arcs (104.4 ± 9.3 seconds) used for treatment delivery. When accounting for intra-fraction motion, prostate V36.25 Gy was on average 96.5 ± 4.0%, 99.1 ± 1.3%, and 99.6 ± 0.4 for the non-adapt, ATP, and intra-adapt groups, respectively. The minimum dose received by the prostate was less than 95% of the prescription dose in 84%, 36%, and 10% of fractions, for the non-adapt, ATP, and intra-adapt groups, respectively.

Conclusions

Intra-fraction re-optimization improves prostate coverage, specifically the minimum dose to the prostate, and enables PTV margin reduction and subsequent OAR sparing. Fast re-optimizations enable uninterrupted treatment delivery.

Racial and Ethnic Demographic Reporting in Phase 2 Proton Therapy Clinical Trials: A Review

Purpose

Equitable inclusion of racial and ethnic participation in clinical trials is crucial to improving disparities in health care, especially for historically marginalized populations. Our study aims to describe the racial and ethnic demographics of patients enrolled in published phase 2 clinical trials involving proton therapy in the United States.

Materials and Methods

Published manuscripts were identified in PubMed, Embase, World of Science, and Cochrane. Phase 2 trials evaluating proton therapy for US patients were included. For each article in the study, data were collected comprising authors, title, and publication year, and clinical trial numbers were verified. Additional data included tumor site, primary institution, sample size, reported race/ethnicity, and raw number/percentile of race/ethnicity. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used.

Results

Overall, 970 titles were identified; 636 remained after duplicate screening, and 75 full-text articles were assessed. We identified 38 eligible manuscripts for inclusion comprising 2648 patients. Only 15 (39%) of the publications reported race/ethnicity. Of these, 8 (21%) and 10 (26%) documented Hispanic or Black trial participants, respectively; however, only 6 (16%) documented trial participation for both Hispanic and Black patients. Of the 1409 patients with a documented race/ethnicity, 89.0% (n = 1254) were non-Hispanic white, 5.3% (n = 75) were Black, and 2.2% (n = 31) were Hispanic. Other and unknown race/ethnicity comprised the remaining patients (3.5%; n = 49).

Conclusion

We identified underreporting of demographic data in published phase 2 proton therapy trials, which unfortunately mirrored underreporting for cancer drug clinical trials. We also noted dramatic Black and Hispanic patient underrepresentation across the trials in which race and ethnicity are reported. Findings highlight the urgent need to identify and address barriers to proton therapy trials for Black and Hispanic patients ensuring clinical trials in radiation oncology are representative of the patients seen in clinical practice.

Dose prescription and reporting in stereotactic body radiotherapy: A multi-institutional study

BACKGROUND AND PURPOSE

Radiation dose prescriptions are foundational for optimizing treatment efficacy and limiting treatment-related toxicity. We sought to assess the lack of standardization of SBRT dose prescriptions across institutions.

MATERIALS & METHODS

Dosimetric data from 1298 patients from 9 academic institutions treated with IMRT and VMAT were collected. Dose parameters D100, D98, D95, D50, and D2 were used to assess dosimetric variability.

RESULTS

Disease sites included lung (48.3 %) followed by liver (29.7 %), prostate (7.5 %), spine (6.8 %), brain (4.1 %), and pancreas (2.5 %). The PTV volume in lung varied widely with bimodality into two main groups (22.0-28.7 cm3) and (48.0-67.1 cm3). A hot spot ranging from 120-150 % was noted in nearly half of the patients, with significant variation across institutions. A D50 ≥ 110 % was found in nearly half of the institutions. There was significant dosimetric variation across institutions.

CONCLUSIONS

The SBRT prescriptions in the literature or in treatment guidelines currently lack nuance and hence there is significant variation in dose prescriptions across academic institutions. These findings add greater importance to the identification of dose parameters associated with improved clinical outcome comparisons as we move towards more hypofractionated treatments. There is a need for standardized reporting to help institutions in adapting treatment protocols based on the outcome of clinical trials. Dosimetric parameters are subsequently needed for uniformity and thereby standardizing planning guidelines to maximize efficacy, mitigate toxicity, and reduce treatment disparities are urgently needed.

Proton versus photon radiation therapy: A clinical review

While proton radiation therapy offers substantially better dose distribution characteristics than photon radiation therapy in certain clinical applications, data demonstrating a quantifiable clinical advantage is still needed for many treatment sites. Unfortunately, the number of patients treated with proton radiation therapy is still comparatively small, in some part due to the lack of evidence of clear benefits over lower-cost photon-based treatments. This review is designed to present the comparative clinical outcomes between proton and photon therapies, and to provide an overview of the current state of knowledge regarding the effectiveness of proton radiation therapy.

Hypofractionation and SABR: 25 years of evolution in medical physics and a glimpse of the future

As we were invited to write an article for celebrating the 50^th Anniversary of Medical Physics journal, on something historically significant, commemorative, and exciting happening in the past decades, the first idea came to our mind is the fascinating radiotherapy paradigm shift from conventional fractionation to hypofractionation and stereotactic ablative radiotherapy (SABR). It is historically and clinically significant since as we all know this RT treatment revolution not only reduces treatment duration for patients, but also improves tumor control and cancer treatment outcomes. It is also commemorative and exciting for us medical physicists since the technology development in medical physics has been the main driver for the success of this treatment regimen which requires high precision and accuracy throughout the entire treatment planning and delivery. This article provides an overview of the technological development and clinical trials evolvement in the past 25 years for hypofractionation and SABR, with an outlook to the future improvement.

Application of individualized multimodal radiotherapy combined with immunotherapy in metastatic tumors

Radiotherapy is one of the mainstays of cancer treatment. More than half of cancer patients receive radiation therapy. In addition to the well-known direct tumoricidal effect, radiotherapy has immunomodulatory properties. When combined with immunotherapy, radiotherapy, especially high-dose radiotherapy (HDRT), exert superior systemic effects on distal and unirradiated tumors, which is called abscopal effect. However, these effects are not always effective for cancer patients. Therefore, many studies have focused on exploring the optimized radiotherapy regimens to further enhance the antitumor immunity of HDRT and reduce its immunosuppressive effect. Several studies have shown that low-dose radiotherapy (LDRT) can effectively reprogram the tumor microenvironment, thereby potentially overcoming the immunosuppressive stroma induced by HDRT. However, bridging the gap between preclinical commitment and effective clinical delivery is challenging. In this review, we summarized the existing studies supporting the combined use of HDRT and LDRT to synergistically enhance antitumor immunity, and provided ideas for the individualized clinical application of multimodal radiotherapy (HDRT+LDRT) combined with immunotherapy.

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry

PURPOSE

Iodination of rectal hydrogel spacer increases the computed tomography (CT) visibility. The effect of iodinated hydrogel spacer material on the accuracy of proton dosimetry has not been fully studied yet. We presented a systematic study to determine the effect of iodination on proton dosimetry accuracy during proton therapy (PT).

METHODS

PT plans were designed for 20 prostate cancer patients with rectal hydrogel spacer. Three variations of hydrogel density were considered. First, as the ground truth, the true elemental composition of hydrogel true material (TM), verified by our measurement of spacer stopping power ratio, was used for plan optimization and Monte Carlo dose calculation. The dose distribution was recalculated with (1) no material (NM) override based on the CT intensity of the iodinated spacer, and (2) the water material (WM) override, where spacer material was replaced by water. The plans were compared with the ground truth using the metrics of gamma index (GI) and dosimetric indices.

