Therapy For High-risk Prostate Cancer Research Articles

Helical Tomotherapy Versus 3-Dimensional Conformal Radiation Therapy in High-Risk Prostate Cancer: A Phase 3 Randomized Controlled Trial

We present long-term outcomes from a phase 3 randomized controlled trial that compared helical tomotherapy with 3-dimensional conformal radiation therapy (3D-CRT) in the treatment of high-risk prostate cancer. Newly diagnosed patients with high-risk prostate cancer were randomly allocated to receive radical radiation therapy (RT) using 3D-CRT or helical tomotherapy. In both arms, patients received an initial dose of 46 Gy in 23 fractions to the prostate and pelvic lymph nodes, followed by an additional boost to the prostate of 32 Gy in 16 fractions. RT was combined with 3 years of adjuvant androgen deprivation. The primary endpoint was late (>90 days since RT initiation) rectal toxicity. Overall,123 patients were randomly assigned to either the 3D-CRT (n = 60) or tomotherapy (n = 63) arms. The median follow-up was 161 months. Overall, the proportion of patients with grade ≥ 2 late rectal toxicity was 8.3% (95% CI, 3.1-19.1; n = 5) in the 3D-CRT arm and 11.1% (95% CI, 5.0-22.2; n = 7) in the tomotherapy arm with no significant between-arm difference (P = .83). There was no significant difference (P = .17) in the proportion of patients with late grade ≥ 2 genitourinary toxicity:10.0% (95% CI, 4.1-21.2) in the 3D-CRT arm and 20.6% (95% CI, 11.9-33.0) in the tomotherapy arm. There was no significant difference in the hazard of biochemical progression or death between the 2 groups (hazard ratio for the tomotherapy arm: 0.72; 95% CI, 0.46-1.15; P = .17). In this phase 3 trial, the overall incidence of grade ≥ 2 rectal toxicity was low and was not significantly different between the 2 arms. There was no significant evidence of improved biochemical progression-free survival in patients treated with tomotherapy. These findings should be interpreted considering the possibility of type II errors due to limited sample size and low event rates.

Combination approach using neoadjuvant therapy with radical prostatectomy for improving oncological outcomes of high-risk prostate cancer: a narrative review.

Prostate cancer (PCa) is the most common cancer in men. High-risk PCa is associated with an increased risk of PCa-related death. The combined use of androgen deprivation therapy (ADT) is essential to improve oncological outcomes in patients with high-risk PCa, and relatively long-term ADT administration is preferred when radiotherapy is performed. Meanwhile, whether neoadjuvant therapy for radical prostatectomy (RP) improves oncological outcomes remains controversial. This study aimed to review the oncological outcomes of RP in high-risk PCa and emphasize the significance of neoadjuvant therapy including neoadjuvant hormonal therapy (NHT) and neoadjuvant chemohormonal therapy (NCHT) followed by RP for managing high-risk PCa. We searched for articles published in the PubMed and Scopus databases from January 1, 2005 to March 30, 2023 using the medical subject headings (MeSH) terms: prostate cancer, prostatectomy, radiation therapy, neoadjuvant therapy, and treatment outcome. The study on NHT before RP for high-risk PCa found that NHT was associated with reduced adverse pathological features, such as pT3, positive surgical margins (PSM), and lymph node involvement. However, despite shorter operative times and improved surgical outcomes, NHT did not significantly enhance biochemical recurrence (BCR) or other oncological outcomes. The combination therapy using ADT and androgen receptor signaling inhibitors (ARSI) showed varying results. Another investigation explored NCHT with taxane-based agents, indicating acceptable treatment benefits and improved BCR-free survival rates in high-risk PCa patients, demonstrating potential feasibility for this approach. Ongoing trials, like the PROTEUS trial, aim to further evaluate the therapeutic efficacy of neoadjuvant therapy in high-risk PCa. NHT for high-risk PCa does not contribute to improved oncological outcome and should not be administered easily for downstaging or PSM reduction. NHT in combination with ARSI has the potential advantage of improving the oncological outcome of high-risk PCa compared to RP alone, but the results are currently unsatisfactory, and the development of individualized treatment strategies using several different therapeutic approaches is needed.

