Radiotherapy For Prostate Cancer Research Articles

Lonidamine Induced Selective Acidification and De-Energization of Prostate Cancer Xenografts: Enhanced Tumor Response to Radiation Therapy.

Prostate cancer is a multi-focal disease that can be treated using surgery, radiation, androgen deprivation, and chemotherapy, depending on its presentation. Standard dose-escalated radiation therapy (RT) in the range of 70-80 Gray (GY) is a standard treatment option for prostate cancer. It could be used at different phases of the disease (e.g., as the only primary treatment when the cancer is confined to the prostate gland, combined with other therapies, or as an adjuvant treatment after surgery). Unfortunately, RT for prostate cancer is associated with gastro-intestinal and genitourinary toxicity. We have previously reported that the metabolic modulator lonidamine (LND) produces cancer sensitization through tumor acidification and de-energization in diverse neoplasms. We hypothesized that LND could allow lower RT doses by producing the same effect in prostate cancer, thus reducing the detrimental side effects associated with RT. Using the Seahorse XFe96 and YSI 2300 Stat Plus analyzers, we corroborated the expected LND-induced intracellular acidification and de-energization of isolated human prostate cancer cells using the PC3 cell line. These results were substantiated by non-invasive 31P magnetic resonance spectroscopy (MRS), studying PC3 prostate cancer xenografts treated with LND (100 mg/kg, i.p.). In addition, we found that LND significantly increased tumor lactate levels in the xenografts using 1H MRS non-invasively. Subsequently, LND was combined with radiation therapy in a growth delay experiment, where we found that 150 µM LND followed by 4 GY RT produced a significant growth delay in PC3 prostate cancer xenografts, compared to either control, LND, or RT alone. We conclude that the metabolic modulator LND radio-sensitizes experimental prostate cancer models, allowing the use of lower radiation doses and diminishing the potential side effects of RT. These results suggest the possible clinical translation of LND as a radio-sensitizer in patients with prostate cancer.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 1. Brain and head and neck.

Advances in radiotherapy (RT) techniques, including intensity-modulated RT and image-guided RT, have allowed hypofractionation, increasing the fraction size over the conventional dose of 1.8-2.0 Gy. Hypofractionation offers advantages such as shorter treatment times, improved compliance, and under specific conditions, particularly in tumors with a low α/β ratio, higher efficacy. It was initially explored for use in RT for prostate cancer and adjuvant RT for breast cancer, and its application has been extended to various other malignancies. Hypofractionated RT (HFRT) may also be effective in patients who are unable to undergo conventional treatment owing to poor performance status, comorbidities, or old age. The treatment of brain tumors with HFRT is relatively common because brain stereotactic radiosurgery has been performed for over two decades. However, re-irradiation of recurrent lesions and treatment of elderly or frail patients are areas under investigation. HFRT for head and neck cancer has not been widely used because of concerns regarding late toxicity. Thus, we aimed to provide a comprehensive summary of the current evidence for HFRT for brain tumors and head and neck cancer and to offer practical recommendations to clinicians faced with the challenge of choosing new treatment options.

New possibilities for dose fractionation in radiotherapy for prostate cancer

New possibilities for dose fractionation in radiotherapy for prostate cancer

Preventing Rectal Toxicity in Prostate Cancer: Diet and Supplement Alternative to Enemas or Rectal Spacer

Background: Rectal toxicity is an important side effect of prostate cancer irradiation affecting 25% of patients. The role of dosimetric variables has a set of dose-volume constraints and curves to estimate the risk of rectal damage. The rectum position at the time of CT planning is different from the position during radiotherapy. Three methods are available to achieve optimal rectum position: enema; prostate cancer spacer; fiber-/fat-free diet. Methods: A 70.2 Gray radiation divided into 26 hypo-fractions was administered to 115 patients with prostate cancer by VMAT referred to a single center in Italy. To empty the rectum, all patients were administered a fiber-/fat-free diet and those with Eating Disorders (ED) were also added with activated charcoal (2 tablets/day) and a macrogol-based medical device (2 sachets/day). During treatment, the volumetric amount of rectum in the target was measured by comparing control-CT with simulation-CT, and acute toxicity was also checked. Results: The rectum position during control-CT in diet-only patients (29) predicted toxicity recorded during treatment, while in the ED group rectum position was adherent to position during simulations. Rectal volume target > 0.25 cc receiving a dose > V70 caused acute G3 toxicity that attenuated or worsened with rectal displacement. Acute rectal toxicity occurred in 6/29 (20.68%) patients (1 G3, 5 G1) in the diet-only group, while only in 1/86 (1.16%) patients (G1) in the ED group. No chronic toxicity was recorded in either group. Conclusion: Prostate cancer patients treated with VMAT, diet, charcoal, and macrogol emptied the rectum optimally and reduced incidence and severity of acute rectal toxicity, also with benefit on late toxicity.