RESULTS

The iodination of hydrogel spacer affected the proton dose distribution with the NM scenario showing the most deviation from the ground truth. The iodination of spacer resulted in a notable increase in CT intensity and led to the treatment planning systems mistreating the iodinated spacer as a high-density material. Among the structures adjacent to the target, neurovascular bundles showed the largest dose difference, up to 350 cGy or about 5% of the prescribed dose with NM. Compared to the WM scenario, dose distribution similarity and GI passing ratios were lower in the NM scenario.

CONCLUSION

The inaccurate CT intensity-based material for iodinated spacer resulted in errors in PT dose calculation. We found that the error was negligible if the iodinated spacer was replaced with water. Water density can be used as a clinically accessible and convenient alternative material override to true spacer material.

Enhancing nanoparticle accumulation in two dimensional, three dimensional, and xenograft mouse cancer cell models in the presence of docetaxel

Recent clinical trials show docetaxel (DTX), given in conjunction with radiation therapy (RT) and androgen suppression, improves survival in high-risk prostate cancer. Addition of gold nanoparticles (GNPs) to this current DTX/RT protocol is expected to further improve therapeutic benefits remarkably. However, the foundation for the triple combination of RT, DTX, and GNPs must be elucidated to ensure quicker facilitation to the clinic. In this study, we explored the use of low concentrations of DTX combined with GNPs in two prostate cancer cell lines in a two-dimensional monolayer, a three-dimensional spheroid, and a mouse xenograft model. When used together, DTX and GNPs induced a nearly identical relative increase in uptake of gold in both the spheroid model and the mouse xenograft, which saw a 130% and 126% increase respectively after 24 h, showcasing the benefit of using spheroids as an in vitro model to better optimize in vivo experiments. Further, the benefits of using low concentrations of DTX combined with GNPs extended for over 72 h, allowing for less frequency in dosing when translating to the clinic. Overall, these results highlight the benefits of using DTX combined with GNPs and lays the groundwork for the translation of the triple combination of RT, GNPs, and DTX to the clinic.

Retrospective analysis of MV-kV imaging-based fiducial tracking in prostate SBRT treatment

PURPOSE

Motion management is critical for prostate stereotactic body radiotherapy (SBRT) due to its high fractional dose and proximity to organs at risk. This study seeks to quantify the advantages of MV-kV tracking over kV imaging alone through a retrospective analysis of over 300 patients who underwent prostate SBRT treatment using MV-kV tracking.

METHODS

An MV-kV imaging-based fiducial tracking technique has been developed at our institute and become a standard clinical practice. This technique calculates three-dimensional (3D) fiducial displacement in real time from orthogonal kV and MV images acquired simultaneously. The patient will be repositioned if for two consecutive MV-kV data points, the motion is larger than a tolerance of 1.5 mm in any of the lateral, superior-inferior, and/or anterior-posterior directions. This study retrospectively analyzed detected 3D motions using an MV-kV approach of 324 patients who recently underwent prostate SBRT treatments. An algorithm was developed to recover the 2D motion components as if they were detected by kV or MV imaging alone.

RESULTS

Our results indicated that out-of-tolerance motions were primarily limited to the range of 1.5-3 mm (>95%). The motions are primarily anterior-posterior and superior-inferior, with less than 14.8% of the occurrences in the lateral direction. Compared to out-of-tolerance occurrences detected by MV-kV approach, kV alone caught 46.6% of motions in all three directions, and MV alone caught 46.7%. kV alone shows an overall missing rate of 45.8% for superior-inferior motions and 38.6% for lateral motions. It is also demonstrated that the detectability of motion in specific directions greatly depends on gantry angles, as does the missing rate.

CONCLUSIONS

Our study demonstrated that MV-kV imaging-based intrafraction motion tracking is superior to single kV imaging for prostate SBRT in clinical practice.

Proton therapy for prostate cancer: current state and future perspectives

OBJECTIVE

Localized prostate cancer can be treated with several radiotherapeutic approaches. Proton therapy (PT) can precisely target tumors, thus sparing normal tissues and reducing side-effects without sacrificing cancer control. However, PT is a costly treatment compared with conventional photon radiotherapy, which may undermine its overall efficacy. In this review, we summarize current data on the dosimetric rationale, clinical benefits, and cost of PT for prostate cancer.

METHODS

An extensive literature review of PT for prostate cancer was performed with emphasis on studies investigating dosimetric advantage, clinical outcomes, cost-effective strategies, and novel technology trends.

RESULTS

PT is safe, and its efficacy is comparable to that of standard photon-based therapy or brachytherapy. Data on gastrointestinal, genitourinary, and sexual function toxicity profiles are conflicting; however, PT is associated with a low risk of second cancer and has no effects on testosterone levels. Regarding cost-effectiveness, PT is suboptimal, although evolving trends in radiation delivery and construction of PT centers may help reduce the cost.

CONCLUSION

PT has several advantages over conventional photon radiotherapy, and novel approaches may increase its efficacy and safety. Large prospective randomized trials comparing photon therapy with proton-based treatments are ongoing and may provide data on the differences in efficacy, toxicity profile, and quality of life between proton- and photon-based treatments for prostate cancer in the modern era.

ADVANCES IN KNOWLEDGE

PT provides excellent physical advantages and has a superior dose profile compared with X-ray radiotherapy. Further evidence from clinical trials and research studies will clarify the role of PT in the treatment of prostate cancer, and facilitate the implementation of PT in a more accessible, affordable, efficient, and safe way.

Treatment Patterns and Overall Survival Outcomes Among Patients Aged 80 yr or Older with High-risk Prostate Cancer

BACKGROUND

Elderly patients diagnosed with high-risk prostate cancer (PCa) present a therapeutic dilemma of balancing treatment of a potentially lethal malignancy with overtreatment of a cancer that may not threaten life expectancy.

OBJECTIVE

To investigate treatment patterns and overall survival outcomes in this group of patients.

DESIGN SETTING AND PARTICIPANTS

A retrospective cohort study was conducted. We queried the National Cancer Database for high-risk PCa in patients aged 80 yr or older diagnosed during 2004-2016.

INTERVENTION

Eligible patients underwent no treatment following biopsy (ie, observation), androgen deprivation therapy (ADT) alone, radiation therapy (RT) alone, RT + ADT, or surgery.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier, log rank, and multivariate Cox proportional hazard regression was performed to compare overall survival (OS).

RESULTS AND LIMITATIONS

A total of 19 920 men were eligible for analysis, and the most common treatment approach was RT + ADT (7401 patients; 37.2%). Observation and ADT alone declined over time (59.3% in 2004 vs 47.5% in 2016). There was no observed difference in OS between observation and ADT alone (adjusted hazard ratio [HR] 1.04, 95% confidence interval [CI], 0.99-1.09; p = 0.105). Definitive local treatment was associated with improved OS compared with ADT alone (RT alone, HR 0.54, 95% CI, 0.50-0.59, p < 0.0001; ADT + RT, HR 0.48, 95% CI, 0.46-0.50, p < 0.0001; surgery, HR 0.50, 95% CI, 0.42-0.59, p < 0.0001).

CONCLUSIONS

This analysis demonstrates that the use of definitive local therapy, including surgery or RT ± ADT, is increasing and is associated with a 50% reduction in overall mortality compared with observation or ADT alone. While prospective validation is warranted, elderly men with high-risk disease eligible for definitive management should be counseled on the risks, including a possible compromise in OS, with deferring definitive management.

