Intrafractional motion and dosimetric analysis in prostate stereotactic body radiation therapy with auto beam hold technique.

Objective: To summarize our institutional prostate stereotactic body radiation therapy (SBRT) experience using auto beam hold (ABH) technique for intrafractional prostate motion and assess ABH tolerance of 10-millimeter (mm) diameter.Approach: Thirty-two patients (160 fractions) treated using ABH technique between 01/2018 and 03/2021 were analyzed. During treatment, kV images were acquired every 20-degree gantry rotation to visualize 3-4 gold fiducials within prostate to track target motion. If the fiducial center fell outside the tolerance circle (diameter = 10 mm), beam was automatically turned off for reimaging and repositioning. Number of beam holds and couch translational movement magnitudes were recorded. Dosimetric differences from intrafractional motion were calculated by shifting planned isocenter.Main Results: Couch movement magnitude (mean ± SD) in vertical, longitudinal and lateral directions were -0.7 ± 2.5, 1.4 ± 2.9 and -0.1 ± 0.9 mm, respectively. For most fractions (77.5%), no correction was necessary. Number of fractions requiring one, two, or three corrections were 15.6%, 5.6% and 1.3%, respectively. Of the 49 corrections, couch shifts greater than 3 mm were seen primarily in the vertical (31%) and longitudinal (39%) directions; corresponding couch shifts greater than 5 mm occurred in 2% and 6% of cases. Dosimetrically, 100% coverage decreased less than 2% for clinical target volume (CTV) (-1 ± 2%) and less than 10% for PTV (-10 ± 6%). Dose to bladder, bowel and urethra tended to increase (Bladder: ΔD10%:184 ± 466 cGy, ΔD40%:139 ± 241 cGy, Bowel: ΔD1 cm3:54 ± 129 cGy; ΔD5 cm3:44 ± 116 cGy, Urethra: ΔD0.03 cm3:1 ± 1%). Doses to the rectum tended to decrease (Rectum: ΔD1 cm3:-206 ± 564 cGy, ΔD10%:-97 ± 426 cGy; ΔD20%:-50 ± 251 cGy).Significance: With the transition from conventionally fractionated intensity modulated radiation therapy to SBRT for localized prostate cancer treatment, it is imperative to ensure that dose delivery is spatially accurate for appropriate coverage to target volumes and limiting dose to surrounding organs. Intrafractional motion monitoring can be achieved using triggered imaging to image fiducial markers and ABH to allow for reimaging and repositioning for excessive motion.

Cone beam CT doses in radiotherapy patient positioning in Finland-prostate treatments.

Imaging parameters, frequencies and resulting patient organ doses in treatments of prostate cancer were assessed in Finnish radiotherapy centres. Based on a questionnaire to the clinics, Monte Carlo method was used to estimate organ doses in International Commission on Radiological Protection standard phantom for prostate, bladder, rectum and femoral head. The results show that doses from cone beam computed tomography imaging have reduced compared to earlier studies and are between 3.6 and 34.5 mGy per image for the above-mentioned organs and for normal sized patients. There still is room for further optimization of the patient exposure, as many centres use the default imaging parameters, and the length of the imaged region may not be optimal for the purpose.

Inter-fractional error and intra-fractional motion of prostate and dosimetry comparisons of patient position registrations with versus without fiducial markers during treatment with carbon-ion radiotherapy.

A few reports have discussed the influence of inter-fractional position error and intra-fractional motion on dose distribution, particularly regarding a spread-out Bragg peak. We investigated inter-fractional and intra-fractional prostate position error by monitoring fiducial marker positions. In 2020, data from 15 patients with prostate cancer who received carbon-ion beam radiotherapy (CIRT) with gold markers were investigated. We checked marker positions before and during irradiation to calculate the inter-fractional positioning and intra-fractional movement and evaluated the CIRT dose distribution by adjusting the planning beam isocenter and clinical target volume (CTV) position. We compared the CTV dose coverages (CTV receiving 95% [V95%] or 98% [V98%] of the prescribed dose) between skeletal and fiducial matching irradiation on the treatment planning system. For inter-fractional error, the mean distance between the marker position in the planning images and that in a patient starting irradiation with skeletal matching was 1.49 ± 1.11 mm (95th percentile = 1.85 mm). The 95th percentile (maximum) values of the intra-fractional movement were 0.79 mm (2.31 mm), 1.17 mm (2.48 mm), 1.88 mm (4.01 mm), 1.23 mm (3.00 mm), and 2.09 mm (8.46 mm) along the lateral, inferior, superior, dorsal, and ventral axes, respectively. The mean V95% and V98% were 98.2% and 96.2% for the skeletal matching plan and 99.5% and 96.8% for the fiducial matching plan, respectively. Fiducial matching irradiation improved the CTV dose coverage compared with skeletal matching irradiation for CIRT for prostate cancer.