Second primary cancers following radiotherapy for prostate cancer: How many are actually due to the radiotherapy?

Second primary cancers following radiotherapy for prostate cancer: How many are actually due to the radiotherapy?

Salvage high-intensity focused ultrasound (S-HIFU) for recurrence after primary radiotherapy of prostate cancer

ObjectivesTo evaluate functional and oncological outcomes of salvage high-intensity focal ultrasound (S-HIFU) after external beam radiotherapy (EBRT) failure in prostate cancer (PCa) patients. MethodsThis single-center study included patients who underwent S-HIFU for local recurrence after EBRT between 2006 and 2023. Cancer-specific survival, metastasis-free survival and progression-free survival were illustrated using Kaplan–Meier curves. Disease progression was defined by one of the following criteria: increase of 2ng/mL or more above the PSA nadir, positive post-S-HIFU biopsy or initiation of androgen deprivation therapy (ADT). Multivariable Cox proportional hazards model was used to identify predictors of disease progression after S-HIFU. ResultsA total of 52 S-HIFU sessions for 48 patients were performed. Median time between EBRT and S-HIFU was 6.5 years. Median PSA before S-HIFU was 3.2ng/mL and median PSA nadir after S-HIFU was 0.58ng/mL. A total of 39 (81.3%) complications was recorded, including 3 (6.3%) high grade complications according to the Clavien-Dindo classification. After a median follow-up period of 6 years, 14 (29.2%) patients developed metastatic disease. Eighteen (37.5%) patients had no recurrence, whereas 30 (62.5%) patients received ADT for disease progression. The estimated 5-yr cancer-specific survival (CSS), metastasis-free survival (MFS) and progression-free survival rates (PFSR) were 100%, 79.9% (95% CI 67–92) and 41.2% (95% CI 74–96), respectively. The estimated 10-yr CSS, MFS and PFSR were 80% (95% CI 45–100), 50.7% (95% CI 19.4–82.1) and 14% (95% CI 10.8–45), respectively. The hazard of progression increased with the intermediate (HR 3.8; 95% CI 0.99 to 15; p=0.049) and high pre-EBRT d’Amico-s risk group (HR 4.1; 95% CI 0.98 to 16.2; p=0.050). Also, the time between EBRT and S-HIFU was significantly associated with risk of progression (HR 0.61; 95% CI 0.43 to 0.86; p=0.004). No significant difference linked to the disease progression (DP) risk was found between focal vs whole-gland treatment (p=0.70). ConclusionPhysicians should consider HIFU as a local salvage treatment after failed EBRT, thus avoiding or delaying palliative androgen deprivation therapy. Further studies are needed to improve patient selection for this therapy. Level of evidence4.

Stereotactic ultrahypofractionated MR-guided radiotherapy for localized prostate cancer – Acute toxicity and patient-reported outcomes in the prospective, multicenter SMILE phase II trial

BackgroundDue to superior image quality and daily adaptive planning, MR-guided stereotactic body radiation therapy (MRgSBRT) has the potential to further widen the therapeutic window in radiotherapy of localized prostate cancer. This study reports on acute toxicity rates and patient-reported outcomes after MR-guided adaptive ultrahypofractionated radiotherapy for localized prostate cancer within the prospective, multicenter phase II SMILE trial. Materials and methodsA total of 69 patients with localized prostate cancer underwent MRgSBRT with daily online plan adaptation. Inclusion criteria comprised a tumor stage ≤ T3a, serum PSA value ≤ 20 ng/ml, ISUP Grade group ≤ 4. A dose of 37.5 Gy was prescribed to the PTV in five fractions on alternating days with an optional simultaneous boost of 40 Gy to the dominant intraprostatic lesion defined by multiparametric MRI. Acute genitourinary (GU-) and gastrointestinal (GI-) toxicity, as defined by CTCAE v. 5.0 and RTOG as well as patient-reported outcomes according to EORTC QLQ-C30 and -PR25 scores were analyzed at completion of radiotherapy, 6 and 12 weeks after radiotherapy and compared to baseline symptoms. ResultsThere were no toxicity-related treatment discontinuations. At the 12-week follow-up visit, no grade 3 + toxicities were reported according to CTCAE. Up until the 12-week visit, in total 16 patients (23 %) experienced a grade 2 GU or GI toxicity. Toxicity rates peaked at the end of radiation therapy and subsided within the 12-week follow-up period. At the 12-week follow-up visit, no residual grade 2 GU toxicities were reported and 1 patient (1 %) had residual grade 2 enteritic symptoms. With exception to a significant improvement in the emotional functioning score following MRgSBRT, no clinically meaningful changes in the global health status nor in relevant subscores were reported. ConclusionDaily online-adaptive MRgSBRT for localized prostate cancer resulted in an excellent overall toxicity profile without any major negative impact on quality of life.