PATIENT SUMMARY

Elderly men are more often diagnosed with higher-risk prostate cancer but are less likely to receive curative treatment options than younger men. Our analysis demonstrates that for men ≥80 yr of age with high-risk prostate cancer, definitive local therapy, including surgery or radiation therapy and/or androgen deprivation therapy, is associated with a 50% reduction in overall mortality compared with observation or androgen deprivation therapy alone. We therefore recommend that life expectancy (ie, physiologic age) be taken into account, over chronologic age, and that elderly men with good life expectancy (eg, >5 yr; minimal comorbidity) should be offered definitive, life-prolonging therapy.

Proton Therapy for Prostate Cancer: Challenges and Opportunities

Simple Summary

Reported clinical outcomes of proton therapy (PT) for localized prostate cancer are similar to photon-based external beam radiotherapy. Apparently, the dosimetric advantages of PT have yet to be translated to clinical benefits. The suboptimal clinical outcomes of PT might be attributable to inadequate dose prescription, as indicated by the ASCENDE-RT trial. Moreover, uncertainties involved in the treatment planning and delivery processes, as well as technological limitations in PT treatment systems, may lead to discrepancies between planned doses and actual doses delivered to patients. In this article, we reviewed the current status of PT for prostate cancer and discussed different clinical implementations that could potentially improve the clinical outcome of PT for prostate cancer. Various technological advancements under which uncertainties in dose calculations can be minimized, including MRI-guided PT, dual-energy photon-counting CT and high-resolution Monte Carlo-based treatment planning systems, are highlighted.

Abstract

The dosimetric advantages of proton therapy (PT) treatment plans are demonstrably superior to photon-based external beam radiotherapy (EBRT) for localized prostate cancer, but the reported clinical outcomes are similar. This may be due to inadequate dose prescription, especially in high-risk disease, as indicated by the ASCENDE-RT trial. Alternatively, the lack of clinical benefits with PT may be attributable to improper dose delivery, mainly due to geometric and dosimetric uncertainties during treatment planning, as well as delivery procedures that compromise the dose conformity of treatments. Advanced high-precision PT technologies, and treatment planning and beam delivery techniques are being developed to address these uncertainties. For instance, external magnetic resonance imaging (MRI)-guided patient setup rooms are being developed to improve the accuracy of patient positioning for treatment. In-room MRI-guided patient positioning systems are also being investigated to improve the geometric accuracy of PT. Soon, high-dose rate beam delivery systems will shorten beam delivery time to within one breath hold, minimizing the effects of organ motion and patient movements. Dual-energy photon-counting computed tomography and high-resolution Monte Carlo-based treatment planning systems are available to minimize uncertainties in dose planning calculations. Advanced in-room treatment verification tools such as prompt gamma detector systems will be used to verify the depth of PT. Clinical implementation of these new technologies is expected to improve the accuracy and dose conformity of PT in the treatment of localized prostate cancers, and lead to better clinical outcomes. Improvement in dose conformity may also facilitate dose escalation, improving local control and implementation of hypofractionation treatment schemes to improve patient throughput and make PT more cost effective.

MRI-Based Radiotherapy Planning to Reduce Rectal Dose in Excess of Tolerance

Materials and Methods

This prospective single-arm study enrolled 15 men treated with IG-IMRT for localized prostate cancer. All participants received a dedicated 3 Tesla MRI examination of the prostate in addition to a pelvic CT examination for treatment planning. Two volumetric modulated arc therapy (VMAT) plans with a prescription dose of 79.2 Gy were designed using identical constraints based on CT- and MRI-defined consensus volumes. The volume of rectum exposed to 70 Gy or more was compared using the Wilcoxon paired signed rank test.

Results

For CT-based treatment plans, the median volume of rectum receiving 70 Gy or more was 9.3 cubic centimeters (cc) (IQR 7.0 to 10.2) compared with 4.9 cc (IQR 4.1 to 7.8) for MRI-based plans. This resulted in a median volume reduction of 2.1 cc (IQR 0.5 to 5.3, P < .001).

Conclusions

Using MRI to plan prostate IG-IMRT to a dose of 79.2 Gy reduces the volume of rectum receiving radiation dose in excess of tolerance (70 Gy or more) and should be considered in men who are at high risk for late rectal toxicity and are not good candidates for other rectal sparing techniques such as hydrogel spacer. This trial is registered with NCT02470910.

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

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

Dosimetric Uncertainties in Dominant Intraprostatic Lesion Simultaneous Boost Using Intensity Modulated Proton Therapy

Purpose

While intensity modulated proton therapy can deliver simultaneous integrated boost (SIB) to the dominant intraprostatic lesion (DIL) with high precision, it is sensitive to anatomic changes. We investigated the dosimetric effects from these changes based on pretreatment cone-beam computed tomographic (CBCT) images and identified the most important factors using a multilayer perceptron neural network (MLPNN).

Methods and Materials

DILs were contoured based on coregistered multiparametric magnetic resonance images for 25 previously treated prostate cancer patients. SIB plans were created with (1) prostate clinical target volume − V70 Gy = 98%; (2) DIL − V98 Gy > 95%; and (3) all organs at risk (OARs)"?> within clinical constraints. SIB plans were applied to daily CBCT-based deformed planning computed tomography (CT)"?>. DIL − V98 Gy, bladder/rectum maximum dose (Dmax) and volume changes, femur shifts, and the distance from DIL to organs at riskOARs"?> in both planning computed tomogramsCT"?> and CBCT were calculated. Wilcoxon signed-ranks tests were used to compare the changes. MLPNNs were used to model the change in ΔDIL − V98 Gy > 10% and bladder/rectum Dmax > 80 Gy, and the relative importance factors for the model were provided. The performances of the models were evaluated with receiver operating characteristic curves.

Results

Comparing initial plan to the average from evaluation plans, respectively, DIL − V98 Gy was 89.3% ± 19.9% versus 86.2% ± 21.3% (P = .151); bladder Dmax 71.9 ± 0.6 Gy versus 74.5 ± 2.9 Gy (P < .001); and rectum Dmax 70.1 ± 2.4 Gy versus 74.9 ± 9.1Gy (P = .007). Bladder and rectal volumes were 99.6% ± 39.5% and 112.8% ± 27.2%, respectively, of their initial volume. The femur shift was 3.16 ± 2.52 mm. In the modeling of ΔDIL V98 Gy > 10%, DIL to rectum distance changes, DIL to bladder distance changes, and rectum volume changes ratio are the 3 most important factors. The areas under the receiver operating characteristic curves were 0.89, 1.00, and 0.99 for the modeling of ΔDIL − V98 Gy > 10%, and bladder and rectum Dmax > 80 Gy, respectively.

Conclusions

Dosimetric changes in DIL SIB with intensity modulated proton therapy can be modeled and classified based on anatomic changes on pretreatment images by an MLPNN.

The Use of High-Intensity Focused Ultrasound (HIFU) Plus 150mg Bicalutamide as First Line Salvage Therapy for Local Recurrent Prostate Cancer

Patients with localized prostate cancer (PCa) are often treated with radical prostatectomy (RP). However, more than 30% of such patients have high risk of recurrence. Salvage radiotherapy (SRT), androgen deprivation therapy (ADT) and combination of radiotherapy and ADT are the standard care for recurrent PCa. Recently, high intensity focused ultrasound (HIFU) has gradually applied in the treatment of recurrent PCa. Here, we proposed a hypothesis that combined HIFU and bicalutamide 150mg as first line salvage therapy to treat patients with local recurrent PCa with visible lesions due to the following advantages: (1) HIFU is effective in reducing local tumor load, and bicalutamide 150mg is a feasible and safety option to combine with HIFU. (2) Compared with radiotherapy, HIFU plus 150mg bicalutamide is minimal invasiveness with fewer adverse effects and better quality of life(QOL); (3) Radiotherapy can be preserved as the second-line salvage method in the cases who are failure to HIFU and 150mg bicalutamide combination. More clinical trials are warranted to confirm this hypothesis in treatment with recurrent PCa.

