Prostate Radiotherapy Research Articles

Comparison of Bladder Volume Measurement Accuracy between Portable Ultrasound Diagnostic Equipment and CBCT for Pelvic Prostate Radiotherapy

We evaluated the measurement accuracy of the CubeScan BioCon-900 (here after BioCon-900), a portable ultrasound imaging diagnostic device capable of measuring bladder volume, to determine if it can accurately assess bladder volume before intensity-modulated radiation therapy (IMRT) for prostate cancer. Bladder volume was measured from kV-Cone Beam computed tomography (CBCT) images obtained immediately before the administration of IMRT for prostate cancer using Halcyon. The bladder volume measured from kV-CBCT images (23 patients, total number of scans: 139) immediately before the IMRT procedure was used as the reference value. The difference between the bladder volume measured by the BioCon-900 was then calculated. The bladder volume measured from kV-CBCT images was 117.5±49.4 cc. In contrast, the bladder volume obtained with BioCon-900 was 104.1±48.6 ml, resulting in an absolute mean difference of 18.4% and a correlation coefficient of 0.881. The measurements by BioCon-900 tended to be, on average, 11% smaller than the bladder volume measured by kV-CBCT imaging. kV-CBCT images demonstrated a strong positive correlation between bladder volume and bladder urine output obtained with BioCon-900. BioCon-900 can be used before kV-CBCT imaging to accurately and conveniently assess bladder volume.

Health-related Quality of Life in Patients With Urethral Stenosis After Radiation Treatment for Prostate Cancer

ObjectiveTo evaluate patient-reported quality of life (PRQoL) in patients presenting with membranous urethral stenosis after prostate radiotherapy. Urethral stenosis is an under-reported complication after prostate radiotherapy with a particular deficiency in PRQoL. MethodsPatients presenting with urethral stenosis after radiotherapy were retrospectively reviewed from 2004-2022. PRQoL was assessed via patient survey using the Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP). Results230 patients were identified at a mean age of 67.7 years and mean time to stricture diagnosis of 63.6 months’ post-radiotherapy. Of 87 patients completing the survey, 29.9% recalled being aware of urethral stenosis as a potential complication and 51.7% had documentation of urethral stenosis as a potential complication. 33.5% of patients underwent urethroplasty, 59.6% repeat endoscopic treatment and 6.1% an indwelling catheter. 64.4% of patients reported urinary dysfunction as a “moderate” or “big” problem, 66.7% reported frequent or total incontinence, 64.4% required daily pad use and 50.6% reported incontinence as either a “moderate” or “big” problem. 85.0% reported poor or absent orgasmic dysfunction and 88.5% reported erections insufficient for sexual activity. Additionally, 47.1% of patients reported rectal pain and 31.0% reported dysuria. Depressive symptoms and fatigue were reported by 41.4% and 60.9% of patients respectively. ConclusionUrethral stenosis after radiotherapy is a clinically complex entity with a broad scope of associated symptoms including high rates of patient-reported incontinence, voiding dysfunction, sexual dysfunction, pain, bowel dysfunction and depression. This multi-focal nature combined with often insidious presentation and patient unawareness creates a uniquely challenging condition to treat.

Determination of internal target volume with Cine-MRI sequence for prostate MRI-Guided radiotherapy.

In prostate radiotherapy, the intrafractional target motion negatively affects treatment accuracy. Generating internal target volume (ITV) using four-dimensional (4D) images may resolve the issue of intrafractional target motion induced by bladder filling and bowel movement. However, no 4D imaging techniques suitable for the prostate are currently available in clinical practice. This study aimed to determine the ITV based on cine magnetic resonance imaging (MRI) sequence for intrafractional target motion management in prostate MRI-guided radiotherapy. A reference ITV was generated in simulation process. Then, the reference ITV was adapted with cine MRI sequence before online planning in each fraction. Finally, the reference ITV was updated with the cine MRI sequence acquired during beam delivery after each fraction. Cine MRI sequences and positioning three-dimensional (3D) MRI from 35 patients were retrospectively collected. Clinical target volume (CTV) coverage was computed according to the two-dimensional contour of CTV and ITV on cine MRI images. Relative target size was calculated as the ratio of the volume of ITV and CTV. Isotropic planning target volume (PTV; 5mm margin) and anisotropic PTV (3mm margin in the posterior direction and 5mm margin in other directions) were generated for comparison. The CTV coverage rate of the proposed ITV had a mean value of 98.61%±0.51%, whereas the CTV coverage rates of the isotropic and anisotropic PTVs were 97.43%±0.41% and 96.58%±0.73%, respectively. The proposed ITV had a relative target size of 1.79±0.17, whereas the anisotropic and isotropic PTVs had relative target sizes of 1.92±0.12 and 2.21±0.19, respectively. For both the CTV coverage rate and target relative size, significant differences were observed between the proposed ITV and the other two PTVs (p<0.05). The ITV achieved higher CTV coverage with smaller size than conventional isotropic and anisotropic PTVs, indicating that it can effectively deal with the intrafractional movement of the prostate.

