Hypofractionated Radiation Therapy for Localized Prostate Cancer: An ASTRO, ASCO, and AUA Evidence-Based Guideline

Overview of Radiation Therapy in the Management of Localized and Metastatic Prostate Cancer

PURPOSE OF REVIEW

The goal is to describe the evolution of radiation therapy (RT) utilization in the management of localized and metastatic prostate cancer.

RECENT FINDINGS

Long term data for a variety of hypofractionated definitive RT dose-fractionation schemes has matured, allowing patients and providers many standard-of-care options to choose from. Post-prostatectomy, adjuvant RT has largely been replaced by an early salvage approach. Multiparametric MRI and PSMA PET have enabled increasingly targeted RT delivery to the prostate and oligometastatic tumors. Areas of active investigation include determining the value of proton beam therapy and perirectal spacers, and optimally incorporate genomic tumor profiling and next generation hormonal therapies with RT in the curative setting. The use of radiation therapy to treat prostate cancer is rapidly evolving. In the coming years, there will be continued improvements in a variety of areas to enhance the value of RT in multidisciplinary prostate cancer management.

Histology-driven hypofractionated radiation therapy schemes for early-stage lung adenocarcinoma and squamous cell carcinoma

BACKGROUND AND PURPOSE

Histology was found to be an important prognostic factor for local tumor control probability (TCP) after stereotactic body radiotherapy (SBRT) of early-stage non-small-cell lung cancer (NSCLC). A histology-driven SBRT approach has not been explored in routine clinical practice and histology-dependent fractionation schemes remain unknown. Here, we analyzed pooled histologic TCP data as a function of biologically effective dose (BED) to determine histology-driven fractionation schemes for SBRT and hypofractionated radiotherapy of two predominant early-stage NSCLC histologic subtypes adenocarcinoma (ADC) and squamous cell carcinoma (SCC).

MATERIAL AND METHODS

The least-χ2 method was used to fit the collected histologic TCP data of 8510 early-stage NSCLC patients to determine parameters for a well-developed radiobiological model per the Hypofractionated Treatment Effects in the Clinic (HyTEC) initiative.

RESULTS

A fit to the histologic TCP data yielded independent radiobiological parameter sets for radiotherapy of early-stage lung ADC and SCC. TCP increases steeply with BED and reaches an asymptotic maximal plateau, allowing us to determine model-independent optimal fractionation schemes of least doses in 1-30 fractions to achieve maximal tumor control for early-stage lung ADC and SCC, e.g., 30, 44, 48, and 51 Gy for ADC, and 32, 48, 54, and 58 Gy for SCC in 1, 3, 4, and 5 fractions, respectively.

CONCLUSION

We presented the first determination of histology-dependent radiobiological parameters and model-independent histology-driven optimal SBRT and hypofractionated radiation therapy schemes for early-stage lung ADC and SCC. SCC requires substantially higher radiation doses to maximize tumor control than ADC, plausibly attributed to tumor genetic diversity and microenvironment. The determined optimal SBRT schemes agree well with clinical practice for early-stage lung ADC. These proposed optimal fractionation schemes provide first insights for histology-based personalized radiotherapy of two predominant early-stage NSCLC subtypes ADC and SCC, which require further validation with large-scale histologic TCP data.

Postoperative Hypofractionated Intensity-Modulated Radiotherapy With Concurrent Chemotherapy in Cervical Cancer: The POHIM-CCRT Nonrandomized Controlled Trial

Importance

Prospective data assessing the safety of hypofractionated (40 Gy in 16 fractions) radiotherapy (RT) among patients who receive postoperative concurrent chemoradiotherapy for cervical cancer are lacking.

Objective

To evaluate the acute toxic effects of hypofractionated pelvic intensity-modulated radiotherapy (IMRT) with concurrent chemotherapy among women with cervical cancer who underwent radical hysterectomy.

Design, Setting, and Participants

The POHIM-CCRT (Postoperative Hypofractionated Intensity-Modulated Radiation Therapy With Concurrent Chemotherapy in Cervical Cancer) study was designed as a multicenter, phase 2 nonrandomized controlled trial that accrued and followed up patients from June 1, 2017, to February 28, 2023. In total, 84 patients were enrolled from 5 institutions affiliated with the Korean Radiation Oncology Group. Eligible patients experienced lymph node metastasis, parametrial invasion, or positive resection margins after radical hysterectomy for treatment of confirmed cervical cancer.

Intervention

Postoperative pelvic radiation using hypofractionated IMRT with 40 Gy in 16 fractions to the whole pelvis combined with concurrent chemotherapy.

Main Outcomes and Measures

The primary end point was incidence of acute grade 3 or higher gastrointestinal tract, genitourinary, and hematologic toxic effects (based on the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0) in the evaluable population during RT or within 3 months after RT completion.

Results

Of 84 patients enrolled, 5 dropped out prior to RT, and data from 79 patients were analyzed. The patients' median (IQR) age was 48 (42-58) years, and the median (IQR) tumor size was 3.7 (2.7-4.5) cm. Of these patients, 31 (39.7%) had lymph node metastasis, 4 (5.1%) had positive resection margins, and 43 (54.4%) had parametrial invasion. Grade 3 or higher acute toxic effects occurred in 2 patients (2.5% [90% CI, 0%-4.8%]). After a median (IQR) follow-up of 43.0 (21.1-59.0) months, the 3-year disease-free survival rate was 79.3%, and the overall survival rate was 98.0%.

Conclusions

Findings from this nonrandomized control trial indicated that postoperative pelvic irradiation combined with concurrent chemotherapy using hypofractionated IMRT with 40 Gy in 16 fractions was safe and well-tolerated in women with cervical cancer. Studies assessing long-term toxic effects and oncological outcomes with longer follow-up periods are needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT03239613.

The impact of advancing the standard of care in radiotherapy on operational treatment resources

PURPOSE

To demonstrate the impact of implementing hypofractionated prescription regimens and advanced treatment techniques on institutional operational hours and radiotherapy personnel resources in a multi-institutional setting. The study may be used to describe the impact of advancing the standard of care with modern radiotherapy techniques on patient and staff resources.

METHODS

This study uses radiation therapy data extracted from the radiotherapy information system from two tertiary care, university-affiliated cancer centers from 2012 to 2021. Across all patients in the analysis, the average fraction number for curative and palliative patients was reported each year in the decade. Also, the institutional operational treatment hours are reported for both centers. A sub-analysis for curative intent breast and lung radiotherapy patients was performed to contextualize the impact of changes to imaging, motion management, and treatment technique.

RESULTS

From 2012 to 2021, Center 1 had 42 214 patient plans and Center 2 had 43 252 patient plans included in the analysis. Averaged over both centers across the decade, the average fraction number per patient decreased from 6.9 to 5.2 (25%) and 21.8 to 17.2 (21%) for palliative and curative patients, respectively. The operational treatment hours for both institutions increased from 8 h 15 min to 9 h 45 min (18%), despite a patient population increase of 45%.

CONCLUSION

The clinical implementation of hypofractionated treatment regimens has successfully reduced the radiotherapy workload and operational treatment hours required to treat patients. This analysis describes the impact of changes to the standard of care on institutional resources.

Image-guided moderately hypofractionated radiotherapy for localized prostate cancer: a multicentric retrospective study (IPOPROMISE)

BACKGROUND

Moderate hypofractionated radiotherapy is a treatment option for the cure of localized prostate cancer (PCa) patients based on the results of randomized prospective trials, but there is a clinical concern about the relatively short length of follow-up, and real-world results on outcome and toxicity based on cutting-edge techniques are lacking. The objective of this study is to present the long-term results of a large multicentric series.

MATERIALS AND METHODS

We retrospectively evaluated 1325 PCa patients treated with daily volumetric image-guided hypofractionated radiotherapy between 2007 and 2020 in 16 Centers. For survival endpoints, we used Kaplan-Meier survival curves and fitted univariate and multivariable Cox's proportional hazards regression models to study the association between the clinical variables and each survival type.

RESULTS

At the end of the follow-up, 11 patients died from PCa. The 15-year values of cancer-specific survival (CSS) and biochemical relapse-free survival (b-RFS) were 98.5% (95%CI 97.3-99.6%) and 85.5% (95%CI 81.9-89.4%), respectively. The multivariate analysis showed that baseline PSA, Gleason score, and the use of androgen deprivation therapy were significant variables for all the outcomes. Acute gastrointestinal (GI) and genitourinary (GU) toxicities of grade ≥ 2 were 7.0% and 16.98%, respectively. The 15-year late grade ≥ 2 GI and GU toxicities were 5% (95%CI 4-6%) and 6% (95%CI 4-8%), respectively.

CONCLUSION

Real-world long-term results of this multicentric study on cutting-edge techniques for the cure of localized PCa demonstrated an excellent biochemical-free survival rate of 85.5% at 15 years, and very low rates of ≥ G3 late GU and GI toxicity (1.6% and 0.9% respectively), strengthening the results of the available published trials.

Safety of Ultrahypofractionated Pelvic Nodal Irradiation in the Definitive Management of Prostate Cancer: Systematic Review and Meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the evidence for ultrahypofractionated pelvic nodal irradiation in patients with prostate cancer, with a focus on reported acute and late toxicities.

METHODS AND MATERIALS

A comprehensive search was conducted in 5 electronic databases (PubMed, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov) from inception until March 23, 2023. Eligible publications included patients with intermediate- and high-risk and node-positive prostate cancer who underwent elective or therapeutic ultrahypofractionated pelvic nodal irradiation. Primary outcomes included the presence of grade ≥2 rates of acute and late gastrointestinal and genitourinary toxicity based on the Common Terminology Criteria for Adverse Events or Radiation Therapy Oncology Group scales. Quality assessment was performed using National Institutes of Health tools for noncontrolled beforeand after (single arm) clinical trials, as well as single-arm observational studies. Because all outcomes were categorical variables, proportion was calculated to estimate the effect size and compare the outcomes after the intervention.