Clinical Efficacy and Safety of Proton and Carbon Ion Radiotherapy for Prostate Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Carbon ion radiotherapy (CIRT) and proton beam therapy (PBT) are promising methods for prostate cancer, however, the consensus of an increasing number of studies has not been reached. We aimed to provide systematic evidence for evaluating the efficacy and safety of CIRT and PBT for prostate cancer by comparing photon radiotherapy.

MATERIALS AND METHODS

We searched for studies focusing on CIRT and PBT for prostate cancer in four online databases until July 2021. Two independent reviewers assessed the quality of included studies and used the GRADE approach to rate the quality of evidence. R 4.0.2 software was used to conduct the meta-analysis. A meta-regression test was performed based on the study design and tumor stage of each study.

RESULTS

A total of 33 studies including 13 CIRT- and 20 PBT-related publications, involving 54,101, participants were included. The quality of the included studies was found to be either low or moderate quality. Random model single-arm meta-analysis showed that both the CIRT and PBT have favorable efficacy and safety, with similar 5-year overall survival (OS) (94 vs 92%), the incidence of grade 2 or greater acute genitourinary (AGU) toxicity (5 vs 13%), late genitourinary (LGU) toxicity (4 vs 5%), acute gastrointestinal (AGI) toxicity (1 vs 1%), and late gastrointestinal (LGI) toxicity (2 vs 4%). However, compared with CIRT and PBT, photon radiotherapy was associated with lower 5-year OS (72-73%) and a higher incidence of grade 2 or greater AGU (28-29%), LGU (13-14%), AGI (14-19%), and LGI toxicity (8-10%). The meta-analysis showed the 3-, 4-, and 5-year local control rate (LCR) of CIRT for prostate cancer was 98, 97, and 99%; the 3-, 4-, 5-, and 8-year biochemical relapse-free rate (BRF) was 92, 91, 89, and 79%. GRADE assessment results indicated that the certainty of the evidence was very low. Meta-regression results did not show a significant relationship based on the variables studied (P<0.05).

CONCLUSIONS

Currently available evidence demonstrated that the efficacy and safety of CIRT and PBT for prostate cancer were similar, and they may significantly improve the OS, LCR, and reduce the incidence of GU and GI toxicity compared with photon radiotherapy. However, the quantity and quality of the available evidence are insufficient. More high-quality controlled studies are needed in the future.

Stereotactic Body Radiation Therapy (SBRT) for prostate cancer: Preliminary results of toxicity

To the Editor, Prostate cancer is the second most common cancer in men in Morocco after lung cancer. External radiotherapy (RTE) is a curative therapeutic option for localized prostate cancer, However the conventional RTE remains a long treatment (7- 8 weeks, 5 days a week) which is demanding for patients and make difficult to manage the waiting lists. The development of imaging and irradiation techniques over the last decades has allowed a high precision in the delivery of the dose to the target organ and a better protection of the organs at risk (OAR), which has encouraged the hypo fractionated irradiation of localized prostate cancer, especially after the results of radiobiology studies that suggested a low report a/b for the prostate.

Early outcomes of high-dose-rate brachytherapy combined with ultra-hypofractionated radiation in higher-risk prostate cancer

PURPOSE

This study evaluated outcomes associated with a high-dose-rate (HDR) brachytherapy boost combined with stereotactic body radiation therapy (SBRT) for patients with higher-risk localized prostate cancer.

MATERIALS AND METHODS

We identified 101 patients with National Comprehensive Cancer Network high-risk, unfavorable intermediate-risk, or favorable intermediate-risk with probable extra-prostatic extension treated with HDR brachytherapy (15 Gy x 1 fraction) followed by SBRT (5 Gy x 5 daily fractions to the prostate and/or seminal vesicles and/or pelvic lymph nodes). Androgen deprivation therapy was used in 55.4% of all patients (90% of high-risk, 33% of intermediate-risk). Toxicities according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0 and International Prostate Symptom Scores were prospectively documented at each followup visit. Biochemical relapse was defined as PSA nadir +2ng/mL.

RESULTS

The median follow-up time after SBRT was 24.1 months. No grade ≥3 toxicities were observed. The incidence of acute and late grade 2 gastrointestinal toxicities was both 0.99%. Acute and late grade 2 genitourinary (GU) toxicities were observed in 5.9% and 9.9%, respectively. Median time to a grade 2 GU toxicity was 6 months with a 14% 2-year actuarial rate of grade 2 GU toxicity. Median International Prostate Symptom Scores at 24 months was not significantly different than baseline (6 vs. 5; p = 0.24). Inclusion of pelvic lymph nodes and absence of a rectal spacer were significantly associated with more frequent grade ≥1 GU toxicity, but not grade ≥2 GU or gastrointestinal toxicity. The 2-year biochemical relapse free survival was 97%.

CONCLUSIONS

HDR brachytherapy combined with SBRT was associated with a favorable early toxicity profile and encouraging cancer control outcomes.

Biologically Effective Dose and Rectal Bleeding in Definitive Proton Therapy for Prostate Cancer

Purpose and Objectives

With increasing use of hypofractionation and extreme hypofractionation for prostate cancer, rectal dose-volume histogram (DVH) parameters that apply across dose fractionations may be helpful for treatment planning in clinical practice. We present an exploratory analysis of biologically effective rectal dose (BED) and equivalent rectal dose in 2 Gy fractions (EQD2) for rectal bleeding in patients treated with proton therapy across dose fractionations.

Materials and Methods

From 2016 to 2018, 243 patients with prostate cancer were treated with definitive proton therapy. Rectal DVH parameters were obtained from treatment plans, and rectal bleeding events were recorded. The BED and EQD2 transformations were applied to each rectal DVH parameter. Univariate analysis using logistic regression was used to determine DVH parameters that were significant predictors of grade ≥ 2 rectal bleeding. Youden index was used to determine optimum cutoffs for clinically meaningful DVH constraints. Stepwise model-selection criteria were then applied to fit a “best” multivariate logistic model for predicting Common Terminology Criteria for Adverse Events grade ≥ 2 rectal bleeding.

Results

Conventional fractionation, hypofractionation, and extreme hypofractionation were prescribed to 117 (48%), 84 (34%), and 42 (17.3%) patients, respectively. With a median follow-up of 20 (2.5-40) months, 10 (4.1%) patients experienced rectal bleeding. On univariate analysis, multiple rectal DVH parameters were significantly associated with rectal bleeding across BED, EQD2, and nominal doses. The BED volume receiving 55 Gy > 13.91% was found to be statistically and clinically significant. The BED volume receiving 55 Gy remained statistically significant for an association with rectal bleeding in the multivariate model (odds ratio, 9.81; 95% confidence interval, 2.4-40.5; P = .002).

Conclusion

In patients undergoing definitive proton therapy for prostate cancer, dose to the rectum and volume of the rectum receiving the dose were significantly associated with rectal bleeding across conventional fractionation, hypofractionation, and extreme hypofractionation when using BED and EQD2 transformations.

