Radiotherapy For Prostate Cancer Research Articles

Hypofractionated radiotherapy with simultaneous integrated boost for localized prostate cancer patients: effects on immune system and prediction of toxicity.

The other side of radiotherapy (RT), in addition to the cytotoxic effect, is the ability to modulate the immune system in terms of activation or suppression, also depending on the dose and fractionation delivered. This immune RT effect can be detected both locally in the irradiated tumor site and in the peripheral blood. The aim of this study was to assess the consequence of pelvic irradiation on peripheral immune cells and cytokine secretions in localized prostate cancer (PC) patients undergoing pelvic irradiation with a simultaneous moderately hypofractionated prostate/prostate bed boost by Volumetric Modulated Arc Therapy (VMAT). Furthermore, we analyzed whether there was a correlation between these peripheral immune parameters and acute and late genitourinary (GU) and gastrointestinal (GI) toxicity. Thirty-eight PC patients were treated with pelvis irradiation (dose per fraction 1.8 Gy) and simultaneous hypofractionated (median dose per fraction: 2.7 Gy) prostate/prostate bed boost. A longitudinal analysis was performed for 12 months on peripheral blood to assess changes in 9 different lymphocyte subpopulations by flow cytometry and 10 circulating cytokines by Multiplex Luminex assay and ELISA. Our analysis revealed that basal IFN-γ serum values were significantly lower in the definitive (curative intent for patients with prostate) patient group respect to the post-operative one. All the lymphocyte subsets and IFN-α, IFN-β and Il-2 peripheral concentrations displayed significant variations between the different time points considered. The immune cell population that suffers the greatest RT toxicity in the blood was B lymphocyte. We found an interesting correlation between basal TGF-β1 and late GU toxicity. In particular, TGF-β1 concentrations before RT were significantly higher in patients that experienced grade 2-3 of late GU toxicity, respect to grade 0-1. Exploring possible correlations between some clinical/biological findings and radiation planning parameters, we found no statistical significance. Our study analyzed, in the context of hypofractionated radiotherapy in prostate cancer, different parameters of the peripheral immune system. We have highlighted longitudinally the peripheral behavior of the different lymphocyte subpopulations and of a group of 10 cytokines during the first year after RT. One of the analyzed cytokines, such as TGF-β1, has proven to be promising predictive factor of severe late GU toxicity.

Mortality rates in radical cystectomy patients with bladder cancer after radiation therapy for prostate cancer.

To conduct a population-based study examining cancer-specific mortality (CSM) and other-cause mortality (OCM) differences in patients with radiation-induced secondary bladder cancer (RT-BCa) vs those with primary bladder cancer (pBCa) undergoing radical cystectomy (RC). Within the Surveillance, Epidemiology, and End Results database (2004-2020), we identified patients with T2-4N0-3M0 bladder cancer treated with RC, who had previously been treated with external beam radiation therapy (EBRT) or brachytherapy for prostate cancer, as well as patients with T2-4N0-3M0 pBCa treated with RC. Cumulative incidence plots and multivariable competing risks regression (CRR) models were used to assess CSM after additional adjustment for OCM. The same methodology was then repeated based on organ-confined (OC: T2N0M0) and non-organ-confined (NOC: T3-4 and/or N1-3) disease. Of 9957 RC patients, RT-BCa was identified in 347 (3%) compared with 9610 (97%) who had pBCa. In multivariable CRR models, no CSM differences were recorded in the overall comparison (P = 0.8), nor in sub-groups based on OC and NOC disease (P = 0.8 and 0.7, respectively). Conversely, multivariable CRR models identified RT-BCa as an independent predictor of 1.3-fold higher OCM in the overall cohort and of 1.5-fold higher OCM in those with NOC disease. In a sensitivity analysis of patients with NOC disease, EBRT was associated with higher OCM rates (hazard ratio 1.5). By contrast, OCM rates were not different in those with OC disease (P = 0.8). Our study showed that RC for RT-BCa was associated with similar CSM rates as RC for pBCa, regardless of disease stage. However, patients who had undergone EBRT exhibited significantly higher OCM in the NOC sub-group.

