Role of enzalutamide in primary and recurrent non-metastatic hormone sensitive prostate cancer: a systematic review of prospective clinical trials.

INTRODUCTION: Enzalutamide, a second-generation androgen receptor inhibitor, is indicated for the treatment of metastatic disease, as well as in the treatment of non-metastatic castration resistant prostate cancer (PCa). This systematic review aims to determine outcomes and toxicity in patients with non-metastatic castration sensitive prostate cancer (nmCSPC) treated with enzalutamide in the primary or salvage settings. METHOD: We performed a systematic review focusing on the role of Enzalutamide in the treatment of nmCSPC, using the PubMed/Medline database. Articles focusing on androgen receptor inhibitors in nmCSPC were included, while articles discussing exclusively metastatic or castration-resistant PCa were excluded. RESULTS: The initial search retrieved 401 articles, of which 15 underwent a thorough assessment for relevance. Ultimately, 12 studies with pertinent outcomes were meticulously examined. Among these, seven studies were dedicated to the investigation of enzalutamide in the primary setting, while the remaining five publications specifically addressed its use in salvage settings. Regardless of the treatment setting, our data revealed two distinct therapeutic strategies. The first advocates for the substitution of enzalutamide for androgen deprivation therapy (ADT), based on the premise of achieving equivalent, if not superior, oncological outcomes while minimizing treatment-related toxicity. The second, adopting a more conventional approach, entails augmenting the effectiveness of ADT by incorporating enzalutamide. CONCLUSION: Enzalutamide has considerable potential as a therapeutic strategy for nmCSPC, either used alone or in combination with ADT in the primary or in the salvage settings. The use of enzalutamide instead of ADT is an appealing strategy. However, more trials will be required to further understand the efficacy and side-effect profile of enzalutamide monotherapy.

Radiotherapy Combined with a Radiosensitizer for Bacillus Calmette-Guérin-unresponsive Non-muscle-invasive Carcinoma In Situ Bladder Cancer: An Open-label, Single-arm, Multicenter, Phase 2 European Organisation for Research and Treatment of Cancer Trial.

Radical cystectomy with pelvic lymph node dissection and urinary diversion is the standard of care for patients with bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer (NMIBC). However, many patients are unwilling or unable to undergo such major surgery associated with high morbidity and a negative impact on quality of life. Chemoradiotherapy is an established treatment option for muscle-invasive bladder cancer. However, it has not been investigated adequately in NMIBC until now. The European Organisation for Research and Treatment of Cancer (EORTC) 2235 study (NCT06310369) is designed as a multicenter, prospective, international, phase 2 trial of moderate hypofractionated radiotherapy combined with a radiosensitizer in BCG-unresponsive NMIBC patients with carcinoma in situ (CIS) who are not eligible for or declined to undergo radical cystectomy. Patients who have received nadofaragene firadenovec or TAR-200 are eligible. The primary endpoint is the 6-mo complete response (CR) rate defined by the absence of CIS proven by a control biopsy of the bladder. The secondary endpoints include overall survival, progression-free survival, durability of CR, grade 3-4 adverse events rate, patients' quality of life, and organ preservation rate. PATIENT SUMMARY: Intravesical instillation of bacillus Calmette-Guérin is the standard treatment of non-muscle-invasive, also coined as superficial, bladder cancer. In case the cancer recurs, even superficially, there is no other proven treatment than a radical cystectomy-the surgical removal of the bladder. Although the surgical technique has improved dramatically over the past few years, it remains contraindicated in patients with severe comorbidities. In addition, because it affects the quality of life, patients may reject this option. This study will assess the efficacy of external beam radiotherapy, a robust alternative to surgery in muscle-invasive bladder cancer. Radiotherapy will be administered 5 d a week for 4 wk. It will be associated with a "radiosensitizer," an intravenous or oral drug, during the radiotherapy treatment. The study will measure the proportion of patients remaining recurrence free at 6 mo and thereafter. It will also evaluate the safety of the treatment and its impact on quality of life.