RESULTS

We identified 16 publications that reported the use of ultrahypofractionated radiation therapy to treat the pelvis in prostate cancer. Seven publications met our criteria and were included in the meta-analysis, including 417 patients. The median total dose to the pelvic lymph nodes was 25 Gy (range, 25-28.5 Gy), with a median of 5 fractions. The prostate received a median dose of 40 Gy (range, 35-47.5 Gy). All studies used androgen deprivation therapy for a median duration of 18 months. The median follow-up period was 3 years (range, 0.5-5.6 years). The rates of acute grade ≥2 gastrointestinal and genitourinary toxicity were 8% (95% CI, 1%-15%) and 29% (95% CI, 18%-41%), respectively. For late grade ≥2 gastrointestinal and genitourinary toxicity, the rates were 13% (95% CI, 5%-21%) and 29% (95% CI, 17%-42%), respectively.

CONCLUSIONS

Ultrahypofractionated pelvic nodal irradiation appears to be a safe approach in terms of acute and late genitourinary and gastrointestinal toxicity.

Assessing the toxicity after moderately hypofractionated prostate and whole pelvis radiotherapy compared to conventional fractionation

OBJECTIVE

To evaluate acute and late gastrointestinal (GI) and genitourinary (GU) toxicities after moderately hypofractionated (HF) or conventionally fractionated (CF) primary whole-pelvis radiotherapy (WPRT).

METHODS

Primary prostate-cancer patients treated between 2009 and 2021 with either 60 Gy at 3 Gy/fraction to the prostate and 46 Gy at 2.3 Gy/fraction to the whole pelvis (HF), or 78 Gy at 2 Gy/fraction to the prostate and 50/50.4 Gy at 1.8-2 Gy/fraction to the whole pelvis (CF). Acute and late GI and GU toxicities were retrospectively assessed.

RESULTS

106 patients received HF and 157 received CF, with a median follow-up of 12 and 57 months. Acute GI toxicity rates in the HF and CF groups were, respectively, grade 2: 46.7% vs. 37.6%, and grade 3: 0% vs. 1.3%, with no significant difference (p = 0.71). Acute GU toxicity rates were, respectively, grade 2: 20.0% vs. 31.8%, and grade 3: 2.9% vs. 0%, (p = 0.04). We compared prevalence of late GI and GU toxicities between groups after 3, 12, and 24 months and did not find any significant differences (respectively, p = 0.59, 0.22, and 0.71 for GI toxicity; p = 0.39, 0.58, and 0.90 for GU toxicity).

CONCLUSION

Moderate HF WPRT was well tolerated during the first 2 years. Randomized trials are needed to confirm these findings.

Long term update on toxicity and survival of a phase II trial of linac-based stereotactic body radiation therapy for low-intermediate risk prostate cancer

BACKGROUND

In 2016 we published a phase II study exploring safety and efficacy of Stereotactic Body Radiation Therapy (SBRT) delivered with Volumetric Modulated Arc Therapy (VMAT) and Flattening Filter Free (FFF) beams techniques in prostate cancer (PC) patients. We present herein the updated results on late toxicity and long-term survival.

METHODS

Patients enrolled in the study had a biopsy-confirmed localized PC and the features of a low- or intermediate-risk disease (National Comprehensive Network Criteria). The radiotherapy (RT) schedule consisted of 35 Gy delivered in five fractions every other day. Toxicities were registered according to the common toxicity adverse events v4.0. Biochemical recurrence was defined as an increase of prostate specific antigen after nadir, confirmed at least once. Local recurrence (LR) and distant metastases were detected either with Choline- or PSMA-PET/CT scans. Kaplan-Meier curves for Biochemical Recurrence-Free Survival (BFS), Local Control (LC), Distant Metastasis Free Survival (DMFS) and Cancer Specific Survival, were calculated by using MedCalc.

RESULTS

Ninety patients were submitted to SBRT between February 2012 and March 2015. Fifty-eight patients (64.5%) had a Gleason Score of 6, while 32 (35.5%) had a Gleason Score of 7. A late grade 1 Genito-Urinary toxicity was observed in 54.5% of patients while a grade 2 in 3.3%. A late Gastro-intestinal grade 1 toxicity was reported in 18.9% of patients, while a grade 2 in 2.2%. Erectile dysfunction was reported by 13% of patients No heavier toxicities were observed. At a median follow-up of 102 months, 5- and 8-year BFS were 93.0% and 84.4% respectively, 5- and 8-year LC were 95.2% and 87.0% respectively, 5- and 8-year DMFS were 95.3% and 88.4%, respectively.

CONCLUSIONS

This long-term update confirms that SBRT is a valid therapeutic strategy for low-intermediate risk PC. RT with VMAT and FFF warrants optimal results in terms of toxicity and disease control.

Variation in communication of side effects in prostate cancer treatment consultations

BACKGROUND

Effective communication of treatment side effects (SE) is critical for shared decision-making (SDM) in localized prostate cancer. We sought to qualitatively characterize how physicians communicate SE in consultations.

METHODS

We transcribed 50 initial prostate cancer treatment consultations across nine multidisciplinary providers (Urologists, Radiation Oncologists, Medical Oncologists) at our tertiary referral, academic center. Coders identified quotes describing SE and used an inductive approach to establish a hierarchy for granularity of communication: (1) not mentioned, (2) name only, (3) generalization("high"), (4) average incidence without timepoint, (5) average incidence with timepoint, and (6) precision estimate. We reported the most granular mode of communication for each SE throughout the consultation overall and across specialty and tumor risk.

RESULTS

Among consultations discussing surgery (n = 40), erectile dysfunction (ED) and urinary incontinence (UI) were omitted in 15% and 12%, not quantified (name only or generalization) in 47% and 30%, and noted as average incidence without timeline in 8% and 8%, respectively. In only 30% and 49% were ED and UI quantified with timeline (average incidence with timeline or precision estimate), respectively. Among consultations discussing radiation (n = 36), irritative urinary symptoms, ED, and other post-radiotherapy SE were omitted in 22%, 42%, and 64-67%, not quantified in 61%, 33%, and 23-28%, and noted as average incidence without timeline in 8%, 22%, and 6-8%, respectively. In only 3-8% were post-radiotherapy SE quantified with timeline. Specialty concordance (but not tumor risk) was associated with higher granularity of communication, though physicians frequently failed to quantify specialty-concordant SE.

CONCLUSIONS

SE was often omitted, not quantified, and/or lacked a timeline in treatment consultations in our sample. Physicians should articulate, quantify, and assign a timeline for SE to optimize SDM.

Quality of Decision Making in Radiation Oncology

High-quality decision making in radiation oncology requires the careful consideration of multiple factors. In addition to the evidence-based indications for curative or palliative radiotherapy, this article explores how, in routine clinical practice, we also need to account for many other factors when making high-quality decisions. Foremost are patient-related factors, including preference, and the complex interplay between age, frailty and comorbidities, especially with an ageing cancer population. Whilst clinical practice guidelines inform our decisions, we need to account for their applicability in different patient groups and different resource settings. With particular reference to curative-intent radiotherapy, we explore decisions regarding dose fractionation schedules, use of newer radiotherapy technologies and multimodality treatment considerations that contribute to personalised patient-centred care.

Long-Term Outcomes Following Fairly Brief Androgen Suppression and Stereotactic Radiation Therapy in High-Risk Prostate Cancer: Update From the FASTR/FASTR-2 Trials

PURPOSE

There is limited data on the long-term outcomes of ultrahypofractionated radiation therapy in high-risk prostate cancer. The FASTR and FASTR-2 trials were designed to assess the tolerability of stereotactic ablative radiation therapy (SABR) in this context. Herein, the long-term results are reported.

METHODS AND MATERIALS

Eligible patients had localized high-risk prostate cancer and were either ≥70 years old, had a score of ≥3 on the Vulnerable Elderly Scale, or declined standard therapy. Nineteen patients from a single institution were enrolled on FASTR between 2011 and 2015. They received 40 Gy to the prostate and 25 Gy to the pelvic lymph nodes in 5 weekly fractions, with 12 months of androgen deprivation therapy (ADT). Thirty patients from the same institution were enrolled on FASTR-2 between 2015 and 2017. They received 35 Gy to the prostate alone in 5 weekly fractions, with 18 months of ADT. Updated toxicity and outcomes were assessed retrospectively. Kaplan-Meier estimates were calculated for biochemical failure-free survival, freedom from distant metastases, prostate cancer-specific survival, and overall survival.

RESULTS

Forty-four patients were eligible for analysis, 16 from FASTR and 28 from FASTR-2. Thirty-four patients (77%) were >70 years old. High-risk features included Gleason score ≥8 (n = 20, 46%), T3-T4 disease (n = 12, 27%), and baseline prostate-specific antigen > 20 (n = 22, 50%). Median follow-up was 6.4 years. The 5-year cumulative incidence of late grade ≥3 genitourinary/gastrointestinal toxicity was 32% in FASTR and 11% in FASTR-2. At 5 years, the combined rates of biochemical failure-free survival, freedom from distant metastases, prostate cancer-specific survival, and overall survival were 72%, 90%, 92%, and 83%, respectively.

CONCLUSIONS

SABR can be safely delivered in high-risk prostate cancer by optimizing technical delivery, particularly with adherence to strict dose constraints for organs at risk. The clinical outcomes in FASTR and FASTR-2 were largely comparable to more standard fractionation schemes plus ADT, but further modifications may improve disease control. Larger randomized trials are necessary to better understand the efficacy and tolerability of this approach.