The Beatson Experience of Hydrogel Vue Rectal Spacers in Patients at High Risk of Rectal Toxicity from Prostate Radiotherapy

The Beatson Experience of Hydrogel Vue Rectal Spacers in Patients at High Risk of Rectal Toxicity from Prostate Radiotherapy

Optimal planning target margin for prostate radiotherapy based on interfractional and intrafractional variability assessment during 1.5T MRI-guided radiotherapy.

We analyzed daily pre-treatment- (PRE) and real-time motion monitoring- (MM) MRI scans of patients receiving definitive prostate radiotherapy (RT) with 1.5 T MRI guidance to assess interfractional and intrafractional variability of the prostate and suggest optimal planning target volume (PTV) margin. Rigid registration between PRE-MRI and planning CT images based on the pelvic bone and prostate anatomy were performed. Interfractional setup margin (SM) and interobserver variability (IO) were assessed by comparing the centroid values of prostate contours delineated on PRE-MRIs. MM-MRIs were used for internal margin (IM) assessment, and PTV margin was calculated using the van Herk formula. We delineated 400 prostate contours on PRE-MRI images. SM was 0.57 ± 0.42, 2.45 ± 1.98, and 2.28 ± 2.08 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively, after bone localization and 0.76 ± 0.57, 1.89 ± 1.60, and 2.02 ± 1.79 mm in the LR, AP, and SI directions, respectively, after prostate localization. IO was 1.06 ± 0.58, 2.32 ± 1.08, and 3.30 ± 1.85 mm in the LR, AP, and SI directions, respectively, after bone localization and 1.11 ± 0.55, 2.13 ± 1.07, and 3.53 ± 1.65 mm in the LR, AP, and SI directions, respectively, after prostate localization. Average IM was 2.12 ± 0.86, 2.24 ± 1.07, and 2.84 ± 0.88 mm in the LR, AP, and SI directions, respectively. Calculated PTV margin was 2.21, 5.16, and 5.40 mm in the LR, AP, and SI directions, respectively. Movements in the SI direction were the largest source of variability in definitive prostate RT, and interobserver variability was a non-negligible source of margin. The optimal PTV margin should also consider the internal margin.

Do all prostate cancer patients want, and experience shared decision making prior to curative treatment?

In comparable men with non-metastatic prostate cancer, radical prostatectomy (RP), radiotherapy (RAD) and active surveillance (AS) are treatment options with similar survival rates, but different side-effects. Healthcare professionals consider pretreatment shared decision making (SDM) to be an essential part of medical care, though the patients' view about SDM is less known. In this article, we explore prostate cancer (PCa) patients' SDM wish (SDMwish), and experiences (SDMexp). Material and methods: This is a registry-based survey performed by the Cancer Registry of Norway (2017-2019). One year after diagnosis, 5,063 curatively treated PCa patients responded to questions about their pre-treatment wish and experience regarding SDM. Multivariable analyses identified factors associated with SDM. Statistical significance level: p < 0.05. Results: Overall, 78% of the patients wished to be involved in SDM and 83% of these had experienced SDM. SDMwish and SDMexp was significantly associated with decreasing age, increasing education, and living with a partner. Compared with the RP group, the probability of SDMwish and SDMexp was reduced by about 40% in the RAD and the AS groups. Conclusion: Three of four curatively treated PCa wanted to participate in SDM, and this wish was met in four of five men. Younger PCa patients with higher education in a relationship, and opting for RP, wanted an active role in SDM, and experienced being involved. Effective SDM requires the responsible physicians' attention to the individual patients' characteristics and needs.