Assessing the Impact of the Prostate Cancer Patient Empowerment Program (PC-PEP) on Relationship Satisfaction, Quality of Life, and Support Group Participation: A Randomized Clinical Trial.

Background/Objectives: The Prostate Cancer Patient Empowerment Program (PC-PEP) is a 6-month, home-based intervention aimed at enhancing mental health in men undergoing curative prostate cancer treatment. This exploratory secondary analysis evaluates PC-PEP's impact on relationship satisfaction, quality of life, and support group attendance among partnered participants. Methods: In a crossover randomized clinical trial ClinicalTrials.gov identifier: NCT03660085) of 128 men aged 50-82 scheduled for curative prostate cancer surgery or radiotherapy, 119 participants in relationships were included. Of these, 59 received the 6-month PC-PEP intervention, while 60 were randomized to a waitlist-control arm, receiving standard care for 6 months before starting PC-PEP. The intervention included daily emails with video instructions on mental and physical health, diet, social support, fitness, stress reduction, and intimacy. Outcomes were assessed using the Dyadic Adjustment Scale (DAS) and the Functional Assessment of Cancer Therapy-Prostate (FACT-P). Results: While relationship satisfaction remained stable, a significant improvement in emotional well-being was observed at 12 months in participants undergoing radiation therapy (p = 0.045). The PC-PEP intervention also led to significantly higher support group attendance at both 6 months (p = 0.001) and 12 months (p = 0.003), emphasizing its role in fostering social support and community engagement. Conclusions: The PC-PEP program effectively maintains relationship satisfaction and enhances emotional well-being, particularly in patients with fewer physical side effects. Its design promotes comprehensive care by integrating physical, psychological, and social support, making it a valuable resource for improving the quality of life in prostate cancer patients and potentially applicable to other cancer types.

Prediction of prostate cancer recurrence after radiotherapy using a fused machine learning approach: utilizing radiomics from pretreatment T2W MRI images with clinical and pathological information

The risk of biochemical recurrence (BCR) after radiotherapy for localized prostate cancer (PCa) varies widely within standard risk groups. There is a need for low-cost tools to more robustly predict recurrence and personalize therapy. Radiomic features from pretreatment MRI show potential as noninvasive biomarkers for BCR prediction. However, previous research has not fully combined radiomics with clinical and pathological data to predict BCR in PCa patients following radiotherapy.
Purpose: This study aims to predict 5-year BCR using radiomics from pretreatment T2W MRI and clinical-pathological data in PCa patients treated with radiation therapy, and to develop a unified model compatible with both 1.5T and 3T MRI scanners.
Methods: A total of 150 T2W scans and clinical parameters were preprocessed. Of these, 120 cases were used for training and validation, and 30 for testing. Four distinct machine learning models were developed: Model 1 used radiomics, Model 2 used clinical and pathological data, and Model 3 combined these using late fusion. Model 4 integrated radiomic and clinical-pathological data using early fusion.
Results: Model 1 achieved an AUC of 0.73, while Model 2 had an AUC of 0.64 for predicting outcomes in 30 new test cases. Model 3, using late fusion, had an AUC of 0.69. Early fusion models showed strong potential, with Model 4 reaching an AUC of 0.84, highlighting the effectiveness of the early fusion model.
Conclusions: This study is the first to use a fusion technique for predicting BCR in PCa patients following radiotherapy, utilizing pre-treatment T2W MRI images and clinical-pathological data. The methodology improves predictive accuracy by fusing radiomics with clinical-pathological information, even with a relatively small dataset, and introduces the first unified model for both 1.5T and 3T MRI images.

Posttreatment surveillance intensity and overall survival in prostate cancer survivors (AFT-30).