ONE SHOT - single shot radiotherapy for localized prostate cancer: 18-month results of a single arm, multicenter phase I/II trial.

PURPOSE: To assess in a prospective, multicenter, single-arm phase I/II study the early safety and efficacy profile of single fraction urethra-sparing stereotactic body radiotherapy (SBRT) for men with localized prostate cancer. MATERIAL AND METHODS: Patients with low- and intermediate-risk localized prostate cancer without significant tumor in the transitional zone were recruited. A single-fraction of 19 Gy was delivered to the prostate, with 17 Gy dose-reduction to the urethra. Intrafraction motion was monitored using intraprostatic electromagnetic transponders with intra-fraction correction of displacements exceeding 3 mm. Genitourinary (GU), gastrointestinal (GI), and sexual toxicity during the first 18 months were evaluated using the CTCAE v4.0 grading scale. Quality of life was assessed using the International Prostate Symptom Score, the Expanded Prostate Cancer Index composite 26 score, and the International Index of Erectile Function score. RESULTS: Among the 45 patients recruited in 5 centers between 2017 and 2022, 43 received the single fraction without protocol deviations, and 34 had a minimal follow-up of 18 months. The worst GU toxicity was observed at day-5 after SBRT (42.5 % and 20 % with grade 1 and 2, respectively), returning to baseline at week-12 and month-6 (<3% with grade 2), with a 12 % grade 2 flare at month 18. Gl toxicity was mild in the acute phase, with no grade ≥ 2 events (12 % grade 1 at month 6). Grade-3 proctitis was observed in one patient at month 12, with < 3 % grade 2 toxicity at month 18. Mean GU and GI bother scores showed a decline at day 5, a complete recovery at month 6, and a flare between month 12 and 18. Mean PSA dropped from 6.2 ng/ml to 1.2 ng/ml at month 18 and 0.7 ng/ml at month 24. After a median follow-up time of 26 months, 3 biochemical failures (7 %) were observed at month 17, 21 and 30. CONCLUSIONS: In this multicenter phase I/II trial, we demonstrated that a 19 Gy single-fraction urethra-sparing SBRT is feasible and associated with an acceptable toxicity rate, mostly returning to the baseline at week-12 and with a symptoms flare between months 12 and 18. Longer follow-up is needed to assess the potential long-term adverse effects and the disease control efficacy.

Stereotactic body radiation therapy for prostate cancer after surgical treatment of prostatic obstruction: Impact on urinary morbidity and mitigation strategies.

In the past decade, stereotactic body radiation therapy (SBRT) has emerged as a valid treatment option for patients with localized prostate cancer. Despite the promising results of ultra-hypofractionation in terms of tolerance and disease control, the toxicity profile of SBRT for prostate cancer patients with a history of surgical treatment of benign prostate hyperplasia is still underreported. Here we present an overview of the available data on urinary morbidity for prostate cancer patients treated with SBRT after prior surgical treatments for benign prostate hyperplasia. Technical improvements useful to minimize toxicity and possible treatments for radiation-induced urethritis are discussed.

Elective Nodal Irradiation for Oligorecurrent Nodal Prostate Cancer: Interobserver Variability in the PEACE V-STORM Randomized Phase 2 Trial.