Abstract 1353: Potentiating salvage radiotherapy in radiorecurrent prostate cancer through anti-CTLA4 therapy: Implications from a syngeneic model

Abstract Background: Advanced prostate cancer (PCa) is a leading cause in cancer death and can elicit significant morbidity and mortality. A common treatment modality for advanced PCa is radiation therapy (RT). Currently, salvage of local disease recurrence after RT is a major clinical problem. Emerging evidence indicates the importance of the immune system in governing RT response. In support of this, immune checkpoint inhibitors (ICIs), which enhance immune activation, have demonstrated clinical therapeutic promise in combination with RT in certain advanced cancers. Irradiation (IR) combined with ICIs may prime the immune system to recognize and target recurrent cancer. Purpose: Investigate the therapeutic efficacy of ICIs in combination with RT for radiorecurrent PCa in a syngeneic pre-clinical model. Methods: TRAMP-C2 cells were treated with 10 Gy of radiation over 5 fractions (similar to clinical hypofractionated (HF) schedule) to generate TRAMP-C2 HF cells. Immune-competent mice were transplanted subcutaneously with TRAMP-C2 HF cells. Once tumors reached palpable size, mice were administered either ICIs (anti-PDL1 or anti-CTLA4) alone or in combination with RT. Tumor volume was monitored to determine the treatment effect. Correlative studies on excised tumors and secondary lymphoid organs included flow cytometry and NanoString gene expression panel to evaluate immunological mechanisms that contribute to anti-tumor effects. Results: TRAMP-C2 HF cells were validated for radiation resistance and exhibited a more aggressive phenotype (reduction in senescence, increase in clonogenicity) similar to clinically recurrent PCa. Radiation resistance of TRAMP-C2 HF tumors was validated in vivo. Administration of anti-PDL1 and anti-CTLA4 as monotherapy or in combination did not achieve significant tumor growth delay compared to control. IR alone produced an observable tumor growth delay compared to ICIs alone. The combination of anti-PDL1 and IR did not yield additional growth delay compared to IR alone. Strikingly, significant tumor growth delay was seen with the combination of IR and anti-CTLA4 compared to IR alone, while also resulting in complete cure in a third of the mice. mice. Lymph nodes and tumors from mice treated with IR and anti-CTLA4 vs. IR and isotype control demonstrated differential expression of genes in T cell functions and enrichment in both CD4+ and CD8+ T cell populations. Conclusion: We generated the first syngeneic radiorecurrent PCa model and demonstrated that combining anti-CTLA4 and IR results in synergistic tumor response. Combined therapy resulted in augmented immune response, most notably enhancement of CD8 T cell activity. Significance: These findings contribute to our understanding of immunological events associated with RT and ICIs in the context of radiorecurrent PCa and support new avenues for salvage therapy in clinical trials. Citation Format: Hanzhi Wang, Linsey Gong, Xiaoyong Huang, Stephanie D. White, Hanz T. Chung, Danny Vesprini, Tera N. Petchiny, Emmanouil Fokas, Hansen He, Robert S. Kerbel, Stanley K. Liu. Potentiating salvage radiotherapy in radiorecurrent prostate cancer through anti-CTLA4 therapy: Implications from a syngeneic model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1353.