Ultrahypofractionated Proton Radiation Therapy in the Treatment of Low and Intermediate-Risk Prostate Cancer-5-Year Outcomes

PURPOSE

To analyze the 5-year biochemical disease-free survival (bDFS) and late toxicity profile in patients with prostate cancer treated with pencil beam scanning (PBS) proton radiation therapy.

METHODS AND MATERIALS

Between January 2013 and March 2016, 284 patients with prostate cancer were treated using intensity modulated proton therapy (IMPT), with an ultrahypofractionated schedule (36.25 GyE in 5 fractions). Five patients were immediately lost from follow-up and thus were excluded from analysis. Data for 279 patients were prospectively collected and analyzed with a median follow-up time of 56.5 (range, 3.4-87.5) months. The mean age at time of treatment was 64.5 (40.1-85.7) years, and the median prostate-specific antigen (PSA) value was 6.35 μg/L (0.67-17.3 μg/L). A total of 121 (43.4%) patients had low-risk, 125 patients (44.8%) had favorable, and 33 (11.8%) unfavorable intermediate-risk cancer. In addition, 49 (17.6%) patients underwent neoadjuvant hormonal therapy, and no patients had adjuvant hormonal therapy. bDFS and late toxicity profiles were evaluated.

RESULTS

The median treatment time was 9 days (range, 7-18 days). The 5-year bDFS was 96.9%, 91.7%, and 83.5% for the low-, favorable, and unfavorable intermediate-risk group, respectively. Late toxicity (Common Terminology Criteria for Adverse Events v.4) was as follows: gastrointestinal: grade 1, 62 patients (22%), grade 2, 20 patients (7.2%), and grade 3, 1 patient (0.36%); genitourinary: grade 1, 80 patients (28.7%), grade 2, 14 patients (5%), and grade 3, 0 patients. PSA relapse was observed in 17 patients (6.1%), and lymph node or bone recurrence was detected in 11 patients. Four (1.4%) local recurrences were detected. Nine patients (3.2%) died of causes unrelated to prostate cancer. No deaths related to prostate cancer were reported.

CONCLUSION

Ultrahypofractionated proton beam radiation therapy for prostate cancer is effective with long-term bDFS comparable with other fractionation schedules and with minimal serious long-term GI and GU toxicity.

A Pooled Toxicity Analysis of Moderately Hypofractionated Proton Beam Therapy and Intensity Modulated Radiation Therapy in Early-Stage Prostate Cancer Patients

PURPOSE

Data comparing moderately hypofractionated intensity modulated radiation therapy (IMRT) and proton beam therapy (PBT) are lacking. We aim to compare late toxicity profiles of patients with early-stage prostate cancer treated with moderately hypofractionated PBT and IMRT.

METHODS AND MATERIALS

This multi-institutional analysis included patients with low- or intermediate-risk biopsy-proven prostate adenocarcinoma from 7 tertiary referral centers treated from 1998 to 2018. All patients were treated with moderately hypofractionated radiation, defined as 250 to 300 cGy per daily fraction given for 4 to 6 weeks, and stratified by use of IMRT or PBT. Primary outcomes were late genitourinary (GU) and gastrointestinal (GI) toxicity. Adjusted toxicity rates were calculated using inverse probability of treatment weighting, accounting for race, National Comprehensive Cancer Network risk group, age, pretreatment International Prostate Symptom Score (GU only), and anticoagulant use (GI only).

RESULTS

A total of 1850 patients were included: 1282 IMRT (median follow-up 80.0 months) and 568 PBT (median follow-up 43.9 months). Overall toxicity rates were low, with the majority of patients experiencing no late GU (56.6%, n = 1048) or late GI (74.4%, n = 1377) toxicity. No difference was seen in the rates of late toxicity between the groups, with late grade 3+ GU toxicity of 2.0% versus 3.9% (odds ratio [OR] 0.47; 95% confidence interval 0.17-1.28) and late grade 2+ GI toxicity of 14.6% versus 4.7% (OR 2.69; confidence interval 0.80-9.05) for the PBT and IMRT cohorts, respectively. On multivariable analysis, no factors were significantly predictive of GU toxicity, and only anticoagulant use was significantly predictive of GI toxicity (OR 1.90; P = .008).

CONCLUSIONS

In this large, multi-institutional analysis of 1850 patients with early-stage prostate cancer, treatment with moderately hypofractionated IMRT and PBT resulted in low rates of toxicity. No difference was seen in late GI and GU toxicity between the modalities during long-term follow-up. Both treatments are safe and well tolerated.

Patient cost sharing during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment in ovarian cancer

BACKGROUND

More patients with ovarian cancer are being treated with poly(adenosine diphosphate-ribose) polymerase inhibitors because regulatory agencies have granted these drugs new approvals for a variety of treatment indications. However, poly(adenosine diphosphate-ribose) polymerase inhibitors are expensive. When administered as a maintenance therapy, these drugs may be administered for months or years. How much of this cost patients experience as out-of-pocket spending is unknown.

OBJECTIVE

This study aimed to estimate the out-of-pocket spending that patients experience during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment and to characterize which healthcare services account for that spending.

STUDY DESIGN

A retrospective cohort study was performed with a sample of patients with ovarian cancer treated between 2014 and 2017 with olaparib, niraparib, or rucaparib. Patients were identified using MarketScan, a health insurance claims database. All insurance claims during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment were collected. The primary outcome variable was the patients' out-of-pocket spending (copayment, coinsurance, and deductibles) during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment for the medication itself. Other outcomes of interest included out-of-pocket spending for other healthcare services, the types and frequency of other healthcare services used, health plan spending, the estimated proportion of patients' household income used each month for healthcare, and patients' out-of-pocket spending immediately before poly(adenosine diphosphate-ribose) polymerase inhibitor treatment.

RESULTS

We identified 503 patients with ovarian cancer with a median age of 55 years (interquartile range, 50-62 years); 83% of those had out-of-pocket spendings during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment. The median treatment duration was 124 days (interquartile range, 66-240 days). The mean out-of-pocket spending for poly(adenosine diphosphate-ribose) polymerase inhibitors was $305 (standard deviation, $2275) per month. On average, this accounted for 44.8% (standard deviation, 34.8%) of the patients' overall monthly out-of-pocket spending. The mean out-of-pocket spending for other healthcare services was $165 (standard deviation, $769) per month. Health plans spent, on average, $12,661 (standard deviation, $15,668) per month for poly(adenosine diphosphate-ribose) polymerase inhibitors and $7108 (standard deviation, $15,254) per month for all other healthcare services. The cost sharing for office visits, laboratory tests, and imaging studies represented the majority of non-poly(adenosine diphosphate-ribose) polymerase inhibitor treatment out-of-pocket spending. The average amount patients paid for all healthcare services per month during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment was $470 (standard deviation, $2407), which was estimated to be 8.7% of the patients' monthly household income. The mean out-of-pocket spending in the 12 months before poly(adenosine diphosphate-ribose) polymerase inhibitor treatment was $3110 (standard deviation, $6987).

CONCLUSION

Patients can face high out-of-pocket costs for poly(adenosine diphosphate-ribose) polymerase inhibitors, although the sum of cost sharing for other healthcare services used during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment is often higher. The spending on healthcare costs consumes a large proportion of these patients' household income. Patients with ovarian cancer experience high out-of-pocket costs for healthcare, both before and during poly(adenosine diphosphate-ribose) polymerase inhibitor treatment.

Effect of three-dimensional conformal radiotherapy and intensity-modulated radiotherapy on parotid gland function and quality of life in patients with nasopharyngeal carcinoma

OBJECTIVE

To investigate the effects of three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) on parotid gland function and quality of life in patients with nasopharyngeal carcinoma (NPC).