A digital male pelvis phantom series showing anatomical variations over the course of fractionated radiotherapy treatment.

Daily IGRT images show day-to-day anatomical variations in patients undergoing fractionated prostate radiotherapy. This is of particular importance in particle beam treatments. To develop a digital phantom series showing variation in pelvic anatomy for evaluating treatment planning and IGRT procedures in particle radiotherapy. A pelvic phantom series was developed from the planning MRI and kVCT (planning CT) images along with six of the daily serial MVCT images taken of a single patient treated with a full bladder on a Tomotherapy unit. The selected patient had clearly visible yet unexceptional internal anatomy variation. Prostate, urethra, bladder, rectum, bowel, bowel gas, bone and soft tissue were contoured and a single Hounsfield Unit was assigned to each region. Treatment plans developed on the kVCT for photon, proton and carbon beams were recalculated on each phantom to demonstrate a clinical application of the series. Proton plans were developed with and without robust optimization. Limited to axial slices with prostate, the bladder volume varied from 6 to 46 cm3, the rectal volume (excluding gas) from 22 to 52 cm3, and rectal gas volume from zero to 18 cm3. The water equivalent path length to the prostate varied by up to 1.5cm . The variations resulted in larger changes in the RBE-weighted Dose Volume Histograms of the non-robust proton plan and the carbon plan compared to the robust proton plan, the latter similar to the photon plan. The prostate coverage (V100%) decreased by an average of 18% in the carbon plan, 16% in the non-robust proton plan, 1.8% in the robust proton plan, and 4.4% in the photon plan. The volume of rectum receiving 75% of the prescription dose (V75%) increased by an average of 3.7 cm3, 4.7 cm3, 1.9 cm3, and 0.6 cm3 in those four plans, respectively. The digital pelvic phantom series provides for quantitative investigation of IGRT procedures and new methods for improving accuracy in particle therapy and may be used in cross-institutional comparisons for clinical trial quality assurance.

Evaluating the Quality-of-Life Effect of Apical Spacing with Hyaluronic Acid Prior to Hypofractionated Prostate Radiation Therapy: A Secondary Analysis

PurposeRecently, a randomized trial demonstrated that a hyaluronic acid (HA) spacer placed prior to prostate hypofractionated intensity-modulated radiation therapy improved rectal dosimetry and reduced acute grade 2+ gastrointestinal toxicity. However, 26.5% of patients receiving the spacer experienced a minimal clinically important decline (MCID) in bowel quality-of-life (QOL). The purpose of this study is to evaluate whether certain characteristics of the rectal spacer, as determined on post-implant imaging, were associated with change in bowel QOL at 3-months. Materials and MethodsThis is a secondary analysis of the 136 patients who received the HA spacer on the randomized trial. Post-implant spacer characteristics (i.e. prostate-rectum spacing at superior/mid-gland/inferior/apex planes, symmetry, prostate volume, spacer volume) were systematically analyzed from structure sets using custom software code. Characteristics demonstrating significant associations with rectal V30 on multivariate linear regression were identified. Linear regression models were used to analyze the associations of such characteristics with change (baseline to 3 months) in both bowel and urinary QOL. ResultsApical spacing (mean 9.7 (standard deviation 4.0)) was significantly smaller than spacing measurements at more superior planes. 95.6% of patients had a symmetric implant. Apical spacing (p < 0.001) and prostate volume (p = 0.01) were significantly associated with rectal V30 on multivariate analysis. However, only apical spacing (0.38/mm; p = 0.01) was associated with change in bowel QOL, even with adjustment of baseline bowel score (-0.33; p <0.01). Percentages of patients with bowel MCID were 14.8% for >= 10 mm versus 36.6% for <10 mm apical spacing (p = 0.01). Apical spacing was not associated with change in urinary QOL (-0.09; p = 0.72). when adjusted for baseline urinary QOL (-0.52; p < 0.01). ConclusionGreater apical spacing was associated with improved rectal dosimetry and smaller decline in bowel QOL at 3-months. Further prospective data are needed to fully understand the ramifications of increased apical spacing.