Purpose: Consistency in delineation of pelvic lymph node regions for prostate cancer elective nodal radiation therapy is still challenging despite current guidelines. The aim of this study was to evaluate the interobserver variability in elective lymph node delineation in the PEACE V - STORM randomized phase 2 trial for oligorecurrent nodal prostate cancer. Methods and Materials: Twenty-three centers were asked to delineate the elective pelvic nodal clinical target volume (CTV) of a postoperative oligorecurrent nodal prostate cancer benchmark case using a modified Radiation Therapy Oncology Group (RTOG) 2009 template (upper limit at the L4/L5 interspace). Overall, intersection and overflow volumes, Dice coefficient, Hausdorff distance, and count maps merged with computed tomography images were analyzed. Results: The mean volume including the 23 nodal CTVs was 430.4 ± 64.1 cm3, larger than the modified RTOG 2009 CTV reference volume (386.1 cm3). The intersection common volume between the modified reference RTOG 2009 and the 23 nodal CTVs was estimated at 83.9%, whereas the overflow volume was 23.4%, mainly located at the level of the presacral and the upper limit of the L4/L5 interspace. The mean Dice coefficient was 0.79 ± 0.02, whereas the mean Hausdorff distance was 27 ± 4.4 mm. Conclusions: In salvage radiation therapy treatment of oligorecurrent nodal prostate cancer, variations in elective lymph node volume delineation were mainly observed in the presacral and common iliac areas. Routine implementation and diffusion of available contouring guidelines together with a constant evaluation and evidence-based updating are expected to further decrease the existing variability in pelvic node contouring.

Role of Radiotherapy and Hormone Therapy in Patients with Node-Positive Locally Advanced Prostate Cancer

New-generation imaging techniques and the increasing use of surgery in high-risk prostate cancer (PCa) allow usto detect many cases of nodal disease at initial diagnosis or after resection. The treatment of PCa with pathologic regional nodeshas evolved from the exclusive use of systemic therapy to its combination with locoregional treatment. It can also represent abenefit in the overall survival. However, the evidence from randomised studies is limited. Thus, we review the most relevantresults in this scenario.Materials and Methods: A literature search was conducted in MEDLINE, PubMed, EMBASE, Clinical-Trials.gov and Webof Science on January 2023 to review node-positive PCa by considering the relevant literature on this topic published with norestrictions on date and language. The search keywords used were “Prostatic Neoplasms” (MeSh) and “Node-positive” (TextWord) and “Radiotherapy” (MeSh) and (“Androgen Antagonists” (MeSh) or “Antineoplastic Agents, Hormonal” (MeSh)), whichare indexed within the Medical Subject Headings database.Results: The management of node-positive PCa has no clear definitive consensus at the initial disease diagnosis or after surgery.However, in this review, we summarise the existing literature for the management of these patients in both scenarios, consideringimaging tests, radiotherapy, hormone therapy and second-generation hormonal treatments.Conclusions: The combination of radiotherapy and androgen-deprivation therapy is the treatment of choice. The addition ofsecond-generation hormone therapy, plus the intensification of radiotherapy schedules, will likely change the treatment paradigm for these patients. (AU)

Urethra-Sparing Prostate Cancer Stereotactic Body Radiation Therapy: Sexual Function and Radiation Dose to the Penile Bulb, the Crura, and the Internal Pudendal Arteries From a Randomized Phase 2 Trial.

PURPOSE: Erectile dysfunction (ED) is a common side effect after prostate cancer stereotactic body radiation therapy (SBRT). We aimed to assess the correlation between the dose to the penile bulb (PB), internal pudendal arteries (IPA), and crura with the development of ED after ultrahypofractionation as part of a phase 2 clinical trial of urethra-sparing prostate SBRT. METHODS AND MATERIALS: Among the 170 patients with localized prostate cancer from 9 centers included in the trial, 90 men with Common Terminology Criteria for Adverse Events version 4.03 grade 0 to 1 ED (ED-) at baseline treated with 36.25 Gy in 5 fractions were selected for the present analysis. Doses delivered to the PB, crura, and IPA were analyzed and correlated with grade 2 to 3 ED (ED+) development. The effect on quality of life, assessed by the European Organisation for Research and Treatment of Cancer (EORTC QLQ-PR25) questionnaire, was reported. RESULTS: After a median follow-up of 6.5 years, 43% (n = 39) of the patients developed ED+, and 57% (n = 51) remained ED-. The dose delivered to the crura was significantly higher in ED+ patients than in ED- patients (7.7 vs 3.6 Gy [P = .014] for the Dmean and 18.5 vs 7.2 Gy [P = .015] for the D2%, respectively). No statistically significant difference between ED+ and ED- patients was observed for the dose delivered to the PB and IPA. The median ED+-free survival was worse in patients receiving a crura Dmean ≥ 4.7 versus < 4.7 Gy (51.5% vs 71.7%, P = .005) and a crura D2% > 12 versus ≤ 12 Gy (54.9% vs 68.9%, P = .015). No ED+-free survival differences were observed for doses delivered to the PB and IPA. Decline in EORTC QLQ-PR25 sexual functioning was significantly more pronounced in patients with higher doses to the crura. CONCLUSIONS: By keeping a Dmean and D2% to crura below 4.7 and 12 Gy, respectively, the risk of developing ED+ after prostate SBRT may be significantly reduced.

