Moderate Hypofractionated Postprostatectomy Volumetric Modulated Arc Therapy With Daily Image Guidance (VMAT-IGRT): A Mono-institutional Report on Feasibility and Acute Toxicity

10-yr Results of Moderately Hypofractionated Postoperative Radiotherapy for Prostate Cancer Focused on Treatment Related Toxicity

INTRODUCTION

To retrospectively report long term outcomes following postoperative hypofractionated radiotherapy (RT) for prostate cancer, emphasizing treatment related toxicity.

MATERIAL AND METHODS

Patients for whom adjuvant or salvage RT was indicated after prostatectomy were treated with a course of moderate hypofractionation consisting in the delivery of 62.5 Gy in 25 fractions (2.5 Gy per fraction) on the prostate bed in 5 consecutive weeks (EQD21.5 = 70 Gy) by means of 3D-CRT in most of them. Androgen deprivation therapy (ADT) was allowed at physician's discretion. Patients were evaluated for urinary and rectal complications according to the Common Terminology Criteria for Adverse Events v4 (CTCAE v.4). Overall survival (OS), biochemical recurrence free survival (bRFS), and metastasis-free survival (MFS) were estimated using the Kaplan-Meier method.

RESULTS

One hundred and ten patients with a median age of 67 years (range 51-78) were enrolled. The majority of them (82%) had adverse pathologic features only, while 31 (28%) had early biochemical relapse. Median PSA level before RT was 0.12 ng/mL (range 0-9 ng/mL). Median time from surgery was 4 months (range 1-136 months). Twenty-eight patients (25.4%) also received ADT. At a median follow up of 103 months (range 19-138 months), late Grade 3 and Grade 4 rectal toxicity were 0.9% (1 case of hematochezia) and 0.9% (1 case of fistula), respectively, while late Grade 3 GU side effects (urethral stenosis) occurred in 9 cases (8%). No late Grade 4 events were observed, respectively. Ten-year OS, b-RFS and MFS were 77.3% (95%CI: 82.1%-72.5%), 53.3% (95%CI: 59.9%-47.6%), and 76.7% (95%CI: 81.2%-72.2%), respectively.

CONCLUSION

Our study provides long term data that a shortened course of postoperative RT is as safe and effective as a long course of conventionally fractionated RT and would improve patients' convenience and significantly reduce RT department workloads.

Hypofractionated Post-Prostatectomy Radiotherapy in 16 Fractions: A Single-Institution Outcome

BACKGROUND

The optimal hypofractionated schedule of post-prostatectomy radiotherapy remains to be established. We evaluated treatment outcomes and toxicity of moderately hypofractionated post-prostatectomy radiotherapy in 16 daily fractions delivered with intensity-modulated radiotherapy. The treatment schedule selection was motivated by limited technology resources and was radiobiologically dose-escalated.

METHODS

One hundred consecutive M0 patients with post-prostatectomy radiotherapy were evaluated. Radiotherapy indication was adjuvant (ART) in 19%, early-salvage (eSRT) in 46% and salvage (SRT) in 35%. The dose prescription for prostate bed planning target volume was 52.8 Gy in 16 fractions of 3.3 Gy. The Common Terminology Criteria v. 4 for Adverse Events scale was used for toxicity grading.

RESULTS

The median follow-up was 61 months. Five-year biochemical recurrence-free survival (bRFS) was 78.6%, distant metastases-free survival (DMFS) was 95.7% and overall survival was 98.8%. Treatment indication (ART or eSRT vs. SRT) was the only significant factor for bRFS (HR 0.15, 95% CI 0.05-0.47, p = 0.001) and DMFS (HR 0.16, 95% CI 0.03-0.90; p = 0.038). Acute gastrointestinal (GI) toxicity grade 2 was recorded in 24%, grade 3 in 2%, acute genitourinary (GU) toxicity grade 2 in 10% of patients, and no grade 3. A cumulative rate of late GI toxicity grade ≥ 2 was observed in 9% and late GU toxicity grade ≥ 2 in 16% of patients.

CONCLUSIONS

The observed results confirmed efficacy and showed a higher than anticipated rate of early GI, late GI, and GU toxicity of post-prostatectomy radiobiologically dose-escalated hypofractionated radiotherapy in 16 daily fractions.

Treatment outcomes of postoperative ultra-hypofractionated stereotactic body radiotherapy in prostate cancer

BACKGROUND

This study aimed to evaluate the safety and efficacy of ultra-hypofractionated stereotactic body radiation therapy (SBRT) to prostate bed.

METHODS

Sixty-six prostate cancer patients treated with postoperative ultra-hypofractionated SBRT between 2018 and 2020 were retrospectively reviewed. All patients received a total dose of 35 Gy to prostate bed in 5 fractions. Biochemical complete response (BCR), biochemical failure (BF), acute and late toxicities were assessed.

RESULTS

After a median follow-up of 24.2 months (range, 6.4-37.2), seven patients (10.6%) developed BF, and the 2-year freedom from BF (FFBF) rate was 88.4%. BCR was observed in 57 patients (86.4%). The 2-year FFBF in patients with pre-SBRT PSA value of <0.2 ng/mL was higher than those with pre-SBRT PSA of ≥0.2 ng/mL (100% vs. 81.4%; P = 0.04). The 2-year FFBF in patients with BCR was significantly higher than in those without BCR (94.5% vs. 58.3%; P < 0.001). In multivariate analysis, pre-SBRT PSA and post-SBRT PSA values were prognostic factors for FFBF (P = 0.009 and P = 0.01, respectively). Nine patients (13.6 %) developed acute and late grade 2 genitourinary (GU) toxicities. There was no acute or late grade ≥3 GU toxicity. Acute and late grade ≥2 gastrointestinal (GI) toxicity was observed in 9 (13.6%) and 2 (3%) patients, respectively.

CONCLUSION

Postoperative ultra-fractionated SBRT showed no severe acute toxicity and late toxicity rates of about 15%, in addition to excellent biochemical control rates. Pre- and post-SBRT PSA levels may be a predictor of BCR in patients receiving post-operative ultra-fractionated SBRT.

Quality-of-Life Outcomes and Toxicity Profile Among Patients With Localized Prostate Cancer After Radical Prostatectomy Treated With Stereotactic Body Radiation: The SCIMITAR Multicenter Phase 2 Trial

PURPOSE

Postoperative radiation therapy (RT) is an underused standard-of-care intervention for patients with prostate cancer and recurrence/adverse pathologic features after radical prostatectomy. Although stereotactic body RT (SBRT) is a well-studied and convenient option for definitive treatment, data on the postprostatectomy setting are extremely limited. The purpose of this study was to evaluate short-term physician-scored genitourinary (GU) and gastrointestinal (GI) toxicities and patient-reported outcomes after postprostatectomy SBRT.

METHODS AND MATERIALS

The SCIMITAR trial was a phase 2, dual-center, open-label, single-arm trial that enrolled patients with postoperative prostate-specific antigen >0.03 ng/mL or adverse pathologic features. Coprimary endpoints were 4-year biochemical recurrence-free survival, physician-scored acute and late GU and GI toxicities by the Common Terminology Criteria for Adverse Events (version 4.03) scale, and patient-reported quality-of-life (QOL) outcomes, as represented by the Expanded Prostate Cancer Index-26 and the International Prostate Symptom Score. Patients received SBRT 30 to 34 Gy/5 fractions to the prostate bed ± bed boost ± pelvic nodes with computed tomography (CTgRT) or magnetic resonance imaging guidance (MRgRT) in a nonrandomized fashion. Physician-scored toxicities and patient-reported QOL outcomes were collected at baseline and at 1, 3, and 6 months of follow-up. Univariable and multivariable analyses were performed to evaluate predictors of toxicities and QOL outcomes.

