To explore the role of Computed tomography (CT)-based radiomics features in prostate cancer risk stratification.
The study population consisted of 506 patients with prostate cancer collected from a ...clinically annotated database. After applying exclusion criteria, 342 patients were included in the final analysis. CT-based radiomics features were extracted from planning CT scans for prostate gland-only structure, and machine learning was used to train models for Gleason score (GS) and risk group (RG) classifications. Repeated cross-validation was used. The discriminatory performance of the developed models was assessed using receiver operating characteristic area under the curve (AUC) analysis.
Classifiers using CT-based radiomics features distinguished between GS ≤ 6 versus GS ≥ 7 with AUC = 0.90 and GS 7(3 + 4) versus GS 7(4 + 3) with AUC = 0.98. Developed classifiers also showed excellent performance in distinguishing low versus high RG (AUC = 0.96) and low versus intermediate RG (AUC = 1.00), but poorer performance was observed for GS 7 versus GS > 7 (AUC = 0.69). An overall modest performance was observed for validation on holdout data sets with the highest AUC of 0.75 for classifiers of low versus high RG and an AUC of 0.70 for GS 7 versus GS > 7.
Our results show that radiomics features from routinely acquired planning CT scans could provide insights into prostate cancer aggressiveness in a noninvasive manner. Assessing models on training data sets, the classifiers were especially accurate in discerning high-risk from low-risk patients and in classifying GS 7 versus GS > 7 and GS 7(3 + 4) versus G7(4 + 3); however, classifiers were less adept at distinguishing high RG versus intermediate RG. External validation and prospective studies are warranted to verify the presented findings. These findings could potentially guide targeted radiation therapy strategies in radical intent radiation therapy for prostate cancer.
This study assessed the use of implanted hydrogel rectal spacers for stereotactic ablative radiotherapy-volumetric modulated arc therapy (SABR-VMAT) patients, investigating practicality, dosimetric ...impact, normal tissue complication probability (NTCP) and early toxicity.
Data from the first 6 patients treated within a prostate SABR and rectal spacer trial were examined to determine spacer insertion tolerability, resultant changes in treatment planning and dosimetry and early toxicity effects. CT scans acquired prior to spacer insertion were used to generate SABR plans which were compared to post-insertion plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data were also collected.
All patients had successful spacer insertion under local anaesthetic with maximal Grade 1 toxicity. All plans were highly conformal, with no significant differences in clinical target volume dose coverage between pre- and post-spacer plans. Substantial improvements in rectal dose metrics were observed in post-spacer plans, e.g. rectal volume receiving 36 Gy reduced by ≥42% for all patients. Median NTCP for Grade 2 + rectal bleeding significantly decreased from 4.9 to 0.8% with the use of a rectal spacer (p = 0.031). To date, two episodes of acute Grade 1 proctitis have been reported following treatment.
The spacer resulted in clinically and statistically significant reduction in rectal doses for all patients. Advances in knowledge: This is one of the first studies to investigate the efficacy of a hydrogel spacer in prostate SABR treatments. Observed dose sparing of the rectum is predicted to result in meaningful clinical benefit.
Traditional CTV-PTV margin recipes are not generally applicable in the situation of stereotactic ablative radiotherapy (SABR) treatments of multiple target volumes with a single isocentre. In this ...work, we present a novel geometric method of margin derivation based on CBCT-derived anatomical data.
Twenty patients with high-risk localized prostate cancer were selected for retrospective review. Individual volumes of interest (prostate, prostate and seminal vesicles and pelvic lymph nodes) were delineated on five representative CBCTs and registered to the planning CT using two registration protocols: bone match or prostate-based soft tissue match. Margins were incrementally expanded around composite CTV structures until 95% overlap was achieved.
CTV-PTV margins of 5.2, 6.5 and 7.6 mm were required for prostate, prostate and seminal vesicles and pelvic lymph nodes respectively using a prostate matching protocol. For the prostate and seminal vesicle structures, margins calculated using our method displayed good agreement with a conventional margin recipe (within ±1.0 mm).
We have presented an alternative method of CTV-PTV margin derivation that is applicable to SABR treatments with more than one isocentric target. These results have informed an institutional trial of prostate and pelvic nodal SABR in men with high-risk localized prostate cancer.
Low-dose-rate permanent prostate brachytherapy (PPB) is an attractive treatment option for patients with localised prostate cancer with excellent outcomes. As standard CT-based post-implant dosimetry ...often correlates poorly with late treatment-related toxicity, this exploratory (proof of concept) study was conducted to investigate correlations between radiation - induced DNA damage biomarker levels, and acute and late bowel, urinary, and sexual toxicity.