Jorge clinical study: 10-year outcomes of risk-adapted radiotherapy defined by multiparametric MRI for prostate cancer.

PURPOSE: To analyze the 10-year biochemical relapse-free survival (BRFS), locoregional relapse-free survival (LRFS), metastasis-free survival (MFS), and overall survival (OS) in patients diagnosed with localized prostate adenocarcinoma treated with radiotherapy (RT) ± androgen deprivation therapy (ADT), according to the risk groups based on multiparametric magnetic resonance imaging (mpMRI) instead of digital rectal exam (DRE). METHODS: We retrospectively evaluated 140 consecutive patients diagnosed with localized prostate adenocarcinoma, stratified into different risk groups-low (LR), intermediate (IR), and high (HR) by mpMRI results. RESULTS: After a median follow-up of 104 months, in LR group (n = 15), 10-year BRFS was 86.7%, 10-year LRFS was 86.7%, 10-year MFS was 93.3%, and 10-year OS was 100%. In IR group (n = 80), 10-year BRFS was 80.5%, 10-year LRFS was 86.1%, 10-year MFS was 92.6%, and 10-year OS was 76%. In HR group (n = 45), 10-year BRFS was 72.8%, 10-year LRFS was 78.7%, 10-year MFS was 82.1%, and 10-year OS was 77% (2 deaths from prostate cancer). According to mpMRI results, 36 (25.7%) patients change the risk group and 125 (89.28%) patients change the TNM stage. There was a trend for higher metastatic relapse in patients who switched from IR to HR (due to mpMRI) versus the patients who remained in the IR (20%, vs. 1.81% p = 0.059). Multivariate analysis showed that locoregional relapse was strongly associated with distant relapse (OR = 9.28; 95%CI: 2.60-33.31). There were no cases of acute grade 3 toxicity. Late grade 3 genitourinary, gastrointestinal, and sexual toxicity were 2.8%, 0.7%, and 1.2%, respectively. CONCLUSION: This is the first study with a 10-year median follow-up of patients diagnosed with localized prostate cancer treated with radiotherapy according to the risk groups established by mpMRI. Our findings show that mpMRI is a key tool to diagnose and establish risk groups in these patients, to optimize their treatment.

PEACE V-Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases (STORM): Acute Toxicity of a Randomized Phase 2 Trial.