Dosimetric benefits and preclinical performance of steerable needles in HDR prostate brachytherapy.

Prostate cancer patients with an enlarged prostate and/or excessive pubic arch interference (PAI) are generally considered non-eligible for high-dose-rate (HDR) brachytherapy (BT). Steerable needles have been developed to make these patients eligible again. This study aims to validate the dosimetric impact and performance of steerable needles within the conventional clinical setting. HDR BT treatment plans were generated, needle implantations were performed in a prostate phantom, with prostate volume > 55 cm3 and excessive PAI of 10 mm, and pre- and post-implant dosimetry were compared considering the dosimetric constraints: prostate V100 > 95 % (13.50 Gy), urethra D0.1cm3 < 115 % (15.53 Gy) and rectum D1cm3 < 75 % (10.13 Gy). The inclusion of steerable needles resulted in a notable enhancement of the dose distribution and prostate V100 compared to treatment plans exclusively employing rigid needles to address PAI. Furthermore, the steerable needle plan demonstrated better agreement between pre- and post-implant dosimetry (prostate V100: 96.24 % vs. 93.74 %) compared to the rigid needle plans (79.13 % vs. 72.86 % and 87.70 % vs. 81.76 %), with no major changes in the clinical workflow and no changes in the clinical set-up. The steerable needle approach allows for more flexibility in needle positioning, ensuring a highly conformal dose distribution, and hence, HDR BT is a feasible treatment option again for prostate cancer patients with an enlarged prostate and/or excessive PAI.

A pooled patient-reported outcomes analysis of moderately hypofractionated proton beam therapy and photon-based intensity modulated radiation therapy for low- or intermediate-risk prostate cancer.

BACKGROUND: We sought to characterize and compare late patient-reported outcomes (PROs) after moderately hypofractionated intensity modulated radiation therapy (IMRT) and proton beam therapy (PBT) for localized prostate cancer (PC). METHODS: This multi-institutional analysis included low- or intermediate-risk group PC patients treated with moderately hypofractionated radiation to an intact prostate stratified by treatment modality: IMRT or PBT. The primary outcomes were prospectively collected patient-reported late gastrointestinal (GI) and genitourinary (GU) toxicity assessed by International Prostate Symptom Score (IPSS) and Expanded PC Index Composite (EPIC). Multivariable regression analysis (MVA) controlling for age, race, and risk group tested the effect of time, treatment, and their interaction. RESULTS: 287 IMRT and 485 PBT patients were included. Intermediate risk group (81.2 vs. 68.2%; p < 0.001) and median age at diagnosis (70 vs. 67 years; p < 0.001) were higher in the IMRT group. On MVA, there was no significant difference between modalities. PBT IPSS did not differ from IMRT IPSS at 12 months (odds ratio [OR], 1.19; p = 0.08) or 24 months (OR, 0.99; p = 0.94). PBT EPIC overall GI function at 12 months (OR, 3.68; p = 0.085) and 24 months (OR 2.78; p = 0.26) did not differ from IMRT EPIC overall GI function. At 24 months, urinary frequency was no different between PBT and IMRT groups (OR 0.35; p = 0.096). CONCLUSIONS: This multi-institutional analysis of low- or intermediate-risk PC treated with moderately hypofractionated PBT and IMRT demonstrated low rates of late patient-reported GI and GU toxicities. After covariate adjustment, late GI and GU PROs were not significantly different between PBT or IMRT cohorts.

Microbiome and metabolome dynamics during radiotherapy for prostate cancer.