Influence of Prostate Volume on the Incidence of Complications and Urinary Incontinence Following Thulium Fiber Laser Enucleation of the Prostate: Results from Multicenter, Real-world Experience of 2732 patients

BackgroundThe use of the new thulium fiber laser in enucleation of the prostate (ThuFLEP) has been introduced recently. ObjectiveTo evaluate complications and urinary incontinence (UI) after ThuFLEP in small and large prostate volume (PV). Design, setting, and participantsWe retrospectively reviewed patients who underwent ThuFLEP in six centers (from January 2020 to January 2023). The exclusion criteria were concomitant lower urinary tract surgery, previous prostate/urethral surgery, prostate cancer, and pelvic radiotherapy. Outcome measurements and statistical analysisPatients were divided into two groups: group 1: PV ≤80 ml; group 2: PV >80 ml. Univariable and multivariable logistic regression analyses were performed to evaluate the independent predictors of overall UI. Results and limitationsThere were 1458 patients in group 1 and 1274 in group 2. There was no significant difference in age. The median PV was 60 (61-72) ml in group 1 and 100 (90-122) ml in group 2. En bloc enucleation was employed more in group 1, while the early apical release technique was used more in group 2. The rate of prolonged irrigation for hematuria, urinary tract infection, and acute urinary retention did not differ significantly. Blood transfusion rate was significantly higher in group 2 (0.5% vs 2.0%, p = 0.001). There was no significant difference in the overall UI rate (12.3% in group 1 vs 14.7% in group 2, p = 0.08). A multivariable regression analysis showed that preoperative postvoiding urine residual (odds ratio 1.004, 95% confidence interval 1.002-1.007, p < 0.01) was the only factor significantly associated with higher odds of UI. A limitation of this study was its retrospective nature. ConclusionsComplications and UI rates following ThuFLEP were similar in patients with a PV up to or larger than 80 ml except for the blood transfusion rate that was higher in the latter. Patient summaryIn this study, we looked at outcomes after thulium fiber laser in enucleation of the prostate stratified by PV. We found that blood transfusion was higher in men with PV >80 ml, but urinary incontinence was similar.

Updated Analysis of Comparative Toxicity of Proton and Photon Radiation for Prostate Cancer.

Previous comparative effectiveness studies have not demonstrated a benefit of proton beam therapy (PBT) compared with intensity-modulated radiation therapy (IMRT) for prostate cancer. An updated comparison of GI and genitourinary (GU) toxicity is needed. We investigated the SEER-Medicare linked database, identifying patients with localized prostate cancer diagnosed from 2010 to 2017. Procedure and diagnosis codes indicative of treatment-related toxicity were identified. As a sensitivity analysis, we also identified toxicity based only on procedure codes. Patients who underwent IMRT and PBT were matched 2:1 on the basis of clinical and sociodemographic characteristics. We then compared GI and GU toxicity at 6, 12, and 24 months after treatment. The final sample included 772 PBT patients matched to 1,544 IMRT patients. The frequency of GI toxicity for IMRT versus PBT was 3.5% versus 2.5% at 6 months (P = .18), 9.5% versus 10.2% at 12 months (P = .18), and 20.5% versus 23.4% at 24 months (P = .11). The frequency of only procedure codes indicative of GI toxicity for IMRT versus PBT was too low to be reported and not significantly different. The frequency of GU toxicity for IMRT versus PBT was 6.8% versus 5.7% (P = .30), 14.3% versus 12.2% (P = .13), and 28.2% versus 25.8% (P = .21) at 6, 12, and 24 months, respectively. When looking only at procedure codes, the frequency of GU toxicity for IMRT was 1.0% at 6 months, whereas it was too infrequent to report for PBT (P = .64). GU toxicity for IMRT versus PBT was 3.3% versus 2.1% (P = .10), and 8.7% versus 6.7% (P = .10) at 12 and 24 months, respectively. In this observational study, there were no statistically significant differences between PBT and IMRT in terms of GI or GU toxicity.

Prostate diffusion-weighted imaging (DWI) in MR-guided radiotherapy: Reproducibility assessment on 1.5 T MR-Linac and 1.5 T MR-simulator