Posttreatment surveillance affects millions of cancer survivors, but empiric data to guide clinical practice are lacking. This study assessed whether the intensity of surveillance testing after radical prostatectomy or radiation therapy for localized prostate cancer is associated with overall survival. Men diagnosed with localized prostate cancer between 2005 and 2010 who underwent radical prostatectomy or radiation therapy at a Commission on Cancer-accredited facility were randomly sampled. Primary data collected from 10147 patients sampled across 1007 facilities were linked with existing data from the National Cancer Database. Analysis examined whether intensity of surveillance measured as the number of prostate-specific antigen (PSA) tests in the first year after primary treatment (categorized as 0-1 [low intensity], 2 [medium], or ≥3 [high intensity] PSA tests) was associated with overall survival. Secondary outcomes included recurrence-free survival (RFS) and subsequent use of imaging tests, biopsy procedures, and salvage treatment. Median follow-up exceeded 8 years from prostate cancer diagnosis. Overall survival was not statistically significantly different across surveillance intensity groups among radiation therapy (P = .59) or radical prostatectomy (P = .29) patients. RFS was not statistically significantly different across surveillance intensity groups for radiation therapy (P = .13) patients but was for radical prostatectomy (P = .01) patients with high intensity associated with the worst RFS. In both treatments, higher surveillance intensity was associated with more procedures and salvage treatments. In patients with localized prostate cancer, more frequent PSA surveillance testing after radical prostatectomy or radiation therapy was associated with increased procedures and salvage treatments but not overall survival.

Investigation of pelvic floor influence on prostate displacement in image-guided radiotherapy.

The uncertainty of target location during prostate cancer radiotherapy plays an important role in accurate dose delivery and radiation toxicity in adjacent organs. This study analyzed displacement correlations between the prostate and pelvic floor. We retrospectively analyzed registration results from 467 daily cone-beam computed tomography (CT) in 12 patients with prostate cancer who received radiation therapy. We analyzed prostate displacement and the pelvic floor relative to the pelvic bone's anatomy in the translational and rotational directions and identified statistical correlations. The systematic (Σ) and random (σ) displacements of the prostate in the three translational directions, anterior-posterior (AP), superior-inferior (SI), and right-left (RL), were 1.49 ± 1.45, 2.10 ± 1.40, and 0.24 ± 0.53 mm, respectively, and in the rotational directions of the pitch, roll, and yaw were 2.10 ± 2.02°, 0.42 ± 0.74°, and 0.42 ± 0.64°, respectively. The pelvic floor displacements were 2.37 ± 1.96, 2.71 ± 2.28, and 0.47 ± 0.84 mm in the AP, SI, and RL directions, respectively, and 0.93 ± 1.49°, 0.98 ± 1.28 °, and 0.87 ± 0.94° in the pitch, roll, and yaw directions, respectively. Additionally, there were statistically significant correlations between the displacement of the prostate and pelvic floor in the AP and SI directions, with correlation coefficients (r) of 0.74 (p < 0.001) and 0.69 (p < 0.001), respectively. The movement of the pelvic floor may be an important factor that causes prostate displacement, affecting the accuracy of radiotherapy. Therefore, it is necessary to take appropriate measures to ensure that the pelvic floor muscle tension is as consistent as possible in the treatment' CT scan and daily treatment.

State-of-the-art application of nanoparticles in radiotherapy: aplatform for synergistic effects in cancer treatment.

Radiotherapy (RT) is agold standard cancer treatment worldwide. However, RT has limitations and many side effects. Nanoparticles (NPs) have exclusive properties that allow them to be used in cancer therapy. Consequently, the combination of NP and RT opens up anew frontier in cancer treatment. Among NPs, gold nanoparticles (GNPs) are the most extensively studied and are considered ideal radiosensitizers for radiotherapy due to their unique physicochemical properties and high X‑ray absorption. This review analyzes the various roles of NPs as radiosensitizers in radiotherapy of glioblastoma (GBS), prostate cancer, and breast cancer and summarizes recent advances. Furthermore, the underlying mechanisms of NP radiosensitization, including physical, chemical, and biological mechanisms, are discussed, which may provide new directions for next-generation GNP optimization and clinical transformation.