BACKGROUND: Treatment recommendations for patients with limited nodal recurrences are lacking, and different locoregional treatment approaches are currently being used. OBJECTIVE: The aim of this trial is to compare metastasis-directed therapy (MDT) with or without elective nodal pelvic radiotherapy (ENRT). DESIGN, SETTING, AND PARTICIPANTS: PEACE V-Salvage Treatment of OligoRecurrent nodal prostate cancer Metastases (STORM) is an international, phase 2, open-label, randomized, superiority trial (ClinicalTrials.gov identifier: NCT03569241). Patients diagnosed with positron emission tomography-detected pelvic nodal oligorecurrence (five or fewer nodes) following radical local treatment for prostate cancer were randomized in a 1:1 ratio between arm A (MDT and 6 mo of androgen deprivation therapy [ADT]) and arm B (ENRT [25 × 1.8 Gy] with MDT and 6 mo of ADT). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We report the secondary endpoint acute toxicity, defined as worst grade ≥2 Common Terminology Criteria for Adverse Events v4.0 gastrointestinal (GI) or genitourinary (GU) toxicity within 3 mo of treatment. The chi-square test was used to compare toxicity between treatment arms. We also compare the quality of life (QoL) using the European Organisation for Research and Treatment of Cancer QLQ C30 and PR25 questionnaires. RESULTS AND LIMITATIONS: Between June 2018 and April 2021, 196 patients were assigned randomly to MDT or ENRT. Ninety-seven of 99 patients allocated to MDT and 93 of 97 allocated to ENRT received per-protocol treatment. Worst acute GI toxicity proportions were as follows: grade ≥2 events in three (3%) in the MDT group versus four (4%) in the ENRT group (p = 0.11). Worst acute GU toxicity proportions were as follows: grade ≥2 events in eight (8%) in the MDT group versus 12 (13%) in the ENRT group (p = 0.95). We observed no significant difference between the study groups in the proportion of patients with a clinically significant QoL reduction from baseline for any subdomain score area. CONCLUSIONS: No clinically meaningful differences were observed in worst grade ≥2 acute GI or GU toxicity or in QoL subdomains between MDT and ENRT. PATIENT SUMMARY: We found no evidence of differential acute bowel or urinary side effects using metastasis-directed therapy and elective nodal radiotherapy for the treatment of patients with a pelvic lymph node recurrence.

The diagnosis and treatment of castrate-sensitive oligometastatic prostate cancer: A review.

BACKGROUND: Oligometastatic prostate cancer (OMPCa) is emerging as a transitional disease state between localized and polymetastatic disease. This review will assess the current knowledge of castrate-sensitive OMPCa. METHODS: A review of the current literature was performed to summarize the definition and classification of OMPCa, assess the diagnostic methods and imaging modalities utilized, and to review the treatment options and outcomes. We further identify gaps in knowledge and areas for future research. RESULTS: Currently there is no unified definition of OMPCa. National guidelines mostly recommend systemic therapies without distinguishing oligometastatic and polymetastatic disease. Next generation imaging is more sensitive than conventional imaging and has led to early detection of metastases at initial diagnosis or recurrence. While mostly retrospective in nature, recent studies suggest that treatment (surgical or radiation) of the primary tumor and/or metastatic sites might delay initiation of androgen deprivation therapy while increasing survival in selected patients. CONCLUSIONS: Prospective data are required to better assess the incremental improvement in survival and quality of life achieved with various treatment strategies in patients with OMPCa.

Post-mastectomy radiotherapy: Impact of bolus thickness and irradiation technique on skin dose.

PURPOSE: To determine 10 MV IMRT and VMAT based protocols with a daily bolus targeting a skin dose of 45 Gy in order to replace the 6 MV tangential fields with a 5 mm thick bolus on alternate days method for post-mastectomy radiotherapy. METHOD: We measured the mean surface dose along the chest wall PTV as a function of different bolus thicknesses for sliding window IMRT and VMAT plans. We analyzed surface dose profiles and dose homogeneities and compared them to our standard 6 MV strategy. All measurements were performed on a thorax phantom with Gafchromic films while dosimetric plans were computed using the Acuros XB algorithm (Varian). RESULTS: We obtained the best compromise between measured surface dose (mean dose and homogeneity) and skin toxicity threshold obtained from the literature using a daily 3 mm thick bolus. Mean surface doses were 91.4 ±â€¯2.8% [85.7% - 95.4%] and 92.2 ±â€¯2.3% [85.6% - 95.2%] of the prescribed dose with IMRT and VMAT techniques, respectively. Our standard 6 MV alternate days 5 mm thick bolus leads to 89.0 ±â€¯3.7% [83.6% - 95.5%]. Mean dose differences between measured and TPS results were < 3.2% for depths as low as 2 mm depth. CONCLUSION: 10 MV IMRT-based protocols with a daily 3 mm thick bolus produce a surface dose comparable to the standard 6 MV 5 mm thick bolus on alternate days method but with an improved surface dose homogeneity. This allows for a better control of skin toxicity and target volume coverage.