Late Urinary Toxicity and Quality of Life With Pelvic Radiation Therapy for High-Risk Prostate Cancer: Dose-Effect Relations in the POP-RT Randomized Phase 3 Trial

PurposeThe POP-RT phase III randomized trial showed improved biochemical failure-free survival and metastasis-free survival with whole pelvic radiotherapy (WPRT) versus prostate-only radiotherapy (PORT) for high/very high-risk prostate cancer, albeit with worse RTOG late urinary toxicity. We report updated late urinary adverse effects and bladder dose-effect relations within this trial. Materials/MethodsLate urinary toxicity, and cumulative severity of each symptom over the follow-up period was graded using CTCAE v5.0. Bladder dosimetry in 5-Gy increments (V5, V10, V15...V65Gy, V68Gy) in the approved radiotherapy plans was compared for urinary symptoms and overall grade 2+ toxicity. Potential factors influencing urinary toxicity were tested using multivariable logistic regression analysis. Updated urinary quality of life (QOL) scores were compared between the trial arms. ResultsComplete combined data for late urinary symptoms and dosimetry was available for 193/224 patients. At a median follow-up of 75 months, cumulative late urinary CTCAE grade 3 toxicity was low and similar for WPRT and PORT (5.2% vs 4.1%, p=0.49), while grade 2 toxicity was 31.3% vs 22.7% respectively (p=0.12). Cumulative rates of each urinary symptom were similar between both arms. Multivariable analysis with age at diagnosis, known diabetes, tumor stage, trial arm, prior TURP, grade 2+ acute urinary toxicity, low bladder dose (V10Gy) and moderate bladder dose (V40Gy) did not identify any significant association with late urinary toxicity. Urinary QOL scores was similar between both the arms for all the symptoms. ConclusionOver long term follow up, whole pelvic radiotherapy resulted in low (∼5%) and similar grade 3 cumulative urinary toxicity as prostate-only radiotherapy. The long term patient-reported QOL scores were similar. No causative factors affecting the late urinary toxicity were identified.

Proton versus photon therapy for high-risk prostate cancer with dose escalation of dominant intraprostatic lesions: a preliminary planning study.

This study aimed to investigate the feasibility of safe-dose escalation to dominant intraprostatic lesions (DILs) and assess the clinical impact using dose-volume (DV) and biological metrics in photon and proton therapy. Biological parameters defined as late grade ≥ 2 gastrointestinal (GI) and genitourinary (GU) derived from planned (D P) and accumulated dose (D A) were utilized. In total, 10 patients with high-risk prostate cancer with multiparametric MRI-defined DILs were investigated. Each patient had two plans with a focal boost to the DILs using intensity-modulated proton therapy (IMPT) and volumetric-modulated arc therapy (VMAT). Plans were optimized to obtain DIL coverage while respecting the mandatory organ-at-risk constraints. For the planning evaluation, DV metrics, tumor control probability (TCP) for the DILs and whole prostate excluding the DILs (prostate-DILs), and normal tissue complication probability (NTCP) for the rectum and bladder were calculated. Wilcoxon signed-rank test was used for analyzing TCP and NTCP data. IMPT achieved a higher Dmean for the DILs compared to VMAT (IMPT: 68.1 GyRBE vs. VMAT: 66.6 Gy, p < 0.05). Intermediate-high rectal and bladder doses were lower for IMPT (p < 0.05), while the high-dose region (V60 Gy) remained comparable. IMPT-TCP for prostate-DIL were higher compared to VMAT (IMPT: 86%; α/β = 3, 94.3%; α/β = 1.5 vs. VMAT: 84.7%; α/β = 3, 93.9%; α/β = 1.5, p < 0.05). Likewise, IMPT obtained a moderately higher DIL TCP (IMPT: 97%; α/β = 3, 99.3%; α/β = 1.5 vs. VMAT: 95.9%; α/β = 3, 98.9%; α/β = 1.5, p < 0.05). Rectal D A-NTCP displayed the highest GI toxicity risk at 5.6%, and IMPT has a lower GI toxicity risk compared to VMAT-predicted Quantec-NTCP (p < 0.05). Bladder D P-NTCP projected a higher GU toxicity than D A-NTCP, with VMAT having the highest risk (p < 0.05). Dose escalation using IMPT is able to achieve a high TCP for the DILs, with the lowest rectal and bladder DV doses at the intermediate-high-dose range. The reduction in physical dose was translated into a lower NTCP (p < 0.05) for the bladder, although rectal toxicity remained equivalent.