METHODS

Ninety-six patients with NPC diagnosed and treated in our hospital were divided into two groups using a random number table. The control group was treated with three-dimensional conformal radiotherapy and the research group was treated with intensity-modulated radiotherapy. Observation and comparison were conducted for differences of baseline indicators between the two groups including; short-term response rate, relevant indicators regarding parotid gland function before and after treatment, uptake index (UI) and excretion index (EI), dry mouth (xerostomia) grading and quality of life indicators after treatment, and the prognosis of patients.

RESULTS

There was no significant difference in baseline data between the two groups (all P>0.05). The short-term response rate in the research group was significantly higher than that in the control group (P<0.05). After treatment, UI and EI in both groups were significantly decreased compared to those before treatment (all P<0.05); UI and EI in the research group were significantly higher than those in control group (all P<0.05). Dry mouth grading in the research group was significantly lower than that in the control group (all P<0.05). After treatment, the levels of related indicators regarding quality of life, local recurrence-free rate, and distant metastasis-free rate in the research group were higher than those in the control group (all P<0.05).

CONCLUSION

IMRT for patients with NPC can significantly improve short-term response rate, reduce mouth dryness and parotid gland injury after radiotherapy, enhance quality of life, and facilitate the prognosis of patients.

Consensus Statement on Proton Therapy for Prostate Cancer

Proton therapy is a promising but controversial treatment in the management of prostate cancer. Despite its dosimetric advantages when compared with photon radiation therapy, its increased cost to patients and insurers has raised questions regarding its value. Multiple prospective and retrospective studies have been published documenting the efficacy and safety of proton therapy for patients with localized prostate cancer and for patients requiring adjuvant or salvage pelvic radiation after surgery. The Particle Therapy Co-Operative Group (PTCOG) Genitourinary Subcommittee intends to address current proton therapy indications, advantages, disadvantages, and cost effectiveness. We will also discuss the current landscape of clinical trials. This consensus report can be used to guide clinical practice and research directions.

Urinary Outcomes for Men With High Baseline International Prostate Symptom Scores Treated With Prostate SBRT

Purpose

There are limited data regarding high-dose stereotactic body radiation therapy (SBRT) for prostate cancer in patients with poor baseline urinary function. The purpose of this study was to evaluate genitourinary (GU) toxicity and changes in patient-reported symptom severity scores after prostate SBRT in men with a high pretreatment International Prostate Symptom Score (IPSS).

Methods and Materials

Seven hundred fifty-three patients treated with prostate SBRT at our institution from 2012 to 2019 were identified, of whom 72 consecutive patients with baseline IPSS ≥15 were selected for this study. GU toxicity according to Common Terminology Criteria for Adverse Events (CTCAE) v3.0 and IPSS were prospectively documented at each follow-up visit. Univariable logistic regression was used to evaluate for potential predictors of GU toxicity.

Results

Median follow-up in survivors was 26.8 months. The rates of acute grade 2 and 3 GU toxicity were 20.8% and 1.4%, respectively. The rates of late grade 2 and 3 GU toxicity were 37.5% and 5.6%, respectively. The majority of grade 2+ toxicities resolved by last follow-up, and when toxicities were regraded per CTCAE v5.0, there were no longer any grade 3 adverse events. Total IPSS and individual symptom subscores improved over time. Compared with baseline, median total IPSS at 24 ± 6 months was significantly lower (18 vs 12; P < .001) and the proportion of patients with severe scores (IPSS ≥20) decreased from 29.2% to 13.9%. Pretreatment urinary urgency was associated with late grade 2+ GU toxicity (odds ratio, 2.10; 95% confidence interval, 1.33-3.31; P = .001).

Conclusions

In men with baseline IPSS ≥15 managed with prostate SBRT, the rate of severe GU toxicity was low and patient-reported symptoms generally improved over time. Thus, high pretreatment IPSS should not deter clinicians from offering prostate SBRT.

Hypofractionated versus conventionally fractionated image-guided volumetric-modulated arc radiotherapy for localized prostate cancer: a phase II randomized trial from China

Purpose: To determine the safety of hypofractionated imaging-guided (IG) volumetric-modulated arc radiotherapy (IG-VMAT; 70 Gy/28 fractions over 5.5 weeks) versus conventionally fractionated regimen (IG-VMAT; 80 Gy/40 fractions over 8 weeks) in Chinese patients with localized prostate cancer.

Method: In this randomized non-comparative phase II trial, 92 patients with localized prostate cancer were assigned to receive either hypofractionated IG-VMAT (HFRT; 70 Gy/2.5Gy/28f) or conventionally fractionated IG-VMAT (CFRT; 80 Gy/2Gy/40f). Primary endpoint was grade 2 or higher late gastrointestinal (GI) and genitourinary (GU) toxicity at 2 years. The GI/GU toxicity and biochemical relapse–free survival (bRFS) were compared between the two treatment groups.

Results: Median follow-up was 26 months. The incidence of grade 2 or higher late GI/GU toxicity was low in both groups; the 5-year cumulative incidence of Radiation Therapy Oncology Group grade 2 or higher GI/GU toxicity at 2 years was 7.6% with HFRT versus 10.3% with CFRT (P = 0.707). Biochemical control was not significantly different between the two groups; the 2-year bRFS was 94.6% for HFRT versus 95.0% for CFRT (P = 0.704).

Conclusion: Hypofractionated IG-VMAT appears to be equivalent to conventionally fractionated IG-VMAT in terms of toxicity in Chinese patients with localized prostate cancer.

Cost-effectiveness of Prostate Radiation Therapy for Men With Newly Diagnosed Low-Burden Metastatic Prostate Cancer

IMPORTANCE

Prostate radiation therapy (PRT) is a treatment option in men with low-volume metastatic prostate cancer based on the results of the Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy Arm H (STAMPEDE-H) trial. However, the cost-effectiveness of this treatment remains unaddressed.

OBJECTIVE

To assess the cost-effectiveness of PRT when added to androgen deprivation therapy (ADT) for men with low-volume metastatic hormone-sensitive prostate cancer (mHSPC).

DESIGN, SETTING, AND PARTICIPANTS

This economic evaluation used microsimulation modeling to evaluate the cost-effectiveness of adding PRT to ADT. A simulated cohort of 10 000 individuals with low-volume mHSPC was created. Data from men with low-volume mHSPC were extracted and analyzed from January 18, 2019, through July 4, 2020. Transition probabilities were extracted from the STAMPEDE-H study. Health states included stable disease, progression, second progression, and death. Individual grade 2 or higher genitourinary and gastrointestinal toxic events associated with PRT were tracked. Univariable deterministic and probabilistic sensitivity analyses explored uncertainty with regard to the model assumptions. Health state utility estimates were based on the published literature.

EXPOSURES

The combination of PRT and ADT using regimens of 20 fractions and 6 weekly fractions.

MAIN OUTCOMES AND MEASURES

Outcomes included net quality-adjusted life-years (QALYs), costs in US dollars, and incremental cost-effectiveness ratios. A strategy was classified as dominant if it was associated with higher QALYs at lower costs than the alternative and dominated if it was associated with fewer QALYs at higher costs than the alternative.