PurposeDiffusion-weighted imaging (DWI) holds promise for image-guided radiotherapy (MRgRT) in prostate cancer. However, challenges persist due to image distortion, artifacts, and apparent diffusion coefficient (ADC) reproducibility issues. This study aimed to assess DWI image quality and ADC reproducibility on both a 1.5 T MR-simulator and a 1.5 T MR-Linac, employing measurements from both an ACR MRI phantom and prostate cancer patients undergoing MRgRT. MethodsDW-MRI scans were conducted on 19 patients (mean age = 69 ± 8 years, with 23 MR-visible intra-prostatic lesions) and an ACR MRI phantom using a 1.5 T MR-simulator (b-values = 0, 800, 1400s/mm2) and a 1.5 T MR-Linac (b-values = 50, 500, 800 s/mm2). ADC homogeneity in the phantom was evaluated via 1D profile flatness (FL) in three directions. Image quality was assessed through qualitative 5-point Likert scale ratings and quantitative ADC and signal-to-noise ratio (SNR) measurements. Intra-observer reproducibility of image quality scores was evaluated using ICC(1, 2). Geometric distortion was measured by comparing landmark sizes on the ACR phantom against the ground truth. Mean ADC and reproducibility were assessed using Bland-Altman plots. ResultsBoth MR-simulator and MR-Linac demonstrated high ADC homogeneity (FL > 87.5% - MR-simulator: 97.23 ± 0.62%, MR-Linac: 94.75 ± 0.62%, p < 0.05) in the phantom. Image quality scores revealed acceptable ratings (≥3) for capsule demarcation, image artifacts, and geometric distortion in patients. However, intra-prostatic lesions were barely discernible in b800 images for both MR-simulator (average score = 2.37 ± 1.33) and MR-Linac (average score = 2.16 ± 1.28). While MR-Linac DWI scans exhibited significantly more severe geometric distortion than MR-simulator scans (p < 0.01), most phantom measurements fell within the image in-plane resolution of 3 mm. Significant differences were noted in MR-simulator ADC (CTV: 1.20 ± 0.14 × 10−3 mm2/s (MR-simulator) vs 1.06 ± 0.10 × 10–3 mm2/s (MR-Linac); GTV: 1.05 ± 0.21 × 10−3 mm2/s vs 0.91 ± 0.16 × 10 mm2/s, all p < 0.05), with a small non-zero bias observed in the Bland-Altman analysis (CTV: 12.3%; GTV: 14.5%). ConclusionThe significantly larger MR-simulator ADC and the small non-zero bias hint at potential systematic differences in ADC values acquired from an MR-simulator and an MR-Linac, both at 1.5 T. Although acceptable ADC homogeneity was noted, caution is warranted in interpreting MR-Linac DWI images due to occasional severe artifacts. Further studies are essential to validate DWI and ADC as reliable imaging markers in prostate cancer MRgRT.

Pelvic bone marrow dose-volume predictors of late lymphopenia following pelvic lymph node radiation therapy for prostate cancer

Background and purposeGiven the substantial lack of knowledge, we aimed to assess clinical/dosimetry predictors of late hematological toxicity on patients undergoing pelvic-nodes irradiation (PNI) for prostate cancer (PCa) within a prospective multi-institute study. Materials and methodsClinical/dosimetry/blood test data were prospectively collected including lymphocytes count (ALC) at baseline, mid/end-PNI, 3/6 months and every 6 months up to 5-year after PNI. DVHs of the Body, ileum (BMILEUM), lumbosacral spine (BMLS), lower pelvis (BMPELVIS), and whole pelvis (BMTOT) were extracted. Current analysis focused on 2-year CTCAEv4.03 Grade ≥ 2 (G2+) lymphopenia (ALC < 800/μL). DVH parameters that better discriminate patients with/without toxicity were first identified. After data pre-processing to limit overfitting, a multi-variable logistic regression model combining DVH and clinical information was identified and internally validated by bootstrap. ResultsComplete data of 499 patients were available: 46 patients (9.2 %) experienced late G2+ lymphopenia. DVH parameters of BMLS/BMPELVIS/BMTOT and Body were associated to increased G2+ lymphopenia. The variables retained in the resulting model were ALC at baseline [HR = 0.997, 95 %CI 0.996–0.998, p < 0.0001], smoke (yes/no) [HR = 2.9, 95 %CI 1.25–6.76, p = 0.013] and BMLS-V ≥ 24 Gy (cc) [HR = 1.006, 95 %CI 1.002–1.011, p = 0.003]. When acute G3+ lymphopenia (yes/no) was considered, it was retained in the model [HR = 4.517, 95 %CI 1.954–10.441, p = 0.0004]. Performances of the models were relatively high (AUC = 0.87/0.88) and confirmed by validation. ConclusionsTwo-year lymphopenia after PNI for PCa is largely modulated by baseline ALC, with an independent role of acute G3+ lymphopenia. BMLS-V24 was the best dosimetry predictor: constraints for BMTOT (V10Gy < 1520 cc, V20Gy < 1250 cc, V30Gy < 850 cc), and BMLS (V24y < 307 cc) were suggested to potentially reduce the risk.