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

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. 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. 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. 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.

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

There has been emerging interest in the role of ultra-hypofractionated radiotherapy for high-risk prostate cancer, especially given its low α/β ratio. However, there is limited data on the long-term outcomes of this treatment strategy. The FASTR and FASTR-2 clinical trials were designed to assess the tolerability of stereotactic ablative body radiotherapy (SABR) in high-risk prostate cancer. FASTR was discontinued early due to unacceptable acute toxicity, whereas the acute toxicities in FASTR-2 were minimal. Herein, the long-term results from these trials are reported. Eligible patients had at least 1 high-risk feature as per the National Comprehensive Cancer Network criteria for high-risk prostate cancer, no evidence of metastatic disease, and either a score of 3+ on the Vulnerable Elderly Scale or declined standard therapy. A total of 19 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 fractions delivered once weekly for 5 weeks, along with 1 year of androgen deprivation therapy (ADT). The excessive acute toxicity in FASTR prompted several modifications in FASTR-2, including the omission of nodal irradiation. A total of 30 patients from the same institution were enrolled on FASTR-2 between 2015 and 2017. They received 35 Gy to the prostate alone in 5 fractions delivered once weekly for 5 weeks, along with 18 months of ADT. A total of 44 patients were eligible for analysis, 16 from FASTR and 28 from FASTR-2. Most patients were >70 years old (77%). High-risk features included Gleason score ≥8 (46%), T3-T4 disease (27%) and baseline PSA >20 (50%). With a median follow-up of 6.4 years, the cumulative incidence of grade ≥3 genitourinary/gastrointestinal toxicity was 50% among FASTR patients and 7% among FASTR-2 patients. 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. A total of 12 patients (27%) required further treatment. No significant differences in clinical outcomes were noted between the FASTR and FASTR-2 cohorts. SABR for high-risk prostate cancer is an attractive option for reducing treatment burden. Clinical outcomes and toxicity with the FASTR-2 protocol were comparable to conventionally-fractionated radiotherapy plus ADT. Larger prospective, randomized trials exploring the role of SABR with ADT in high-risk disease are necessary to better understand the efficacy and tolerability of this approach.

Longitudinal Profiling of Tumor RNA Expression Signatures Reveal Key Biological Features Associated with Response to Neoadjuvant Stereotactic Body Radiation Therapy in High-Risk Prostate Cancer

Stereotactic body radiation therapy (SBRT) is a safe and effective treatment for localized prostate cancer (PCa). PREPARE-SBRT is a clinical trial testing the safety of neoadjuvant MRI-guided SBRT for men with high-risk localized PCa. We leveraged paired samples from pre-treatment biopsy and irradiated prostatectomy (RP) specimens to evaluate transcriptomic changes in irradiated tumors at acute time points following neoadjuvant SBRT. Tumor RNA expression profiles were generated using Decipher GRID by Veracyte on 12 subjects with paired pre- and post-SBRT tissues (n = 24). Descriptive statistics using gene expression profiles describing key biological features [DNA damage & repair (DDR), tumor proliferation, suppressed immune, activated immune, tumor microenvironment (TME)] and an exploratory analysis of RT sensitivity score with binary classification as sensitive or resistant were reported. A control cohort of transcriptomic profiles of 803 matched untreated biopsy and matching RP samples from the same subjects were used to control for signature differences attributable to sample type. Key tumor biology signatures most frequently observed were DDR (15/24), TME (11/24) and tumor proliferation (11/24). Signatures associated with tumor proliferation were disproportionately represented in pre-treatment samples (10/11) whereas TME-associated signatures were enriched predominantly in irradiated RP samples (8/11). Collectively, immune-related immune signatures skewed towards immune activation. All 3 samples annotated with suppressed immune signatures were from pre-treatment specimens whereas 75% (6/8) of samples annotated with activated immune status were from irradiated specimens. Additionally, conversion from suppressed to activated immune status was observed in 2 of 3 subjects (66%). In total, 42% of specimens (10/24) were designated as radio-resistant by RT sensitivity score. Among 8 baseline specimens annotated with RT resistant status, 75% of subjects (6/8) converted to RT sensitive status after neoadjuvant SBRT. Interestingly, in the two subjects with persistent radio-resistant status in pre- and post-samples there was associated with upregulation of TGF-β or PI3K-AKT pathway activation signatures. Pre- and post-SBRT transcriptomic signatures were heterogeneous and dynamic in a cohort of 12 patients with high-risk localized PCa highlighting the importance of studying longitudinal changes in individual patients. These data highlight an opportunity to leverage tumor RNA expression profiles to personalize patient and treatment selection and augment radiation response assessment. gov ID (NCT03663218).