RESULTS

One hundred participants were enrolled (CTgRT, n = 69; MRgRT, n = 31). The median follow-up was 29.5 months (CTgRT: 33.3 months, MRgRT: 22.6 months). The median (range) prostate bed dose was 32 (30-34) Gy. Acute and late grade 2 GU toxicities were both 9% while acute and late grade 2 GI toxicities were 5% and 0%, respectively. Three patients had grade 3 toxicity (n = 1 GU, n = 2 GI). No patient receiving MRgRT had grade 3 GU or grade ≥2 GI toxicity. Compared with CTgRT, MRgRT was associated with a 30.5% (95% confidence interval, 11.6%-49.5%) reduction in any-grade acute GI toxicity (P = .006). MRgRT was independently associated with improved any-grade GI toxicity and improved bowel QOL.

CONCLUSIONS

Postprostatectomy SBRT was well tolerated at short-term follow-up. MRgRT may decrease GI toxicity. Longer toxicity and/or efficacy follow-up and randomized studies are needed.

Preliminary Analysis of a Phase II Trial of Stereotactic Body Radiation Therapy for Prostate Cancer With High-Risk Features After Radical Prostatectomy

Purpose

There are limited data regarding using stereotactic body radiation therapy (SBRT) in the postprostatectomy setting. Here, we present a preliminary analysis of a prospective phase II trial that aimed to evaluate the safety and efficacy of postprostatectomy SBRT for adjuvant or early salvage therapy.

Materials and Methods

Between May 2018 and May 2020, 41 patients fulfilled inclusion criteria and were stratified into 3 groups: group I (adjuvant), prostate-specific antigen (PSA) < 0.2 ng/mL with high-risk features including positive surgical margins, seminal vesicle invasion, or extracapsular extension; group II (salvage), with PSA ≥ 0.2 ng/mL but < 2 ng/mL; or group III (oligometastatic), with PSA ≥ 0.2 ng/mL but < 2 ng/mL and up to 3 sites of nodal or bone metastases. Androgen deprivation therapy was not offered to group I. Androgen deprivation therapy was offered for 6 months for group II and 18 months for group III patients. SBRT dose to the prostate bed was 30 to 32 Gy in 5 fractions. Baseline-adjusted physician reported toxicities (Common Terminology Criteria for Adverse Events), patient reported quality-of-life (Expanded Prostate Index Composite, Patient-Reported Outcome Measurement Information System), and American Urologic Association scores were evaluated for all patients.

Results

The median follow-up was 23 months (range, 10-37). SBRT was adjuvant in 8 (20%) patients, salvage in 28 (68%), and salvage with the presence of oligometastases in 5 (12%) patients. Urinary, bowel, and sexual quality of life domains remained high after SBRT. Patients tolerated SBRT with no grade 3 or higher (3+) gastrointestinal or genitourinary toxicities. The baseline adjusted acute and late toxicity grade 2 genitourinary (urinary incontinence) rate was 2.4% (1/41) and 12.2% (5/41). At 2 years, clinical disease control was 95%, and biochemical control was 73%. Among the 2 clinical failures, 1 was a regional node and the other a bone metastasis. Oligometastatic sites were salvaged successfully with SBRT. There were no in-target failures.

Conclusions

Postprostatectomy SBRT was very well tolerated in this prospective cohort, with no significant effect on quality of life metrics postirradiation, while providing excellent clinical disease control.

Postoperative moderately hypofractionated radiotherapy in prostate cancer: a mono-institutional propensity-score-matching analysis between adjuvant and early-salvage radiotherapy

AIM

To evaluate the impact of moderately hypofractionated postoperative radiotherapy (RT) in prostate cancer (PCa).

MATERIALS AND METHODS

The data of 304 surgically resected PCa patients were analyzed. One hundred and five patients underwent adjuvant RT (aRT), 77 early-savage RT (esRT), and 123 salvage RT (sRT). Biochemical relapse-free survival (BRFS), progression-free survival (PFS) and toxicity were analyzed. A propensity score matching (PSM) was performed to account for potential confounders between aRT and esRT groups.

RESULTS

The median follow-up was 33 months. Three-year BRFS and PFS were 82 and 85.2%, respectively, in the overall population. At the multivariate analysis, Gleason score and hormone therapy were factors independently correlated with BRFS and PFS. After PSM, there was no difference in BRFS and PFS between aRT and esRT patients. Severe toxicity was represented by grade 3 urinary incontinence (3.5%) and urgency (1%), and aRT correlated with increased any-grade acute toxicity. Severe grade 3 gastrointestinal late toxicity occurred in 1.3% of cases.

CONCLUSION

Postoperative moderately hypofractionated RT achieved acceptable disease control rate and demonstrated no increased or unexpected toxicity. Future prospective studies should evaluate the role of postoperative RT in patients with unfavorable disease characteristics.

Stereotactic Radiotherapy after Radical Prostatectomy in Patients with Prostate Cancer in the Adjuvant or Salvage Setting: A Systematic Review

Simple Summary

Stereotactic body radiotherapy, a type of high-precision radiotherapy delivering high doses within few treatment sessions has proven to be effective and well tolerated in prostate cancer patients treated with definite radiotherapy. This systematic review summarizes the available data and analyzes whether this modern treatment may routinely be offered to prostate cancer patients after radical prostatectomy.

Abstract

(1) Background: Prostate cancer is the most common cancer in men and can be treated with radical prostatectomy (RPE) or radiotherapy in the primary setting. Stereotactic radiotherapy (SBRT) has proven to be effective and well tolerated in this setting. However, if SBRT is an equally promising treatment option if applied in the adjuvant or salvage setting after RPE remains unknown. (2) Methods: We searched the PubMed and Embase databases with the following full-text queries in August 2021 for any combination of the terms “SBRT”, “prostate”, “adjuvant”, “postoperative”, “salvage”, “stereotactic radiotherapy”, “prostate bed”. There were no limitations regarding publication date or language. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. (3) Results: We identified 11 individual studies that were included in this systematic review. Three publications included patients without prior radiotherapy and the remaining eight patients with prior radiotherapy. In all but two publications the radiation target was the macroscopic recurrence. SBRT was overall well tolerated with acceptable rates of acute and late gastrointestinal or genitourinary toxicity. Quality of life was published for two phase I trials with good results. There was a very heterogeneous reporting on biochemical control after SBRT. (4) Conclusions: At this point, ultra-hypofractionated RT using SBRT to the prostate bed remains experimental and its use should be restricted to clinical trials. Given the biological rationale for extreme hypofractionation in patients with prostate cancer and the acceptable toxicity rates that have been reported, further exploration of this field is warranted.

Post-operative hypofractionated radiotherapy for prostate cancer: a mono-institutional analysis of toxicity and clinical outcomes

BACKGROUND

As the use of hypofractionation has spread in the setting of curative prostate radiotherapy, few data are available in the post-operative scenario. This study reports a mono-institutional experience of moderate post-operative hypofractionated radiotherapy for prostate cancer.

METHODS

In February 2021, we retrospectively assessed the outcomes of 129 patients who received between April 2013 and May 2020 hypofractionated post-operative radiotherapy using Helical Tomotherapy. Toxicity was assessed using CTCAE criteria v4.0. Survival endpoints were calculated with Kaplan-Meier method.

RESULTS

Median age and follow-up were, respectively, 67 years and 43 months. Adjuvant and salvage treatment were delivered to 63.5% and 36.4% of patients to a median total dose of 63.8 Gy (61.6-65.25 Gy) in 29 fractions (2.12-2.25 Gy/fraction). Pelvic lymph-nodes irradiation was performed in 67.4% of cases. ADT was added in 50%. Acute toxicity was: G1 and G2 GU events in 36% and 9.3% of cases; G1 and G2 GI events in 29.4% and 13.9%. Late GU toxicity occurred in 12.4% of cases: 3.1% G1, 7.7% G2 and 1.5% G3 events; GI toxicity consisted of 1.5% G1 and 7.7% G2 events. Biochemical relapse occurred in 26.3% of cases, recording no significant differences between adjuvant and salvage (p = 0.67), with 4- and 5-years bRFS rates of 78.7% and 75.6%. Two patients died of progressive disease and eight for non-oncological causes resulting in 3-years overall survival and cancer-specific survival rates of 98% and 98.4%.