Metastases-directed radiotherapy in castration resistant oligo metastatic prostate cancer: A multicentric retrospective study from the French group COLib

Oligometastases aredefined as a number of detectable metastases less or equal to 5. In castrate-resistant oligo metastatic prostate Cancer (CR oligoM PC), Metastases-Directed Ablative radiotherapy (MDRT) is poorly investigated. Our study retrospectively reviewed the cases of CR oligoM PC treated with MDRT in 8 French high-volume radiotherapy centers.OS and PFS are defined as the delay between the first day of MDRT and death (OS) or progression according to PCWG criteria (PFS). OS and PFS are evaluated according to Kaplan Meyer, curves are compared with log rank test. Logistic regression was used to identify predictive factors for outcome: bone versus node metastasis, ISUP grade, PSA doubling Time (PSADT) at the time of MDRT, time to castration resistance.107 patients were included in the study, among those 197 metastases received MDRT. For the overall population, the median follow-up was 25.2 months (1,4–145). OS was 93 % at 2 years and 81,4% at 3 years. At 2 years, 100 % of patients with node-only metastasis were alive versus 88,7% among those who have bone metastases (p = 0,72). The median PFS was 12,6 months (IC 95 % [9,6; 17]), with no difference among patients with node only disease versus the rest of the cohort.The PFS was 18,2 months (10,0; 32,4) in patients with PSADT >6 months versus 10,7 months (8,9; 14,3) when PSADT was inferior to 6 months. However, this difference did not reach significant.We did not find a correlation neither between ISUP grade (1–2 versus 3–4-5) and PFS, nor between hormone-sensitivity duration and PFS.Patients receiving MDRT for CR oligoM PC have a good prognosis with 81,6% OS at 3 years. PSA DT longer than 6 months could be related to better PFS. MDRT strategy could postpone the onset of new systemic treatment with median PFS >1 year.

Treatment intensification strategies for men undergoing definitive radiotherapy for high-risk prostate cancer.

Treatment intensification of external beam radiotherapy (EBRT) plays a crucial role in the treatment of high-risk prostate cancer. We performed a critical narrative review of the relevant literature and present new developments in evidence-based treatment intensification strategies. For men with high-risk prostate cancer, there is strong evidence to support prolonging androgen deprivation therapy (ADT) to 18-36months and escalating the dose to the prostate using a brachytherapy boost. A potentially less toxic alternative to a brachytherapy boost is delivering a focal boost to dominant intraprostatic lesions using EBRT. In patients who meet STAMPEDE high-risk criteria, there is evidence to support adding a second-generation anti-androgen agent, such as abiraterone acetate, to long-term ADT. Elective pelvic lymph node irradiation may be beneficial in select patients, though more prospective data is needed to elucidate the group of patients who may benefit the most. Tumor genomic classifier (GC) testing and advanced molecular imaging will likely play a role in improving patient selection for treatment intensification as well as contribute to the evolution of treatment intensification strategies for future patients. Treatment intensification using a combination of EBRT, advanced hormonal therapies, and brachytherapy may improve patient outcomes and survival in men with high-risk prostate cancer. Shared decision-making between patients and multidisciplinary teams of radiation oncologists, urologists, and medical oncologists is essential for personalizing care in this setting and deciding which strategies make sense for individual patients.

Radiotherapy in localized prostate cancer: amulticenter analysis evaluating tumor control and late toxicity after brachytherapy and external beam radiotherapy in 1293 patients.

Comparing oncological outcomes and toxicity after primary treatment of localized prostate cancer using HDR- or LDR-mono-brachytherapy (BT), or conventionally (CF) or moderately hypofractionated (HF) external beam radiotherapy. Retrospectively, patients with low- (LR) or favorable intermediate-risk (IR) prostate cancer treated between 03/2000 and 09/2022 in two centers were included. Treatment was performed using either CF with total doses between 74and 78 Gy, HF with 2.4-2.6 Gy per fraction in 30fractions, or LDR- or HDR-BT. Biochemical control (BC) according to the Phoenix criteria, and late gastrointestinal (GI), and genitourinary (GU) toxicity according to RTOG/EORTC criteria were assessed. We identified 1293 patients, 697 with LR and 596 with IR prostate cancer. Of these, 470, 182, 480, and 161 were treated with CF, HF, LDR-BT, and HDR-BT, respectively. For BC, we did not find asignificant difference between treatments in LR and IR (p = 0.31 and 0.72). The 5‑year BC for LR was between 93and 95% for all treatment types. For IR, BC was between 88% in the CF and 94% in the HF group. For CF and HF, maximum GI and GU toxicity grade ≥ 2 was between 22and 27%. For LDR-BT, we observed 67% grade ≥ 2 GU toxicity. Maximum GI grade ≥ 2 toxicity was 9%. For HDR-BT, we observed 1% GI grade ≥ 2 toxicity and 19% GU grade ≥ 2 toxicity. All types of therapy were effective and well received. HDR-BT caused the least late toxicities, especially GI.

