Regression Analysis of Rectal Cancer and Possible Application of Artificial Intelligence (AI) Utilization in Radiotherapy

Artificial Intelligence (AI) has been widely employed in the medical field in recent years in such areas as image segmentation, medical image registration, and computer-aided detection. This study explores one application of using AI in adaptive radiation therapy treatment planning by predicting the tumor volume reduction rate (TVRR). Cone beam computed tomography (CBCT) scans of twenty rectal cancer patients were collected to observe the change in tumor volume over the course of a standard five-week radiotherapy treatment. In addition to treatment volume, patient data including patient age, gender, weight, number of treatment fractions, and dose per fraction were also collected. Application of a stepwise regression model showed that age, dose per fraction and weight were the best predictors for tumor volume reduction rate.

Mapping the road to elimination: a 5-year evaluation of implementation strategies associated with hepatitis C treatment in the veterans health administration

Background While few countries and healthcare systems are on track to meet the World Health Organization’s hepatitis C virus (HCV) elimination goals, the US Veterans Health Administration (VHA) has been a leader in these efforts. We aimed to determine which implementation strategies were associated with successful national viral elimination implementation within the VHA. Methods We conducted a five-year, longitudinal cohort study of the VHA Hepatic Innovation Team (HIT) Collaborative between October 2015 and September 2019. Participants from 130 VHA medical centers treating HCV were sent annual electronic surveys about their use of 73 implementation strategies, organized into nine clusters as described by the Expert Recommendations for Implementing Change taxonomy. Descriptive and nonparametric analyses assessed strategy use over time, strategy attribution to the HIT, and strategy associations with site HCV treatment volume and rate of adoption, following the Theory of Diffusion of Innovations. Results Between 58 and 109 medical centers provided responses in each year, including 127 (98%) responding at least once, and 54 (42%) responding in all four implementation years. A median of 13–27 strategies were endorsed per year, and 8–36 individual strategies were significantly associated with treatment volume per year. Data warehousing, tailoring, and patient-facing strategies were most commonly endorsed. One strategy—“identify early adopters to learn from their experiences”—was significantly associated with HCV treatment volume in each year. Peak implementation year was associated with revising professional roles, providing local technical assistance, using data warehousing (i.e., dashboard population management), and identifying and preparing champions. Many of the strategies were driven by a national learning collaborative, which was instrumental in successful HCV elimination. Conclusions VHA’s tremendous success in rapidly treating nearly all Veterans with HCV can provide a roadmap for other HCV elimination initiatives.

Iskustva Klinike za onkologiju i radioterapiju u konkomitantnoj kemoradioterapiji nesitnostaničnog raka pluća trodimenzionalnom konformalnom tehnikom - dozimetrijska studija

Cilj: Ispitati dozimetrijske trendove na organe od rizika i akutnu toksičnost u pacijenata s karcinomom pluća nemalih stanica liječenih trodimenzionalnom konformalnom kemoradioterapijom u jednom onkološkom centru. Metode: Ovo je retrospektivna studija provedena na Klinici za onkologiju i radioterapiju KBC-a Split. Prikupljeni su podatci oboljelih od lokalno uznapredovalog nesitnostaničnog karcinoma pluća liječenih trodimenzionalnom konformalnom radioterapijom od 2011. godine do početka 2019. godine. Prikupljeni su podatci pacijenata koji su se zračili primarno, adjuvantno i/ili neoadjuvantno. Uključeni pacijenti primili su najmanje jedan ciklus kemoterapije. Ciljni volumeni i organi od rizika ocrtani su prema radioterapijskim smjernicama. Rezultati: Medijan doze na “planing treatment volume” bio je 56 Gy. Najčešća akutna radijacijska toksičnost bila je akutni ezofagitis. Nije zabilježen nijedan slučaj akutnog radijacijskog pneumonitisa. Nije pokazana korelacija između prekoračenja doze na zadane volumene organa od rizika i toksičnosti istih, te smo ukazali na trend poboljšanja dozimetrijskih rezultata kroz godine liječenja. Zaključak: Toksičnost liječenja 3D KRT-om lokalno uznapredovalog raka pluća u Klinici za onkologiju i radioterapiju KBC-a Split usporediva je s objavljenim rezultatima drugih svjetskih institucija. S duljim vremenom primjene trodimenzionalne konformalne radioterapije u kliničkoj praksi postiže se optimalna raspodjela doza zračenja na rizične organe.