CONCLUSIONS

Our experience supports the use of moderate hypofractionation for prostate bed radiotherapy, with minimal toxicity and promising results in terms of clinical outcomes.

Quantifying the impact of SpaceOAR hydrogel on inter-fractional rectal and bladder dose during 0.35 T MR-guided prostate adaptive radiotherapy

PURPOSE

To investigate the impact of rectal spacing on inter-fractional rectal and bladder dose and the need for adaptive planning in prostate cancer patients undergoing SBRT with a 0.35 T MRI-Linac.

MATERIALS AND METHODS

We evaluated and compared SBRT plans from prostate cancer patients with and without rectal spacer who underwent treatment on a 0.35 T MRI-Linac. Each group consisted of 10 randomly selected patients that received prostate SBRT to a total dose of 36.25 Gy in five fractions. Dosimetric differences in planned and delivered rectal and bladder dose and the number of fractions violating OAR constraints were quantified. We also assessed whether adaptive planning was needed to meet constraints for each fraction.

RESULTS

On average, rectal spacing reduced the maximum dose delivered to the rectum by more than 8 Gy (p < 0.001). We also found that D3cc received by the rectum could be 12 Gy higher in patients who did not have rectal spacer (p < 9E-7). In addition, the results show that a rectal spacer can reduce the maximum dose and D15cc to the bladder wall by more than 1 (p < 0.004) and 8 (p < 0.009) Gy, respectively. Our study also shows that using a rectal spacer could reduce the necessity for adaptive planning. The incidence of dose constraint violation was observed in almost 91% of the fractions in patients without the rectal spacer and 52% in patients with implanted spacer.

CONCLUSION

Inter-fractional changes in rectal and bladder dose were quantified in patients who underwent SBRT with/without rectal SpaceOAR hydrogel. Rectal spacer does not eliminate the need for adaptive planning but reduces its necessity.

Pathological stage, surgical margin and lymphovascular invasion as prognostic factors after salvage radiotherapy for post-prostatectomy relapsed prostate cancer - outcomes and optimization strategies

Background

Salvage radiotherapy (sRT) is the main potentially curative treatment after biochemical failure/locoregional relapse post-radical prostatectomy (RP). The aim of the study was to characterize the population who underwent sRT after RP at our Department, to understand the influence of several potential prognosis factors, and to determine possible optimization strategies.

Materials and methods

We retrospectively analyzed patients undergoing sRT at our department between 2012 and 2017, evaluating patient, tumor and treatment characteristics, restaging procedures and clinical outcomes - namely biochemical relapse-free survival (BC-RFS), clinical relapse-free survival (C-RFS), additional hormone therapy-free survival (HT-FS) and overall survival (OS). We assessed potential prognostic factors by univariate and multivariate models (MVA).

Results

We included 277 patients (median age 68 years). Median pre-sRT PSA was > 0.5ng/mL in 54.9%. All underwent prostate bed irradiation. Pelvic lymph nodes were included in 9.7%. Outcome analysis was performed for 264 patients (35.6 months median follow-up). At 3 years, BC-RFS was 61.4%, C-RFS was 81.3%, HT-FS was 79.9% and OS was 96.6%. Most relapses occurred in regional lymph nodes only (47.9% patients who relapsed). On MVA, lymphovascular invasion, advanced pT-stages and negative margins negatively influenced BC-RFS (p = 0.029, p = 0.002 and p < 0.001) and HT-FS (p = 0.001, p = 0.029 and p = 0.002). C-RFS was worsened by lymphovascular invasion (p = 0.009) and negative margins (p = 0.015). These had no effect on OS. BC-RFS and HT-FS were improved when sRT started while PSA ≤ 0.5 ng/mL (p < 0.05).

Conclusion

Lymphovascular invasion, higher pT-stages and negative margins negatively affected prognosis. An early start of sRT (PSA ≤ 0.5 ng/mL) predicted better BC-RFS and HT-FS.

Postoperative radiotherapy after upfront radical prostatectomy: debated issues at a turning point-a survey exploring management trends on behalf of AIRO (Italian Association of Radiotherapy and Clinical Oncology)

OBJECTIVES

Postoperative prostate cancer patients are a heterogeneous population, and many prognostic factors (e.g., local staging, PSA kinetics, margin status, histopathological features) may influence their clinical management. In this complex scenario, univocal recommendations are often lacking. For these reasons, the present survey was developed by the Italian Association of Radiotherapy and Clinical Oncology (AIRO) to collect the opinion of Italian radiation oncologists and delineate a representation of current clinical practice in our country.

METHODS

A questionnaire was administered online to AIRO (Italian Association of Radiotherapy and Clinical Oncology) members registered in 2020 with a clinical interest in uro-oncological disease.

RESULTS

Sixty-one per cent of AIRO members answered the proposed survey. Explored topics included career and expertise, indications to adjuvant RT, additional imaging in biochemical recurrence setting, use of salvage radiotherapy (SRT), management of clinically evident locoregional recurrence and future considerations.

CONCLUSIONS

Overall, good level of agreement was found between participants for most of the topics. Most debated issues regarded, as expected, implementation of new imaging methods in this setting. Notably, trend in favour of early SRT vs. immediate adjuvant RT was underlined, and preference for global evaluation rather than isolated risk factors for RT indications was noticed.

Comparison of hypofractionation and standard fractionation for post-prostatectomy salvage radiotherapy in patients with persistent PSA: single institution experience

BACKGROUND

Hypofractionated post-prostatectomy radiotherapy is emerging practice, however with no randomized evidence so far to support it's use. Additionally, patients with persistent PSA after prostatectomy may have aggressive disease and respond less well on standard salvage treatment. Herein we report outcomes for conventionally fractionated (CFR) and hypofractionated radiotherapy (HFR) in patients with persistent postprostatectomy PSA who received salvage radiotherapy to prostate bed.

METHODS

Single institution retrospective chart review was performed after Institutional Review Board approval. Between May 2012 and December 2016, 147 patients received salvage postprostatectomy radiotherapy. PSA failure-free and metastasis-free survival were calculated using Kaplan-Meier method. Cox regression analysis was performed to test association of fractionation regimen and other clinical factors with treatment outcomes. Early and late toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE) Version 4.0.

RESULTS

Sixty-nine patients who had persistent PSA (≥ 0.1 ng/mL) after prostatectomy were identified. Median follow-up was 67 months (95% CI 58-106 months, range, 8-106 months). Thirty-six patients (52.2%) received CFR, 66 Gy in 33 fractions, 2 Gy per fraction, and 33 patients (47.8%) received HFR, 52.5 Gy in 20 fractions, 2.63 Gy per fraction. Forty-seven (68%) patients received androgen deprivation therapy (ADT). 5-year PSA failure- and metastasis-free survival rate was 56.9% and 76.9%, respectively. Thirty patients (43%) experienced biochemical failure after salvage radiotherapy and 16 patients (23%) experienced metastatic relapse. Nine patients (13%) developed metastatic castration-resistant disease and died of advanced prostate cancer. Median PSA failure-free survival was 72 months (95% CI; 41-72 months), while median metastasis-free survival was not reached. Patients in HFR group were more likely to experience shorter PSA failure-free survival when compared to CFR group (HR 2.2; 95% CI 1.0-4.6, p = 0.04). On univariate analysis, factors significantly associated with PSA failure-free survival were radiotherapy schedule (CFR vs HFR, HR 2.2, 95% CI 1.0-4.6, p = 0.04), first postoperative PSA (HR 1.02, 95% CI 1.0-1.04, p = 0.03), and concomitant ADT (HR 3.3, 95% CI 1.2-8.6, p = 0.02). On multivariate analysis, factors significantly associated with PSA failure-free survival were radiotherapy schedule (HR 3.04, 95% CI 1.37-6.74, p = 0.006) and concomitant ADT (HR 4.41, 95% CI 1.6-12.12, p = 0.004). On univariate analysis, factors significantly associated with metastasis-free survival were the first postoperative PSA (HR 1.07, 95% CI 1.03-1.12, p = 0.002), seminal vesicle involvement (HR 3.48, 95% CI 1.26-9.6,p = 0.02), extracapsular extension (HR 7.02, 95% CI 1.96-25.07, p = 0.003), and surgical margin status (HR 2.86, 95% CI 1.03-7.97, p = 0.04). The first postoperative PSA (HR 1.04, 95% CI 1.00-1.08, p = 0.02) and extracapsular extension (HR 4.24, 95% CI 1.08-16.55, p = 0.04) remained significantly associated with metastasis-free survival on multivariate analysis. Three patients in CFR arm (8%) experienced late genitourinary grade 3 toxicity.