Plan robustness evaluation strategies in whole-pelvic proton therapy for high-risk prostate cancer patients within a randomised clinical trial

Background Inter-fractional anatomical changes challenge robust delivery of whole-pelvic proton therapy for high-risk prostate cancer. Pre-treatment robust evaluation (PRE) takes uncertainties in isocenter shifts and distal beam edge in treatment plans into account. Using weekly control computed tomography scans (cCTs), the aim of this study was to evaluate the PRE strategy by comparing to an off-line during-treatment robust evaluation (DRE) while also assessing plan robustness with respect to protocol planning constraints. Material and methods Treatment plans and cCTs from ten patients included in the pilot phase of the PROstate PROTON Trial 1 were analysed. Treatment planning followed protocol guidelines with 78 Gy to the primary clinical target volume (CTVp) and 56 Gy to the elective target (CTVe) in 39 fractions. Recalculations of the treatment plans were performed for a total of 64 cCTs and dose/volume measures corresponding to clinical constraints were evaluated for this DRE against the simulated scenario interval from the PRE. Results Of the 64 cCTs, 59 showed DRE CTVp measures within the robustness range from the PRE; this was also the case for 39 of the cCTs for the CTVe measures. However, DRE CTVe coverage was still within constraints for 57 of the 64 cCTs. DRE dose/volume measures for CTVp fulfilled target coverage constraints in 59 of 64 cCTs. All DRE measures for the rectum, bladder, and bowel were inside the PRE range in 63, 39, and 31 cCTs, respectively. Conclusion The PRE strategy predicted the DRE scenarios for CTVp and rectum. CTVe, bladder, and bowel showed more complex anatomical variations than simulated by the PRE isocenter shift. Both original and recalculated nominal treatment plans showed robust treatment delivery in terms of target coverage.

Long-term outcomes of whole-pelvis radiation therapy using volumetric modulated arc therapy for high-risk prostate cancer†.

This study investigated the outcomes of whole-pelvis radiation therapy (WPRT) using volumetric modulated arc therapy (VMAT) for high-risk prostate cancer. We retrospectively analysed 112 patients with high-risk prostate cancer who started WPRT at our hospital between August 2011 and August 2015. The prescribed dose was 78Gy in 39 fractions to the prostate and 46.8Gy in 26 fractions to the pelvic lymph node (LN) area. All patients received long-term androgen deprivation therapy. We evaluated late gastrointestinal (GI) and genitourinary (GU) toxicities using the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up period for censored cases was 97 (interquartile range [IQR] = 85-108) months. The median age was 72 (IQR = 67-75) years. The high-risk and very-high-risk groups included 41 (36.6%) and 71 patients (63.4%), respectively. The median risk of LN invasion calculated by the Roach formula was 36.9 (IQR = 26.6-56.3) %. The 8-year overall survival, biochemical failure-free survival, disease-free survival and distant metastasis-free survival rates were 88.4, 91.9, 83.8 and 98.0%, respectively. Only one patient experienced common iliac LN recurrence, which was outside the pelvic irradiation area. All patients with recurrent disease were categorized into the very-high-risk group. The 8-year cumulative rates of ≥Grade 2 late GI and GU toxicities were 12.8 and 11.8%, respectively. No patients experienced Grade 4 or higher toxicities. WPRT using VMAT for high-risk prostate cancer was well tolerated and effective.