RADT-02. FACTORS ASSOCIATED WITH NEW-ONSET SEIZURES AFTER STEREOTACTIC RADIOSURGERY FOR NEWLY DIAGNOSED BRAIN METASTASES

INTRODUCTION Stereotactic radiosurgery (SRS) is a highly effective therapy for newly diagnosed brain metastases. Risk factors for new-onset seizures after SRS have not been well established. In this study, we aimed to characterize the variables predictive of seizure risk. METHODS Patients treated with SRS for newly diagnosed brain metastases were retrospectively reviewed at a single institution. Data on baseline demographics, radiation parameters, and clinical courses were collected. RESULTS 120 patients without previous seizure history were identified. Median age was 65 years (56-70.8) and baseline KPS 90 (80-90). 16 (13%) patients developed new-onset seizures within 3 months of SRS. In analyses comparing patients with and without new-onset seizures, there was no association between new-onset seizures and baseline KPS(90:80, p=0.48), prior resection (31%:28%, p=0.76), prior WBRT (6%:10%, p=1), immunotherapy or chemotherapy within 1 month (31%:21%, p=0.52 and 56%:57%, p=1), primary tumor site (p=0.07), number of lesions (2.2:3, p=0.21), cerebellar (25%:37%, p=0.41) or brainstem involvement (19%:14%, p=0.71), irradiated maximum target diameter (2.8:2.0cm p=0.191), maximum target volume (7.6:2.9 cm3 p=0.133), total dose of radiation (25:20Gy, p = 0.12), or use of fractionation (56%:35%, p=0.11). However, there was a significant difference in the total irradiated target volume (11.6 vs. 3.8 cm3, p=0.019) and a trend toward increased post-treatment seizures among patients with a total irradiated volume greater than 10cm3 (20%:9%, p=0.11, OR 2.4 [0.85-6.4]). Patients with seizures were also more likely to have received steroids (69%:34%, p=0.012) and AEDs (28%:15%, p=0.021) prior to SRS. CONCLUSIONS Our data suggest that total treatment volume is associated with new-onset seizures within 3 months of SRS. The association between seizures and exposure to steroids or AEDs prior to SRS may be a surrogate for neurologic symptoms at presentation. Patients undergoing SRS to larger volumes and necessitating prophylactic steroids or AEDs may benefit from counseling or intensification of anti-seizure therapy.

Monte Carlo evaluation of out-of-field dose in 18-MV pelvic radiotherapy using a simplified female MIRD phantom

This study was devoted to determining the unwanted dose due to scattered photons to the out-of-field organs and subsequently estimate the risk of secondary cancers in the patients undergoing pelvic radiotherapy. A typical 18-MV Medical Linear Accelerator (Varian Clinac 2100 C/D) was modeled using MCNPX® code to simulate pelvic radiotherapy with four treatment fields: anterior-posterior, posterior-anterior, right lateral, left lateral. Dose evaluation was performed inside Medical Internal Radiation Dose (MIRD) revised female phantom. The average photon equivalent dose in out-of-field organs is 8.53 mSv/Gy, ranging from 0.17 to 72.11 mSv/Gy, respectively, for the organs far from the Planning Treatment Volume (Brain) and those close to the treatment field (Colon). Evidence showed that colon with 4.3049 % and thyroid with 0.0020 % have the highest and lowest risk of secondary cancer, respectively. Accordingly, this study introduced the colon as an organ with a high risk of secondary cancer which should be paid more attention in the follow-up of patients undergoing pelvic radiotherapy. The authors believe that this simple Monte Carlo (MC) model can be also used in other radiotherapy plans and mathematical phantoms with different ages (from childhood to adults) to estimate the out-of-field dose. The extractable information by this simple MC model can be also employed for providing libraries for user-friendly applications (e.g. “.apk”) which in turn increase the public knowledge about fatal cancer risk after radiotherapy and subsequently decrease the concerns in this regard among the public.