CONCLUSIONS

In our experience, commonly used hypofractionated radiotherapy regimen was associated with lower biochemical control compared to standard fractionation in patients with persistent PSA receiving salvage radiotherapy. Reason for this might be lower biological dose in HFR compared to CFR group. However, this observation is limited due to baseline imbalances in ADT use, ADT duration and Grade Group distribution between two radiotherapy cohorts. In patients with persistent PSA post-prostatectomy, the first postoperative PSA is an independent risk factor for treatment failure. Additional studies are needed to corroborate our observations.

Hypofractionated Postprostatectomy Radiation Therapy for Prostate Cancer to Reduce Toxicity and Improve Patient Convenience: A Phase 1/2 Trial

PURPOSE

The phase 1 portion of this multicenter, phase 1/2 study of hypofractionated (HypoFx) prostate bed radiation therapy (RT) as salvage or adjuvant therapy aimed to identify the shortest dose-fractionation schedule with acceptable toxicity. The phase 2 portion aimed to assess the health-related quality of life (QoL) of using this HypoFx regimen.

METHODS AND MATERIALS

Eligibility included standard adjuvant or salvage prostate bed RT indications. Patients were assigned to receive 1 of 3 daily RT schedules: 56.6 Gy in 20 Fx, 50.4 Gy in 15 Fx, or 42.6 Gy in 10 Fx. Regional nodal irradiation and androgen deprivation therapy were not allowed. Participants were followed for 2 years after treatment with outcome measures based on prostate-specific antigen levels, toxicity assessments (Common Terminology Criteria for Adverse Events, v4.0), QoL measures (the Expanded Prostate Cancer Index Composite [EPIC] and EuroQol EQ-5D instruments), and out-of-pocket costs.

RESULTS

There were 32 evaluable participants, and median follow-up was 3.53 years. The shortest dose-fractionation schedule with acceptable toxicity was determined to be 42.6 Gy in 10 Fx, with most patients (23) treated with this schedule. Grade 3 genitourinary (GU) and gastrointestinal (GI) toxicities occurred in 3 patients and 1 patient, respectively. There was 1 grade 4 sepsis event. Higher dose to the hottest 25% of the rectum was associated with increased risk of grade 2+ GI toxicity; no dosimetric factors were found to predict for GU toxicity. There was a significant decrease in the mean bowel, but not bladder, QoL score at 1 year compared with baseline. Prostate-specific antigen failure occurred in 34.3% of participants, using a definition of nadir plus 2 ng/mL. Metastases were more likely to occur in regional lymph nodes (5 of 7) than in bones (2 of 7). The mean out-of-pocket cost for patients during treatment was $223.90.

CONCLUSIONS

We identified 42.6 Gy in 10 fractions as the shortest dose-fractionation schedule with acceptable toxicity in this phase 1/2 study. There was a higher than expected rate of grade 2 to 3 GU and GI toxicity and a decreased EPIC bowel QoL domain with this regimen. Future studies are needed to explore alternative adjuvant/salvage HypoFx RT schedules after radical prostatectomy.

Moderate hypofractionated post-prostatectomy radiation therapy is feasible and well tolerated: experience from a single tertiary cancer centre

PURPOSE

Conventional post-prostatectomy radiation therapy comprises 6.5-8 weeks of treatment, therefore, hypofractionated and shortened schemes arouse increasing interest. We describe our experience regarding feasibility and clinical outcome of a post-prostatectomy moderate hypofractionated image-guided radiotherapy schedule MATERIALS AND METHODS: From Oct 2015-Mar 2020, 113 patients, median age of 62 years-old (range 45-76) and prostate adenocarcinoma of low risk (30%), intermediate risk (49%) and high risk (21%) were included for adjuvant (34%) or salvage radiation therapy (66%) after radical prostatectomy (RP). All patients underwent radiotherapy with image-guided IMRT/VMAT to a total dose of 62.5 Gy in 2.5 Gy/fraction in 25 fractions. Sixteen patients (14%) received concomitant androgen deprivation therapy.

RESULTS

With a median follow-up of 29 months (range 3-60 months) all patients but three are alive. Eleven patients (10%) developed exclusive biochemical relapse while 19 patients (17%) presented macroscopically visible relapse: prostatectomy bed in two patients (2%), pelvic lymph nodes in 13 patients (11.5%) and distant metastases in four patients (4%). The 3 years actuarial rates for OS, bFRS, and DMFS were 99.1, 91.1 and 91.2%, respectively. Acute and late tolerance was satisfactory. Maximal acute genitourinary (AGU) toxicity was G2 in 8% of patients; maximal acute gastrointestinal (AGI) toxicity was G2 in 3.5% of patients; maximal late genitourinary (LGU) toxicity was G3 in 1% of patients and maximal late gastrointestinal (LGI) toxicity was G2 in 2% of patients. There were no cases of severe acute or late toxicity. No relationship was found between acute or late GI/GU adverse effects and dosimetric parameters, age, presence of comorbidities or concomitant treatments.

CONCLUSIONS

Hypofractionated radiotherapy (62.5 Gy in 25 2.5 Gy fractions) is feasible and well tolerated with low complication rates allowing for a moderate dose-escalation that offers encouraging clinical results for biochemical control and survival in patients with prostate cancer after radical prostatectomy.

Rectal spacer hydrogel in 1.5T MR-guided and daily adapted SBRT for prostate cancer: dosimetric analysis and preliminary patient-reported outcomes

OBJECTIVE

The main aim of the current analysis was to explore the hypothetical advantages using rectal spacer during 1.5T MR-guided and daily adapted prostate cancer stereotactic body radiotherapy (SBRT) compared to a no-rectal spacer hydrogel cohort of patients.

METHODS

The SBRT-protocol consisted of a 35 Gy schedule delivered in 5 fractions. Herein, we present a dosimetric analysis between spacer and no-spacer patients. Furthermore, treatment tolerability and feasibility were preliminarily assessed according to clinicians-reported outcomes at the end of treatment and patient-reported outcomes measures (PROMs) in both arms. Toxicity and quality of life were assessed at baseline and after treatment using the Common Terminology Criteria for Adverse Events v. 5.0, International Prostatic Symptoms Score, ICIQ-SF, IIEF-5, and EORTC-QLQ-C30 and PR-25 questionnaires.

RESULTS

120 plans (pre- and daily adaptive SBRT planning) were analyzed in 20 patients (10 patients in spacer group and 10 patients in no-spacer group) treated using 1.5T MR-guided adaptive SBRT. Statistically significant dosimetric advantages were observed in favor of the spacer insertion, improving the planning target volume coverage in terms of V33.2Gy >95% and planning target volume 37.5 Gy <2% mainly during daily-adapted SBRT. Also, rectum V32, V28 and V18Gy and bladder V35Gy <1 cc were significantly reduced in the spacer cohort. Concerning the PROMS, all questionnaires showed no difference between the pre- and post-SBRT evaluation in both arms, excepting the physical functioning item of EORTC QLQ-C30 questionnaire that was declined in the no-spacer group.

CONCLUSION

These preliminary results strongly suggest the adoption of perirectal spacer due to dosimetric advantages not only for rectal sparing but also for target coverage. Longer follow-up is required to validate the clinical impact in terms of clinicians-reported toxicity and PROMs.