Feasibility of simultaneous integrated boost for high-dose treatment of high-risk prostate cancer

Background. Radiation therapy for high-risk prostate cancer presents a challenge for cancer radiotherapists. The improvement of treatment outcomes is associated with radiation dose escalation and prophylactic irradiation of lymph nodes, therefore, the development of the new treatment schemes is needed. Simultaneous integrated boost technique based on the volumetric modulated arc therapy is the most efficient treatment option. Material and Methods. The anatomical data of 10 patients with high-risk prostate cancer was used for dosimetry-based treatment planning. Both simultaneous integrated boost and sequential boost technique were considered. The treatment planning goal was to deliver the equivalent dose of 96 Gy at 2 Gy per fraction (EQD2=96 Gy) (α/β=1.5 Gy) to the prostate, EQD2=62.5 Gy to the seminal vesicles and EQD2=50 Gy to lymph nodes avoiding damaging the organs at risk, mainly the bladder and rectum. The irradiation was based on volumetric modulated arc therapy with two partially coplanar arcs and two rotations at each arc. The obtained dose distributions were compared with respect to dose-volume histograms and equivalent uniform doses (EUD). Results. In the case of sequential boost, the minimal dose delivered to the prostate was equal to 95.9 ± 2.1 Gy, EUD=104.9 ± 1.7 Gy. The dose delivered to 2 cm3 (D2cc) bladder was 97.4 ± 2.0 Gy. Normal tissue complication probability (NTCP) was 1.64 %. The dose delivered to 2 cm3 (D2cc) rectum was 103.4 ± 9.2 Gy and NTCP was 27.4 %. In the case of simultaneous integrated boost, the minimal dose delivered to the prostate was equal to 90.4 ± 2.3 Gy, EUD=103.9 ± 1.3 Gy. The bladder dose was as high as D2cc=96.1 ± 5.2 Gy, NTCP=0.176 ± 0.132 %, the rectum dose - D2cc=81.1 ± 6.0 Gy, NTCP=2.34 ± 1.92 %. Conclusion. Volumetric modulated arc therapy along with simultaneous integrated boost have shown the feasibility of simultaneous irradiation of the prostate, seminal vesicles and lymph nodes up to the prescribed dose values without significant over irradiation of the organs at risk (OARs). Dose values in the tumor as high as EUD=103.9 ± 1.3 Gy along with prophylactic irradiation of lymph nodes may result in higher tumor control probability value and should be considered for clinical trials.

Radical prostatectomy versus external beam radiotherapy with androgen deprivation therapy for high-risk prostate cancer: a systematic review

BackgroundTo summarize recent evidence in terms of health-related quality of life (HRQoL), functional and oncological outcomes following radical prostatectomy (RP) compared to external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) for high-risk prostate cancer (PCa).MethodsWe searched Medline, Embase, Cochrane Database of Systematic Reviews, Cochrane Controlled Trial Register and the International Standard Randomized Controlled Trial Number registry on 29 march 2021. Comparative studies, published since 2016, that reported on treatment with RP versus dose-escalated EBRT and ADT for high-risk non-metastatic PCa were included. The Newcastle–Ottawa Scale was used to appraise quality and risk of bias. A qualitative synthesis was performed.ResultsNineteen studies, all non-randomized, met the inclusion criteria. Risk of bias assessment indicated low (n = 14) to moderate/high (n = 5) risk of bias. Only three studies reported functional outcomes and/or HRQoL using different measurement instruments and methods. A clinically meaningful difference in HRQoL was not observed. All studies reported oncological outcomes and survival was generally good (5-year survival rates > 90%). In the majority of studies, a statistically significant difference between both treatment groups was not observed, or only differences in biochemical recurrence-free survival were reported.ConclusionsEvidence clearly demonstrating superiority in terms of oncological outcomes of either RP or EBRT combined with ADT is lacking. Studies reporting functional outcomes and HRQoL are very scarce and the magnitude of the effect of RP versus dose-escalated EBRT with ADT on HRQoL and functional outcomes remains largely unknown.

Efficacy and Safety of Neoadjuvant Luteinizing Hormone-Releasing Hormone Antagonist and Tegafur-Uracil Chemohormonal Therapy for High-Risk Prostate Cancer.