The march toward single-fraction stereotactic body radiotherapy for localized prostate cancer-Quo Vadimus?

PURPOSE

Stereotactic body radiotherapy (SBRT) is an emerging treatment option for localized prostate cancer. There is increasing interest to reduce the number of fractions for prostate SBRT.

METHODS

We provide a narrative review and summary of prospective trials of different fractionation schedules for prostate SBRT, focusing on efficacy, toxicities, and quality of life outcomes.

RESULTS

There are two randomized phase 3 trials comparing standard external beam radiotherapy with ultra-hypofractionated radiotherapy. HYPO-RT-PC compared 78 Gy in 39 fractions vs 42.7 Gy in 7 fractions (3D-CRT or IMRT) showing non-inferiority in 5-year biochemical recurrence-free survival and equivalent tolerability. PACE-B trial compared 78 Gy in 39-fraction or 62 Gy in 20-fraction vs 36.25 Gy in 5-fraction prostate SBRT, with no significant differences in toxicity outcomes at 2 years. Five-year efficacy data for PACE-B are expected in 2024. Five-fraction prostate SBRT is currently the most common and well-established fractionation schedule with multiple prospective phase 2 trials published to date. There is more limited data on 1-4 fraction prostate SBRT. All fractionation schedules had acceptable toxicity outcomes. Experience from a high-dose-rate brachytherapy randomized trial showed inferior efficacy with single-fraction compared to two-fraction brachytherapy. Hence, caution should be applied in adopting single-fraction prostate SBRT.

CONCLUSION

Two-fraction SBRT is likely the shortest fractionation schedule that maintains the therapeutic ratio. Several randomized trials currently recruiting will likely provide us with more definite answers about whether two-fraction prostate SBRT should become a standard-of-care option. Enrollment of eligible patients into these trials should be encouraged.

Long-Term Outcomes of a Prospective Study on Highly Hypofractionated Intensity Modulated Radiation Therapy for Localized Prostate Cancer for 3 Weeks

PURPOSE

Reports of radiation therapy for prostate cancer using dose fractions between moderate hypofractionation and ultrahypofractionation are limited. This pilot study involved the application of highly hypofractionated intensity modulated radiation therapy (IMRT) in 15 fractions for 3 weeks and the number of fractions was intermediate between the 2 previously mentioned dose fractions. The long-term outcomes are reported.

METHODS AND MATERIALS

From April 2014 to September 2015, patients with low- to intermediate-risk prostate cancer received 54 Gy in 15 fractions (3.6 Gy per fraction) for 3 weeks using IMRT without intraprostatic fiducial markers or a rectal hydrogel spacer. Neoadjuvant hormone therapy (HT) was administered for 4 to 8 months. Adjuvant HT was not administered to any patients. Rates of biochemical relapse-free survival, clinical relapse-free survival, overall survival, and the cumulative incidence of late grade ≥2 toxicities were analyzed.

RESULTS

Twenty-five patients were enrolled in this prospective study; 24 of them were treated with highly hypofractionated IMRT (17% had low-risk and 83% had intermediate-risk disease). The median neoadjuvant HT duration was 5.3 months. The median follow-up period was 77 months (range, 57-87 months). Biochemical relapse-free survival, clinical relapse-free survival, and overall survival rates were 91.7%, 95.8%, and 95.8% at 5 years, and 87.5%, 86.3%, and 95.8% at 7 years, respectively. Neither grade ≥2 late gastrointestinal toxicity nor grade ≥3 late genitourinary toxicity was observed. The cumulative incidence rates of grade 2 genitourinary toxicity were 8.5% and 18.3% at 5 and 7 years, respectively.

CONCLUSIONS

Highly hypofractionated IMRT delivering 54 Gy in 15 fractions for 3 weeks for prostate cancer without intraprostatic fiducial markers facilitated favorable oncological outcomes without severe complications. This treatment approach may be a possible alternative to moderate hypofractionation, but further validation is needed.

Challenges and Opportunities With the Use of Hypofractionated Radiation Therapy in Cancer Care: Regional Perspectives From South Korea, Japan, Singapore, and Australia

Hypofractionated radiotherapy schedules provide higher per-fraction radiation doses delivered in fewer fractions than conventional schedules. This novel delivery method is supported by a large body of clinical trial evidence across various cancer sites in both curative and palliative settings. Hypofractionation is associated with benefits such as lower costs, improved patient access and increased treatment precision, which has led to its inclusion in various treatment guidelines. Despite this, utilization is not uniform across cancer sites and geographic regions due to reasons such as reimbursement models, nuances in healthcare systems, and professional culture. Key factors to ensure patients benefit from access to high quality radiotherapy include publishing clinical evidence, cross-country collaboration to fill knowledge gaps, reviewing reimbursement models, and improving patient advocacy in treatment decision-making.

From once-weekly to semi-weekly whole prostate gland stereotactic radiotherapy with focal boosting: Primary endpoint analysis of the multicenter phase II hypo-FLAME 2.0 trial

BACKGROUND AND PURPOSE

The hypo-FLAME trial showed that once-weekly (QW) focal boosted prostate stereotactic body radiotherapy (SBRT) is associated with acceptable acute genitourinary (GU) and gastrointestinal (GI) toxicity. Currently, we investigated the safety of reducing the overall treatment time (OTT) of focal boosted prostate SBRT from 29 to 15 days.

MATERIAL AND METHODS

Patients with intermediate- and high-risk prostate cancer were treated with SBRT delivering 35 Gy in 5 fractions to the whole prostate gland with an iso-toxic boost up to 50 Gy to the intraprostatic lesion(s) in a semi-weekly (BIW) schedule. The primary endpoint was radiation-induced acute toxicity (CTCAE v5.0). Changes in quality of life (QoL) were examined in terms of proportions achieving a minimal clinically important change (MCIC). Finally, acute toxicity and QoL scores of the BIW schedule were compared with the results of the prior QW hypo-FLAME schedule (n = 100).

RESULTS

Between August 2020 and February 2022, 124 patients were enrolled and treated BIW. No grade ≥3 GU or GI toxicity was observed. The 90-days cumulative incidence of grade 2 GU and GI toxicity rates were 47.5% and 7.4%, respectively. Patients treated QW scored significant less grade 2 GU toxicity (34.0%, p = 0.01). No significant differences in acute GI toxicity were observed. Furthermore, patients treated QW had a superior acute bowel and urinary QoL.

CONCLUSION

Semi-weekly prostate SBRT with iso-toxic focal boosting is associated with acceptable acute GU and GI toxicity. Based on the comparison between the QW and BIW schedule, patients should be counselled regarding the short-term advantages of a more protracted schedule. Registration number ClinicalTrials.gov: NCT04045717.

Hypofractionated Radiotherapy in Localized, Low-Intermediate-Risk Prostate Cancer: Current and Future Prospectives

At the time of diagnosis, the vast majority of prostate carcinoma patients have a clinically localized form of the disease, with most of them presenting with low- or intermediate-risk prostate cancer. In this setting, various curative-intent alternatives are available, including surgery, external beam radiotherapy and brachytherapy. Randomized clinical trials have demonstrated that moderate hypofractionated radiotherapy can be considered as a valid alternative strategy for localized prostate cancer. High-dose-rate brachytherapy can be administered according to different schedules. Proton beam radiotherapy represents a promising strategy, but further studies are needed to make it more affordable and accessible. At the moment, new technologies such as MRI-guided radiotherapy remain in early stages, but their potential abilities are very promising.

Treatment outcomes of simultaneous integrated boost to intraprostatic lesions with external beam radiotherapy in localized prostate cancer patients

BACKGROUND

To evaluate the treatment outcomes and toxicity of definitive radiotherapy (RT) for prostate cancer (PC) patients using the simultaneous integrated boost (SIB) technique, which delivered 78 Gy to the entire prostate and 86 Gy to the intraprostatic lesion (IPL) in 39 fractions.

MATERIALS AND METHODS

Univariable and multivariable analyses were conducted of the prognostic factors for freedom from biochemical failure (FFBF), progression-free survival (PFS), and PC-specific survival (PCSS) of 619 PC patients who received definitive RT between September 2012 and August 2021. Predictors of late Grade ≥2 genitourinary (GU) and gastrointestinal (GI) toxicities were also identified using logistic regression.

RESULTS

The median follow-up for entire cohort was 68.5 months. The 5-year FFBF, PFS, and PCSS rates were 93.2%, 83.2%, and 98.6%, respectively. They were predicted by the serum prostate-specific antigen, Gleason score (GS), clinical nodal stage, and D'Amico risk group. Only 45 patients (7.3%) developed disease recurrence 41.9 months after RT. The 5-year FFBF rates for low-, intermediate-, and high-risk disease were 98.0%, 93.1%, and 88.5%, respectively (p < 0.001). The 5-year PFS and PCSS rates according to risk groups were 91.0%, 82.1%, and 77.4% (p < 0.001), and 99.2%, 96.4%, and 95.9% (p = 0.03), and, respectively. GS > 7 and lymph node metastasis negatively predicted FFBF and PCSS in multivariable analysis. Ninety (14.6%) and 44 (7.1%) patients had acute Grade ≥2 GU and GI toxicities, respectively, and 42 (6.8%) and 27 (4.4%) patients had late Grade ≥2 GU and GI toxicities, respectively. Diabetes and transurethral resection independently predicted late Grade 2 GU toxicity, but no significant predictor of late Grade ≥2 GI toxicity was found.

CONCLUSIONS

Localized PC was effectively and safely treated with definitive RT using the SIB technique to deliver 86 Gy to the IPL in 39 fractions without severe late toxicity. This finding must be validated with long-term results.