ADVANCES IN KNOWLEDGE

This the first experience reporting preliminary data concerning the potential dosimetric impact of rectal hydrogel spacer on MR-guided SBRT for prostate cancer.

Hypofractionated Radiation Therapy to the Prostate Bed With Intensity-Modulated Radiation Therapy (IMRT): A Phase 2 Trial

PURPOSE

Postoperative radiation therapy (RT) is a common therapy used for patients with prostate cancer. Although clinical trials have established the safety and efficacy of hypofractionation as a primary therapy, there are limited data in a postoperative setting. We conducted a prospective trial to evaluate the safety and feasibility of postoperative hypofractionated RT to the prostate bed.

METHODS AND MATERIALS

In this phase 2 trial, patients submitted to radical prostatectomy were treated with hypofractionated RT to the prostate bed (adjuvant or salvage). The prescribed dose was 51 Gy in 15 fractions (3.4 Gy per fraction), using intensity modulated and image guided radiation therapy techniques. The primary endpoint was the rate of acute genitourinary (GU) grade ≥2 toxicity. Secondary endpoints included acute gastrointestinal (GI) and late GU/GI toxicities, biochemical failure-free survival (BFFS), metastasis-free survival, cancer-specific survival, overall survival, and health-related quality of life.

RESULTS

Of 64 enrolled patients, 61 received radiation therapy (57 salvage and 4 adjuvant radiation therapy). After a median follow-up of 16 months, 11.5% of patients experienced acute grade ≥2 GU symptoms and 13.1% experienced acute grade ≥2 GI symptoms. The late grade ≥2 GU toxicity rate was 8.2%, and 1 patient (1.6%) developed both acute and late grade 3 GU toxicity. The late grade ≥2 GI toxicity rate was 11.5%, and no grade 3 GI adverse events were reported. The short follow-up limits our ability to perform a robust oncologic endpoint assessment; however, the 2-year BFFS, use of subsequent salvage therapy, and the development of metastasis were 95.1%, 0%, and 0%, respectively.

CONCLUSIONS

Hypofractionated RT to the prostate bed in 15 treatments was safe, with an acceptable GU and GI toxicity profile. Further study in large, randomized trials is warranted.

Hypofractionated Postoperative Radiotherapy for Prostate Cancer: Is the Field Ready Yet?

Context

Radiotherapy (RT) is a valid adjuvant treatment for men with high-risk pathological features after radical prostatectomy and a salvage treatment for biochemical recurrence. A major inconvenience is that RT takes course over 7–8 wk in these settings, which has been shown to limit its use. Retrospective and pilot prospective investigations suggest that hypofractionation may provide noninferior outcomes but report variable results regarding toxicities. Additionally, our evolving understanding of prostate cancer radiobiology suggests that hypofractionated regimens may not increase toxicity.

Objective

We examine and review the rationale and clinical evidence of hypofractionated RT in the adjuvant and salvage settings for prostate cancer.

Evidence acquisition

We reviewed relevant literature, with a particular focus on recent studies employing hypofractionated RT.

Evidence synthesis

Hypofractionated RT in the adjuvant or salvage setting is not a standard option for prostate cancer RT outside of an investigational trial. While smaller studies show conflicting data regarding toxicity, initial evidence from larger clinical trials appears to demonstrate that hypofractionated postoperative RT is as effective and safe as conventionally fractionated courses.

Conclusions

With the growing acceptance of hypofractionation across other cancer sites and the rise of extreme hypofractionation for definitive prostate cancer treatment, hypofractionated postoperative therapy for prostate cancer is poised to become an option, as it may reduce the burden on men and treatment centers while maintaining clinical efficacy and safety. Prospective trials are currently ongoing to address efficacy and safety concerns.

Patient summary

Postoperative radiotherapy is a potentially curative treatment for patients with high-risk disease or recurrence after surgery. Shortening of the treatment regimen with the availability of modern treatment delivery techniques in conjunction with the integration of molecular imaging information to refine treatment volumes may improve therapeutic benefit without increasing toxicity.

Moderate hypofractionated radiotherapy for post-operative treatment of prostate cancer: long-term outcome and pattern of toxicity

OBJECTIVE

Postoperative radiotherapy (RT) is an established treatment for prostate cancer (PC). Though hypofractionation is commonly used for radical treatments, open issues still remain in the postoperative setting due to the lack of long-term data. Aim of this study was to evaluate long-term results of postoperative moderately hypofractionated RT (MHRT).

METHODS

We conducted a retrospective analysis including PC patients treated with prostatectomy and postoperative MHRT delivered with volumetric modulated arc therapy (VMAT). Endpoints of the analysis included biochemical relapse-free survival (BRFS), distant metastases free-survival (DMFS), overall survival (OS), and pattern of acute and late toxicity.

RESULTS

181 patients were included. Pathological stage was classified as pT3a in 33.6% and pT3b in 30%. Median PSA value before RT was 0.23 ng/ml and median RT total dose was 70 Gy (65-74.2 Gy) in 25/28 fractions. With a median follow-up of 54.5 months, rates of BRFS at 3 and 5 years were 80.7 and 72.3%. ISUP grade group (HR 1.44, p = 0.015), pathological T stage (HR 2.03; p = 0.009), and pre-RT PSA >0.2 ng/ml (HR 2.64; p = 0.015) were correlated with BRFS. Three and 5‑year DMFS were 87.4 and 80.8%. ISUP grade group (HR 1.50; p = 0.011) and pre-RT PSA (HR 5.34; p = 0.001) were correlated with DMFS. Five (2.7%) and 3 (1.6%) patients reported late grade 3 GU and GI toxicity, respectively.

CONCLUSION

Our results confirm the long-term safety and efficacy of postoperative MHRT for PC.

ADVANCES IN KNOWLEDGE

The present paper demonstrates the long-term safety and efficacy of MHRT for postoperative prostate cancer. Reduction of treatment time in long-course radiotherapy has advantages in terms of both patients' quality of life and departmental organization.

Prostate re-irradiation: current concerns and future perspectives

INTRODUCTION

To date, the optimal management of locally relapsed prostate cancer patients after an initial course of radiotherapy remains a matter of debate. In recent years, local approaches have been proposed as a therapeutic option, which may potentially delay the initiation of hormone therapy. In the case of external beam radiotherapy (EBRT), re-irradiation has been supported by growing evidence in the literature, mostly represented by extreme hypofractionated schedules delivered with stereotactic body radiotherapy (SBRT).

AREAS COVERED

We performed a systematic review of the literature using the PICO methodology to explore the available evidence regarding the use of EBRT in the setting of locally relapsed prostate cancer, both in terms of safety, tolerability and preliminary clinical outcomes.

EXPERT OPINION

Current literature data report the use of EBRT and particularly of SBRT for the safe and feasible re-treatment of locally recurrent prostate cancer after an initial treatment course of radiotherapy. When extreme hypofractionation is adopted, only occasional grade ≥3 late adverse events are reported. Despite the current lack of high-level evidence and the short follow-up, preliminary clinical outcomes are promising and allow clinicians to hypothesize further prospective studies to evaluate SBRT as an alternative to the early initiation of androgen-deprivation therapy.

Prostate bed and organ-at-risk deformation: Prospective volumetric and dosimetric data from a phase II trial of stereotactic body radiotherapy after radical prostatectomy

PURPOSE

Stereotactic body radiotherapy (SBRT) in the post-prostatectomy setting is investigational. A major concern is the deformable prostate bed clinical target volume (CTV) and the closely juxtaposed organs-at-risk (OARs). We report a volumetric and dosimetric analysis of kilovoltage cone-beam CT (CBCT) data from the first 18 patients enrolled on a phase II trial of post-prostatectomy SBRT. With instructions on bladder filling and rectal preparation, we hypothesized acceptable CTV coverage while minimal overdosing to OARs could be achieved.