Prostatectomy Bed Image-guided Dose-escalated Salvage Radiotherapy (SPIDER): An International Multicenter Retrospective Study.

BACKGROUND: Management of macroscopic local recurrence (MLR) after radical prostatectomy is a challenging situation with no standardized approach. OBJECTIVE: The objective of our study was to assess the efficacy and safety of functional image-guided salvage radiotherapy (SRT) in patients with MLR in the prostate bed. DESIGN, SETTING, AND PARTICIPANTS: In this international multicenter retrospective study across 16 European centers, eligible patients were initially treated by radical prostatectomy (RP) with or without pelvic lymph node dissection for localized or locally advanced adenocarcinoma of the prostate. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Prostate-specific antigen (PSA) measured 4 wk after RP was <0.1 ng/ml. All patients presented a biochemical relapse after RP defined by an increase in PSA level of ≥0.2 ng/ml on two successive measures. Only patients with an MLR lesion in the prostatectomy bed visualized on functional imaging (multiparametric magnetic resonance imaging, positron emission tomography/computed tomography [PET/CT] choline, or PET/CT prostate-specific membrane antigen) were eligible. Patients with lymph node, bone, or visceral dissemination at restaging imaging (CT and/or bone scintigraphy and/or magnetic resonance imaging and/or PET) were excluded. Dose escalation was defined as a dose of >66 Gy prescribed to the prostate bed or to MLR. Toxicities were classified using the Common Terminology Criteria for Adverse Events scale, version 4.03. The primary endpoint was progression-free survival (PFS). Secondary outcomes were metastasis-free survival (MPFS), biochemical progression-free survival, and overall survival. Genitourinary (GU) and gastrointestinal (GI) toxicities were analyzed. RESULTS AND LIMITATIONS: Between January 2000 and December 2019, 310 patients received at least one dose escalation on MLR and 25 patients did not receive any dose escalation. The median PSA level before SRT was 0.63 ng/ml (interquartile range [IQR], 0.27-1.7). The median follow-up was 54 mo (IQR, 50-56). Five-year PFS and MPFS were 70% (95% confidence interval [CI]: [64; 75]) and 84% (95% CI: [78; 88]), respectively. Grade ≥2 GU and GI late toxicities were observed in 43 (12%) and 11 (3%) patients, respectively. When the prescribed dose on the MLR lesion was ≥72 Gy, an improvement in 5-yr PFS was found for patients received at least one dose escalation (73% [95% CI: 65-79]) vs 60% [95% CI: 48; 70]; p = 0.03). CONCLUSIONS: In this contemporary study integrating functional imaging data, we found potential efficacy of SRT with dose escalation ≥72 Gy for patients with MLR in the prostate bed and with an acceptable toxicity profile. Prospective data exploring this MLR dose escalation strategy are awaited. PATIENT SUMMARY: In this report, we looked at the outcomes from salvage radiotherapy for prostate cancer and macroscopic relapse in a large European population. We found that outcomes varied with prostate-specific antigen at relapse, Gleason score, and dose escalation. We found potential efficacy of salvage radiotherapy with dose escalation for macroscopic relapse in the prostate bed, with an acceptable toxicity profile.

Oligometastatic Hormone-Sensitive Prostate Cancer. Why Radiotherapy?

