[Moderately hypofractionated dose escalation radiotherapy for localized prostate cancer, ESHYPRO: Results of a retrospective single-centre series evaluating safety and efficacy]

PURPOSE

Prostate cancer is the most frequent cancer among men and radiotherapy hypofractionation regimens have become standard treatments for the localized stages, but the absence of increased risk of acute and late genitourinary or gastrointestinal toxicity of the dose escalation still must be demonstrated.

MATERIAL AND METHODS

The study population included all patients with localized prostatic adenocarcinoma treated at the institut Curie from February 2016 to March 2018 by external radiation delivered by a linear accelerator using an image-guided conformal intensity modulation technique at a total dose of 75Gy in 30 fractions of 2.5Gy in the planning target volume that included the prostate and the proximal seminal vesicles, and could be paired with a prophylactic lymph node radiotherapy at 46Gy in 23 fractions with simultaneous integrated boost.

RESULTS

A total of 166 patients were included. Among them, 68.6% were unfavourable intermediate or (very) high risk. The median age and follow-up were 71.4years and 3.96years. One hundred and forty-nine patients received prophylactic lymph node radiotherapy (89.8%). One hundred and thirty-one patients received hormonotherapy (78.9%). Genito-urinary toxicity events of grades 2 or above during radiotherapy, at 6months, 1year and 5years were respectively 36.7%, 8.8%, 3.1% and 4.7%. Two patients had late grade 4 toxicity at 5years (1.6%). Grade 2 gastrointestinal toxicity events during radiotherapy, 6months, 1year and 5years were respectively 15.1%, 1.9%, 14.6% and 9.3%. Of these, eight patients had grade 3 toxicity (6.2%). There was no grade 4 toxicity. Analyses did not reveal any predictive factor for toxicity. The 5-year overall, progression-free, and specific survival rates were respectively 82.4%, 85.7%, and 93.3%. Serum prostate specific antigen concentration and cardiovascular risk factors were found to be predictive factors of deterioration in overall survival (P=0.0028 for both).

CONCLUSION

External radiotherapy for localized prostatic cancer with our moderately hypofractionated dose escalation regimen is well tolerated. In the absence of increased late toxicity, the analysis of the modes of long-term relapses will be interesting to determine the benefit of this dose escalation on local and distant relapses.

A Personalized Clinical Dynamic Prediction Model to Characterize Prognosis for Patients With Localized Prostate Cancer: Analysis of the CHHiP Phase 3 Trial

PURPOSE

The CHHiP trial assessed moderately hypofractionated radiation therapy in localized prostate cancer. We utilized longitudinal prostate-specific antigen (PSA) measurements collected over time to evaluate and characterize patient prognosis.

METHODS AND MATERIALS

We developed a clinical dynamic prediction joint model to predict the risk of biochemical or clinical recurrence. Modeling included repeated PSA values and adjusted for baseline prognostic risk factors of age, tumor characteristics, and treatment received. We included 3071 trial participants for model development using a mixed-effect submodel for the longitudinal PSAs and a time-to-event hazard submodel for predicting recurrence of prostate cancer. We evaluated how baseline prognostic factor subgroups affected the nonlinear PSA levels over time and quantified the association of PSA on time to recurrence. We assessed bootstrapped optimism-adjusted predictive performance on calibration and discrimination. Additionally, we performed comparative dynamic predictions on patients with contrasting prognostic factors and investigated PSA thresholds over landmark times to correlate with prognosis.

RESULTS

Patients who developed recurrence had generally higher baseline and overall PSA values during follow-up and had an exponentially rising PSA in the 2 years before recurrence. Additionally, most baseline risk factors were significant in the mixed-effect and relative-risk submodels. PSA value and rate of change were predictive of recurrence. Predictive performance of the model was good across different prediction times over an 8-year period, with an overall mean area under the curve of 0.70, mean Brier score of 0.10, and mean integrated calibration index of 0.048; these were further improved for predictions after 5 years of accrued longitudinal posttreatment PSA assessments. PSA thresholds <0.23 ng/mL after 3 years were indicative of a minimal risk of recurrence by 8 years.