This retrospective single-center cohort study evaluated the efficacy and safety of a combination of neoadjuvant luteinizing hormone-releasing hormone (LHRH) antagonist and tegafur-uracil (UFT) therapy (NCHT) and investigated the medical records of patients with high-risk PCa who underwent robot-assisted radical prostatectomy (RARP). The therapy was followed by RARP for high-risk PCa. The enrolled patients were divided into two groups: low-intermediate-risk PCa patients who underwent RARP without neoadjuvant therapy (non-high-risk) and those who underwent NCHT followed by RARP (high-risk group). This study enrolled 227 patients (126: non-high-risk and 101: high-risk group). Patients in the high-risk-group had high-grade cancer compared to those in the non-high-risk-group. At the median follow-up period of 12.0 months, there were no PCa deaths; two patients (0.9%) died of other causes. Twenty patients developed biochemical recurrence (BCR); the median time until BCR was 9.9 months after surgery. The 2-year biochemical recurrence-free survival rates were 94.2% and 91.1% in the non-high-risk and high-risk-group, respectively (p = 0.465). Grade ≥3 NCHT-related adverse events developed in nine patients (8.9%). This study indicates that combining neoadjuvant LHRH antagonists and UFT followed by RARP may improve oncological outcomes in patients with high-risk PCa.

Proton therapy for high-risk prostate cancer: Results from the Proton Collaborative Group PCG 001-09 prospective registry trial.

Data for proton therapy in high-risk prostate cancer (HRPC) are limited. Using the Proton Collaborative Group prospective registry, we evaluated outcomes for HRPC patients treated with proton therapy. A totsl of 605 men with localized HRPC treated with proton therapy from 8/2009 to 3/2019 at nine institutions were selected. Outcomes examined included freedom from progression (FFP), metastasis free survival (MFS), overall survival (OS), and toxicity. Multivariable cox/binomial regression models were used to assess predictors of FFP and toxicity. Median age was 71 years. Gleason grade groups 4 (49.4%) and 5 (31.7%) were most common, as were clinical stage T1c (46.1%) and cT2 (41.3%). The median pretreatment prostate specific antigen (PSA) was 9.18 and median International Prostate Symptom Score (IPSS) was 6. Androgen deprivation therapy was given in 63.6%. Median dose was 79.2 GyE in 44 fractions. Pelvic lymph nodes were treated in 58.2% of cases. Pencil beam scanning was used in 54.5%, uniform scanning in 38.8%, and a rectal spacer in 14.2%. At a median followup of 22 months, the 3- and 5-year FFP were 90.7% and 81.4%, respectively. Five-year MFS and OS were 92.8% and 95.9%, respectively. Independent correlates of FFP included Gleason ≥8, PSA > 10, and cT2 (all p < 0.05). No grade 4 or 5 adverse events were reported. There were 23 (5%) grade 2 and 0 grade 3 gastrointestinal events. Prevalence of late grade 3, late grade 2, acute grade 3, and acute grade 2 genitourinary toxicity was 1.7%, 5.8%, 0%, and 21.8%, respectively. Prevalence of grade 2 and 3 erectile dysfunction at 2 years was 48.4% and 8.4%, respectively. In the largest series published to date, our results suggest early outcomes using proton therapy for HRPC are encouraging for both safety and efficacy. Further evaluation is needed to determine if an advantage exists to use protons over other radiation techniques in this population.

Neo-adjuvant PARP inhibition prior to prostatectomy: A phase II biomarker-driven trial for men with high-risk, localized prostate cancer and alterations in DNA repair genes.

TPS401 Background: Many men with localized prostate cancer will experience recurrence and progression after radical prostatectomy. While radiation therapy for high-risk prostate cancer is routinely given with systemic androgen therapy, peri-operative systemic therapy is not part of the standard of care with prostatectomy. Defective DNA repair pathways represent a non-hormonal target for PARP inhibitors which have proven efficacy in the metastatic, castrate resistant setting. We designed a novel biomarker driven neoadjuvant trial with niraparib prior to prostatectomy for men with clinically localized high risk prostate cancer and alterations in DNA repair genes (NCT04030559). Methods: We instituted a phase II trial for men with NCCN high and very high-risk prostate cancer. All men who met inclusion by clinical variables underwent targeted genomic sequencing for somatic and/or germline alterations in genes involved in DNA repair pathways. Enrolled patients are treated with oral Niraparib 300mg/day for 90 days before surgery. The primary endpoint is pathologic response at prostatectomy defined as complete response or minimal residual disease (&lt;0.5 cc3) of histological viable cancer. The secondary endpoint is biochemical free survival as well as molecular endpoints including disease responses stratified by mutational status. We have screened 37 men and 10 have met genomic criteria. We have enrolled 8 out of planned 30 men to date, 7 have undergone prostatectomy. Enrolled men have alterations in BRCA2 (germline), MSH6, ZMYM3, MUTYH, ATM, CDK12, ERCC3 and KMT2c. Clinical trial information: NCT04030559 .