BACKGROUND: Prostate cancer patients treated with radiotherapy are susceptible to acute gastrointestinal (GI) toxicity due to substantial overlap of the intestines with the radiation volume. Due to their intimate relationship with GI toxicity, faecal microbiome and metabolome dynamics during radiotherapy were investigated. MATERIAL & METHODS: This prospective study included 50 prostate cancer patients treated with prostate (bed) only radiotherapy (PBRT) (n = 28) or whole pelvis radiotherapy (WPRT) (n = 22) (NCT04638049). Longitudinal sampling was performed prior to radiotherapy, after 10 fractions, near the end of radiotherapy and at follow-up. Patient symptoms were dichotomized into a single toxicity score. Microbiome and metabolome fingerprints were analyzed by 16S rRNA gene sequencing and ultra-high-performance liquid chromatography hybrid high-resolution mass spectrometry, respectively. RESULTS: The individual α-diversity did not significantly change over time. Microbiota composition (ß-diversity) changed significantly over treatment (PERMANOVA p-value = 0.03), but there was no significant difference in stability when comparing PBRT versus WPRT. Levels of various metabolites were significantly altered during radiotherapy. Baseline α-diversity was not associated with any toxicity outcome. Based on the metabolic fingerprint, no natural clustering according to toxicity profile could be achieved. CONCLUSIONS: Radiation dose and treatment volume demonstrated limited effects on microbiome and metabolome fingerprints. In addition, no distinctive signature for toxicity status could be established. There is an ongoing need for toxicity risk stratification tools for diagnostic and therapeutic purposes, but the current evidence implies that the translation of metabolic and microbial biomarkers into routine clinical practice remains challenging.

The Current Trend of Radiation Therapy for Patients with Localized Prostate Cancer.

A recent approach to radiotherapy for prostate cancer is the administration of high doses of radiation to the prostate while minimizing the risk of side effects. Thus, image-guided radiotherapy utilizes advanced imaging techniques and is a feasible strategy for increasing the radiation dose. New radioactive particles are another approach to achieving high doses and safe procedures. Prostate brachytherapy is currently considered as a combination therapy. Spacers are useful to protect adjacent organs, specifically the rectum, from excessive radiation exposure.

A Randomized Feasibility Trial of Stereotactic Prostate Radiation Therapy With or Without Elective Nodal Irradiation in High-Risk Localized Prostate Cancer (SPORT Trial).

PURPOSE: The aim of this study was to establish the feasibility of a randomized clinical trial comparing SABR with prostate-only (P-SABR) or with prostate plus pelvic lymph nodes (PPN-SABR) in patients with unfavorable intermediate- or high-risk localized prostate cancer and to explore potential toxicity biomarkers. METHODS AND MATERIALS: Thirty adult men with at least 1 of the following features were randomized 1:1 to P-SABR or PPN-SABR: clinical magnetic resonance imaging stage T3a N0 M0, Gleason score ≥7 (4+3), and prostate-specific antigen >20 ng/mL. P-SABR patients received 36.25 Gy/5 fractions/29 days, and PPN-SABR patients received 25 Gy/5 fractions to pelvic nodes, with the final cohort receiving a boost to the dominant intraprostatic lesion of 45 to 50 Gy. Phosphorylated gamma-H2AX (γH2AX) foci numbers, citrulline levels, and circulating lymphocyte counts were quantified. Acute toxicity information (Common Terminology Criteria for Adverse Events, version 4.03) was collected weekly at each treatment and at 6 weeks and 3 months. Physician-reported late Radiation Therapy Oncology Group (RTOG) toxicity was recorded from 90 days to 36 months postcompletion of SABR. Patient-reported quality of life (Expanded Prostate Cancer Index Composite and International Prostate Symptom Score) scores were recorded with each toxicity time point. RESULTS: The target recruitment was achieved, and treatment was successfully delivered in all patients. A total of 0% and 6.7% (P-SABR) and 6.7% and 20.0% (PPN-SABR) experienced acute grade ≥2 gastrointestinal (GI) and genitourinary (GU) toxicity, respectively. At 3 years, 6.7% and 6.7% (P-SABR) and 13.3% and 33.3% (PPN-SABR) had experienced late grade ≥2 GI and GU toxicity, respectively. One patient (PPN-SABR) had late grade 3 GU toxicity (cystitis and hematuria). No other grade ≥3 toxicity was observed. In addition, 33.3% and 60% (P-SABR) and 64.3% and 92.9% (PPN-SABR) experienced a minimally clinically important change in late Expanded Prostate Cancer Index Composite bowel and urinary summary scores, respectively. γH2AX foci numbers at 1 hour after the first fraction were significantly higher in the PPN-SABR arm compared with the P-SABR arm (P = .04). Patients with late grade ≥1 GI toxicity had significantly greater falls in circulating lymphocytes (12 weeks post-radiation therapy, P = .01) and a trend toward higher γH2AX foci numbers (P = .09) than patients with no late toxicity. Patients with late grade ≥1 bowel toxicity and late diarrhea experienced greater falls in citrulline levels (P = .05). CONCLUSIONS: A randomized trial comparing P-SABR with PPN-SABR is feasible with acceptable toxicity. Correlations of γH2AX foci, lymphocyte counts, and citrulline levels with irradiated volume and toxicity suggest potential as predictive biomarkers. This study has informed a multicenter, randomized, phase 3 clinical trial in the United Kingdom.