Comparison of online adaptive and non-adaptive magnetic resonance image-guided radiation therapy in prostate cancer using dose accumulation

Background and purposeConventional image-guided radiotherapy (conv-IGRT) is standard in prostate cancer (PC) but does not account for inter-fraction anatomical changes. Online-adaptive magnetic resonance-guided RT (OA-MRgRT) may improve organ-at-risk (OARs) sparing and clinical target volume (CTV) coverage. The aim of this study was to analyze accumulated OAR and target doses in PC after OA-MRgRT and conv-IGRT in comparison to pre-treatment reference planning (refPlan). Material and methodsTen patients with PC, previously treated with OA-MRgRT at the 1.5 T MR-Linac (20x3Gy), were included. Accumulated OA-MRgRT doses were determined by deformably registering all fraction’s MR-images. Conv-IGRT was simulated through rigid registration of the planning computed tomography with each fraction’s MR-image for dose mapping/accumulation. Dose-volume parameters (DVPs), including CTV D50% and D98%, rectum, bladder, urethra, Dmax and V56Gy for OA-MRgRT, conv-IGRT and refPlan were compared using the Wilcoxon signed-rank test. Clinical relevance of accumulated dose differences was analyzed using a normal-tissue complication-probability model. ResultsCTV-DVPs were comparable, whereas OA-MRgRT yielded decreased median OAR-DVPs compared to conv-IGRT, except for bladder V56Gy. OA-MRgRT demonstrated significantly lower median rectum Dmax over conv-IGRT (59.1/59.9 Gy, p = 0.006) and refPlan (60.1 Gy, p = 0.012). Similarly, OA-MRgRT yielded reduced median bladder Dmax compared to conv-IGRT (60.0/60.4 Gy, p = 0.006), and refPlan (61.2 Gy, p = 0.002). Overall, accumulated dose differences were small and did not translate into clinically relevant effects. ConclusionDeformably accumulated OA-MRgRT using 20x3Gy in PC showed significant but small dosimetric differences comparted to conv-IGRT. Feasibility of a dose accumulation methodology was demonstrated, which may be relevant for evaluating future hypo-fractionated OA-MRgRT approaches.

Simulation-free magnetic resonance-guided radiation therapy of prostate cancer

Background and purposeDespite recent advances of online image-guided high-precision patient positioning and adaptation using magnetic resonance imaging (MRI) or cone-beam computed tomography (CT), standard radiation therapy pathway still involves a dedicated simulation scan. The aim of this study was to evaluate the feasibility and planning quality of integrating a simulation-free treatment planning workflow for adaptive online MRI-guided radiation therapy on a 1.5 T MRI linear accelerator (MRI-Linac) in prostate cancer using diagnostic CT (dCT) scans. Materials and methodsFor ten patients with prostate cancer previously treated at the MRI-Linac with adaptive radiation therapy (42.7 Gy in 7 fractions), simulation-free reference plans based on dCT were retrospectively created, and adaptive plans were simulated for the first treatment fraction. Reference and adapted plans derived from both standard and simulation-free workflows were compared with regard to institutional dose volume criteria, followed by statistical assessment using the paired Wilcoxon signed-rank test with a Bonferroni-corrected significance level of α = 0.025. ResultsSimulation-free reference and adapted plans consistently met dose volume criteria. Statistical analysis revealed no significant differences between both workflows, except median values for near-maximum dose (D2%) in the planning target volume: 44.2 Gy (standard) vs. 44.5 Gy (simulation-free) in reference plans (p = 0.014), and 44.5 Gy vs. 44.6 Gy in adapted plans (p = 0.009). ConclusionThis study demonstrated the feasibility of simulation-free radiation therapy planning using dCT. Comparable treatment plan quality was observed for both reference and adapted radiation therapy plans in a curative setting for patients with prostate cancer.