Functional Outcomes after Radiation Therapy or Radical Prostatectomy with Postoperative Radiation Therapy for High-Risk Prostate Cancer

<h3>Purpose/Objective(s)</h3> The use of radical prostatectomy (RP) for men with high-risk prostate cancer (PC) is increasing. RP is often utilized as a component of multi-modality therapy, as a method to intensify treatment. Many patients who undergo RP will subsequently require radiation therapy (RT), exposing patients to side effects from both treatments. While the side effects of RT and RP have been directly compared in previous studies, there is limited data comparing side effects of primary RT with those of patients undergoing RP and RT (RP/RT). We hypothesize that patients undergoing RP/RT for high-risk PC will experience significantly higher side effects than those undergoing primary RT. <h3>Materials/Methods</h3> We used the Surveillance Epidemiology and End Results (SEER) database with Medicare insurance claims to identify patients 66 years or older with primary high-risk PC who underwent RP, RT, or both between January 1, 2004 and December 31, 2013. High-risk PC was defined as disease meeting one or more of the following criteria: stage ≥ T3a, grade group ≥ 4, PSA >20. Outcomes of interest included treatment for urinary incontinence, urethral stricture, erectile dysfunction (ED), proctitis and cystitis at least 1 year after completion of primary prostate cancer treatment, which were captured using diagnosis and procedure codes. Rates of these endpoints were compared using cumulative incidence functions as well as cox proportional hazard models. Patients who were lost to follow up or died were censored at the time of their last encounter. <h3>Results</h3> The cohort included 17,649 patients, of which 15,399 were treated with primary RT (87.25%) and 2,250 were treated with RP/RT (12.75%). On multivariable analysis, compared to primary RT, RP/RT was associated with an increased risk of incontinence therapy [HR 1.907 (1.679-2.166)], stricture therapy [HR 1.865 (95% CI: 1.589-2.190)] and ED therapy [HR 2.869 (95% CI: 2.046-4.023)] after treatment for prostate cancer. Rates of therapy for cystitis or proctitis were not significantly different between these two groups. <h3>Conclusion</h3> For men with high-risk PC, treatment with RP/RT was associated with increased utilization of incontinence therapy, stricture therapy, and ED therapy after completion of prostate cancer treatment. With multiple curative treatment options and long duration of survival after treatment, the side effect profile of treatment is a major factor in determining the most appropriate course of treatment for an individual patient. Patients considering primary RP as a component of multimodality therapy for high-risk PC should be informed about the increased risk of side effects. Clinical trials are required to better evaluate this treatment paradigm.

Salvage Radiotherapy Plus Androgen Deprivation Therapy for High-Risk Prostate Cancer with Biochemical Failure after High-Intensity Focused Ultrasound as Primary Treatment.

We conduct a retrospective analysis of salvage radiotherapy plus androgen deprivation therapy (SRT+ADT) for high-risk prostate cancer patients with biochemical failure after high-intensity focused ultrasound (HIFU) as the primary treatment. A total of 38 patients, who met the criteria of biochemical failure and were consecutively treated with SRT+ADT, were enrolled. All patients received intensity modulated radiotherapy with a median dose of 70 Gy to the clinical target volume. ADT was given before, during or after the course of SRT with the duration of ≦6 months (n = 14), 6–12 months (n = 12) or >12 months (n = 12). The median follow-up was 45.9 months. A total of 10 (26.3%) patients had biochemical failure after SRT+ADT. The cumulative 5-year biochemical progression free survival (b-PFS) and overall survival (OS) rate was 73.0% and 80.3%, respectively. A nadir prostate-specific antigen (nPSA) value 0.02 ng/mL was observed to predict the b-PFS in multivariate analysis. The 5-year b-PFS was 81.6% for those with nPSA < 0.02 compared with 25.0% with nPSA ≧ 0.02. The adverse effects related to SRT+ADT were mild in most cases and only three (8%) patients experienced grade 3 urinary toxicities. For high-risk prostate cancer after HIFU as primary treatment with biochemical failure, our study confirms the feasibility of SRT+ADT with high b-PFS, OS and low toxicity.