Linac-based stereotactic salvage reirradiation for intraprostatic prostate cancer recurrence: toxicity and outcomes.

BACKGROUND: The rates of local failure after curative radiotherapy for prostate cancer (PC) remain high despite more accurate locoregional treatments available, with one third of patients experiencing biochemical failure and clinical relapse occurring in 30-47% of cases. Today, androgen deprivation therapy (ADT) is the treatment of choice in this setting, but with not negligible toxicity and low effects on local disease. Therefore, the treatment of intraprostatic PC recurrence represents a challenge for radiation oncologists. Prostate reirradiation (Re-I) might be a therapeutic possibility. We present our series of patients treated with salvage stereotactic Re­I for intraprostatic recurrence of PC after radical radiotherapy, with the aim of evaluating feasibility and safety of linac-based prostate Re­I. MATERIALS AND METHODS: We retrospectively evaluated toxicities and outcomes of patients who underwent salvage reirradiation using volumetric modulated arc therapy (VMAT) for intraprostatic PC recurrence. Inclusion criteria were age ≥ 18 years, histologically proven diagnosis of PC, salvage Re­I for intraprostatic recurrence after primary radiotherapy for PC with curative intent, concurrent/adjuvant ADT with stereotactic body radiation therapy (SBRT) allowed, performance status ECOG 0-2, restaging choline/PSMA-PET/TC and prostate MRI after biochemical recurrence, and signed informed consent. RESULTS: From January 2019 to April 2022, 20 patients were recruited. Median follow-up was 26.7 months (range 7-50). After SBRT, no patients were lost at follow-up and all are still alive. One- and 2­year progression free survival (PFS) was 100% and 81.5%, respectively, while 2­year biochemical progression-free survival (bFFS) was 88.9%. Four patients (20%) experienced locoregional lymph node progression and were treated with a further course of SBRT. Prostate reirradiation allowed the ADT start to be postponed for 12-39 months. Re­I was well tolerated by all patients and none discontinued the treatment. No cases of ≥ G3 genitourinary (GU) or gastrointestinal (GI) toxicity were reported. Seven (35%) and 2 (10%) patients experienced acute G1 and G2 GU toxicity, respectively. Late GU toxicity was recorded in 10 (50%) patients, including 8 (40%) G1 and 2 (10%) G2. ADT-related side effects were found in 7 patients (hot flashes and asthenia). CONCLUSION: Linac-based SBRT is a safe technique for performing Re­I for intraprostatic recurrence after primary curative radiotherapy for PC. Future prospective, randomized studies are desirable to better understand the effectiveness of reirradiation and the still open questions in this field.

Evaluation of incidental testicular dose with thermoluminescence dosimetry during prostate radiotherapy.