CONCLUSIONS

We successfully developed a joint statistical model to predict prostate cancer recurrence, evaluating prognostic factors and longitudinal PSA. We showed dynamically updated PSA information can improve prognostication, which can be used to guide follow-up and treatment management options.

Reducing the margin in prostate radiotherapy: optimizing radiotherapy with a general-purpose linear accelerator using an in-house position monitoring system

Purpose

To study the feasibility of optimizing the Clinical Target Volume to Planning Target Volume (CTV-PTV) margin in prostate radiotherapy(RT) with a general-purpose linear accelerator using an in-house developed position monitoring system, SeedTracker.

Methods

A cohort of 30 patients having definitive prostate radiotherapy treated within an ethics-approved prospective trial was considered for this study. The intrafraction prostate motion and the position deviations were measured using SeedTracker system during each treatment fraction. Using this data the CTV-PTV margin required to cover 90% of the patients with a minimum of 95% of the prescription dose to CTV was calculated using van Herk's formula. The margin calculations were performed for treatment scenarios both with and without applying the position corrections for observed position deviations. The feasibility of margin reduction with real-time monitoring was studied by assessing the delivered dose that incorporates the actual target position during treatment delivery and comparing it with the planned dose. This assessment was performed for plans generated with reduced CTV-PTV margin in the range of 7mm-3mm.

Results

With real-time monitoring and position corrections applied the margin of 2.0mm, 2.1mm and 2.1mm in LR, AP and SI directions were required to meet the criteria of 90% population to receive 95% of the dose prescription to CTV. Without position corrections applied for observed position deviations a margin of 3.1mm, 4.0mm and 3.0mm was required in LR, AP and SI directions to meet the same criteria. A mean ± SD reduction of 0.5 ± 1.8% and 3 ± 7% of V60 for the rectum and bladder can be achieved for every 1mm reduction of PTV margin. With position corrections applied, the CTV D99 can be delivered within -0.2 ± 0.3 Gy of the planned dose for plans with a 3mm margin. Without applying corrections for position deviations the CTV D99 was reduced by a maximum of 1.1 ± 1.1 Gy for the 3mm margin plan and there was a statistically significant difference between planned and delivered dose for 3mm and 4mm margin plans.

Conclusion

This study demonstrates the feasibility of reducing the margin in prostate radiotherapy with SeedTracker system without compromising the dose delivery accuracy to CTV while reducing dose to critical structures.

Neighborhood Deprivation and Rurality Associated With Patient-Reported Outcomes and Survival in Men With Prostate Cancer in NRG Oncology RTOG 0415

PURPOSE

Rurality and neighborhood deprivation can contribute to poor patient-reported outcomes, which have not been systematically evaluated in patients with specific cancers in national trials. Our objective was to examine the effect of rurality and neighborhood socioeconomic and environmental deprivation on patient-reported outcomes and survival in men with prostate cancer in NRG Oncology RTOG 0415.

METHODS AND MATERIALS

Data from men with prostate cancer in trial NRG Oncology RTOG 0415 were analyzed; 1,092 men were randomized to receive conventional radiation therapy or hypofractionated radiation therapy. Rurality was categorized as urban or rural. Neighborhood deprivation was assessed using the area deprivation index and air pollution indicators (nitrogen dioxide and particulate matter with a diameter less than 2.5 micrometers) via patient ZIP codes. Expanded Prostate Cancer Index Composite measured cancer-specific quality of life. The Hopkins symptom checklist measured anxiety and depression. EuroQoL-5 Dimension assessed general health.