METHODS

All patients received 5 fractions of 6-6.8 Gy to the prostate bed. CBCT were taken prior to and halfway through each fraction. CTV and OARs were contoured for each CBCT. Changes in inter- and intra-fraction volume and dose were calculated. Relative changes in CTV V95%, bladder V32.5 Gy, and rectal V32.5 Gy and V27.5 Gy were evaluated.

RESULTS

Interfraction CTV volume remained stable, with median change +5.69% (IQR -1.73% to +9.84%). CTV V95% exhibited median change -0.74% (IQR -9.15% to -0.07%). Volumetric and dosimetric changes were minor from interfraction rotation and intrafraction motion. CTV V95% was ≥93% in 13 of 18 (72%) patients; in the remaining five, median change was -14.09% (IQR -16.64% to -13.56%). Interfraction CTV volume change was significantly larger among patients with CTV V95% <93% (+25.04% vs. +2.85%, p = 0.002).

CONCLUSIONS

With specific bladder and rectum filling protocols, CTV underdosing and overdosing to bladder and rectum are avoided in majority of patients. Changes in CTV shape may account for the underdosing that may be observed.

1.5 T MR-guided and daily adapted SBRT for prostate cancer: feasibility, preliminary clinical tolerability, quality of life and patient-reported outcomes during treatment

Background

Unity Elekta is a unique magnetic resonance (MR)-linac that conjugates a 1.5 Tesla MR unit with a 7 MV flattening filter free accelerator.A prospective observational study for the clinical use of Elekta Unity is currently ongoing in our department. Herein, we present our preliminary report on the feasibility, quality of life, and patient-reported outcomes measures (PROMs) for localized prostate cancer (PC) treated with stereotactic body radiotherapy (SBRT).

Methods

The SBRT protocol consisted of a 35 Gy schedule delivered in 5 fractions within 2 weeks. Toxicity and quality of life (QoL) were assessed at baseline and after treatment using the Common Terminology Criteria for Adverse Events v5.0, International Prostatic Symptoms Score (IPSS), ICIQ-SF, IIEF-5, and EORTC-QLQ-C30 and PR-25 questionnaires.

Results

Between October 2019 and January 2020, 25 patients with localized PC were recruited. The median age was 68 years (range, 54–82); 4 were low risk, 11 favorable intermediate risk (IR) and 10 unfavorable IR. Median iPSA was 6.8 ng/ml (range, 1–19), and 9 of these patients (36%) received concurrent androgen deprivation therapy. Median prostate volume was 36 cc (range, 20–61); median baseline IPSS was 5 (range, 0–10). Median time for fraction was 53 min (range, 34–86); adaptive strategy with daily critical structure and target re-contouring and daily replanning (adapt to shape) was performed in all cases. No grade ≥ 3 adverse event was observed, three patients (12%) reported grade 2 acute genitourinary toxicity (urinary frequency, urinary tract pain and urinary retention), while only one patient reported mild rectal pain. No relevant deteriorations were reported in PROMs.

Conclusion

To the best of our knowledge, this is the first experience reporting feasibility, clinician-reported outcome measurements, and PROMs for 1.5 T MR-guided adaptive SBRT for localized prostate cancer. The preliminary data collected here report optimal safety and excellent tolerability, as also confirmed by PROMs questionnaires. Moreover, the data on technical feasibility and timing of online daily adapted planning and delivery are promising. More mature data are warranted.

Trial registration

Date of approval April 2019 and numbered MRI/LINAC n°23,748.

Ten-Year Outcomes of Moderately Hypofractionated Salvage Postprostatectomy Radiation Therapy and External Validation of a Contemporary Multivariable Nomogram for Biochemical Failure

PURPOSE

Although high-level evidence supports moderately hypofractionated radiation therapy for definitive prostate treatment, there is less evidence for its use in the postprostatectomy setting. We externally validated a contemporary nomogram predicting biochemical failure (BF) after salvage radiation therapy (SRT) and report long-term disease control outcomes for hypofractionated SRT to the prostate bed.

METHODS AND MATERIALS

A retrospective review was performed for 112 patients treated with hypofractionated SRT (52.5 Gy in 20 fractions using 3-dimensional conformal radiation therapy) for pT2-4R0-1N0/XM0 prostate adenocarcinoma, with postoperative prostate-specific antigen (PSA) greater than 0.1 ng/mL or rising. Freedom from BF (FFBF), distant metastasis, cancer-specific mortality, and overall survival were analyzed from commencement of radiation therapy. Cox regression was performed on FFBF to account for covariates. BF was defined as a PSA ≥0.4 ng/mL and rising after SRT. Early SRT was defined as SRT commencing at a pre-SRT PSA of ≤0.2 ng/mL.

RESULTS

Median follow-up was 10.0 years (interquartile range, 9.3-10.7 years), median pre-SRT PSA was 0.4 ng/mL, and androgen deprivation therapy was used in 14% of patients. The 5/10-year FFBF, distant metastasis, cancer-specific mortality, and overall survival were 68%/51%, 7%/16%, 5%/11%, and 90%/75%, respectively. FFBF for early SRT compared with late SRT was 81% versus 66% at 5 years and 68% versus 49% at 10 years. On multivariable analysis, pre-SRT PSA, International Society of Urologic Pathology grade group, seminal vesicle invasion, and androgen deprivation therapy use were associated with FFBF. The nomogram c-index was 0.67, and it overestimated FFBF by 10% and 15% at 5 and 10 years, respectively, with confidence intervals overlapping the line of unity.

CONCLUSIONS

Hypofractionated SRT provides long-term disease control outcomes comparable to conventionally fractionated radiation therapy. Early SRT provides improved disease control, with two-thirds of patients with pre-SRT PSA of ≤0.2 ng/mL free of BF at 10 years. We performed the first external validation of the Tendulkar salvage nomogram, which showed a robust model performance.

[Moderate or extreme hypofractionation and localized prostate cancer: The times are changing]

There are many treatment options for localized prostate cancers, including active surveillance, brachytherapy, external beam radiotherapy, and radical prostatectomy. Quality of life remains a primary objective in the absence of superiority of one strategy over another in terms of specific survival with similar long-term biochemical control rates. Despite a significant decrease in digestive and urinary toxicities thanks to IMRT and IGRT, external radiotherapy remains a treatment that lasts approximately 2 months or 1.5 months, when combined with a brachytherapy boost. Given the specific radiosensitivity of this tumor, several randomized studies have shown that a hypofractionated scheme is not inferior in terms of biochemical control and toxicities, allowing to divide the number of fractions by a factor 2 to 8. Given that SBRT becomes a validated therapeutic option for a selected population of patients with localized prostate cancer, extreme hypofractionation is becoming a strong challenger of conventional external radiotherapy or brachytherapy.

Moderate versus extreme hypofractionated radiotherapy: a toxicity comparative analysis in low- and favorable intermediate-risk prostate cancer patients

PURPOSE

External beam radiotherapy (EBRT) is an effective treatment option for low- and favorable intermediate-risk prostate cancer (PCa) and it is usually delivered in conventional fractionation or with moderate hypofractionation (hRT), with comparable results. In the last years, a new treatment approach with stereotactic body radiotherapy (SBRT) has shown promising results. The aim of the present study was to directly compare the toxicity and outcome between hRT and SBRT in low and favorable intermediate PCa patients.

MATERIALS AND METHODS

The hRT schedules were: 71.4 Gy or 74.2 Gy in 28 fractions for low- or favorable intermediate-risk PCa, respectively, while the SBRT schedules were: 35 Gy or 37.5 Gy in five fractions, for low or favorable intermediate risk, respectively. Toxicity assessment was performed according to CTCAE v5.0 grading. The International Prostatic Symptoms Score (IPSS) was also recorded.

RESULTS

One hundred forty-nine patients were analyzed, overall 81 (54.36%) patients were low risk and 68 (45.64%) were favorable intermediate risk. Sixty-nine (46.3%) patients were treated with hypo-RT and 80 (53.7%) with SBRT. Median follow-up was 33 months (range 11-58 months). The actuarial survival rate was 98.66%. The 3-years BFS rates were 95.5% and 100% for hRT and SBRT, respectively (p = 0.051). One case (0.6%) of acute grade 3 urinary toxicity occurred in a patient with favorable intermediate risk treated with hRT. He initially suffered gross hematuria and acute urinary retention not treatable with urinary catheter, therefore a suprapubic catheter was placed and steroids were administered. No differences in acute, late or severe toxicity were detected.