Androgen deprivation therapy (ADT) has been considered for years the standard initial treatment for patients with metastatic prostate cancer (mPC). Recently published results support the use of taxanes, second-generation antiandrogens or radiotherapy to the primary tumor as part of the treatment in these patients, considering ADT alone as suboptimal. Metastasis-directed therapy (MDT) is used as part of the treatment for oligometastatic patients in different tumor types. In oligometastatic hormone-sensitive prostate cancer the role of MDT is being studied with promising results. In the present review we assess the available evidence for radiotherapy to the primary tumor in newly diagnosed mPC and for MDT in oligometastatic prostate cancer, as well as future directions in this clinical setting.

Role of Radiotherapy and Hormone Therapy in Patients with Node-Positive Locally Advanced Prostate Cancer.

BACKGROUND: New-generation imaging techniques and the increasing use of surgery in high-risk prostate cancer (PCa) allow us to detect many cases of nodal disease at initial diagnosis or after resection. The treatment of PCa with pathologic regional nodes has evolved from the exclusive use of systemic therapy to its combination with locoregional treatment. It can also represent a benefit in the overall survival. However, the evidence from randomised studies is limited. Thus, we review the most relevant results in this scenario. MATERIALS AND METHODS: A literature search was conducted in MEDLINE, PubMed, EMBASE, Clinical-Trials.gov and Web of Science on January 2023 to review node-positive PCa by considering the relevant literature on this topic published with no restrictions on date and language. The search keywords used were "Prostatic Neoplasms" (MeSh) and "Node-positive" (Text Word) and "Radiotherapy" (MeSh) and ("Androgen Antagonists" (MeSh) or "Antineoplastic Agents, Hormonal" (MeSh)), which are indexed within the Medical Subject Headings database. RESULTS: The management of node-positive PCa has no clear definitive consensus at the initial disease diagnosis or after surgery. However, in this review, we summarise the existing literature for the management of these patients in both scenarios, considering imaging tests, radiotherapy, hormone therapy and second-generation hormonal treatments. CONCLUSIONS: The combination of radiotherapy and androgen-deprivation therapy is the treatment of choice. The addition of second-generation hormone therapy, plus the intensification of radiotherapy schedules, will likely change the treatment paradigm for these patients.

Urinary toxicity after salvage re-irradiation for prostate cancer local failure after definitive radiotherapy: a clinical and dosimetric prognostic factors analysis.

Purpose: Predictors of long-term toxicity after prostate cancer re-irradiation are scarce. In this study, we retrospectively assessed the impact of clinical/dosimetric data on late genitourinary (GU) toxicity on fourteen radio-recurrent prostate cancer patients treated with salvage radiotherapy (RT). Material and methods: To identify dose parameters and clinical factors potentially associated to severe long-term GU toxicity, study population was stratified in two groups according to toxicity, including one low-grade group (grade ≤ 2, n = 6) and one high-grade group (grade ≥ 3, n = 8). Dose prescription at primary and salvage-RT in 2 Gy equivalent dose (EQD2Gy) per fraction, treatment techniques, and clinical factors potentially associated to severe GU toxicity were analyzed. Results: At salvage-RT, the median EQD2Gy α/ß = 3 Gy was significantly higher in the high-toxicity group (85 Gy, range, 71-85 Gy) compared to the low-toxicity group (77 Gy, range, 61-85 Gy) (p = 0.01). All patients treated using salvage-RT with a brachytherapy (BT) boost and with a baseline Framingham risk-score of > 20% (n = 8) developed severe GU toxicity, while none of the remaining patients developed a grade 3 or more GU toxicity (p = 0.0003). V70 > 0 and V75 > 0 of the primary treatment were associated with an increased rate of toxicity. Conclusions: Our analysis shows that the delivery of doses up to 75-80 Gy (EQD2Gy, α/ß = 3 Gy) in salvage-RT can be safe in terms of severe GU toxicity avoidance. Furthermore, concomitant cardiovascular comorbidities seem to increase the risk to develop severe GU toxicity.