Twelve patients treated with
I PPB monotherapy (145Gy) for prostate cancer were included in this prospective study. Post-implant CT based dosimetry assessed the minimum dose encompassing 90% (D
) of the whole prostate volume (global), sub-regions of the prostate (12 sectors) and the near maximum doses (D
, D
) for the rectum and bladder. Six blood samples were collected from each patient; pre-treatment, 1 h (h), 4 h, 24 h post-implant, at 4 weeks (w) and at 3 months (m). DNA double strand breaks were investigated by staining the blood samples with immunofluorescence antibodies to γH2AX and 53BP1 proteins (γH2AX/53BP1). Patient self-scored quality of life from the Expanded Prostate Cancer Index Composite (EPIC) were obtained at baseline, 1 m, 3 m, 6 m, 9 m, 1 year (y), 2y and 3y post-treatment. Spearman's correlation coefficients were used to evaluate correlations between temporal changes in γH2AX/53BP1, dose and toxicity.
The minimum follow up was 2 years. Population mean prostate D
was 144.6 ± 12.1 Gy and rectal near maximum dose D
= 153.0 ± 30.8 Gy and D
= 62.7 ± 12.1 Gy and for the bladder D
= 123.1 ± 27.0 Gy and D
= 70.9 ± 11.9 Gy. Changes in EPIC scores from baseline showed high positive correlation between acute toxicity and late toxicity for both urinary and bowel symptoms. Increased production of γH2AX/53BP1 at 24 h relative to baseline positively correlated with late bowel symptoms. Overall, no correlations were observed between dose metrics (prostate global or sector doses) and γH2AX/53BP1 foci counts.
Our results show that a prompt increase in γH2AX/53BP1foci at 24 h post-implant relative to baseline may be a useful measure to assess elevated risk of late RT - related toxicities for PPB patients. A subsequent investigation recruiting a larger cohort of patients is warranted to verify our findings.
The purpose of this study is to find the optimal planning settings for prostate SABR-VMAT for high-risk prostate cancer patients irradiated to prostate only (PO) or prostate and pelvic lymph nodes ...(PPLN).
For 10 patients, plans using 6MV flattened, flattening-filter-free (FFF) 6MV (6 F) and FFF 10MV (10 F) photon beams with full and partial arc arrangements were generated and compared. The prescribed dose was 40Gy to the prostate with 25Gy to the PLN in 5 fractions. Plans were then evaluated for PTV coverage, dose fall-off, and OAR doses. The number of monitor units and the treatment delivery times were also compared. Statistical differences were evaluated using a paired sample Wilcoxon signed rank test with a significance level of 0.05%.
A total of 150 plans were generated for this study. Acceptable PO plans were obtained using single arcs, while two arcs were necessary for PPLN. All plans were highly conformal (CI ≥1.3 and CN ≥0.90) with no significant differences in the PTV dose coverage. 6MV plans required significantly longer treatment time and had higher dose spillage compared to FFF plans. Superior plans were obtained using 10 F 300° partial arcs for PO with the lowest rectal dose, dose spillage and the shortest treatment times. For PPLN, 6 F and 10 F plans were equivalent.
SABR-VMAT with FFF photon beams offers a clear benefit with respect to shorter treatment delivery times and reduced dose spillage. Class solutions using a single 10 F 300° arc for PO and two 10 F or 6 F partial 300° arcs for PPLN are proposed.
Abstract
Background. To assess the temporal patterns of late gastrointestinal (GI) and genitourinary (GU) radiotherapy toxicity and resolution rates in a randomised controlled trial (All-Ireland ...Cooperative Oncology Research Group 97-01) assessing duration of neo-adjuvant (NA) hormone therapy for localised prostate cancer.
Material and methods. Node negative patients with > 1 of: PSA > 20 ng/mL, Gleason score ≥ 7, and stage T3 or more, were included. Follow-up, including toxicity assessment, was three-monthly in the early stages and yearly thereafter.
Results. Median follow-up from the end of RT was 6.8 years. In the interval between 90 days following the end of RT and the last toxicity assessment, GI and GU toxicity (any grade) was found in 50% and 51% of 240 and 241 patients, respectively. For those who did develop toxicity, the median time from end of RT until the first development of any grade GI or GU toxicity was 1.2 years and 1.6 years, respectively, whilst median time to final resolution was 1.6 years and 2.2 years, respectively. Grade 2 (G2) or greater GI and GU toxicity occurred in 29 (12.1%) and 40 (16.6%) patients, respectively. The proportion with unresolved G2 + GI and GU toxicity was 89% and 79%, respectively, in year 1, 69% and 65% in year 2, 59% and 52% in year 3 and 27% and 32% in year 5.