CONCLUSION

Stereotactic body radiotherapy reported a good clinical outcome and safe toxicity profile. Results are comparable to hRT, but a longer follow-up is needed to assess the late effectiveness and toxicity.

Prostate bed irradiation with alternative radio-oncological approaches (PAROS) - a prospective, multicenter and randomized phase III trial

Background

For patients with treatment-naïve carcinoma of the prostate, hypofractionated irradiation becomes more and more popular. Due to the low α/β value of prostate cancer, increased single dose leading to a shortened treatment period seems to be safe and feasible. However, reliable data is lacking for post-prostatectomy patients so far. Further, the role of proton therapy is still under debate. Two prospective phase II trials with both, hypofractionated photon and proton therapy, provided promising results.

Methods/ design

The PAROS trial is a prospective, multicenter and randomized phase III trial for men with localized prostate carcinoma after surgery. Post-prostatectomy patients will be randomized to either normofractionated radiotherapy (nRT) with photons (70.0/ 2.0 Gy), or hypofractionated radiotherapy (hRT) with photons (57.0/ 3.0 Gy) or hRT with protons (57.0/ 3.0 Gy relative biological effectiveness [RBE]). Block randomization is stratified by Gleason Score (≤ 7 vs. > 7) and treatment indication (adjuvant vs. salvage). The trial is planned to enroll 897 patients. The primary objective is to show an improvement in the bowel-score according to EORTC QLQ-PR25 after proton therapy compared to photon irradiation (week 12 vs. baseline). Secondary aims are non-inferiority of hRT compared to nRT with regard to biochemical progression-free survival (bPFS), overall survival (OS), quality of life and toxicity.

Discussion

The present study aims to evaluate the role of hypofractionated radiotherapy to the prostate bed with photons and protons leading to significant impact on future management of operated men with prostate cancer.

Trial registration

Deutsches Register klinischer Studien: DRKS00015231; registered 27 September 2018.

Does Interfraction Cone Beam Computed Tomography Improve Target Localization in Prostate Bed Radiotherapy?

Purpose:

In this prospective phase II study, we investigated whether cone beam computed tomography scan was a superior method of image-guided radiotherapy relative to 2D orthogonal kilovoltage images in the post-radical prostatectomy setting.

Methods:

A total of 419 treatment fractions were included in this analysis. The shifts required to align the patient for each treatment were performed using 3D matching between cone beam computed tomography scans and the corresponding computed tomography images used for planning. This was compared with the shifts obtained from 2D orthogonal kilovoltage images, matching with the corresponding digitally reconstructed radiographs. Patients did not have fiducials inserted to assist with localization. Interfractional changes in the bladder and rectal volumes were subsequently measured on the cone beam computed tomography images for each fraction and compared to the shift differences between orthogonal kilovoltage and cone beam computed tomography scans. The proportion of treatment fractions with a shift difference exceeding the planning target volume of 7 mm, between orthogonal kilovoltage and cone beam computed tomography scans, was calculated.

Results:

The mean vertical, lateral, and longitudinal shifts resulted from 2D match between orthogonal kilovoltage images and corresponding digitally reconstructed radiographs were 0.353 cm (interquartile range: 0.1-0.5), 0.346 cm (interquartile range: 0.1-0.5), and 0.289 cm (interquartile range: 0.1-0.4), compared to 0.388 cm (interquartile range: 0.1-0.5), 0.342 cm (interquartile range: 0.1-0.5), and 0.291 cm (interquartile range: 0.1-0.4) obtained from 3D match between cone beam computed tomography and planning computed tomography scan, respectively. Our results show a significant difference between the kilovoltage and cone beam computed tomography shifts in the anterior–posterior direction (P = .01). The proportion of treatment fractions in which the differences in kilovoltage and cone beam computed tomography shifts between exceeded the 7 mm planning target volume margin was 6%, 2%, and 3% in the anterior–posterior, lateral, and superior–inferior directions, respectively.

Conclusion:

We prospectively demonstrated that the daily use of volumetric cone beam computed tomography for treatment localization in post-radical prostatectomy patients demonstrated an increased need for a shift in patient position. This suggests that in post-radical prostatectomy patients the daily cone beam computed tomography imaging improved localization of the prostate bed and may have prevented a limited number of geographic misses, compared to daily kilovoltage imaging that was not assisted with fiducials.

Phase 1 Trial of SBRT to the Prostate Fossa After Prostatectomy

PURPOSE

The primary objective was to evaluate the maximum tolerated dose (within 10 weeks after treatment) associated with increasing hypofractionation to the prostate fossa (PF). We hypothesized that escalating the dose per fraction (fx) to the PF would have acceptable toxicity.

MATERIALS AND METHODS

Tested dose levels (DLs) were 3.6 Gy × 15 fx (DL1); 4.7 Gy × 10 fx (DL2); and 7.1 Gy × 5 fx (DL3). Escalation followed a 6 + 6 rules-based design with 12 patients required at the maximum tolerated dose. Dose-limiting toxicity was defined as grade (G) ≥3, gastrointestinal (GI) or genitourinary (GU) toxicity by National Cancer Institute Common Terminology Criteria for Adverse Events (version 4.03). Patients completed quality-of-life questionnaires.

RESULTS

Twenty-four patients with indications for adjuvant or salvage radiation therapy (RT) enrolled (6 at DL1 and 2; 12 at DL3). All patients had at least 6 months of follow-up (median follow-up, 14.1 months). Four patients received concurrent androgen deprivation therapy. No G ≥ 3 GI or GU toxicity was seen at any DL; 2 of 6 patients in the DL1 group, 3 of 6 in DL2, and 7 of 12 in DL3 experienced G2 GI toxicity during RT. Except in 1 patient, all acute G2 GI toxicity resolved by 10 weeks. Three of 12 patients reported an increase to G1 and G2 GU toxicity in the 2 weeks after RT in groups DL1 and DL2 and 1 of 12 patients in DL3. At week 2 after RT, decline in the 26-item Expanded Prostate Cancer Index Composite bowel domain met criteria for a minimally important difference in 71% of patients. At week 10, 1 of 6, 2 of 6, and 7 of 11 patients at DLs 1, 2, and 3, respectively, still met minimally important difference criteria. International Prostate Symptom Scores worsened 2 weeks after treatment but improved by 6 to 10 weeks.

CONCLUSIONS

Dose escalation up to 7.1 Gy × 5 fx to the PF was completed without acute G ≥ 3 toxicity. There was transient G2 rectal toxicity at all DLs during and immediately after RT. We must perform long-term follow-up and assessment of late toxicity of SBRT to the PF.

Hypofractionated postoperative helical tomotherapy in prostate cancer: a mono-institutional report of toxicity and clinical outcomes

Purpose

This is a mono-institutional study of acute and late toxicities and early biochemical control of a retrospective series of 75 prostate cancer patients treated with moderate postoperative hypofractionation delivered by helical tomotherapy (HT).

Patients and methods

From April 2013 to June 2017, 75 patients received adjuvant (n=37) or salvage (n=38) treatment, delivering to prostate bed a total dose of 63.8 Gy (equivalent dose in 2-Gy fractions=67.4 Gy) using 2.2 Gy fractions. Whole-pelvis irradiation was performed in 63% of cases (median dose, 49.3 Gy; range, 48–55.1 Gy). Concurrent hormonal therapy was administered in 46% of cases. Common Terminology Criteria for Adverse Events (version 4.0) was adopted for acute and late genitourinary (GU) and gastrointestinal (GI) toxicity evaluations. Biochemical progression was defined as PSA level increase of ≥0.2 or more above the postoperative radiotherapy (RT) nadir.