Integrated framework for quantitative T2-weighted MRI analysis following prostate cancer radiotherapy

PurposeThe aim of this study is to develop a framework for quantitative analysis of longitudinal T2-weighted MRIs (T2w) following radiotherapy (RT) for prostate cancer. Materials and methodsThe developed methodology includes: (i) deformable image registration of longitudinal series to pre-RT T2w for automated detection of prostate, peripheral zone (PZ), and gross tumor volume (GTV); and (ii) T2w signal-intensity harmonization based on three reference tissues. The REgistration and HARMonization (REHARM) framework was applied on T2w acquired in a clinical trial consisting of two pre-RT and three post-RT MRI exams. Image registration was assessed by the DICE coefficient between automatic and manual contours, and intensity normalization via inter-patient histogram intersection. Longitudinal consistency was evaluated by the repeatability coefficient and Pearson correlation (r) between the two T2w exams before RT. ResultsT2w from 107 MRI exams (23 patients) were utilized. Following REHARM, the histogram intersections for prostate, PZ and GTV increased from median = 0.43/0.16/0.13 to 0.66/0.44/0.46. The repeatability in T2w intensity estimation was better for the automatic than the manual contours for all three regions of interest (r = 0.9, p < 0.0001, for GTV). The changes in the tissues’ T2w values pre- and post-RT became significant, indicating the measurable quantitative signal related to radiation. ConclusionsThe developed methodology allows to automate longitudinal analysis reducing data acquisition-related variation and improving consistency. The quantitative characterization of RT-induced changes in T2w will lead to new understanding of radiation effects enabling prediction modeling of RT response.

Time to Next Systemic Therapy After Stereotactic Body Radiation Therapy for Oligoprogressive Metastatic Castrate-Resistant Prostate Cancer

Patients with metastatic castrate-resistant prostate cancer (CRPC) with progressive disease generally require a change or escalation in systemic therapy. For patients with limited (1-3) sites of progressive disease (oligoprogression), metastasis-directed therapy with stereotactic body radiation therapy (SBRT) may allow a longer interval before next-line systemic therapy. This is a retrospective study of patients with oligoprogressive metastatic CRPC (mCRPC) treated with SBRT at a single center between 2011 and 2022. The primary endpoint was time to next systemic therapy (TTNST) after SBRT stratified by the presence/absence of untreated nonprogressing metastases. Secondary endpoints included TTNST of the overall cohort and median overall survival (OS) after SBRT. Thirty-two patients with oligoprogressive mCRPC received SBRT to 38 metastases. Patients had a median age of 72.5 years (range, 50.6-84.3) and a median PSA of 6.85 ng/mL (range, 0.39-922.0) at the time of SBRT. The most commonly used SBRT regimen was 3000 cGy in 5 fractions (18 metastases, 47.4%). Sixteen patients were treated to all known sites of disease, whereas 16 patients received SBRT to oligoprogressive metastases but had at least 1 untreated nonprogressing metastasis at the time of SBRT. Patients had received a median of 1.0 prior line of androgen receptor signaling inhibitors and were predominantly (26 patients, 81.3%) chemotherapy naïve. Following SBRT, the median TTNST was 10.1 months and the median OS was 41.3 months. For patients with 0 versus ≥1 untreated nonprogressing metastasis, TTNST was 11.3 versus 8.7 months, respectively (HR, 0.67; 95% CI, 0.33-1.36, logrank P = .24). There was no grade ≥3 toxicities because of SBRT. In this cohort, patients with oligoprogressive mCRPC treated with SBRT delayed the next line of systemic therapy for a median of 10.1 months. SBRT in patients with oligoprogressive mCRPC may delay initiation of the next-line systemic therapy in well-selected patients, including those with ≥1 untreated nonprogressing metastasis.