Spatial Pattern of Intraprostatic Recurrence after Definitive External-Beam Radiation Therapy for Prostate Cancer: Implications for Focal Boost to Intraprostatic Dominant Lesion

Background/PurposeWe retrospectively investigated spatial pattern associations between primary and recurrent tumor sites following definitive external-beam radiation therapy (EBRT) for prostate cancer, using positron emission tomography/computed tomography (PET/CT) with a prostate-specific membrane antigen (PSMA)-targeted probe, 18F-FSU-880. MethodsAmong the patients who received PET/CT with 18F-FSU-880 in a phase 2 trial, which evaluated the tumor detection efficacy of PSMA-PET/CT for recurrent prostate cancer, patients with local intra-prostatic recurrence detected by PSMA-PET/CT following definitive EBRT were retrospectively analyzed. The prostate and seminal vesicles were divided into 14 sections in total. Two diagnostic radiologists separately re-evaluated the intra-prostatic location of the primary tumor on magnetic-resonance imaging and that of the recurrent tumor on PSMA-PET/CT, respectively, and the rate of overlap between primary and recurrent tumors was calculated. The overlap rate was defined as “the number of sections which overlapped between the primary tumor and recurrent tumor” divided by “the total number of sections of recurrent tumor”. A recurrent tumor was considered to be at the same location with an overlap rate equal to or greater than 75%, and a partial overlap was defined as an overlap rate between 25 and 74%. ResultsTwelve patients had local recurrence detected by PSMA-PET/CT. The median time to the diagnosis of local recurrence was 9.1 (range: 2.2–12.3) years after definitive EBRT.The recurrent tumor was detected at the same location in 25.0%, and a partial overlap was noted in 41.7%. ConclusionsLocal intra-prostatic recurrence after definitive EBRT often occurs at the same site or at a partially overlapping site adjacent to the primary IPDL. Our results support the merit of focal dose-escalation for intra-prostatic dominant lesions in definitive EBRT.

Effect of Bacille Calmette-Guérin for Non-Muscle-Invasive Bladder Cancer After Prostate Radiotherapy.

Little is known about the impact of prior prostate radiation therapy (RT) on the Bacille Calmette-Guerin (BCG) immunotherapy response in patients with non-muscle invasive bladder cancer (NMIBC). We hypothesized that the damaging radiation effects on the bladder could negatively influence BCG efficacy. Men with a history of high-risk NMIBC were identified within the Surveillance, Epidemiology, and End Results-Medicare database. All patients completed adequate BCG defined as at least 5 plus 2 treatments completed within 12 months. Patients were stratified into 2 groups: with prior RT for prostate cancer and without prior RT before the diagnosis of NMIBC. The primary endpoint was a 5-year composite for progression defined as disease progression requiring systemic chemotherapy, checkpoint inhibitors, radical or partial cystectomy, or cancer-specific death. We identified 3,466 patients with NMIBC, including 145 with prior RT for prostate cancer. Five-year progression occurred in 471 patients (13.6%). Patients with prior RT were older than patients without prior RT (77.0 vs 75.0 years; P < .001). The distribution of T stage was significantly different at diagnosis between the RT and non-RT groups (RT: Ta, 44.8%; Tis, 18.6%; T1, 36.6%; without RT: Ta, 40.9%; Tis, 10.8%; T1, 48.3%; P = .002). No difference in the risk of total progression was observed between patients with and without prior RT (P = .67). Similarly, no difference was observed after multivariable adjustment (hazard ratio, 0.99; 95% CI, 0.61-1.58; P = .95). For patients with NMIBC who undergo adequate BCG treatment, prior RT for prostate cancer was not associated with worse 5-year progression-free survival.

Five-year clinical outcomes of scanning carbon-ion radiotherapy for prostate cancer.