Management of high-risk and post-operative non-metastatic prostate cancer in Catalonia: an expert Delphi consensus

BACKGROUND

To reach a consensus on recommendations for the management of high-risk and post-operative non-metastatic prostate cancer by a group of Radiation Oncologists in Catalonia dedicated to prostate cancer.

METHODS

A modified Delphi approach was employed to reach consensus on controversial topics in Radiation Oncology on high-risk non-metastatic (eight questions) and post-operative (eight questions) prostate cancer. An agreement of at least 75% was considered as consensus. The survey was electronically sent 6 weeks before an expert meeting where topics were reviewed and discussed. A second-round survey for the controversial questions only was sent and answered by participants after the meeting.

RESULTS

After the first round of the survey, 19 experienced Radiation Oncologists attended the meeting and 74% fulfilled the second-round online questionnaire. An agreement of 9 of the 16 questions was accounted for the first round. After the meeting, an additional agreement was reached in 3 questions leading to a final consensus on 12 of the 16 questions. There are still controversial topics like the use of PET for staging of high-risk and post-operative non-metastatic prostate cancer and the optimal dose to the prostate bed in the salvage setting.

CONCLUSION

This consensus contributes to establish recommendations and a framework to help in prostate cancer radiation therapy and pharmacological management in daily clinical practice of high-risk and post-operative non-metastatic prostate cancer.

Comprehensive review of the use of hydrogel spacers prior to radiation therapy for prostate cancer

OBJECTIVES

To provide a comprehensive narrative review of the published data on the impact of hydrogel spacers on rectal dosimetry and toxicity and to outline the practicalities of inserting hydrogel spacers.

RESULTS

A growing body of evidence suggests that the administration of hydrogel spacers is safe and is associated with limited peri-operative morbidity. The impact on rectal dosimetry has been clearly established and use of hydrogel spacers is associated with reduced rectal morbidity. These results have been corroborated by several Phase II and III clinical trials and subsequent meta-analysis. There are several areas for future research, including the role of hydrogel spacers in prostate stereotactic beam radiotherapy and post-radiotherapy local recurrence.

CONCLUSIONS

Hydrogel spacers provide a low-morbidity method to potential reduce rectal toxicity after radiation therapy in men with prostate cancer. Data outlining sexual function and oncological outcomes are limited to date. Future studies, currently being conducted, may provide further clarification of the role of hydrogel spacers in prostate cancer management.

Updating a clinical Knowledge-Based Planning prediction model for prostate radiotherapy

BACKGROUND AND PURPOSE

Clinical knowledge-based planning (KBP) models dedicated to prostate radiotherapy treatment may require periodical updates to remain relevant and to adapt to possible changes in the clinic. This study proposes a paired comparison of two different update approaches through a longitudinal analysis.

MATERIALS AND METHODS

A clinically validated KBP model for moderately hypofractionated prostate therapy was periodically updated using two approaches: one was targeted at achieving the biggest library size (M_t), while the other one at achieving the highest mean sample quality (R_t). Four subsequent updates were accomplished. The goodness, robustness and quality of the outcomes were measured and compared to those of the common ancestor. Plan quality was assessed through the Plan Quality Metric (PQM) and plan complexity was monitored.

RESULTS

Both update procedures allowed for an increase in the OARs sparing between +3.9 % and +19.2 % compared to plans generated by a human planner. Target coverage and homogeneity slightly reduced [-0.2 %;-14.7 %] while plan complexity showed only minor changes. Increasing the sample size resulted in more reliable predictions and improved goodness-of-fit, while increasing the mean sample quality improved the outcomes but slightly reduced the models reliability.

CONCLUSIONS

Repeated updates of clinical KBP models can enhance their robustness, reliability and the overall quality of automatically generated plans. The periodical expansion of the model sample accompanied by the removal of the unacceptable low quality plans should maximize the benefits of the updates while limiting the associated workload.

High weekly integral dose and larger fraction size increase risk of fatigue and worsening of functional outcomes following radiotherapy for localized prostate cancer

Introduction

We hypothesized that increasing the pelvic integral dose (ID) and a higher dose per fraction correlate with worsening fatigue and functional outcomes in localized prostate cancer (PCa) patients treated with external beam radiotherapy (EBRT).

Methods

The study design was a retrospective analysis of two prospective observational cohorts, REQUITE (development, n=543) and DUE-01 (validation, n=228). Data were available for comorbidities, medication, androgen deprivation therapy, previous surgeries, smoking, age, and body mass index. The ID was calculated as the product of the mean body dose and body volume. The weekly ID accounted for differences in fractionation. The worsening (end of radiotherapy versus baseline) of European Organisation for Research and Treatment of Cancer EORTC) Quality of Life Questionnaire (QLQ)-C30 scores in physical/role/social functioning and fatigue symptom scales were evaluated, and two outcome measures were defined as worsening in ≥2 (WS2) or ≥3 (WS3) scales, respectively. The weekly ID and clinical risk factors were tested in multivariable logistic regression analysis.

Results

In REQUITE, WS2 was seen in 28% and WS3 in 16% of patients. The median weekly ID was 13.1 L·Gy/week [interquartile (IQ) range 10.2-19.3]. The weekly ID, diabetes, the use of intensity-modulated radiotherapy, and the dose per fraction were significantly associated with WS2 [AUC (area under the receiver operating characteristics curve) =0.59; 95% CI 0.55-0.63] and WS3 (AUC=0.60; 95% CI 0.55-0.64). The prevalence of WS2 (15.3%) and WS3 (6.1%) was lower in DUE-01, but the median weekly ID was higher (15.8 L·Gy/week; IQ range 13.2-19.3). The model for WS2 was validated with reduced discrimination (AUC=0.52 95% CI 0.47-0.61), The AUC for WS3 was 0.58.

Conclusion

Increasing the weekly ID and the dose per fraction lead to the worsening of fatigue and functional outcomes in patients with localized PCa treated with EBRT.

Joint models for dynamic prediction in localised prostate cancer: a literature review

BACKGROUND

Prostate cancer is a very prevalent disease in men. Patients are monitored regularly during and after treatment with repeated assessment of prostate-specific antigen (PSA) levels. Prognosis of localised prostate cancer is generally good after treatment, and the risk of having a recurrence is usually estimated based on factors measured at diagnosis. Incorporating PSA measurements over time in a dynamic prediction joint model enables updates of patients' risk as new information becomes available. We review joint model strategies that have been applied to model time-dependent PSA trajectories to predict time-to-event outcomes in localised prostate cancer.

METHODS

We identify articles that developed joint models for prediction of localised prostate cancer recurrence over the last two decades. We report, compare, and summarise the methodological approaches and applications that use joint modelling accounting for two processes: the longitudinal model (PSA), and the time-to-event process (clinical failure). The methods explored differ in how they specify the association between these two processes.

RESULTS

Twelve relevant articles were identified. A range of methodological frameworks were found, and we describe in detail shared-parameter joint models (9 of 12, 75%) and joint latent class models (3 of 12, 25%). Within each framework, these articles presented model development, estimation of dynamic predictions and model validations.

CONCLUSIONS

Each framework has its unique principles with corresponding advantages and differing interpretations. Regardless of the framework used, dynamic prediction models enable real-time prediction of individual patient prognosis. They utilise all available longitudinal information, in addition to baseline prognostic risk factors, and are superior to traditional baseline-only prediction models.

A Prospective Study of Stereotactic Body Radiotherapy (SBRT) with Concomitant Whole-Pelvic Radiotherapy (WPRT) for High-Risk Localized Prostate Cancer Patients Using 1.5 Tesla Magnetic Resonance Guidance: The Preliminary Clinical Outcome

Background: Conventionally fractionated whole-pelvic nodal radiotherapy (WPRT) improves clinical outcome compared to prostate-only RT in high-risk prostate cancer (HR-PC). MR-guided stereotactic body radiotherapy (MRgSBRT) with concomitant WPRT represents a novel radiotherapy (RT) paradigm for HR-PC, potentially improving online image guidance and clinical outcomes. This study aims to report the preliminary clinical experiences and treatment outcome of 1.5 Tesla adaptive MRgSBRT with concomitant WPRT in HR-PC patients. Materials and methods: Forty-two consecutive HR-PC patients (72.5 ± 6.8 years) were prospectively enrolled, treated by online adaptive MRgSBRT (8 Gy(prostate)/5 Gy(WPRT) × 5 fractions) combined with androgen deprivation therapy (ADT) and followed up (median: 251 days, range: 20−609 days). Clinical outcomes were measured by gastrointestinal (GI) and genitourinary (GU) toxicities according to the Common Terminology Criteria for Adverse Events (CTCAE) Scale v. 5.0, patient-reported quality of life (QoL) with EPIC (Expanded Prostate Cancer Index Composite) questionnaire, and prostate-specific antigen (PSA) responses. Results: All MRgSBRT fractions achieved planning objectives and dose specifications of the targets and organs at risk, and they were successfully delivered. The maximum cumulative acute GI/GU grade 1 and 2 toxicity rates were 19.0%/81.0% and 2.4%/7.1%, respectively. The subacute (>30 days) GI/GU grade 1 and 2 toxicity rates were 21.4%/64.3% and 2.4%/2.4%, respectively. No grade 3 toxicities were reported. QoL showed insignificant changes in urinary, bowel, sexual, and hormonal domain scores during the follow-up period. All patients had early post-MRgSBRT biochemical responses, while biochemical recurrence (PSA nadir + 2 ng/mL) occurred in one patient at month 18. Conclusions: To our knowledge, this is the first prospective study that showed the clinical outcomes of MRgSBRT with concomitant WPRT in HR-PC patients. The early results suggested favorable treatment-related toxicities and encouraging patient-reported QoLs, but long-term follow-up is needed to confirm our early results.