The Influence of the Pretreatment Immune State on Response to Radiation Therapy in High-Risk Prostate Cancer: A Validation Study From NRG/RTOG 0521

The immunoinflammatory state has been shown to be associated with poor outcomes after radiation therapy (RT). We conducted an a priori designed validation study using serum specimens from Radiation Therapy Oncology Group (RTOG) 0521. It was hypothesized the pretreatment inflammatory state would correlate with clinical outcomes. Patients on RTOG 0521 had serum banked for biomarker validation. This study was designed to validate previous findings showing an association between elevations in C-reactive protein (CRP) and shorter biochemical disease free survival (bDFS). CRP levels were measured in pretreatment samples. An exploratory panel of related cytokines was also measured including: monocyte chemotactic protein-1, granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin (IL)-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17A, IL-23, and tumor necrosis factor. The primary endpoint examined was bDFS. Additional exploratory endpoints included overall survival, distant metastases, and toxicity events attributed to RT. Two hundred and two patients in RTOG/NRG 0521 had serum samples available. Median age was 66 years (48-83), and 90% of patients were White. There was not an association between CRP and bDFS (adjusted hazard ratio [HR], 1.07 per 1 log increase in CRP; 95% confidence interval, 0.83-1.38; P = .60). In the exploratory, unplanned analysis, pretreatment IL-10 was significantly associated with worse bDFS (adjusted HR, 1.61 per log increase; P = .0027) and distant metastases (HR, 1.55 per log increase; P = .028). The association of IL-10 with bDFS was maintained on a multiplicity adjustment. The exploratory analyses of pretreatment levels of interferon-γ, IL-1b, IL-2, IL-13, IL-23 were negatively associated with grade 2 or higher pollakiuria (adjusted odds ratio, 0.64, 0.65, 0.71, 0.72, and 0.74, respectively, all P < .05), and IL-6 was negatively associated with grade 2 or higher erectile dysfunction (odds ratio, 0.62; P = .027). Pretreatment CRP was not associated with a poorer bDFS after RT. In a hypothesis- generating analysis, higher baseline levels of IL-10 were associated with lower rates of bDFS. These findings require additional prospective evaluation.

PO-0251 clinical outcomes of radiation therapy for high-risk prostate cancer

PO-0251 clinical outcomes of radiation therapy for high-risk prostate cancer

Incidence and dosimetric predictive factors of late rectal toxicity after low-dose-rate brachytherapy combined with volumetric modulated arc therapy in high-risk prostate cancer at a single institution: Retrospective study

PurposeThe purpose of this study is to investigate the incidence of rectal toxicity and to identify the associated dosimetric predictive parameters after I-125 seed low-dose-rate brachytherapy (LDR-BT) combined with volumetric modulated arc therapy (VMAT) and dose constraints. Methods and MaterialsIn total, 110 patients with high-risk prostate cancer received 110 Gy LDR-BT, followed by 45 Gy VMAT. Rectal toxicity was recorded according to Common Terminology Criteria for Adverse Events v.4.03. The dosimetric factors associated with LDR-BT and VMAT were analyzed to determine their relationship with rectal toxicity. Receiver operating characteristic (ROC) curve analysis was performed for ≥ grade 2 (G2) rectal toxicity prediction. ResultsThe follow-up duration was 10.1–115.2 months (median 60.5 months). Seven patients had G2 rectal hemorrhage, and none of the patients had grade 3 rectal hemorrhage. In the univariate analysis, the rectal volume receiving 100% of the prescribed dose (rV100) (p < 0.001), the dose covering 2 cc of the rectum (rD2cc) during LDR-BT (p = 0.002), and the combined rD2cc during LDR-BT and VMAT (p = 0.001) were identified as predictors of G2 rectal hemorrhage. In the ROC curve analysis, the cutoff value was 0.46 cc for rV100, 74.0 Gy for rD2cc, and 86.8 GyEQD2 for combined rD2cc. ConclusionPredictors of late ≥ G2 rectal hemorrhage are rV100, rD2cc, and combined rD2cc. The incidence of rectal toxicity is low and acceptable in this setting and is highly dependent on the rectal dose of LDR-BT. The use of higher-quality LDR-BT and VMAT dose constraints may further reduce the rate of rectal hemorrhage.

Dosimetric comparison of three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and volumetric modulated arc therapy in high-risk prostate cancer

Dosimetric comparison of three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and volumetric modulated arc therapy in high-risk prostate cancer