Carbon-ion radiotherapy (CIRT) has been associated with favorable clinical outcomes in patients with prostate cancer. At our facility, all patients are treated using scanning CIRT (sCIRT). We retrospectively analyzed five-year clinical outcomes of prostate cancer treated with sCIRT to investigate treatment efficacy and toxicity. In this study, we included 253 consecutive prostate cancer patients treated with sCIRT at the Kanagawa Cancer Center from December 2015 to December 2017. The total dose of sCIRT was set at 51.6 Gy (relative biological effect) in 12 fractions over three weeks. We employed the Phoenix definition for biochemical relapse. The overall survival (OS), biochemical relapse-free (bRF) rate, and cumulative incidence of late toxicity were estimated using the Kaplan-Meier method. Toxicity was assessed using the Common Terminology Criteria for Adverse Events version 4.0. The median age of the patients was 70 years (range: 47-86 years). The median follow-up duration was 61.1 months (range: 4.1-80.3 months). Eight (3.2%), 88 (34.8%), and 157 (62.1%) patients were in the low-risk, intermediate-risk, and high-risk groups, respectively, according to the D'Amico classification system. The five-year OS and bRF were 97.5% and 93.3%, respectively. The five-year bRF rates for the low-risk, intermediate-risk, and high-risk groups were 87.5%, 93.7%, and 93.4%, respectively (p = 0.7215). The five-year cumulative incidence of Grade 2 or more late genitourinary and gastrointestinal toxicity was 7.4% and 1.2%, respectively. The results of this study show that sCIRT has a favorable therapeutic effect and low toxicity in the treatment of prostate cancer.

Pretreatment prostate-specific antigen density as a predictor of biochemical recurrence in patients with prostate cancer: a meta-analysis

BackgroundA consensus has not been reached on the value of prostate-specific antigen density (PSAD) as a predictor of biochemical recurrence of prostate cancer. This meta-analysis aimed to evaluate the association between PSAD and biochemical recurrence of prostate cancer after primary treatment.MethodsTwo authors systematically searched PubMed, Web of Science, and Embase databases (up to August September 10, 2023) to identify studies that assessed the value of pretreatment PSAD in predicting biochemical recurrence after primary treatment (radical prostatectomy or radiotherapy) of prostate cancer. A random effect model was used to pool adjusted hazard ratios (HR) with 95% confidence intervals (CI) for biochemical recurrence.ResultsNine studies with 4963 patients were eligible for the meta-analysis. The reported prevalence of biochemical recurrence ranged from 4 to 55.1%. For patients with higher PSAD compared to those with low PSAD, the pooled HR of biochemical recurrence was 1.59 (95% CI 1.21–2.10). Subgroup analysis showed that the pooled HR of biochemical recurrence was 1.80 (95% CI 1.34–2.42) for patients who received radical prostatectomy, and 0.98 (95% CI 0.66–1.45) for patients who received radiotherapy.ConclusionsElevated pretreatment PSAD may be an independent predictor for biochemical recurrence of prostate cancer after radical prostatectomy. Determining PSAD could potentially improve the prediction of biochemical recurrence in patients with prostate cancer.

(161) Is there a Difference in Inflatable Penile Prosthesis Mechanical Failure and Infections Rates in Relation to Prostate Cancer Treatment Modality (Radiation Therapy vs Radical Prostatectomy)

Abstract Introduction Inflatable Penile Prosthesis (IPP) implantation as a treatment for ED has high satisfaction rates in the general population; however, there is limited literature on quantification of complication rates as stratified by ED etiology. Objective Our aim was to compare mechanical failure and infection rates in patients undergoing IPP implantation for ED following Radical Prostatectomy (RP) versus radiation therapy (RT) for prostate cancer. Methods A retrospective chart review from our institutional database was conducted to identify 405 patients who underwent IPP placement at our institution from 2015–2019, then selecting for those whose etiology of ED was following RP or RT. To prevent crossover confounding; patients with history of pelvic radiation or salvage radiotherapy were excluded from the RP group and patients with history of RP were excluded from the RT group. Data was obtained from 75 patients who met criteria for inclusion: 44 patients in the RP group and 31 patients in the RT group. Mechanical failure, infection rates, mean EDITS scores and additional survey questions were compared between the radiation and RP groups. Results Patient demographic information and IPP complication and satisfaction rates are listed below in Table 1 and Figure 1. There was a statistically significant difference in number of patients experiencing IPP complications, 19.4% (n=6) of patients in the RT cohort and 4.5% (n=2) in the RP cohort, respectively. There was no statistically significant difference found in stratified complications- infection rates, device erosion rates, mechanical failure rates, or device removal and/or replacement rates between the two groups. The RP cohort had a significantly higher mean Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaire score versus the RT cohort, 91.58 to 76.02, respectively. Conclusions These preliminary findings, while requiring large-scale follow up, suggest that there is a higher rate of IPP related complications in patients with device placement following RT for prostate cancer versus RP. Disclosure No.