Stereotactic Body Radiotherapy: Hitting Harder, Faster, and Smarter in High-Risk Prostate Cancer

Stereotactic body radiotherapy (SBRT) is a technologically sophisticated form of radiotherapy that holds significant potential to effectively treat high-risk prostate cancer (HRPC). Prostate SBRT has been the subject of intense investigation in the context of low- and intermediate-risk disease, but less so for HRPC. However, emerging data are demonstrating its potential to safely and efficiently delivery curative doses of radiotherapy, both to the prostate and elective lymph nodes. SBRT theoretically hits harder through radiobiological dose escalation facilitated by ultra-hypofractionation (UHRT), faster with only five treatment fractions, and smarter by using targeted, focal dose escalation to maximally ablate the dominant intraprostatic lesion (while maximally protecting normal tissues). To achieve this, advanced imaging modalities like magnetic resonance imaging and prostate specific membrane antigen positron emmission tomography (PSMA-PET) are leveraged in combination with cutting-edge radiotherapy planning and delivery technology. In this focused narrative review, we discuss key evidence and upcoming clinical trials evaluating SBRT for HRPC with a focus on dose escalation, elective nodal irradiation, and focal boost.

Radiobiological analysis of preliminary results of a phase II study of pelvic hypofractionated and accelerated radiotherapy for high-risk prostate cancer patients

Purpose

Conventionally fractionated radiotherapy (CRT) is widely applied for the treatment of high-risk prostate cancer. Pelvic node irradiation improves control of the disease. Although the therapeutic guidelines support the use of hypofractionated and accelerated radiotherapy (HypoAR), this is addressed to prostate and seminal vesicles. At the same time, the safety and efficacy of HypoAR for pelvic node irradiation remain obscure.

Material and Methods

In a phase II study, we evaluated the feasibility of pelvic HypoAR in 22 high-risk prostate cancer patients. The RT scheme delivers 14 consecutive fractions of 3.67 Gy (total 51.38 Gy) to the prostate, 3.5 Gy (total 49 Gy) to the seminal vesicles, and 2.7 Gy (total 37.8 Gy) to the lymph nodes, using image-guided volumetric modulated arc therapy. A comparative radiobiological analysis of dose-volume histogram is performed (HypoAR vs. hypothetical equivalent CRT regimens, without and with time correction).

Results

Our clinical experience shows impressively low early and short-term late toxicities, without any grade III events, within a median follow-up of 30 months. Only one biochemical relapse was recorded 30 months after irradiation. In radiobiological analysis, considering an α/β-value of 4 Gy and a λ-value of 0.2 Gy/day for late effects, all comparisons predicted significantly lower toxicity for the HypoAR regimen (p < 0.05). For early toxicities (α/β = 10 Gy), a λ-value lower than 0.4 Gy/day favors the HypoAR regimen, which is along with the clinical results.

Conclusion

Radiobiological analysis favors HypoAR as a safe and effective regimen for high-risk prostate cancer patients, which is confirmed in the current phase II clinical study.

Health Disparities in Prostate Cancer and Approaches to Advance Equitable Care

The American Cancer Society estimates approximately 268,490 new cases of prostate cancer and approximately 34,500 deaths caused by prostate cancer in the United States for 2022. Globally, a total of 1,414,259 new cases of prostate cancer and 375,304 related deaths were reported in 2020. Well-documented health disparities and inequities exist along the continuum of care for prostate cancer management-from screening to diagnostic and staging work-up, surveillance, and treatment-ultimately impacting clinical outcomes. This session-based article discusses innovative patient-centered approaches to advance equitable prostate cancer care. It begins with a review of domestic health disparities in diagnostic imaging and radiotherapy for prostate cancer, and it summarizes barriers and solutions to achieving health equity, such as equity metrics and practice quality improvement projects. Next, a global perspective is provided that describes approaches to address financial and geographic barriers to prostate cancer care, including specific examples of strategies that emphasize the use of the cheapest method of care delivery while maintaining outcomes for drug delivery and radiotherapy.

"Meta-analysis of elective pelvic nodal irradiation using moderate hypofractionation for high-risk prostate cancer" (MENHYP-ENI)

OBJECTIVES

Despite several advances in planning and delivery of radiotherapy (RT) for prostate cancer, the role of elective pelvic nodal irradiation (EPNI) remains controversial for high-risk disease. We performed a meta-analysis to evaluate the outcomes of patients treated with moderate hypofractionated RT (MHF-RT) with EPNI using modern radiotherapy techniques.

METHODS

Eligible studies were identified on Medline, Embase, the Cochrane Library, and proceedings of annual meetings through October 2021. We followed the PRISMA and MOOSE guidelines. A meta-regression analysis was performed to assess a possible correlation between selected variables and outcomes. A p-value <0.05 was considered significant.

RESULTS

Eighteen studies with a total of 1745 patients, median follow-up 61 months, treated with EPNI employing MHF-RT were included. The biochemical relapse-free survival (bRFS) at 5-, 7- and 10-year was 90% (95% CI 88-94%), 83% (95%CI 78-91%) and 78% (95%CI 68-88%). The 5-year prostate cancer-specific survival, disease-free survival, distant metastases-free survival and overall survival were 98% (95%CI 97-99%), 88.7% (95%CI 85-93%), 91.2% (95%CI 88-92%), and 93% (95%CI 90-96%), respectively. The rates of local, pelvic, and distant recurrence were 0.38% (95%CI 0-2%), 0.13% (95%CI 0-1.5%), and 7.35% (95%CI 2-12%), respectively. The rate of late GI and GU toxicity grade ≥ 2 were 6.7% (95%CI 4-9%), and 11.3% (95%CI 7.6-15%), with heterogeneity, but with rare cases of toxicity grade 3-5.

CONCLUSION

EPNI with concomitant MHF-RT provides satisfactory bRFS in the long-term follow-up, with low rates of GU and GI severe toxicities and minimal pelvic and local failure.

Ganetespib selectively sensitizes cancer cells for proximal and distal spread-out Bragg peak proton irradiation

Objective

Hypersensitivity towards proton versus photon irradiation was demonstrated in homologous recombination repair (HRR)-deficient cell lines. Hence, combined treatment concepts targeting HRR provide a rational for potential pharmaceutical exploitation. The HSP90 inhibitor ganetespib (STA-9090) downregulates a multitude of HRR-associated proteins and sensitizes for certain chemotherapeutics. Thus, the radiosensitizing effect of HSP90-inhibiting ganetespib was investigated for reference photon irradiation and proton irradiation at a proximal and distal position in a spread-out Bragg peak (SOBP).

Methods

A549 and FaDu cells were treated with low-dose (2 nM resp. 1 nM) ganetespib and irradiated with 200 kV photons. Proton irradiation was performed at a proximal and a distal position within a SOBP, with corresponding dose-averaged linear-energy transfer (LET_D) values of 2.1 and 4.5 keV/µm, respectively. Cellular survival data was fitted to the linear-quadratic model to calculate relative biological effectiveness (RBE) and the dose-modifying factor (DMF). Additionally, A549 cells were treated with increasing doses of ganetespib and investigated by flow cytometry, immunoblotting, and immunofluorescence microscopy to investigate cell cycle distribution, Rad51 protein levels, and γH2AX foci, respectively.

Results

Low-dosed ganetespib significantly sensitized both cancer cell lines exclusively for proton irradiation at both investigated LET_D, resulting in increased RBE values of 10–40%. In comparison to photon irradiation, the fraction of cells in S/G2/M phase was elevated in response to proton irradiation with 10 nM ganetespib consistently reducing this population. No changes in cell cycle distribution were detected in unirradiated cells by ganetespib alone. Protein levels of Rad51 are downregulated in irradiated A549 cells by 10 nM and also 2 nM ganetespib within 24 h. Immunofluorescence staining demonstrated similar induction and removal of γH2AX foci, irrespective of irradiation type or ganetespib administration.

Conclusion

Our findings illustrate a proton-specific sensitizing effect of low-dosed ganetespib in both employed cell lines and at both investigated SOBP positions. We provide additional experimental data on cellular response and a rational for future combinatorial approaches with proton radiotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-022-02036-z.

Propensity-Weighted Survival Analysis of SBRT vs. Conventional Radiotherapy in Unfavorable Intermediate-Risk Prostate Cancer

BACKGROUND

Prostate stereotactic body radiotherapy (SBRT), which delivers high-dose precision treatment in ≤5 fractions, is a shorter, more convenient, and less expensive alternative to conventionally fractionated radiotherapy (CRFT; ∼44 fractions) or moderately hypofractionated radiotherapy (MFRT; 20-28 fractions). SBRT has not been widely adopted but may have radiobiologic advantages over CFRT/MFRT. We hypothesized that SBRT would be associated with improved overall survival (OS) versus CFRT or MFRT ± androgen deprivation therapy (ADT) for unfavorable-intermediate-risk prostate cancer (UIR-PCa).

METHODS

Men with UIR-PCa treated with SBRT (35-40Gy in ≤5 fractions) or biologically equivalent doses of CFRT (72-86.4Gy in 1.8-2.0Gy/fraction) or MRFT (≥60Gy in 2.4-3.2Gy/fraction; biologically effective doses ≥120) were identified in the National Cancer Database (NCDB). Unweighted and propensity-weighted multivariable Cox analysis (MVA) was used to compare OS hazard ratios.