ПРИМЕНЕНИЕ АУТОЛОГИЧНОЙ МИКРОФРАГМЕНТИРОВАННОЙ АДИПОЗНОЙ ТКАНИ В ЛЕЧЕНИИ ПОСТЛУЧЕВОГО ЯЗВЕННОГО ПРОКТИТА

Abstract. Introduction. Radiation-induced ulcerative proctitis is a serious complication of cancer radiotherapy for prostate, cervix, uterine body, anal canal, and other pelvic tumors. Given the development pattern, there are currently no pathogenetic methods for the treatment of radiation-induced ulcerative proctitis. Aim: To develop a technique for and evaluate its effectiveness in the treatment of patients with radiation-induced rectal ulcers using autologous microfragmented adipose tissue. Materials and Methods. The study included 30 patients, of which 24 (80.0%) were women and 6 (20.0%) were men. Manual lipoaspiration was used to obtain autologous adipose tissue. Then we performed its microfragmentation via transfers. Concentrated autologous adipose tissue was introduced into the edges of the radiation-induced ulcerative defect on the rectal wall under endoscopic control. При контрольной ректоскопии через 6 месяцев у 28 (93,3 %) пациентов была отмечена полная эпителизация постлучевых язвенных дефек- тов прямой кишки. Results and Discussion. The manipulation, from sampling the adipose tissue through the end of injection lasted a little more than an hour (Me = 75.0 min). No intraoperative complications were detected. In one female patient (3.3%), a local recurrence of cervical cancer was found, and therefore that patient was excluded from the study. Control rectoscopy showed the complete epithelialization of post-radiation ulcerative rectal defects in 28 (93.3%) patients after 6 months. Conclusions. The technique proposed to use autologous microfragmented adipose tissue is affordable and effective in the treatment of patients with radiation-induced ulcerative proctitis.

BIOPROP20: biologically optimised IMRT for prostate radiotherapy in 20 fractions. Hypofractionated radiotherapy with intraprostatic boosts to tumour nodules in men with intermediate- and high-risk prostate cancer: a phase II trial – five-year outcomes

BIOPROP20: biologically optimised IMRT for prostate radiotherapy in 20 fractions. Hypofractionated radiotherapy with intraprostatic boosts to tumour nodules in men with intermediate- and high-risk prostate cancer: a phase II trial – five-year outcomes

Gynecological technical notes for appropriate spacer injections

BackgroundDespite its efficacy, if adherence to dose constraints for surrounding normal tissues proves unattainable, the risk of late radiation-related adverse events after primary radiotherapy involving brachytherapy remains a noteworthy concern. Some studies suggest that similar to prostate radiotherapy, spacers may potentially reduce doses to surrounding healthy rectal or bladder tissues. However, guidance on spacer injections for gynecologic brachytherapy is scarce, and the optimal anatomical location for spacer placement remains undefined. We discuss maximizing the effects of spacers from an anatomical perspective. FindingsAs vesicovaginal and rectovaginal septa form part of the endopelvic fascia and are not uniform tissues, spacer injection resistance varies. In pelvic organ prolapse surgery, saline is injected into the anterior and posterior vaginal walls as a spacer, and the vagina, vesicovaginal septum, and bladder can be fluidly dissected. Relatively firm vesicovaginal septum tissue is used as a reconstructive organ, whereas rectovaginal septum tissue is less dense. Cervical cancer is invasive, involving surrounding fascia and ligaments. Ideally, the vesicovaginal and rectovaginal septa should be resected in radical hysterectomy. Here, spacer adaptation and the technical details of injection are described. When using ultrasound guidance for spacer injection, the target site should be adequately magnified, and the spacer ideally injected into the incision layer during radical hysterectomy. Finally, posthysterectomy, the intestinal tract may adhere to the vaginal cuffs. Therefore, artificial ascites may be useful; however, the spread depends on perioperative manipulation. ConclusionsAnatomical and surgical viewpoints are advantageous for safe, therapeutic, and replicable spacer injection administration.

Radiotherapy of prostate and head-and-neck tumour: An optimal treatment planning comparison for intensity modulated radiotherapy and volumetric modulated arctherapy techniques.