RESULTS

We analyzed 751 patients in trial NRG Oncology RTOG 0415. At baseline, patients from the most deprived neighborhoods had worse bowel (P = .011), worse sexual (P = .042), and worse hormonal (P = .015) scores; patients from the most deprived areas had worse self-care (P = .04) and more pain (P = .047); and patients from rural areas had worse urinary (P = .03) and sexual (P = .003) scores versus patients from urban areas. Longitudinal analyses showed that the 25% most deprived areas (P = .004) and rural areas (P = .002) were associated with worse EuroQoL-5 Dimension visual analog scale score. Patients from urban areas (hazard ratio, 1.81; P = .033) and the 75% less-deprived neighborhoods (hazard ratio, 0.68; P = .053) showed relative decrease in risk of recurrence or death (disease-free survival).

CONCLUSIONS

Patients with prostate cancer from the most deprived neighborhoods and rural areas had low quality of life at baseline, poor general health longitudinally, and worse disease-free survival. Interventions should screen populations from deprived neighborhoods and rural areas to improve patient access to supportive care services.

Consensus Quality Measures and Dose Constraints for Prostate Cancer From the Veterans Affairs Radiation Oncology Quality Surveillance Program and American Society for Radiation Oncology Expert Panel

PURPOSE

There are no agreed upon measures to comprehensively determine the quality of radiation oncology (RO) care delivered for prostate cancer. Consequently, it is difficult to assess the implementation of scientific advances and adherence to best practices in routine clinical practice. To address this need, the US Department of Veterans Affairs (VA) National Radiation Oncology Program established the VA Radiation Oncology Quality Surveillance (VA ROQS) Program to develop clinical quality measures to assess the quality of RO care delivered to Veterans with cancer. This article reports the prostate cancer consensus measures.

METHODS AND MATERIALS

The VA ROQS Program contracted with the American Society for Radiation Oncology to commission a Blue Ribbon Panel of prostate cancer experts to develop a set of evidence-based measures and performance expectations. From February to June 2021, the panel developed quality, aspirational, and surveillance measures for (1) initial consultation and workup, (2) simulation, treatment planning, and delivery, and (3) follow-up. Dose-volume histogram (DVH) constraints to be used as quality measures for definitive and post-prostatectomy radiation therapy were selected. The panel also identified the optimal Common Terminology Criteria for Adverse Events, version 5.0 (CTCAE V5.0), toxicity terms to assess in follow-up.

RESULTS

Eighteen prostate-specific measures were developed (13 quality, 2 aspirational, and 3 surveillance). DVH metrics tailored to conventional, moderately hypofractionated, and ultrahypofractionated regimens were identified. Decision trees to determine performance for each measure were developed. Eighteen CTCAE V5.0 terms were selected in the sexual, urinary, and gastrointestinal domains as highest priority for assessment during follow-up.

CONCLUSIONS

This set of measures and DVH constraints serves as a tool for assessing the comprehensive quality of RO care for prostate cancer. These measures will be used for ongoing quality surveillance and improvement among veterans receiving care across VA and community sites. These measures can also be applied to clinical settings outside of those serving veterans.

Long-term outcomes of prostate intensity-modulated radiation therapy incorporating a simultaneous intra-prostatic MRI-directed boost

Purpose/objectives

This retrospective study demonstrates the long-term outcomes of treating prostate cancer using intensity modulated (IMRT) with incorporation of MRI-directed boost.

Materials/methods

From February 2009 to February 2013, 78 men received image-guided IMRT delivering 77.4 Gy in 44 fractions with simultaneously integrated boost to 81-83 Gy to an MRI-identified lesion. Patients with intermediate-risk or high-risk prostate cancer were recommended to receive 6 and 24-36 months of adjuvant hormonal therapy, respectively.

Results

Median follow-up was 113 months (11-147). There were 18 low-risk, 43 intermediate-risk, and 17 high-risk patients per NCCN risk stratification included in this study. Adjuvant hormonal therapy was utilized in 32 patients (41%). The 10-year biochemical control rate for all patients was 77%. The 10-year biochemical control rates for low-risk, intermediate-risk, and high-risk diseases were 94%, 81%, and 88%, respectively (p = 0.35). The 10-year rates of local control, distant control, and survival were 99%, 88%, and 66%, respectively. Of 25 patients who died, only four (5%) died of prostate cancer. On univariate analysis, T-category and pretreatment PSA level were associated with distant failure rate (p = 0.02). There was no grade =3 genitourinary and gastrointestinal toxicities that persisted at the last follow-up.