Conclusion. Long-term toxicities continue to occur many years after NA hormone therapy and RT. The rate of occurrence does not appear to reduce within the time frame during which our patients were followed. The percentage of patients suffering from G2 + toxicity at any time is however low. Resolution of these toxicities continues for the duration of the follow-up.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract only
234
Background: A full bladder for prostate radiotherapy treatment limits overall dose to the bladder and displaces bowel from high dose regions. There is currently no clear consensus ...on optimum bladder volume for prostate radiotherapy. Inconsistent bladder volumes can cause dosimetric uncertainty, distress, treatment delay and negative toxicity outcomes for patients. To identify potential ways to improve bladder filling consistency we retrospectively analysed bladder volume variation over the course of patients’ treatment and its relationship to various patient and treatment factors. Methods: We included all patients treated with 60gy in 20 fractions to the prostate only over a 1-year period. Standard fractionation, palliative, post-operative, and whole pelvis treatment regimens were excluded from our study. Patient, tumour, and treatment characteristics were collected retrospectively. We recorded patient reported IPSS scores that were completed pre and post treatment. Daily bladder volumes were recorded from cone beam CT (CBCT) retrospectively for a subset of 34 patients and included in correlative analyses with various treatment and patient factors. Results: 69 men were included in this study with a mean planning CT bladder volume of 272ml (79-574). Patients were divided into large ( > 180ml) and small subgroups (N = 46 vs 23). Smaller bladders resulted in a greater post treatment IPSS score (10.2 vs 7.7 (p = 0.2)) and greater change in IPSS (+3.3 vs +1.4 (p = 0.23). The variation of daily bladder volumes as measured by the standard deviation was positively associated with planning CT volume (p < 0.05), variation in daily treatment time (p < 0.05) and urinary symptoms (p = 0.29). Greater discordances between planning CT time and mean radiotherapy time resulted in a greater average difference between CBCT bladder volume and planning CT volume (p = 0.16). There were no appreciable seasonal or diurnal associations for all recorded bladder volumes. Conclusions: Smaller bladder volumes at planning CT are associated with increased urinary symptoms whereas larger volumes undergo more daily variation. This data suggests an optimal planning bladder volume of 200-400ml to minimise on treatment variation. This is the first study to demonstrate a relationship between variation in daily treatment times and daily bladder variation. Synchronisation of planning CT time with patient treatment time preference will enable patients to better replicate planning CT bladder volumes. This, along with several other areas for improvement highlighted by this study have formed the basis for a prospective single centre pilot study.
•Low ORN incidence 4.4% (47/1,050)•Increased risk ORN with mandibular surgery.•Complete ORN resolution in 17% of patients.•Opportunities for risk reduction identified.•Intensive lifelong dental care ...essential.
To assess osteoradionecrosis (ORN) incidence in a population of Irish Head and Neck cancer (HNC) patients, and assess precipitating factors that may contribute to ORN development to aid prevention.
Review of 1050 HNC patients attending the Dental Oncology Clinic, CUDSH between 2010 and 2021 identified 47 cases of ORN. Medical, dental and radiotherapy records of these forty-seven patients were retrospectively reviewed. Patient-, tumour-, and treatment-related variables were investigated in association with osteoradionecrosis development. Analysis conducted using SPSS, Pearson’s Chi-square test (p < 0.05), and ordinal regression model.
ORN incidence was 4.4 %. Median time from radiotherapy (RT) to ORN development was 9.5 months (range 1–98.5 months). ORN development within the mandibular surgical site was significant (p <.001), presenting at a higher Notani grade (p =.002), in mid-mandibular body region (p =.028), at radiation doses ≥ 60 Gy (p =.035), due to induced causes (p =.029), and without resolution (p =.019).
This is the first retrospective study of ORN in HNC patients in Ireland over 10-year period. ORN incidence was extremely low (4.4%). As patients reported high smoking/alcohol use and poor dental attendance pre-diagnosis, this suggests intensive dental intervention pre/post-diagnosis contributed to low ORN rates. Mandibular surgery pre-RT increased risk of developing ORN at the surgical site. Therefore, we recommend future treatment planning should contour the surgical site, designating it an organ at risk (OAR), assigning a dose constraint, where oncologically possible, with emphasis on reducing the hot-spot to this region; findings reinforce importance of life-long expert dental care to reduce ORN incidence.
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