RESULTS

For the base case scenario of men 68 years of age with low-volume mHSPC, the modeled outcomes were similar to the target clinical data for overall survival, failure-free survival, and rates of PRT-related toxic effects. The addition of PRT was a dominant strategy compared with ADT alone, with a gain of 0.16 QALYs (95% CI, 0.15-0.17 QALYs) and a reduction in net costs by $19 472 (95% CI, $23 096-$37 362) at 37 months of follow-up and a gain of 0.81 QALYs (95% CI, 0.73-0.89 QALYs) and savings of $30 229 (95% CI, $23 096-$37 362) with lifetime follow-up.

CONCLUSIONS AND RELEVANCE

In the economic evaluation, PRT was a dominant treatment strategy compared with ADT alone. These findings suggest that addition of PRT to ADT is a cost-effective treatment for men with low-volume mHSPC.

Comparative Analysis of 5-Year Clinical Outcomes and Patterns of Failure of Proton Beam Therapy Versus Intensity Modulated Radiation therapy for Prostate Cancer in the Postoperative Setting

PURPOSE

Although proton beam therapy (PBT) is a rapidly expanding modality to treat prostate cancer compared with intensity modulated radiation therapy (IMRT), data comparing disease control outcomes and patterns of failure in the postprostatectomy setting remain substantially limited.

METHODS AND MATERIALS

All patients who underwent postoperative IMRT or PBT to the prostate bed only at a single institution were included (2009-2017). Endpoints included biochemical failure (BF; using institutional and recent cooperative group trial definitions), local failure (LF), regional failure (RF), distant failure (DF), and all-cause mortality. A case-matched cohort analysis was performed using 3-to-1 nearest-neighbor matching; multivariable Cox proportional hazards modeling (MVA) estimated hazard ratios for disease-related outcomes by treatment modality.

RESULTS

Of 295 men, 260 were matched (n = 65 PBT, 195 IMRT); after matching, only age at diagnosis (P < .01) significantly differed between cohorts. At a median follow-up of 59 months, BF (institution-defined), LF, RF, DF, and mortality rates were 45% (n = 29), 2% (n = 1), 9% (n = 6), 9% (n = 6), and 2% (n = 1) for PBT, and 41% (n = 80), 3% (n = 5), 7% (n = 13), 9% (n = 18), and 5% (n = 9) for IMRT (all P > .05). RT modality was not significantly associated with BF on MVA using institutional or cooperative group definitions (all P > .05), nor with LF (P = .82), RF (P = .11), DF (P = .36), or all-cause mortality (P = .69). Patterns of failure were qualitatively similar between cohorts (DF: bone, retroperitoneal nodes, lung).

CONCLUSIONS

In this single institution, case-matched analysis, PBT yielded similar long-term disease-related outcomes and patterns of failure to IMRT in the postprostatectomy setting.

Biochemical Control and Toxicity Outcomes of Stereotactic Body Radiation Therapy Versus Low-Dose-Rate Brachytherapy in the Treatment of Low- and Intermediate-Risk Prostate Cancer

PURPOSE

Low-dose-rate (LDR) brachytherapy and stereotactic body radiation therapy (SBRT) have both shown acceptable outcomes in the treatment of low- and intermediate-risk prostate cancer. Minimal data have been published directly comparing rates of biochemical control and toxicity with these 2 modalities. We hypothesize that LDR and SBRT will provide similar rates of biochemical control.

METHODS AND MATERIALS

All low- and intermediate-risk patients with prostate cancer treated definitively with SBRT or LDR between 2010 and 2018 were captured. Phoenix definition was used for biochemical failure. Independent t tests were used to compare baseline characteristics, and repeated measure analysis of variance test was used to compare American Urologic Association (AUA) and the Expanded Prostate Cancer Index Composite (EPIC) scores between treatment arms over time. Biochemical control was estimated using the Kaplan-Meier method. Differences in acute and late toxicity were assessed via Pearson χ².

RESULTS

In the study, 219 and 118 patients were treated with LDR and SBRT. Median follow-up was 4.3 years (interquartile range, 3.1-6.1). All patients treated with LDR received 125.0 Gy in a single fraction. SBRT consisted of 42.5 Gy in 5 fractions. Five-year biochemical control for LDR versus SBRT was 91.6% versus 97.6% (P = .108). LDR patients had a larger increase in mean AUA scores at 1 month (17.2 vs 10.3, P < .001) and 3 months posttreatment (14.0 vs 9.7, P < .001), and in mean EPIC scores at 1 month (15.7 vs 13.8, P < .001). There was no significant difference between LDR and SBRT in late grade 3 genitourinary toxicity (0.9% vs 2.5%, P = .238); however, LDR had lower rates of late grade 3 gastrointestinal toxicity (0.0% vs 2.5%, P = .018).

CONCLUSIONS

Our data show similar biochemical control and genitourinary toxicity rates at 5 years for both SBRT and LDR, with slightly higher gastrointestinal toxicity with SBRT and higher AUA and EPIC scores with LDR.

Stereotactic body radiotherapy versus conventional/moderate fractionated radiation therapy with androgen deprivation therapy for unfavorable risk prostate cancer

Background

Ultrahypofractionation using stereotactic body radiotherapy (SBRT) is an increasingly utilized technique for men with prostate cancer (PC). The comparative efficacy of SBRT plus androgen deprivation therapy (ADT) compared to fractionated radiotherapy (EBRT) plus ADT in higher-risk prostate cancer is unknown.

Methods

Men > 40 years old with localized PC treated with external beam radiation and concomitant ADT for curative intent between 2004 and 2016 were analyzed from the National Cancer Database. Patients who lacked ADT or risk stratification data were excluded. 558 men treated with SBRT versus 40,797 men treated with conventional or moderately hypofractionated EBRT were included. Patients were stratified by unfavorable intermediate (UIR) and high (HR) risk using NCCN criteria. Kaplan Meier and Cox proportional hazards were used to compare overall survival (OS) between RT modality, adjusting for age, race, and comorbidity index.

Results

With a median follow up of 74 months, there was no difference in estimated 6-year OS between men treated with SBRT versus EBRT regardless of risk group. On multivariable analysis, there was no difference in risk of death for men treated with SBRT compared to EBRT (UIR: adjusted HR 1.09, 95% CI 0.68–1.74, p = .72; HR: adjusted HR 0.93, 95% CI 0.76–1.14, p = .51). On sensitivity analyses, when confining the cohort to men treated with NCCN-preferred dose fractionations, with no comorbidities, or < 65 years old, there remained no survival difference between treatment groups for both UIR and HR.

Conclusion

Within study limitations, we found no difference in survival between SBRT+ADT and standard of care EBRT+ADT for UIR or HR PC. These results support recent NCCN guideline updates, which include SBRT as a non-preferred option for higher risk men. Prospective validation would further strengthen the evidence basis behind these recommendations.

Overall Survival After Treatment of Localized Prostate Cancer With Proton Beam Therapy, External-Beam Photon Therapy, or Brachytherapy

With limited high-level evidence, we carried out a comparative effectiveness study for the effect of proton beam therapy (PBT) on overall survival compared to external-beam radiotherapy (EBRT) and brachytherapy (BT) among patients with localized prostate cancer using a national database. PBT was associated with a significant overall survival benefit compared to EBRT and had a similar performance as BT.

Patient preferences for reducing bowel adverse events following prostate radiotherapy

BACKGROUND

The Extended Prostate Cancer Index Composite (EPIC) instrument is a commonly used patient reported outcome (PRO) tool in prostate cancer clinical trials. Summary scores for EPIC subscales are calculated by averaging patient scores for attributes (e.g., side effects), implying equal weighting of the attributes in the absence of evidence showing otherwise.