Conclusions

This study demonstrated the long-term efficacy of using MRI to define an intra-prostatic lesion for SIB to 81-83Gy while treating the entire prostate gland to 77.4 Gy with IMRT. Our study confirms that modern MRI can be used to locally intensify dose to prostate tumors providing high long-term disease control while maintaining favorable long-term toxicity.

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 Dmean ≥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.

Comparison of outcomes of radiotherapy-treated localized prostate cancer patients within a clinical trial setting versus real-life setting

AIM

To assess whether clinical trial participation affects survival outcomes of radiotherapy-treated localized prostate cancer patients compared with similar treatment within a real-world setting.

METHODS

This is a comparative analysis of the outcomes of localized prostate cancer patients treated within two clinical trials (NCT00331773; NCT00004054) versus the outcomes of similar cohorts of patients registered within the SEER database and treated with radiotherapy. Propensity score matching was conducted to account for heterogeneity in background patient information. Within the postmatching cohort, Kaplan-Meier survival according to treatment setting was reconducted. Moreover, an assessment of the impact of treatment setting on overall survival (OS) was conducted in a multivariate Cox regression model adjusted for age, race, ethnicity, T-stage, PSA and Gleason score.

RESULTS

A total of 5209 low-risk patients and 2115 high-risk patients were included in the current analysis. For both low- and high-risk disease, Kaplan-Meier analysis for OS in the postmatching cohort did not show any difference in OS between patients treated within clinical trial setting versus patients treated within SEER database (p = 0.176; p = 0.097; respectively). Likewise in multivariate Cox regression analysis, treatment context (clinical trial vs SEER) does not affect OS for either low- or high-risk disease (p = 0.470; p = 0.412; respectively).

CONCLUSION

After accounting for possible confounders in baseline characteristics, there was no conclusive evidence of a survival difference between localized prostate cancer patients treated with external beam radiotherapy within routine, real-world settings compared with patients treated within clinical trials.

Moderately hypofractionated prostate external-beam radiotherapy: an emerging standard

Research over recent years has demonstrated that curative external-beam radiotherapy can be safely and efficaciously delivered with roughly half the number of treatments which was previously considered standard. We review the data supporting this change in practice, methods for implementation, as well as emerging future directions.

Prostate Cancer: Improving the Flow of Research

Prostate cancer is the most common nonskin cancer diagnosed in U.S. men and kills over 27 000 men annually. Thus, improving the outcomes for patients diagnosed with this disease is imperative. There has been a considerable amount of research done over the past several decades resulting in more cures than ever, but the death rate is still unacceptable. This oration addresses the progress that we have made over the past several decades and outlines the work yet to be done, as well as some processes to make that work happen. ^© RSNA, 2018.

Advances in Radiotherapy for Prostate Cancer Treatment

Major categories of radiotherapy (RT) for prostate cancer (CaP) treatment are: (1) external beam RT (EBRT), and (2) brachytherapy (BT). EBRT are performed using different techniques like three-dimensional conformal RT (3D-CRT), intensity modulated RT (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiation therapy (SBRT), stereotactic radiosurgery (SRS) and intensity modulated proton therapy (IMPT), etc., using a variety of radiation delivery machines, such as a linear accelerator (Linac), Cyberknife robotic system, Gamma knife, Tomotherapy and proton beam machine. The primary advantage of proton beam therapy is sparing of normal tissues and organ at risks (OARs) with comparable coverage of the tumor volume. MR-Linac is the latest addition in the image-guided RT. Robot-assisted brachytherapy is one of the latest technological innovations in the field. With the advancement of technology, radiation therapy for prostate cancer can be improved using high quality multimodal imaging, robot-assistance for brachytherapy as well as EBRT. This chapter presents the advances in radiation therapy for the treatment of prostate cancer.