The aim of this study was to investigate incidental testicular doses during intensity modulated radiation therapy (IMRT) in patients treated with prostate radiotherapy only (PORT) and whole pelvis radiotherapy (WPRT). A total of 34 prostate cancer patients with intermediate and high risk were included in this prospective study. Each patient in the intermediate risk group received a total of 78 Gy in 39 fractions for prostate and seminal vesicles. In patients in the high risk group, 2 Gy daily fraction dose for pelvic lymphatics was given to 50 Gy, and then 78 Gy was given to prostate and seminal vesicles volumes. Treatment plans were created for all patients using the IMRT technique with 6MV. Testicular doses were measured for WPRT and PORT by thermoluminescence dosimetry (TLD) detectors placed on testis surface. Testicular doses measured for WPRT and PORT were compared. The isocenter to testicular distance for WPRT and PORT was 16.83-cm (13.20 to 18.80-cm) and 11.15 cm (9.10 to 13.00-cm), respectively. The mean testicular dose measurements of TPS and TLD per fraction during PORT were 2.41 cGy (1.95 to 3.60 cGy) and 3.70 cGy (2.80 to 5.10 cGy), respectively (p = 0.00). In WPRT irradiation, mean testicular dose values of TPS and TLD per fraction were measured as 3.85 cGy (2.00 to 5.70 cGy) and 5.85 cGy (4.25 to 7.55 cGy), respectively (p = 0.00). The cumulative mean scattered dose for PORT irradiation of 78 Gy in 39 fractions was 144.30 cGy. The mean cumulative dose received by the testis for the high-risk prostate patient was 228.15 cGy. There was a significant difference in testicular dose between WPRT and PORT irradiation. Testicular doses decreased significantly with increasing isocenter-testis distance. Incidental testicular dose during prostate radiotherapy can be significantly detrimental to spermatogenesis. Therefore, the testicles should be contoured as an organ at risk for the estimation of absorbed doses. The use of in vivo dosimetry is recommended for accurate measurement of testicular dose in radiotherapy of prostate cancer for men desiring continued fertility.

Creation of a protective space between the rectum and prostate prior to prostate radiotherapy using a hydrogel spacer.

The placement of a polyethylene glycol (PEG) hydrogel spacer is a recently developed technique employed to reduce the radiation dose administered to the rectum during prostate radiotherapy. This procedure has been adopted by urologists and radiation oncologists involved in transperineal prostate biopsy and brachytherapy, and more recently by radiologists with experience in transperineal prostate procedures. Radiologists should be familiar with the product, which may be encountered on computed tomography (CT) or magnetic resonance imaging (MRI). Radiologists may wish to become involved in the delivery of this increasingly utilised procedure. This review familiarises radiologists with the technique and risks and benefits of the use of transperineal delivery of hydrogel spacers with imaging examples.

Survival rates with external beam radiation therapy in newly diagnosed elderly metastatic prostate cancer patients.

BACKGROUND: The survival benefit of primary external beam radiation therapy (EBRT) has never been formally tested in elderly men who were newly diagnosed with metastatic prostate cancer (mPCa). We hypothesized that elderly patients may not benefit of EBRT to the extent as younger newly diagnosed mPCa patients, due to shorter life expectancy. METHODS: We relied on Surveillance, Epidemiology and End Results (2004-2016) to identify elderly newly diagnosed mPCa patients, aged >75 years. Kaplan-Meier, univariable and multivariable Cox regression models, as well as Competing Risks Regression models tested the effect of EBRT versus no EBRT on overall mortality (OM) and cancer-specific mortality (CSM). RESULTS: Of 6556 patients, 1105 received EBRT (16.9%). M1b stage was predominant in both EBRT (n = 823; 74.5%) and no EBRT (n = 3908; 71.7%, p = 0.06) groups, followed by M1c (n = 211; 19.1% vs. n = 1042; 19.1%, p = 1) and M1a (n = 29; 2.6% vs. n = 268; 4.9%, p < 0.01). Median overall survival (OS) was 23 months for EBRT and 23 months for no EBRT (hazard ratio [HR]: 0.97, p = 0.6). Similarly, median cancer-specific survival (CSS) was 29 months for EBRT versus 30 months for no EBRT (HR: 1.04, p = 0.4). After additional multivariable adjustment, EBRT was not associated with lower OM or lower CSM in the entire cohort, as well as after stratification for M1b and M1c substages. CONCLUSIONS: In elderly men who were newly diagnosed with mPCa, EBRT does not affect OS or CSS. In consequence, our findings question the added value of local EBRT in elderly newly diagnosed mPCa patients.