METHODS

We estimated patient preferences for each of the attributes included in the bowel subscale of the EPIC instrument using best-worst (B-W) scaling among a cohort of men with prostate cancer. Patients were presented with multiple tasks in which they were asked to indicate which attribute they would find most and least bothersome at different levels of severity. Analysis utilized both (simple) B-W counts and scores to estimate patient preferences for each attribute as well as attribute levels.

RESULTS

A total of 174 respondents from two institutions participated in the survey. Preference estimates for each of the five attributes included in the EPIC-26 bowel subscale showed wide variation preferences: 'losing control of bowel movements' was found to be the most bothersome attribute, with a B-W score of -0.48, followed by bowel urgency which also had negative B-W score (-0.04). Increased frequency of bowel movements was the least bothersome attribute, with a B-W score of +0.33, followed by bloody stools (+0.12), and pelvic/rectal pain (+0.06). Analysis of preference weights for attribute bother levels showed preference estimates be linear.

CONCLUSIONS

We provide novel evidence on patient preferences for side effect reduction following prostate radiotherapy. Within the bowel sub-scale of the EPIC-26 short form, we found that bowel incontinence was perceived to be the most bothersome treatment effect, while increased bowel frequency was least bothersome to patients.

Costs and Complications After a Diagnosis of Prostate Cancer Treated With Time-Efficient Modalities: An Analysis of National Medicare Data

PURPOSE

Recent trends in payer and patient preferences increasingly incentivize time-efficient (≤2-week treatment time) prostate cancer treatments.

METHODS AND MATERIALS

National Medicare claims from January 1, 2011, through December 31, 2014, were analyzed to identify newly diagnosed prostate cancers. Three "radical treatment" cohorts were identified (prostatectomy, brachytherapy, and stereotactic body radiation therapy [SBRT]) and matched to an active surveillance (AS) cohort by using inverse probability treatment weighting via propensity score. Total costs at 1 year after biopsy were calculated for each cohort, and treatment-specific costs were estimated by subtracting total 1-year costs in each radical treatment group from those in the AS group.

RESULTS

Mean 1-year adjusted costs were highest among patients receiving SBRT ($26,895), lower for prostatectomy ($23,632), and lowest for brachytherapy ($19,980), whereas those for AS were $9687. Costs of radical modalities varied significantly by region, with the Mid-Atlantic and New England regions having the highest cost ranges (>$10,000) and the West South Central and Mountain regions the lowest range in costs (<$2000). Quantification of toxic effects showed that prostatectomy was associated with higher genitourinary incontinence (hazard ratio [HR] = 10.8 compared with AS) and sexual dysfunction (HR = 3.5), whereas the radiation modalities were associated with higher genitourinary irritation/bleeding (brachytherapy HR = 1.7; SBRT HR = 1.5) and gastrointestinal ulcer/stricture/fistula (brachytherapy HR = 2.7; SBRT HR = 3.0). Overall mean toxicity costs were highest among patients treated with prostatectomy ($3500) followed by brachytherapy ($1847), SBRT ($1327), and AS ($1303).

CONCLUSIONS

Time-efficient treatment techniques exhibit substantial variability in toxicity and costs. Furthermore, geographic location substantially influenced treatment costs.

Whole Pelvic Radiotherapy With Stereotactic Body Radiotherapy Boost vs. Conventionally Fractionated Radiotherapy for Patients With High or Very High-Risk Prostate Cancer

Background: Whole pelvic radiotherapy (WPRT) with stereotactic body radiotherapy (SBRT) boost has been shown to be effective in patients with high-risk prostate cancer (PC). However, no study has directly compared the efficacy of WPRT with SBRT boost with that of conventionally fractionated radiotherapy (CFRT). We compared the clinical outcomes between CFRT and WPRT with SBRT boost in patients with high or very high-risk PC (National Comprehensive Cancer Network definition).

Methods: In total, 132 patients treated with CFRT and 121 patients treated with WPRT followed by SBRT boost were retrospectively analyzed. For the CFRT group, the prescribed dose range was 74–79.2 Gray (Gy) administered at 1.8–2 Gy per fraction. For WPRT with SBRT boost, the prescribed doses were 45 Gy administered in 25 fractions to the whole pelvis followed by 21 Gy boost (3 fractions of 7 Gy each) to prostate and seminal vesicles. The overall survival (OS) and biochemical failure (Phoenix definition) free survival (bFFS) were assessed by using the Kaplan–Meier method or the Cox proportional hazards regression model. The gastrointestinal (GI) and genitourinary (GU) tract toxicity were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) v3.0.

Results: The estimated 4-years overall survival in the CFRT and WPRT with SBRT boost groups was 91.6 and 97.7%, respectively (P = 0.18). The estimated 4-years biochemical failure-free survival in the CFRT and WPRT with SBRT boost groups was 89.1 and 93.9%, respectively (P = 0.41). No acute grade 3 or higher GI and GU toxicity was observed in both groups. Late grade 3 GI and GU toxicity occurred in 2.3 and 2.3% in the CFRT group, and in 1.7 and 0.8% in the WPRT with SBRT boost group, respectively. There was no significant between-group difference with respect to acute or late toxicity.

Conclusions: In patients with high or very high-risk localized PC, compared with CFRT, WPRT with SBRT boost resulted in similar biochemical-free and overall survival rate with minimal toxicity. WPRT with SBRT boost is a feasible option for patients with high or very high-risk PC.

Prostate SBRT With Intrafraction Motion Management Using a Novel Linear Accelerator-Based MV-kV Imaging Method

PURPOSE

This study reports clinical experience using a linear accelerator-based MV-kV imaging system for intrafraction motion management during prostate stereotactic body radiation therapy (SBRT).

METHODS AND MATERIALS

From June 2016 to August 2018, 193 prostate SBRT patients were treated using MV-kV motion management (median dose 40 Gy in 5 fractions). Patients had 3 fiducials implanted then simulated and treated with a full bladder and empty rectum. Pretreatment orthogonal kVs and cone beam computed tomography were used to position patients and evaluate internal anatomy. Motion was tracked during volumetric modulated arc therapy delivery using simultaneously acquired kV and MV images from standard on-board systems. Treatment was interrupted to reposition patients when motion >1.5-2 mm was detected. Motion traces were analyzed and compared with Calypso traces from a previously treated similar patient cohort. To evaluate "natural motion" (ie, if we had not interrupted treatment and repositioned), intrafraction couch corrections were removed from all traces. Clinical effectiveness of the MV-kV system was explored by evaluating toxicity (Common Terminology Criteria for Adverse Events v3.0) and biochemical recurrence rates (nadir + 2 ng/mL).

RESULTS

Median number of interruptions for patient repositioning was 1 per fraction (range, 0-9). Median overall treatment time was 8.2 minutes (range, 4.2-44.8 minutes). Predominant motion was inferior and posterior, and probability of motion increased with time. Natural motion >3 mm and >5 mm in any direction was observed in 32.3% and 10.2% of fractions, respectively. Calypso monitoring (n = 50) demonstrated similar motion results. In the 151 MV-kV patients with ≥3-month follow-up (median, 9.5 months; range, 3-26.5 months), grade ≥2 acute genitourinary/gastrointestinal and late genitourinary/gastrointestinal toxicity was observed in 9.9%/2.0% and 11.9%/2.7%, respectively. Biochemical control was 99.3% with a single failure in a high-risk patient.

CONCLUSIONS

The MV-kV system is an effective method to manage intrafraction prostate motion during SBRT, offering the opportunity to correct for prostate clinical target volume displacements that would have otherwise extended beyond typical planning target volume margins.