Results

Acute GU toxicities were as follows: G1 in 46% and G2 in 4%, detecting no G≥3 events. For GI toxicity, we recorded G1 in 36% and G2 in 18%. With a median follow-up of 30 months (range, 12–58 months), we found late toxicity G2 GI in 6.6% and G≥2 GU in 5.3%, including two patients who underwent surgical incontinence correction. Acute GI≥2 toxicity and diabetes were found to be predictive of late GI≥2 toxicity (P=0.04 and P=0.0019). Actuarial 2- and 3-year biochemical recurrence-free survivals were 88% and 73%, respectively, for the entire population.

Conclusion

In our experience, moderate hypofractionated postoperative RT with HT was feasible and safe, with reports of low incidence of toxicity and promising biochemical control rates.

Acute Toxicity Profiles of Hypofractionated Adjuvant and Salvage Radiation Therapy After Radical Prostatectomy: Results of a Prospective Study

PURPOSE

Hypofractionated radiation therapy (RT) is controversial after radical prostatectomy (RP). In this interim analysis, our prospective observational study assessed acute genitourinary (GU) and gastrointestinal (GI) toxicity after hypofractionated adjuvant and salvage RT, as delivered by helical tomotherapy (HT), in patients with prostate cancer.

METHODS AND MATERIALS

After undergoing RP with or without pelvic lymph node dissection, 112 patients were enrolled. Hypofractionated adjuvant RT (2.25 Gy daily for 29 fractions; total 65.25 Gy) was administered to 40 patients with high-risk features. Hypofractionated salvage RT (2.25 Gy daily for 32 or 33 fractions; total 72-74.25 Gy) was prescribed for 72 patients (24 with biochemical relapse, 48 with local relapse). Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 4.02. The impact of RT on urinary flow was assessed by uroflowmetry.

RESULTS

Acute GU toxicity occurred in 41 of 112 patients (36%) (G1 31, G2 10). Acute GI toxicity was observed in 55 (49%) patients (G1 44, G2 11). Uroflowmetry showed that only salvage RT reduced maximum flow significantly (maximum, 68 vs 50 mL/s; P = .003), perhaps because a higher RT dose had been administered.

CONCLUSIONS

After RP, moderate hypofractionated adjuvant and salvage RT were associated with acceptable incidences of slight-to-moderate acute GU and GI toxicity and had little impact on urinary flow. Prospective trials are warranted with longer follow-up in larger cohorts to confirm these findings.

Impact of interfractional motion on hypofractionated pencil beam scanning proton therapy and VMAT delivery for prostate cancer

PURPOSE

Hypofractionated radiotherapy of prostate cancer is gaining clinical acceptance given its potential increase in therapeutic ratio and evidence for noninferiority and lack of added late toxicities compared to conventional fractionation. However, concerns have been raised that smaller number of fractions might lead to larger dosimetric influence by interfractional motion. We aim to compare the effect of these variations on hypofractionated pencil beam scanning (PBS) proton therapy and volumetric modulated arc therapy (VMAT) for localized prostate cancer.

METHODS

Weekly CT images were acquired for 6 patients participating in a randomized clinical trial. PBS plans featuring bilateral (BL) and a combination of lateral and anterior-oblique beams (AOL), and VMAT plans were created. All patients were treated to a conventional 79.2 Gy total dose in 44 fractions. For this study, hypofractionated dose to the prostate gland was 51.6 Gy in 12 fractions or 36.25 Gy in 5 fractions, and 32.8, and 23.1 Gy to proximal seminal vesicles, respectively. Patients were simulated with endorectal balloons to aid gland immobilization. Three fiducial markers were implanted for setup guidance. All plans were recomputed on the weekly CT images after aligning with the simulation CT. The entire set of 9 CT images was used for dose recalculation for 12-fraction and only 5 used for the 5-fraction case. Adaptive range adjustments were applied to anterior-oblique beams assuming clinical availability of in vivo range verification. Fractional doses were summed using deformable dose accumulation to approximate the delivered dose. Biologically equivalent dose to 2 Gy(EQD2) was calculated assuming α/β of 1.5 Gy for prostate and 3 Gy for bladder and rectum.

RESULTS

The median delivered prostate D98 was 0.13/0.14/0.13 Gy(EQD2) smaller than planned for PBS-BL, 0.13/0.27/0.17 Gy(EQD2) for PBS-AOL and 0.59/0.66/0.59 Gy(EQD2) for VMAT, for 44/12/5 fractions, respectively. The largest D98 reduction was 1.5 and 3.5 Gy(EQD2) for CTV1 and CTV2, respectively. Target dose degradation was comparable for all fractionation schemes within each modality. The maximum increase in rectum D2 was 0.98 Gy(EQD2) for a 5-fraction PBS case.

CONCLUSIONS

The robustness of PBS and VMAT were comparable for all patients for the studied fractionations. The delivered target dose generally remained within clinical tolerance and the deviations were relatively minor for both fractionation schemes. The delivered OAR dose stayed in compliance with the RTOG hypofractionation constraints for all cases.

Contemporary role of postoperative radiotherapy for prostate cancer

While radical prostatectomy (RP) has provided long-term disease control for the majority of patients with localized prostate cancer (CaP), nearly 30% of all surgical patients have disease progression. For high-risk patients, more than half of men experience disease recurrence within 10 years. Postoperative radiotherapy is the only known potentially curative treatment for a large number of patients following prostatectomy. Lately, there have been several advances with the potential to improve outcomes for patients undergoing postoperative radiotherapy. This article will give an overview of the existing literature and current controversies on: (I) timing of postoperative radiation; (II) use of concomitant androgen deprivation therapy; (III) optimal dose to the prostate bed; (IV) use of hypofractionation; (V) elective treatment of the pelvic lymph nodes; (VI) novel imaging modalities, and (VII) genomic biomarkers.

Moderate hypofractionated radiotherapy after prostatectomy for cancer patients: toxicity and clinical outcome

Background

After radical prostatectomy (RP) radiotherapy (RT) plays a role, both as adjuvant or salvage treatment. If negative features are present such as extracapsular extension, seminal vesicle invasion, lymph invasion, and positive surgical margins, RT after RP reduces the risk of recurrence, although it is associated with an increased risk of acute and late toxicities. An intensified RT delivered in a shortened time could improve clinical outcome and be safely combined with hormonal therapy (HT). The aim of this study was to determine the acute and late toxicities associated with hypofractionated RT and to assess the impact of the addition of HT to RT in high-risk prostate cancer (PC) patients on overall response and toxicity.

Materials and methods

Sixty-four PC patients undergoing RP were included in this retrospective study. All patients were recommended to receive adjuvant or salvage RT. Prescription doses were 62.5 Gy in 25 fractions to prostate bed, 56.25 Gy in 25 fractions to seminal vesicles bed, and 50 Gy in 25 fractions to pelvis if indicated. HT was administered to patients with additional adverse pathologic features including Gleason score >7, prostate-specific antigen >20 ng/mL before surgery, or prostate-specific antigen with rapid doubling time after relapse or nodal involvement. After completion of RT, patients were observed after 4 weeks, and then followed-up every 3–6 months. Acute and late toxicities were assessed using Common Terminology Criteria for Adverse Events v4 and Radiation Therapy Oncology Group scale, respectively.

Results

For acute toxicity, only grade 1 gastrointestinal and genitourinary toxicities were detected in 17% and 11% of patients, respectively. As regards late toxicity, only 5% of the patients developed grade 1 gastrointestinal adverse event; grade 1, grade 2, and grade 3 genitourinary toxicity was recorded in 5%, 3.3%, and 3.3% of patients, respectively. Two and 5 years overall survival were 98% and 96%, respectively. The curves stratified for treatment show a slight difference between patients receiving RT or RT+HT, but the differences did not reach statistical significance (p=0.133).

Conclusion

In patients with PC undergoing RP, hypofractionated RT may contribute to achieve a high overall survival with an acceptable toxicity profile. Combination of RT and HT is also well tolerated and efficacious.