Survival after Radical Prostatectomy versus Radiation Therapy in High-Risk and Very High-Risk Prostate Cancer.

PURPOSE: Our goal was to compare cancer-specific mortality (CSM) rates between radical prostatectomy (RP) vs external beam radiotherapy (EBRT) in National Comprehensive Cancer Network© (NCCN©) high risk (HR) patients, as well as in Johns Hopkins University (JH) HR and very high risk (VHR) subgroups. MATERIALS AND METHODS: Within the Surveillance, Epidemiology, and End Results database (2010-2016), we identified 24,407 NCCN HR patients, of whom 10,300 (42%) vs 14,107 (58%) patients qualified for JH HR vs VHR, respectively. Overall, 9,823 (40%) underwent RP vs 14,584 (60%) EBRT. Cumulative incidence plots and competing-risks regression addressed CSM after 1:1 propensity score matching (according to age, prostate specific antigen, clinical T and N stages, and biopsy Gleason score) between RP and EBRT patients. All analyses addressed the combined NCCN HR cohort, as well as in JH HR and JH VHR subgroups. RESULTS: In the combined NCCN HR cohort 5-year CSM rates were 2.3% for RP vs 4.1% for EBRT and yielded a multivariate hazard ratio of 0.68 (95% CI 0.54-0.86, p <0.001) favoring RP. In VHR patients 5-year CSM rates were 3.5% for RP vs 6.0% for EBRT, yielding a multivariate hazard ratio of 0.58 (95% CI 0.44-0.77, p <0.001) favoring RP. Conversely, in HR patients no significant difference was recorded between RP vs EBRT (HR 0.7, 95% CI 0.39-1.25, p=0.2). CONCLUSIONS: Our data suggest that RP holds a CSM advantage over EBRT in the combined NCCN HR cohort, and in its subgroup of JH VHR patients.

Efficacy and efficiency of Green-Light XPS 180-watt laser system for benign prostatic enlargement in patients treated with 5α-reductase inhibitors.

OBJECTIVE: Aim of the study was to evaluate efficacy and efficiency of 180-watt Green-Light XPS (GL-XPS) laser photoselective vaporization of the prostate (PVP) in patients under 5-Alpha-Reductase Inhibitors (5ARI) treatment. PATIENTS AND METHODS: A consecutive series of patients with lower urinary tract symptoms due to benign prostatic enlargement treated by PVP with the GL-XPS were enrolled. Patients were divided in two groups according to the chronic use (>6 months) of 5ARI. These two groups were compared on lasing density (kilojoules per prostate volume), vaporization efficiency (prostate volume per lasing time), vaporization power (kilojoules per lasing time), Prostate Specific Antigen (PSA) reduction from baseline, symptom score change from baseline and uroflowmetry parameters improvement. Follow-up was performed at 3, 6 and 12 months with International Prostate Symptom Score, Uroflowmetry parameters and PSA. RESULTS: Overall 193 patients were enrolled. Out of them 87/193 (45%) were on 5ARI treatment. No significant differences were recorded between the two groups at baseline. Median age was 68 years old and median prostate volume was 60 ml. In terms of laser efficiency, no statistically significant differences were recorded in terms of lasing time (25 min vs. 24.5 min; p>0.05); energy used (250 kJ vs. 221 kJ; p>0.05), lasing density (6.8 kJ/ml vs. 6.6 kJ/ml, p>0.05), vaporization efficiency (1.4 ml/min vs. 1.3 ml/min, p>0.05) and vaporization power (9.6 kJ/min vs. 9.4 kJ/min; p>0.05). Finally, no significant differences were also recorded postoperatively in the two groups in terms of PSA reduction, improvement in symptom score and uroflowmetry parameters (p>0.05). CONCLUSIONS: Thirty-seven efficacy and efficiency outcomes were not statistically different between the two groups. 5ARI does not reduce the performance and ability of the 180-watt Green-Light XPS laser system.