To evaluate and compare merits between intensity modulated radiotherapy and volumetric modulated arc-therapy radiotherapy techniques to determine which technique can achieve better treatment plan quality and efficient delivery. The retrospective study was conducted at the Radiation Oncology Department of SanBorotlo Hospital, Vicenza, Italy, in 2019, and comprised data from Jan 2019 to Dec 2019 related to prostate and head-and-neck patients in whom Pinnacle³ treatment planning system was used for optimisation with different prescribed doses and target geometries for intensity modulated radiotherapy and volumetric modulated arc-therapy techniques. Treatment plans were simulated using 6MV photon beam of SynergyS® Linac (Linear accelerator). The plan quality was evaluated using dose-volume indices for planning target-volume and organs-at-risk. ArcCHECK™ phantom was used for dose agreement verification between planed and delivered doses. Data of 8 patients was analysed. Intensity modulated radiotherapy and volumetric modulated arc-therapy treatment plan quality for prostate was found to be similar, but volumetric modulated arc-therapy had significant results for maximum dose (p=0.005). Intensity modulated radiotherapy and volumetric modulated arc-therapy plans for head-and-neck achieved adequate target coverage and sparing of organs at risk, and produced clinically acceptable treatment plans. The percentage of target coverage (p=0.001), dose maximum (p=0.013) and conformity index (p=0.000) were significant. A significant gain for all planning target volume dose-volume indices was noted (p<0.05). Volumetric modulated arc-therapy obtained better plan with significant values and improved sparing of organs at risk compared to intensity modulated radiotherapy for both prostate and head-and-neck treatments while maintaining doses to the organs at risk (p<0.05). Dynamic arc mode of beam delivery provided increased degrees of freedom of volumetric modulated arc-therapy beam intensity modulation, depicting superior dose distribution than intensity modulated radiotherapy.

A feasibility study of adaptive radiation therapy for postprostatectomy prostate cancer

Postoperative prostate radiotherapy requires large planning target volume (PTV) margins to account for motion and deformation of the prostate bed. Adaptive radiation therapy (ART) can incorporate image-guidance data to personalize PTVs that maintain coverage while reducing toxicity. We present feasibility and dosimetry results of a prospective study of postprostatectomy ART. Twenty-one patients were treated with single-adaptation ART. Conventional treatments were delivered for fractions 1 to 6 and adapted plans for the remaining 27 fractions. Clinical target volumes (CTVs) and small bowel delineated on fraction 1 to 4 CBCT were used to generate adapted PTVs and planning organ-at-risk (OAR) volumes for adapted plans. PTV volume and OAR dose were compared between ART and conventional using Wilcoxon signed-rank tests. Weekly CBCT were used to assess the fraction of CTV covered by PTV, CTV D99, and small bowel D1cc. Clinical metrics were compared using a Student's t-test (p < 0.05 significant). Offline adaptive planning required 1.9 ± 0.4 days (mean ± SD). ART decreased mean adapted PTV volume 61 ± 37 cc and bladder wall D50 compared with conventional treatment (p < 0.01). The CTV was fully covered for 96% (97%) of fractions with ART (conventional). Reconstructing dose on weekly CBCT, a nonsignificant reduction in CTV D99 was observed with ART (94%) compared to conventional (96%). Reduced CTV D99 with ART was significantly correlated with large anterior-posterior rectal diameter on simulation CT. ART reduced the number of fractions exceeding our institution's small bowel D1c limit from 14% to 7%. This study has demonstrated the feasibility of offline ART for post-prostatectomy cancer. ART facilitates PTV volume reduction while maintaining reasonable CTV coverage and can reduce the dose to adjacent normal tissues.

Risk and Prognostics of Second Primary Cancer After Prostate Radiation Therapy.