RESULTS

Of 28,028 men with UIR-PCa who received CFRT with (n = 12,872) or without ADT (n = 12,984); MFRT with (n = 251) or without ADT (n = 281); and SBRT with (n = 212) or without ADT (n = 1,428) were identified. Relative to CFRT without ADT, CFRT+ ADT (HR 0.92, 95% CI 0.87-0.97, P = .002) and SBRT without ADT (HR 0.74, 95% CI 0.61-0.89, P = .002) were both associated with improved OS on MVA. Relative to CFRT+ADT, SBRT without ADT correlated with improved OS on MVA (HR:0.81, 95% CI 0.67-0.99, P = .04). Propensity-weighted MVA demonstrated that SBRT (HR:0.80, 95% CI 0.65-0.98, P = .036) and ADT (HR:0.91, 95% CI 0.86-0.97, P = .002) correlated with improved OS. SBRT was not associated with improved OS versus MFRT.

CONCLUSION

SBRT, which offers a cheaper and shorter treatment course that mitigates COVID-19 exposure, was associated with improved OS versus CFRT for UIR-PCa. These results confirm guideline-based recommendations that SBRT is a viable option for UIR prostate cancer. The results from this large retrospective study require further validation in clinical trials.

Highly hypofractionated schedules for localized prostate cancer: Recommendations of the GETUG radiation oncology group

Stereotactic body radiotherapy (SBRT) has become treatment option for localized prostate cancer but the evidence base remains incomplete. Several clinical studies, both prospective and retrospective, have been published. However, treatment techniques, target volumes and dose constraints lack consistency between studies. Based on the current available literature, the French Genito-Urinary Group (GETUG) suggests that.

Comparison of toxicities between ultrahypofractionated radiotherapy versus brachytherapy with or without external beam radiotherapy for clinically localized prostate cancer

To compare gastrointestinal (GI) and genitourinary (GU) toxicities in patients with localized prostate cancer treated with ultrahypofractionated radiotherapy (UHF) or brachytherapy [BT; low dose rate, LDR or high dose rate (HDR) with or without external beam radiotherapy (EBRT)]. We compared 253 UHF and 1664 BT ± EBRT groups. The main outcomes were the incidence and severity of acute and late GU and GI toxicities. The secondary endpoint was biochemical control rate. Cumulative late actuarial GU toxicity did not differ for grade ≥ 2 (8.6% at 5-years in UHF and 13.3% in BT ± EBRT, hazard ratio [HR], 0.7066; 95% CI, 0.4093–1.22, p = 0.2127). Actuarial grade ≥ 2 late GI toxicity was higher in UHF (5.8% at 5-years, HR: 3.619; 95% CI, 1.774–7.383, p < 0.001) than in BT ± EBRT (1.1%). In detailed subgroup analyses, the high-dose UHF group (H-UHF) using BED ≥ 226 Gy_1.5, showed higher GI toxicity profiles than the other subgroups (HDR + EBRT, LDR + EBRT, and LDR monotherapy, and L-UHF BED < 226 Gy_1.5) with equivalent GU toxicity to other modalities. With a median follow-up period of 32 months and 75 months, the actuarial biochemical control rates were equivalent between the UHF and BT ± EBRT groups. UHF showed equivalent efficacy, higher GI and equivalent GU accumulated toxicity to BT ± EBRT, and the toxicity of UHF was largely dependent on the UHF schedule.

Dosimetric Comparison of Ultra-Hypofractionated and Conventionally Fractionated Radiation Therapy Boosts for Patients with High-Risk Prostate Cancer

Recent comparison of an ultra-hypofractionated radiotherapy (UF-RT) boost to a conventionally fractionated (CF-RT) option showed similar toxicity and disease control outcomes. An analysis of the treatment plans for these patients is needed for evaluating calculated doses for different organs, treatment beam-on time, and requirements for human and financial resources. Eighty-six plans for UF-RT and 93 plans for CF-RT schemes were evaluated. The biologically equivalent dose, EQD2, summed for the first phase and the boost, was calculated for dose-volume parameters for organs at risk (OARs), as well as for the PTV1. ArcCHECK measurements for the boost plans were used for a comparison of planned and delivered doses. Monitor units and beam-on times were recorded by the Eclipse treatment planning system. Statistical analysis was performed with a significance level of 0.05. Dosimetric parameter values for OARs were well within tolerance for both groups. EQD2 for the PTV1 was on average 84 Gy for UF-RT patients and 76 Gy for CF-RT patients. Gamma passing rate for planned/delivered doses comparison was above 98% for both groups with 3 mm/3% distance to agreement/dose difference criteria. Total monitor units per fraction were 647 ± 94 and 2034 ± 570 for CF-RT and UF-RT, respectively. The total delivery time for boost radiation for the patients in the UF-RT arm was, on average, four times less than the total time for a conventional regimen with statistically equal clinical outcomes for the two arms in this study.

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.

Patient-Reported Quality of Life Outcomes after Moderately Hypofractionated and Normofractionated Proton Therapy for Localized Prostate Cancer

We retrospectively evaluated the three-year patient-reported quality of life (QOL) after moderately hypofractionated proton therapy (MHPT) for localized prostate cancer in comparison with that after normofractionated PT (NFPT) using the Expanded Prostate Cancer Index Composite-50. Patients who received MHPT (60-63 Gy (relative biological effectiveness equivalents; RBE)/20-21 fractions) (n = 343) or NFPT (74-78 Gy (RBE)/37-39 fractions) (n = 296) between 2013 and 2016 were analyzed. The minimum clinically important difference (MCID) threshold was defined as one-half of a standard deviation of the baseline value. The median follow-up was 56 months and 83% completed questionnaires at 36 months. Clinically meaningful score deterioration was observed in the urinary domain at 1 month in both groups and in the sexual domain at 6-36 months in the NFPT group, but not observed in the bowel domain. At 36 months, the mean score change for urinary summary was -0.3 (MHPT) and -1.6 points (NFPT), and that for bowel summary was +0.1 and -2.0 points; the proportion of patients with MCID was 21% and 24% for urinary summary and 18% and 29% for bowel summary. Overall, MHPT had small negative impacts on QOL over three years, and the QOL after MHPT and NFPT was similar.

Prospective Randomized Phase II Study of Stereotactic Body Radiotherapy (SBRT) vs. Conventional Fractionated Radiotherapy (CFRT) for Chinese Patients with Early-Stage Localized Prostate Cancer

Background: Stereotactic body radiotherapy (SBRT) has potential radiobiologic and economic advantages over conventional fractionated radiotherapy (CFRT) in localized prostate cancer (PC). This study aimed to compare the effects of these two distinct fractionations on patient-reported quality of life (PRQOL) and tolerability. Methods: In this prospective phase II study, patients with low- and intermediate-risk localized PC were randomly assigned in a 1:1 ratio to the SBRT (36.25 Gy/5 fractions/2 weeks) or CFRT (76 Gy/38 fractions/7.5 weeks) treatment groups. The primary endpoint of variation in PRQOL at 1 year was assessed by changes in the Expanded Prostate Cancer Index Composite (EPIC) questionnaire scores and analysed by z-tests and t-tests. Results: Sixty-four eligible Chinese men were treated (SBRT, n = 31; CFRT, n = 33) with a median follow-up of 2.3 years. At 1 year, 40.0%/46.9% of SBRT/CFRT patients had a >5-point decrease in bowel score (p = 0.08/0.28), respectively, and 53.3%/46.9% had a >2-point decrease in urinary score (p = 0.21/0.07). There were no significant differences in EPIC score changes between the arms at 3, 6, 9 and 12 months, but SBRT was associated with significantly fewer grade ≥ 1 acute and 1-year late gastrointestinal toxicities (acute: 35% vs. 87%, p < 0.0001; 1-year late: 64% vs. 84%, p = 0.03), and grade ≥ 2 acute genitourinary toxicities (3% vs. 24%, p = 0.04) compared with CFRT. Conclusion: SBRT offered similar PRQOL and less toxicity compared with CFRT in Chinese men with localized PC.

Practical Guidelines on Implementing Hypofractionated Radiotherapy for Prostate Cancer in Africa

Among a growing body of literature in global oncology, several articles project increased cost savings and radiotherapy access by adopting hypofractionated radiotherapy (HFRT) in low- and middle-income countries (LMICs) like those in Africa. Clinical trials in Europe and the USA have demonstrated HFRT to be non-inferior to conventional radiotherapy for eligible patients with several cancers, including prostate cancer. This could be a highly recommended option to battle a severely large and growing cancer burden in resource-limited regions. However, a level of implementation research may be needed in limited resource-settings like in Africa. In this article, we present a list of evidence-based recommendations to practice HFRT on eligible prostate cancer patients. As literature on HFRT is still developing, these guidelines were compiled from review of several clinical trials and professionally accredited material with minimal resource requirements in mind. HFRT guidelines presented here include patient eligibility, prescription dose schedules, treatment planning and delivery techniques, and quality assurance procedures. The article provides recommendations for both moderately hypofractionated (2.4-3.4Gy per fraction) and ultrahypofractionated (5Gy or more per fraction) radiation therapy when administered by 3D-Conformal Radiotherapy, Intensity Modulated Radiation Therapy, or Image-Guided Radiotherapy. In each case radiation oncology health professionals must make the ultimate judgment to ensure safety as more LMIC centers adopt HFRT to combat the growing scourge of cancer.

SpaceOAR hydrogel spacer injection prior to stereotactic body radiation therapy for men with localized prostate cancer: A systematic review

BACKGROUND

Conventionally fractionated radiotherapy is a common treatment for men with localized prostate cancer. A growing consensus suggests that stereotactic body radiation therapy (SBRT) is similarly effective but less costly and more convenient for patients. The SpaceOAR hydrogel rectal spacer placed between the prostate and rectum reduces radiation-induced rectal injury in patients receiving conventionally fractionated radiotherapy, but spacer efficacy with SBRT is unclear. The purpose of this research was to assess the clinical utility of the hydrogel rectal spacer in men receiving SBRT for prostate cancer.