Stereotactic body radiation therapy for the treatment of localized prostate cancer in men with underlying inflammatory bowel disease.

BACKGROUND: Historically, IBD has been thought to increase the underlying risk of radiation related toxicity in the treatment of prostate cancer. In the modern era, contemporary radiation planning and delivery may mitigate radiation-related toxicity in this theoretically high-risk cohort. This is the first manuscript to report clinical outcomes for men diagnosed with prostate cancer and underlying IBD curatively treated with stereotactic body radiation therapy (SBRT). METHODS: A large institutional database of patients (n = 4245) treated with SBRT for adenocarcinoma of the prostate was interrogated to identify patients who were diagnosed with underlying IBD prior to treatment. All patients were treated with SBRT over five treatment fractions using a robotic radiosurgical platform and fiducial tracking. Baseline IBD characteristics including IBD subtype, pre-SBRT IBD medications, and EPIC bowel questionnaires were reviewed for the IBD cohort. Acute and late toxicity was evaluated using the CTCAE version 5.0. RESULTS: A total of 31 patients were identified who had underlying IBD prior to SBRT for the curative treatment of prostate cancer. The majority (n = 18) were diagnosed with ulcerative colitis and were being treated with local steroid suppositories for IBD. No biochemical relapses were observed in the IBD cohort with early follow up. High-grade acute and late toxicities were rare (n = 1, grade 3 proctitis) with a median time to any GI toxicity of 22 months. Hemorrhoidal flare was the most common low-grade toxicity observed (n = 3). CONCLUSION: To date, this is one of the largest groups of patients with IBD treated safely and effectively with radiation for prostate cancer and the only review of patients treated with SBRT. Caution is warranted when delivering therapeutic radiation to patients with IBD, however modern radiation techniques appear to have mitigated the risk of GI side effects.

Emerging role for local therapy in oligometastatic prostate cancer.

Oligometastatic prostate cancer is a subtype of metastatic disease that generally is defined by the presence of 5 or fewer metastatic lesions. Metastatic prostate cancer currently is treated with androgen deprivation therapy and additional systemic therapy, such as novel antiandrogen medications or chemotherapy. The management of metastatic prostate cancer is evolving, however, with the notion that some patients with low-burden metastatic disease may benefit from both local and systemic therapy. Local therapy of the prostate in the setting of oligometastatic prostate cancer is a new concept. Evidence from retrospective studies suggests that cytoreductive therapy, including radical prostatectomy, can improve overall survival in these patients. Ongoing randomized trials are comparing cytoreductive therapy with standard-of-care treatment options. Local therapy in the form of radiation has also been investigated in phase 2 randomized trials. In this review, we discuss the biological and clinical rationales for local therapy, review the current evidence for local therapy, and compare the clinical designs of various ongoing trials.

Towards real-time PGS range monitoring in proton therapy of prostate cancer.

Proton therapy of prostate cancer (PCPT) was linked with increased levels of gastrointestinal toxicity in its early use compared to intensity-modulated radiation therapy (IMRT). The higher radiation dose to the rectum by proton beams is mainly due to anatomical variations. Here, we demonstrate an approach to monitor rectal radiation exposure in PCPT based on prompt gamma spectroscopy (PGS). Endorectal balloons (ERBs) are used to stabilize prostate movement during radiotherapy. These ERBs are usually filled with water. However, other water solutions containing elements with higher atomic numbers, such as silicon, may enable the use of PGS to monitor the radiation exposure of the rectum. Protons hitting silicon atoms emit prompt gamma rays with a specific energy of 1.78 MeV, which can be used to monitor whether the ERB is being hit. In a binary approach, we search the silicon energy peaks for every irradiated prostate region. We demonstrate this technique for both single-spot irradiation and real treatment plans. Real-time feedback based on the ERB being hit column-wise is feasible and would allow clinicians to decide whether to adapt or continue treatment. This technique may be extended to other cancer types and organs at risk, such as the oesophagus.

Effectiveness of rectal displacement devices during prostate external-beam radiation therapy: A review.