As overall survival in prostate cancer increases due to advances in early detection and management, there is a growing need to understand the long-term morbidity associated with treatment, including secondary tumors. The significance of developing radiation-associated secondary cancers in an elderly population remains unknown. Patients diagnosed with prostate cancer between 1975 and 2016 in one of 9 Surveillance, Epidemiology, and End Results registries were included in this study. Risk of second primary pelvic malignancies (SPPMs) were assessed with death as a competing risk using the Fine-Gray model. Time-varying Cox proportional hazard models were employed to analyze risk to overall mortality based on secondary tumor status. A total of 569,167 primary prostate cancers were included in analysis with an average follow-up of 89 months. Among all prostate cancer patients, 4956 SPPMs were identified. After controlling for differences in age, year of diagnosis, and surgery at time of prostate cancer treatment, radiation receipt was associated with a significantly higher incidence of SPPMs (1.1% vs 1.8% at 25 years). Among those who received radiation during initial prostate cancer treatment (n = 195,415), developing an SPPM is significantly associated with worse survival (adjusted hazard ratio = 1.76), especially among younger patients (under age 63, adjusted hazard ratio = 2.36). While developing a secondary malignancy carries a detrimental effect on overall survival, the absolute risk of developing such tumors is exceedingly low regardless of radiation treatment.

Quality of life comparison based on testosterone recovery after androgen deprivation therapy in patients cured from high-risk prostate cancer: Long term data from a phase III trial.

333 Background: Using data from a randomized Phase III trial and based on testosterone recovery after androgen suppression therapy (ADT), we compared quality of life (QOL) between patients (pts) considered cured of high-risk prostate cancer (HRPC). Methods: 630 pts with HRPC were randomised to pelvic and prostate radiotherapy plus either 36 or 18 months (m) of ADT (10-2000 / 01-2008). Serum testosterone (T) was measured at baseline then at each visit. Abnormal T was defined as below the normal level. We considered cured pts those with a PSA nadir &lt; 2 ng/ml, QOL was assessed by the validated EORTC30 (30 items). Patient-reported outcomes were filled out before treatments, every 6 m during ADT, 4 m after ADT and then once a year for 5 years. The 30 items were regrouped into 9 scales. All items and scales scores were linearly transformed to a 0-100 points scale. We analysed all items and scales scores with general linear model and repeated measures to evaluate changes between pts who did versus those who did not recover normal levels of T over time. Effect of T recovery was adjusted in multivariable model including age, initial normal/abnormal T and ADT duration (18 or 36 m). P-value &lt; 0.01 was considered statistically significant to account for multiple comparisons and a difference in mean scores of ≥ 10 points was considered clinically relevant. Results: We selected those pts considered cured to avoid subsequent T variations due to reintroduction of ADT for recurrence. We excluded 361 pts: not receiving exactly 18 or 36 m of ADT (63), survival &lt; 1 year (15), no T measured at baseline or during follow-up (55), biochemical failure (105) or evidence of metastatic/recurrent disease (92), no QOL questionnaire (31). 269 pts were retained for the analysis. With a median follow-up of 14 years, 140/269 (52%) pts recovered T to a normal level: 94/166 (56.6%) in 18 m and 46/103 (44.7%) in 36 m ADT, p=0.056. Among pts regaining a normal T, the median time to recovery was 3 years (IQR: 2.5 to 3.6) for 18 m vs. 5 years (IQR: 4.5 to 6.0) for 36 m, p&lt;0.001. The global adherence to QOL questionnaires was 83.9% (2649/3156) and it was higher for 36m than for 18 m [86.4% (1255/1452) vs. 81.8% (1394/1704) p&lt;0.001]. When comparing EORTC30 between pts who recovered with those who did not recover T, pts with T recovery had a better QOL: 15/30 items and 6/9 scales were statistically significant principally scale and items related to physical, role, emotional, fatigue, pain, dyspnoea, insomnia, diarrhoea, and financial difficulties. 2 items were also clinically relevant, trouble to take a long walk and feeling tense. Conclusions: In pts cured from HRPC, T recovery is associated with a betterQOL. 18 m of ADT should be the preferred duration since a significantly faster and a higher proportion of pts recover a normal T level with the shorter schedule without detriment in long term outcomes, as previously reported.