METHODS

We performed systematic searches of Medline, Embase, and the Cochrane Central Register of Controlled Trials for studies in men who received the SpaceOAR hydrogel spacer prior to SBRT (≥5.0 Gy fractions) for treatment of localized prostate center. Rectal irradiation results were compared to controls without spacer implant; all other outcomes were reported descriptively owing to lack of comparative data incuding perirectal separation distance, rectal irradiation on a dosimetric curve, gastrointestinal (GI) toxicity, and freedom from biochemical failure. GI toxicity was reported as the risk of a grade 2 or 3+ bowel complication in early (≤3 months) and late (>3 months) follow-up.

RESULTS

In 11 studies with 780 patients, SBRT protocols ranged from 7 to 10 Gy per fraction with total dose ranging from 19 to 45 Gy. Perirectal distance achieved with the rectal spacer ranged from 9.6 to 14.5 mm (median 10.8 mm). Compared to controls receiving no spacer, SpaceOAR placement reduced the radiation delivered to the rectum by 29% to 56% across a dosimetric profile curve. In early follow-up, grade 2 GI complications were reported in 7.0% of patients and no early grade 3+ GI complications were reported. In late follow-up, the corresponding rates were 2.3% for grade 2 and 0.3% for grade 3 GI toxicity. Over 16 months median follow-up, freedom from biochemical failure ranged from 96.4% to 100% (pooled mean 97.4%).

CONCLUSIONS

SpaceOAR hydrogel spacer placed between the prostate and rectum prior to SBRT is a promising preventative strategy that increases the distance between the prostate and rectum, reduces rectal radiation exposure, and may lower the risk of clinically important GI complications.

Lifetime Health and Economic Outcomes of Active Surveillance, Radical Prostatectomy, and Radiotherapy for Favorable-Risk Localized Prostate Cancer

OBJECTIVES

To estimate the lifetime health and economic outcomes of selecting active surveillance (AS), radical prostatectomy (RP), or radiation therapy (RT) as initial management for low- or favorable-risk localized prostate cancer.

METHODS

A discrete-event simulation model was developed using evidence from published randomized trials. Health outcomes were measured in life-years and quality-adjusted life-years (QALYs). Costs were included from a public payer perspective in Australian dollars. Outcomes were discounted at 5% over a lifetime horizon. Probabilistic and scenario analyses quantified parameter and structural uncertainty.

RESULTS

A total of 60% of patients in the AS arm eventually received radical treatment (surgery or radiotherapy) compared with 90% for RP and 91% for RT. Although AS resulted in fewer treatment-related complications, it led to increased clinical progression (AS 40.7%, RP 17.6%, RT 19.9%) and metastatic disease (AS 13.4%, RP 6.1%, RT 7.0%). QALYs were 10.88 for AS, 11.10 for RP, and 11.13 for RT. Total costs were A$17 912 for AS, A$15 609 for RP, and A$15 118 for RT. At a willingness to pay of A$20 000/QALY, RT had a 61.4% chance of being cost-effective compared to 38.5% for RP and 0.1% for AS.

CONCLUSIONS

Although AS resulted in fewer and delayed treatment-related complications, it was not found to be a cost-effective strategy for favorable-risk localized prostate cancer over a lifetime horizon because of an increase in the number of patients developing metastatic disease. RT was the dominant strategy yielding higher QALYs at lower cost although differences compared with RP were small.

SAbR for High-Risk Prostate Cancer-A Prospective Multilevel MRI-Based Dose Escalation Trial

PURPOSE

Radiation dose intensification improves outcome in men with high-risk prostate cancer (HR-PCa). A prospective trial was conducted to determine safety, feasibility, and maximal tolerated dose of multilevel magnetic resonance imaging (MRI)-based 5-fraction SAbR in patients with HR-PCa.

METHODS AND MATERIALS

This phase I clinical trial enrolled patients with HR-PCa with grade group ≥4, prostate-specific antigen (PSA) ≥20 ng/mL, or radiographic ≥T3, and well-defined prostatic lesions on multiparametric MRI (mpMRI) into 4 dose-escalation cohorts. The initial cohort received 47.5 Gy to the prostate, 50 Gy to mpMRI-defined intraprostatic lesion(s), and 22.5 Gy to pelvic lymph nodes in 5 fractions. Radiation doses were escalated for pelvic nodes to 25 Gy and mpMRI lesion(s) to 52.5 Gy and then 55 Gy. Escalation was performed sequentially according to rule-based trial design with 7 to 15 patients per cohort and a 90-day observation period. All men received peri-rectal hydrogel spacer, intraprostatic fiducial placement, and 2 years of androgen deprivation. The primary endpoint was maximal tolerated dose according to a 90-day acute dose-limiting toxicity (DLT) rate <33%. DLT was defined as National Cancer Institute Common Toxicity Criteria for Adverse Events ≥grade 3 treatment-related toxicity. Secondary outcomes included acute and delayed gastrointestinal (GI)/genitourinary (GU) toxicity graded with Common Toxicity Criteria for Adverse Events.

RESULTS

Fifty-five of the 62 enrolled patients were included in the analysis. Dose was escalated through all 4 cohorts without observing any DLTs. Median overall follow-up was 18 months, with a median follow-up of 42, 24, 12, and 7.5 months for cohorts 1 to 4 respectively. Acute and late grade 2 GU toxicities were 25% and 20%, while GI were 13% and 7%, respectively. Late grade 3 GU and GI toxicities were 2% and 0%, respectively.

CONCLUSIONS

SAbR dose for HR-PCa was safely escalated with multilevel dose painting of 47.5 Gy to prostate, 55 Gy to mpMRI-defined intraprostatic lesions, and 25 Gy to pelvic nodal region in 5 fractions. Longer and ongoing follow-up will be required to assess late toxicity.

Patient-Reported Outcomes in the Acute Phase of the Randomized Hypofractionated Irradiation for Prostate Cancer (HYPRO) Trial

PURPOSE

Many patients experience bowel and bladder toxicity during the acute phase of radiation therapy for prostate cancer. Recent literature indicates that hypofractionation (HF) might increase this acute response but little is known on patient-reported outcome during this phase with HF. We evaluated the course of patient-reported acute symptoms during HF versus standard fractionated (SF) radiation therapy within the hypofractionated irradiation for prostate cancer (HYPRO) trial.

METHODS AND MATERIALS

In the HYPRO trial patients were treated with either 64.4 Gy (HF) in 19 fractions (3 times per week) or 78 Gy (SF) in 39 fractions (5 times per week). Normalized total dose for 2 Gy/fractions (NTD_2Gy)for acute toxicity (α/β ratio of 10) for HF was 72.1 Gy with a similar dose rate of 10.2 Gy per week. Among the 794 patients who were previously eligible for acute grade ≥2 toxicity assessment, 717 had filled out ≥1 symptom questionnaires. For each maximum symptom, we scored "any complaint" and "moderate-severe complaint." Differences were tested by χ² test, and associations with clinical factors were tested using logistic regression. Significance was set at P ≤ .008 to adjust for multiple testing.

RESULTS

We observed significantly higher rates of moderate-severe painful defecation (HF 10.8%, SF 5.3%), any mucus discharge (HF 47.1%, SF 37.4%), any rectal blood loss (HF 16.1%, SF 9.3%), increased daily stool frequency ≥4 and ≥6 (HF 34.6%/13.8%, SF 25.6%/7.0%), and any urinary straining (HF 69.9%, SF 58.0%). At 3 months postradiation therapy, rates dropped considerably with similar levels for HF and SF. Hormonal treatment was associated with less acute gastrointestinal symptoms.

CONCLUSION

The increased patient-reported acute rectal symptoms with HF confirmed the previously reported results on acute grade ≥2 rectal toxicity. The increase in bladder symptoms with HF was not identified previously. These observations contradict the NTD_2Gy calculations. We observed no patterns of persisting complaints with HF after the acute period; therefore, HF is well tolerated and only associated with a temporary increase of symptoms.

Ten Year Results of Extensive Nodal Radiotherapy and Moderately Hypofractionated Simultaneous Integrated Boost in Unfavorable Intermediate-, High-, and Very High-Risk Prostate Cancer

Simple Summary

Several phase III randomized trials of moderate hypofractionation, including a higher proportion of high-risk prostate cancer patients treated only to the prostate, failed to demonstrate the superiority of hypofractionated regimens. There is only one randomized phase III trial, of moderately hypofractionated high-dose radiotherapy to the prostate-only versus pelvic irradiation and prostate boost, with a sufficiently long follow-up. It demonstrated better biochemical and disease-free survival when lymph nodal radiotherapy was added. Here we present the 10-year results of our experience based on an Institutional protocol adopted after a phase I–II study, on patients with unfavorable intermediate- (UIR), high- (HR), and very high-risk (VHR) prostate cancer (PCa) treated with pelvic lymph nodal irradiation (WPRT) and moderately hypofractionated high-dose (HD) simultaneous integrated boost (SIB) to the prostate. Prognostic factors for relapse, as well as acute and late gastro-intestinal (GI) and genito-urinary (GU) toxicity were also analyzed.