Dose-escalated prostate radiotherapy (RT) can improve treatment outcomes, but rectal toxicity is the main limiting factor for introducing dose-escalated RT. Pushing rectal wall away from the prostate reduces the volume of the rectum in high-dose region, which can decrease both short- and long-term rectal toxicities after RT. This review focuses on the literature using different rectal displacement devices such as endorectal balloons, tissue spacers, rectal retractor, and ProSpare during prostate External beam radiotherapy, with regard to dosimetric effects, clinical benefits, prostate motion, and postoperative RT setting.

Calculation of radium-223 and actinium-225 α-emitter radiopharmaceuticals dose rates in treatment of metastatic castration-resistant prostate cancer.

AIM OF STUDY: There is limited information regarding the α-emitter radiopharmaceuticals dose calculation used in the setting of men with prostate cancer (PCa). The present study investigates the α-emitter radiopharmaceuticals absorbed dose distribution in the body organs. MATERIALS AND METHODS: The α-emitter radiopharmaceuticals dose coefficient and absorbed doses biokinetics distribution, which are used for the treatment of PCa in all over the world, were performed using the "Internal Dose Assessed by Computer" (IDAC-Dose 2.1) program. The results of absorbed dose distribution in any organ of the body, were compared in studied α-emitter radiopharmaceuticals. RESULTS: The absorbed dose value of 223Ra radiopharmaceutical in the prostate organ was evaluated 9.47E-9 Gy/Bq. The maximum and minimum absorbed doses due to biokinetics distribution of 223Ra were found in the thymus (9.53E-8 Gy/Bq) and eye lenses (1.30E-10 Gy/Bq) organs, respectively. Furthermore, the 225Ac absorbed dose in the prostate organ was obtained 1.91E-9 Gy/Bq, where this value is 1% of total body dose. While the absorbed dose distribution of 225Ac in body organs shows the highest concentration in the spleen (1.47E-8 Gy/Bq) and lowest in the eye lenses (7.93E-12 Gy/Bq). CONCLUSION: The absorbed dose in the body organs due to 223Ra and 225Ac α-emitter radiopharmaceuticals which are used in metastasized castration-resistant prostate cancer (mCRPC), calculated in this study. The results of this study will assist in evaluating and analyzing human body organ doses from application of 223Ra and 225Ac that used in mCRPC patients.

Helical tomotherapy for prostate cancer radiation therapy: An audit of early toxicity and quality of life.

BACKGROUND: Radiation plays a major role in the management of localized prostate cancer (CaP). There are limited studies reporting the quality of life (QOL) and toxicity with CaP tomotherapy. MATERIALS AND METHODS: This is a single-institutional prospective observational study evaluating the acute toxicity and QOL of patients with CaP receiving tomotherapy from May 2018 to October 2019. Toxicity assessed using radiation therapy oncology group toxicity grading. QOL assessed using International Prostate Symptom Score (IPSS) and QOL score. RESULTS: A total number of 74 patients received radiation therapy (RT), of which 25 had postoperative RT and 49 had radical RT. The median age was 71 years. During RT, 8 (10.8%) had Grade 2 gastrointestinal (GI) and 4 (5.4%) had Grade 2 genito urinary (GU) toxicities. At 3 months, 1 (1.4%) had Grade 2 GI, 1 (1.4%) had Grade 2 GU, and 1 (1.4%) had Grade 3 GU toxicities. At 6 months, 1 patient had Grade 2 GU and no Grade 2 GI toxicity noted. In postoperative RT Group, 2 (8%) Grade 2 GI and 1 (1.4%) Grade 2 genitourinary toxicity reported during radiation. At 3 months, 1 (1.4%) Grade 2 GI, 1 (1.4%) G2 GU, and 1 (1.4%) G3 GU toxicities noted. At 6 months, no ≥ Grade 2 noted. In radical RT group, during radiation 6 (12.2%) Grade 2 GI and 3 (6.1%) Grade 2 GU recorded. At 3 and 6 months, no ≥ Grade 2 GI/GU toxicity was recorded. No Grade 3/Grade 4 observed in radical RT group. One patient in radical RT and one in postoperative RT had severe IPSS symptom score. Results are comparable to reported studies. CONCLUSION: Our initial clinical experience with helical tomotherapy in CaP confirms lower rate of toxicities and no significant worsening of QOL with RT.