Management of de novo Metastatic Hormone-Sensitive Prostate Cancer (mHSPC) and the role of Radiation Therapy: A Consensus by the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

Prostate cancer treatments paradigms are in continuous evolution, especially in metastatic setting. In this context, the Genito-Urinary (GU) Group of Italian Association of Radiotherapy and Clinical Oncology (AIRO) aimed to create a Consensus on radiotherapy indication in de novo metastatic hormone sensitive prostate cancer both on primary tumour and metastatic sites. A panel of experts, involved in clinical management of prostate cancer, through the estimate-talk-estimate (ETE) method, developed a list of items and correspondent statements on the identified topic. Seven conclusive items were identified with 12 statements about the chosen topic, radiotherapy in metastatic hormone sensitive prostate cancer on primary tumour and metastatic sites. This consensus might help clinicians in prostate cancer managing in daily clinical practice.

A deep learning model for predicting the modified micro-dosimetric kinetic model-based dose and the dose-averaged linear energy transfer for prostate cancer in carbon ion therapy

Adaptive carbon ion radiotherapy for localized prostate cancer requires accurate evaluation of biological dose and dose-averaged linear energy transfer (LETd) changes. This study developed a deep learning model to rapidly predict the modified micro-dosimetric kinetic model (mMKM)-based dose and LETd distributions. Using data from fifty patients for training and testing, the model achieved gamma passing rates exceeding 96% compared to true mMKM-based dose and LETd recalculated from local effect model I (LEM I) plans. Incorporating computed tomography images, contours, physical dose, and LEM I-based dose as inputs, this model provided a rapid, accurate tool for comprehensive evaluations.

Critical evaluation of the prevalence and severity of erectile dysfunction (ED) amongst people receiving radical external beam radiotherapy (EBRT) for prostate cancer at one UK radiotherapy centre and the examination of current management practice against national guidelines to explore the need for a radiographer-led ED clinic.

Critical evaluation of the prevalence and severity of erectile dysfunction (ED) amongst people receiving radical external beam radiotherapy (EBRT) for prostate cancer at one UK radiotherapy centre and the examination of current management practice against national guidelines to explore the need for a radiographer-led ED clinic.

Five-year outcomes of fractionated stereotactic body radiotherapy for oligometastatic prostate cancer from the TRANSFORM phase II trial.

Metastasis-directed therapy (MDT) for oligometastatic prostate cancer (PCa), including stereotactic body radiotherapy (SBRT), has shown promise but is still considered investigational. This is the 5-year analysis of the TRANSFORM trial, the largest prospective cohort of men with oligometastatic PCa treated with SBRT-based MDT. The primary endpoint was 5-year treatment escalation-free survival (TE-FS), defined as freedom from any new cancer therapy other than further SBRT. In total, 199 men received SBRT; 76.4% were hormone-naïve at baseline. The rate of 5-year TE-FS was 21.7% (95% confidence interval [CI]: 15.7%-28.7%) overall and 25.4% (95% CI: 18.1%-33.9%) in the hormone-naïve subgroup. The subgroups with International Society of Urological Pathology Grade Groups 4-5 disease (hazard ratio [HR] = 1.48, 95% CI: 1.05-2.01, p = .026), a higher baseline prostate-specific antigen (PSA) (HR = 1.06, 95% CI: 1.03-1.09, p < .001) and those who received prior androgen deprivation therapy (ADT) (HR = 2.13, 95% CI: 1.40-3.26, p < .001), were at greater risk of treatment escalation. Outcomes for participants with four or five initial lesions were comparable to those with one to three lesions. At last follow-up, 18.9% (95% CI: 13.2%-25.7%) of participants were free from treatment escalation (median follow-up of 67.9 months) and two participants had an undetectable PSA level. No treatment-related grade three or higher adverse events were reported. The findings of this study demonstrate that SBRT-based MDT is an effective option for delaying systemic treatment escalation in the context of oligometastatic PCa. Future randomised trials comparing SBRT-based MDT to standard-of-care ADT-based approaches are required to evaluate the impact of delaying ADT on survival.