Abstract

Aims: To report 10-year outcomes of WPRT and HD moderately hypofractionated SIB to the prostate in UIR, HR, and VHR PCa. Methods: From 11/2005 to 12/2015, 224 UIR, HR, and VHR PCa patients underwent WPRT at 51.8 Gy/28 fractions and SIB at 74.2 Gy (EQD2 88 Gy) to the prostate. Androgen deprivation therapy (ADT) was prescribed in up to 86.2% of patients. Results: Median follow-up was 96.3 months (IQR: 71–124.7). Median age was 75 years (IQR: 71.3–78.1). At last follow up, G3 GI–GU toxicity was 3.1% and 8%, respectively. Ten-year biochemical relapse-free survival (bRFS) was 79.8% (95% CI: 72.3–88.1%), disease-free survival (DFS) 87.8% (95% CI: 81.7–94.3%), overall survival (OS) 65.7% (95% CI: 58.2–74.1%), and prostate cancer-specific survival (PCSS) 94.9% (95% CI: 91.0–99.0%). Only two patients presented local relapse. At univariate analysis, VHR vs. UIR was found to be a significant risk factor for biochemical relapse (HR: 2.8, 95% CI: 1.17–6.67, p = 0.021). After model selection, only Gleason Score ≥ 8 emerged as a significant factor for biochemical relapse (HR = 2.3, 95% CI: 1.12–4.9, p = 0.023). Previous TURP (HR = 3.5, 95% CI: 1.62–7.54, p = 0.001) and acute toxicity ≥ G2 (HR = 3.1, 95% CI = 1.45–6.52, p = 0.003) were significant risk factors for GU toxicity ≥ G3. Hypertension was a significant factor for GI toxicity ≥ G3 (HR = 3.63, 95% CI: 1.06–12.46, p = 0.041). ADT (HR = 0.31, 95% CI: 0.12–0.8, p = 0.015) and iPsa (HR = 0.37, 95% CI: 0.16–0.83, p = 0.0164) played a protective role. Conclusions: WPRT and HD SIB to the prostate combined with long-term ADT, in HR PCa, determine good outcomes with acceptable toxicity.

Toxicity at 1 Year After Stereotactic Body Radiation Therapy in 3 Fractions for Localized Prostate Cancer

PURPOSE

To assess the toxicity profile of prostate cancer stereotactic body radiation therapy (SBRT) in 3 fractions.

METHODS AND MATERIALS

This was a prospective, multicenter phase 2 toxicity study enrolling patients with low to favorable intermediate-risk prostate cancer. Before simulation, 3 to 4 fiducial markers along with a rectal spacer were placed. The target (prostate only) was prescribed 40 Gy, whereas the maximum dose to the urethra was limited to 33 Gy with the highest priority at planning; less stringent objectives were placed on the bladder, the filling of which was controlled via a Foley catheter. Treatment was delivered every other day. Toxicity was prospectively scored with Common Terminology Criteria for Adverse Events, and several patient-reported outcomes were collected. The maximum allowed prevalence rate of grade 2+ genitourinary (GU) toxicity at 1 year was set at 15%, and the study was sized accordingly.

RESULTS

Between November 2015 and May 2019, 59 patients were enrolled by 3 participating institutions. Acute gastrointestinal toxicity was occasional and mild, whereas 11.9% of patients developed acute grade 2 GU toxicity and 1.7% developed acute grade 3 GU toxicity. No patient had persistent treatment-related grade 2+ GU toxicity at 12 months after SBRT; thus, the null hypothesis was rejected. We observed a clinically relevant worsening of both International Prostate Symptom Score (IPSS) and International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) scores at 12 months compared with baseline. Moreover, we found a strong association between all selected bladder dose/volume metrics at planning and ICIQ-SF worsening at 12 months, whereas for the IPSS, the correlation with bladder dose metrics was marginal.

CONCLUSIONS

The results suggest that at 12 months after treatment, the toxicity profile of SBRT in 3 fractions is acceptable.

Prospective validation of stringent dose constraints for prostatic stereotactic radiation monotherapy: results of a single-arm phase II toxicity-oriented trial

PURPOSE

There are no safety-focused trials on stereotactic body radiotherapy (SBRT) for localized prostate cancer. This prospective 3‑year phase II trial used binomial law to validate the safety and efficacy of SBRT with stringent organ at risk dose constraints that nevertheless permitted high planning target volume doses.

METHODS

All consecutive ≥ 70-year-old patients with localized prostate adenocarcinoma who underwent SBRT between 2014 and 2018 at the National Radiotherapy Center in Luxembourg were included. Patients with low Cancer of Prostate Risk Assessment (CAPRA) scores (0-2) and intermediate scores (3-5) received 36.25 Gy. High-risk (6-10) patients received 37.5 Gy. Radiation was delivered in 5 fractions over 9 days with Cyberknife-M6™ (Accuray, Sunnyvale, CA, USA). Primary study outcome was Common Terminology Criteria for Adverse Events version 4 (CTCAEv4) genitourinary and rectal toxicity scores at last follow-up. Based on binomial law, SRBT was considered safe in this cohort of 110 patients if there were ≤ 2 severe toxicity (CTCAEv4 grade ≥ 3) cases. Secondary outcomes were biochemical progression-free survival (bPFS) and patient quality of life (QOL), as determined by the IPPS and the Urinary Incontinence QOL questionnaire.

RESULTS

The first 110 patients who were accrued in a total cohort of 150 patients were included in this study and had a median follow-up of 36 months. Acute grade ≥ 3 toxicity never occurred. One transient late grade 3 case was observed. Thus, our SBRT program had an estimated severe toxicity rate of < 5% and was safe at the p < 0.05 level. Overall bPFS was 90%. QOL did not change relative to baseline.

CONCLUSION

The trial validated our SBRT regimen since it was both safe and effective.

Highly hypofractionated intensity-modulated radiation therapy for nonmetastatic prostate cancer with a simultaneous integrated boost to intraprostatic lesions: a planning study

PURPOSE

The purpose of this planning study was to develop an acceptable technique for highly hypofractionated intensity-modulated radiation therapy using simultaneous integrated boost technique (SIB-hHF-RT) for nonmetastatic National Comprehensive Cancer Network high-risk prostate cancer.

MATERIALS AND METHODS

We created SIB-hHF-RT plans for 14 nonmetastatic prostate cancer patients with MRI-detectable intraprostatic lesions (IPLs) and without intestines locating close to the seminal vesicle and prostate. We prescribed 57 Gy for IPLs and 54 Gy for the remainder of planning target volume (PTV) in 15 fractions. The IPLs were contoured based on magnetic resonance imaging, and PTV was generated by adding 6-8-mm margins to the clinical target volume. For the dose-volume constraints of organs at risk (OARs), the same constraints as 54 Gy plans were used so as not to increase the toxicity.

RESULTS

All created plans fulfilled the dose-volume constraints of all targets and OARs. The median estimated beam-on time was 108.5 s. For patient-specific quality assurance, the global gamma passing rates (3%/2 mm) with 10% dose threshold criteria were greater than 93% in all cases and greater than 95% in 11 cases.

CONCLUSION

SIB-hHF-RT plans were developed that fulfill the acceptable dose-volume constraints and pass patient-specific quality assurance. We believe these plans can be applied to selected patients with nonmetastatic prostate cancer.

Extreme Hypofractionation with SBRT in Localized Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer among men around the world. Radiotherapy is a standard of care treatment option for men with localized prostate cancer. Over the years, radiation delivery modalities have contributed to increased precision of treatment, employing radiobiological insights to shorten the overall treatment time, improving the control of the disease without increasing toxicities. Stereotactic body radiation therapy (SBRT) represents an extreme form of hypofractionated radiotherapy in which treatment is usually delivered in 1–5 fractions. This review assesses the main efficacy and toxicity data of SBRT in non-metastatic prostate cancer and discusses the potential to implement this scheme in routine clinical practice.

Toxicity after moderately hypofractionated versus conventionally fractionated prostate radiotherapy: A systematic review and meta-analysis of the current literature

BACKGROUND

Moderately hypofractionated radiotherapy (RT) currently represents the standard RT approach for all prostate cancer (PCa) risk categories. We performed a systematic review and meta-analysis of available literature, focusing on acute and late genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) of moderate hypofractionation for localized PCa.

MATERIALS AND METHODS

Literature search was performed and two independent reviewers selected the records according to the following Population (P) Intervention (I) Comparator (C) and Outcomes (O) (PICO) question: "In patients affected by localized PCa (P), moderately hypofractionated RT (defined as a treatment schedule providing a single dose per fraction of 3-4.5 Gy) (I) can be considered equivalent to conventionally fractionated RT (C) in terms of G > 2 GI and GU acute and late adverse events (O)?". Bias assessment was performed using Cochrane Cochrane Collaboration's Tool for Assessing Risk of Bias.

RESULTS

Thirteen records were identified and a meta-analysis was performed. Risk of acute GI and GU > 2 adverse events in the moderately hypofractionated arm was increased by 9.8 % (95 %CI 4.8 %-14.7 %; I² = 57 %) and 1.5 % (95 % CI -1.5 %-4.4 %; I² = 0%), respectively.

DISCUSSION

Overall, majority of trials included in our meta-analysis suggested that moderately hypofractionated RT is equivalent, in terms of GI and GU adverse events, to conventional fractionation. Pooled analysis showed a trend to increased GI toxicity after hypofractionated treatment, but this might be related to dose escalation rather than hypofractionation.

A 25-year perspective on the evolution of radiation treatment of urologic cancers

Advances in radiotherapy technology and technique over the last 3 decades have revolutionized radiation treatment options for genitourinary malignancies. The development of more focused and accurate radiation treatment has facilitated safe delivery of dose-escalated treatment that improves disease control and the development of shorter-duration hypofractionated treatment regimens that are more convenient for patients and improve access to treatment. The management of oligometastatic disease is evolving with ablative treatment of oligometastasis and the primary for select patients and shorter-duration palliative treatment regimens. Work is ongoing to personalize radiation treatment regimens for genitourinary malignancies based on molecular biomarkers.