P060 - Minimizing neurovascular bundle dose while maintaining target coverage in prostate radiotherapy

P060 - Minimizing neurovascular bundle dose while maintaining target coverage in prostate radiotherapy

P032 - Stereotactic prostate radiotherapy with or without androgen deprivation therapy: A phase III, multi-institutional randomized-controlled trial. The SPA trial

P032 - Stereotactic prostate radiotherapy with or without androgen deprivation therapy: A phase III, multi-institutional randomized-controlled trial. The SPA trial

P128 - The influence of the prostate radiotherapy dose in the prediction of complete response in synchronous oligometastatic prostate cancer patients

P128 - The influence of the prostate radiotherapy dose in the prediction of complete response in synchronous oligometastatic prostate cancer patients

NTCP Modeling and Dose-Volume Correlations of Significant Hematocrit Drop 3 Months After Prostate Radiation Therapy

Our purpose was to determine and model the dose-response relations of different parts of the pelvis regarding the endpoint of hematocrit level drop after pelvic radiation therapy (RT). Two hundred and twenty-one patients treated with RT for prostate adenocarcinoma between 2014 and 2016 were included. All patients had complete blood counts collected at baseline and 3 months post-RT. The net difference of hematocrit level post-RT versus baseline was calculated, and the level of the 15th percentiles defined the thresholds of response in each case. The doses to 8 different pelvic structures were derived and fitted to the hematocrit levels using the relative seriality normal tissue complication probability model and the biologically equivalent uniform dose (). Pelvic structures that correlated with significant decreases in hematocrit were the os coxae bilaterally superior to the acetabulum (OCUB), the total os coxae bilaterally, and the bone volume of the whole pelvis. The structure showing the highest correlation was OCUB with a maximum area under the curve (AUC) of 0.74. For V20 Gy < 30% the odds ratio was 9.8 with 95% CI of 2.9 to 32.9. For mean dose (Dmean) to OCUB, an AUC of 0.73 was observed where the dose threshold was 23 Gy and the odds ratio was 2.7 and 95% CI 1.3 to 5.6. The values for the D50, γ, and s parameters of the relative seriality model were 26.9 Gy (25.9-27.9), 1.3 (1.2-2.2), and 0.12 (0.10-0.83), respectively. The AUC of was 0.73 and patients with to OCUB ≥ 27 Gy had 8.2 times higher rate of significant hematocrit drop versus <27 Gy. These findings confirm the association of radiation-induced damage to pelvic bone marrow with a drop in hematocrit. A threshold of V20 Gy < 30%, Dmean < 23 Gy, or < 27 Gy to OCUB may significantly reduce the risk for this endpoint.

Prostatic Urethral Length on MRI Potentially Predicts Late Genitourinary Toxicity After Prostate Cancer Radiation

The purpose of our study was to evaluate pretreatment prostate quantitative magnetic resonance imaging (MRI) measurements and clinical characteristics in predicting genitourinary (GU) toxicity after radiotherapy (RT) for prostate cancer. In this single-institutionretrospective cohort study, we evaluated patients with prostate adenocarcinoma who underwent MRI within 6 months before completing definitive RT and follow-up information in our GU toxicity database from June 2016 to February 2023. MRI measurements included quantitative urethra, prostate, and bladder measurements. GU toxicity was physician-scored using theCommon Terminology Criteria for Adverse Events (CTCAE v4.0) with acute toxicity defined as ≤180 days and late defined as >180 days. Multivariable logistic regression model was constructed for grade≥2 acute toxicity and Cox proportional hazards regression for late toxicity, adjusted for clinical factors and RT method. A total of 361 men (median age 68 years, interquartile range [IQR] 62-73) were included; 14.4% (50/347) men experienced grade≥2 acute toxicity. Brachytherapy (odds ratio [OR]:2.9, 95% confidence interval [CI]:1.5-5.8), P<0.01) was associated with increased odds of acute GU toxicity, and longer MUL (OR: 0.41[95%CI: 0.18-0.92], P=0.03) with decreased odds. Median follow-up for late toxicity was 15.0 months (IQR: 9.0-28.0) with approximately 88.7% and 72.0% patients free of toxicity at 1 and 3 years, respectively. Only longer prostatic urethral length (hazard ratio [HR]:1.6, 95%CI: 1.2-2.1, P<0.01) was associated with increased risk of late GU toxicity, notably urinary frequency/urgency symptoms (HR: 1.7 [95%CI: 1.3-2.3], P<0.01). Longer prostatic urethral length measured on prostate MRI is independently associated with higher risk of developing late grade≥2 GU toxicity after radiation therapy for prostate cancer. This pretreatment metric may be potentially valuable in risk-stratification models for quality of life following prostate RT.