Deep learning based clinical target volumes contouring for prostate cancer: Easy and efficient application.

Radiotherapy has been crucial in prostate cancer treatment. However, manual segmentation is labor intensive and highly variable among radiation oncologists. In this study, a deep learning based automated contouring model is constructed for clinical target volumes (CTVs) of intact and postoperative prostate cancer. Computed tomography (CT) data sets of 197 prostate cancer patients were collected. Two auto-delineation models were built for radical radiotherapy and postoperative radiotherapy of prostate cancer respectively, and each model included CTVn for pelvic lymph nodes and CTVp for prostate tumors or prostate tumor beds. In the radical radiotherapy model, the volumetric dice (VD) coefficient of CTVn calculated by AI, was higher than that of the one delineated by the junior physicians (0.85vs. 0.82, p=0.018); In the postoperative radiotherapy model, the quantitative parameter of CTVn and CTVp, counted by AI, was better than that of the junior physicians. The median delineation time for AI was 0.23min in the postoperative model and 0.26min in the radical model, which were significantly shorter than those of the physicians (50.40 and 45.43min, respectively, p<0.001). The correction time of the senior physician for AI was much shorter compared with that for the junior physicians in both models (p<0.001). Using deep learning and attention mechanism, a highly consistent and time-saving contouring model was built for CTVs of pelvic lymph nodes and prostate tumors or prostate tumor beds for prostate cancer, which also might be a good approach to train junior radiation oncologists.

Prostate-specific Membrane Antigen Positron Emission Tomography Before Reaching the Phoenix Criteria for Biochemical Recurrence of Prostate Cancer After Radiotherapy: Earlier Detection of Recurrences

Background and objectiveBiochemical recurrence (BCR) of prostate cancer (PCa) after curative radiotherapy (RT) is defined according to the Phoenix criteria, which is a prostate-specific antigen (PSA) rise of ≥2.0 ng/ml above the PSA nadir. Prostate-specific membrane antigen (PSMA)-based positron emission tomography/computed tomography (PET/CT) can identify PCa recurrences at very low PSA values. Our aim was to investigate the detection rate and extent of PCa recurrences using PSMA PET/CT after curative RT among patients with a PSA rise of ≥2.0 ng/ml above the nadir (Phoenix positive, Ph+) and patients not reaching this threshold (Phoenix negative, Ph−) and to compare therapeutic management and clinical outcomes in terms of time to androgen deprivation therapy (ADT) and castration-resistance PCa (CRPC), as well as overall survival. MethodsWe conducted a retrospective analysis of the Prostate Cancer Network Amsterdam (2015–2023) cohort of 568 patients who received curative-intent RT for PCa. Data on PSMA PET/CT outcomes, therapeutic management, and clinical follow-up were collected, including (re)initiation of ADT, progression to CRPC, and survival. Results were compared between groups using logistic regression and survival analyses. Key findings and limitationsThe study cohort comprised 222 patients (39.1%) classified as Ph− and 346 (60.9%) classified as Ph+. PSMA-avid lesions were detected in 170 Ph− patients (76.6%) and 322 (93.1%) Ph+ patients. In these groups, 75.9% of Ph− patients and 45.0% of Ph+ patients were eligible for local salvage therapy (odds ratio [OR 3.84]; p < 0.001). Distant metastases were less frequent in the Ph− group (n = 37, 21.8%) than in the Ph+ group (n = 157, 48.8%; OR 0.29; p < 0.001). Survival analyses revealed longer times to ADT (re)initiation and progression to CRPC, as well as lower overall mortality, in the Ph− group (log-rank p < 0.001). The retrospective study design is the main limitation. Conclusions and clinical implicationsFor patients with PCa recurrence, PSMA PET/CT can detect this recurrence in the majority of cases not meeting the Phoenix criteria for BCR. Early imaging detects recurrences at a less advanced disease stage, allowing potential salvage treatments. In addition, early PSMA PET/CT is associated with longer times to ADT (re)initiation and progression to CRPC, as well as longer overall survival. These positive clinical implications warrant confirmation of our results in prospective studies to reduce potential leadtime bias. Patient summaryWe investigated early use of a special type of scan called PSMA PET (prostate-specific membrane antigen positron emission tomography) in patients with suspicion of recurrence of their prostate cancer after radiotherapy. Early scans can detect recurrence before the cancer progresses to a more advanced stage.

470 - An Institutional experience of Prostate cancer Radiotherapy treatment with Full bladder Vs Gold fiducial marker: Pro and Cons

470 - An Institutional experience of Prostate cancer Radiotherapy treatment with Full bladder Vs Gold fiducial marker: Pro and Cons

Changes in Bladder Volume During Radiotherapy for Prostate Cancer.

Patients irradiated for prostate cancer may experience urinary toxicity, particularly if the bladder volume is small. A mobile application (app) that reminds the patients to drink water prior to each radiation fraction may help avoid small volumes. This study investigating bladder volumes during a radiotherapy course is a prerequisite for a prospective trial testing such a reminder app. Frequency of bladder volumes <200 ml and seven potential risk factors were retrospectively evaluated in 72 patients receiving external beam radiotherapy for non-metastatic prostate cancer. The mean and median values of the numbers of radiation fractions with bladder volumes <200 ml were 17.8 (standard deviation=12.0) and 16.5 (interquartile range Q1-Q3=7.5-29.5) fractions, respectively. Higher numbers of fractions with volumes <200 ml were significantly associated with pre-radiotherapy bladder volumes <200 ml (p<0.001) and high-risk prostate cancer (p=0.014). The proportion of bladder volumes <200 ml during the radiotherapy course was high and needs to be decreased. Pre-radiotherapy bladder volume and risk level of prostate cancer were significant risk factors for higher numbers of fractions with volumes <200 ml. These results are important for designing a prospective trial.

Assessment of prostate cancer radiotherapy using three-dimensional treatment planning technique.

To assess the available commercial treatment planning system using three-dimensional conformal radiation therapy with respect to treatment for prostate cancer patients. This is a cross-sectional study was conducted from June 2021 to February 2022 at the Baghdad Centre for Radiation Therapy and Nuclear Medicine, Baghdad, Iraq, and comprised patients with prostate cancer who were treated with 6MV or 10MV energy using three-dimensional conformal radiation therapy technique, and irradiated using a linear accelerator. The patents were divided into three treatment phases. The prescribed dose in Phase I was 5000 centigrade, in Phase II it was 1800 centigrade, and in Phase III it was 600 centigrade. The number of beams used was 5 and 7. Data was analysed using SPSS 24. Out of 35 patients, 10 (28.6%) in phase I, 15 (42.8%) in phase II, and 10 (28.6%) in phase III. The PTV dose of 5 and 7 beams 6MV energy at the centre was higher than at 1mm, 2mm, and 3mm p values = (0.351, 0.013*, 0.076, 0.295), respectively. Dose to the rectum comparing 6MV and 10MV for beams 5, and 7. The dose to the rectum on phase one at 6MV and 10MV was similar for 5 beams (p=0.611) and 7 beams (p=0.778). A significant difference was seen for 7 beams (p-value=0.008). Phase three showed significant variations in rectum dose at 6 MV and 10MV for 5 beams (p=0.0004). For bladder, a significant difference observed between the energies for 5 beams on phase one and three (p-value=<0.00001*, 0.002*), while at 7 beams only phase 3 were significant (p-value=0.041*). The three-dimensional conformal radiation therapy plan with 10MV energy and a higher number of beams gave a higher coverage of dose for prostate tumours and was found to be a safe dose for the rectum and bladder.