Stereotactic radiosurgery for glioblastoma considering tumor genetic profiles: an international multicenter study

OBJECTIVE Molecular profiles, such as isocitrate dehydrogenase (IDH) mutation and O6-methylguanine-DNA methyltransferase (MGMT) methylation status, have important prognostic roles for glioblastoma patients. The authors studied the efficacy and safety of stereotactic radiosurgery (SRS) for glioblastoma patients with consideration of molecular tumor profiles. METHODS For this retrospective observational multiinstitutional study, the authors pooled consecutive patients who were treated using SRS for glioblastoma at eight institutions participating in the International Radiosurgery Research Foundation. They evaluated predictors of overall and progression-free survival with consideration of IDH mutation and MGMT methylation status. RESULTS Ninety-six patients (median age 56 years) underwent SRS (median dose 15 Gy and median treatment volume 5.53 cm3) at 147 tumor sites (range 1 to 7). The majority of patients underwent prior fractionated radiation therapy (92%) and temozolomide chemotherapy (98%). Most patients were treated at recurrence (85%), and boost SRS was used for 12% of patients. The majority of patients harbored IDH wild-type (82%) and MGMT-methylated (62%) tumors. Molecular data were unavailable for 33 patients. Median survival durations after SRS were similar between patients harboring IDH wild-type tumors and those with IDH mutant tumors (9.0 months vs 11 months, respectively), as well as between those with MGMT-methylated tumors and those with MGMT-unmethylated tumors (9.8 vs. 9.0 months, respectively). Prescription dose > 15 Gy (OR 0.367, 95% CI 0.190–0.709, p = 0.003) and treatment volume > 5 cm3 (OR 1.036, 95% CI 1.007–1.065, p = 0.014) predicted overall survival after controlling for age and IDH status. Treatment volume > 5 cm3 (OR 2.215, 95% CI 1.159–4.234, p = 0.02) and absence of gross-total resection (OR 0.403, 95% CI 0.208–0.781, p = 0.007) were associated with inferior local control of SRS-treated lesions in multivariate models. Nine patients experienced adverse radiation events after SRS, and 7 patients developed radiation necrosis at 59 to 395 days after SRS. CONCLUSIONS Post-SRS survival was similar as a function of IDH mutation and MGMT promoter methylation status, suggesting that molecular profiles of glioblastoma should be considered when selecting candidates for SRS. SRS prescription dose > 15 Gy and treatment volume ≤ 5 cm3 were associated with longer survival, independent of age and IDH status. Prior gross-total resection and smaller treatment volume were associated with superior local control.

Reduction of Elective Radiotherapy Treatment Volume in Definitive Treatment of Locally Advanced Head and Neck Cancer—Comparison of a Prospective Trial with a Revised Simulated Contouring Approach

Definitive radiochemotherapy of locally advanced head and neck squamous cell cancer (HNSCC) achieves high locoregional tumor control rates; but is frequently associated with long-term toxicity. A future direction could be a de-escalation strategy focusing on treated volume rather than radiotherapy dose. This analysis evaluates radiotherapy dose and volume parameters of patients treated with a standard contouring approach in a clinical trial context compared with a revised volume-reduced contouring approach. In this case, 30 consecutive patients from the CheckRad-CD8 trial treated at a single study center were included in this analysis. Treatment toxicity and quality of life were assessed at the end of radiotherapy. Standard treatment plans (ST) following state of the art contouring guidelines that were used for patient treatment and volume reduced treatment plans (VRT) according to a revised simulated approach were calculated for each patient. Planning target volumes (PTV) and mean doses to 38 organs-at-risk structures were compared. At the end of radiotherapy patients reported high rates of mucositis; dysphagia and xerostomia. In addition; patient reported quality of life as assessed by the EORTC QLQ-HN35 questionnaire deteriorated. Comparing the two contouring approaches; the elective PTV_56 Gy and the high risk PTV_63 Gy (shrinking field) were significantly smaller in the VRT group. Significant reduction of mean dose to structures of the oral cavity; the larynx as well as part of the swallowing muscles and the submandibular glands was achieved in the simulated VRT-plan. Treatment de-intensification by reduction of the irradiated volume could potentially reduce treatment volume and mean doses to organs at risk. The proposed contouring approach should be studied further in the context of a clinical trial.

Reduction of inter-observer differences in the delineation of the target in spinal metastases SBRT using an automatic contouring dedicated system

Background Approximately one third of cancer patients will develop spinal metastases, that can be associated with back pain, neurological symptoms and deterioration in performance status. Stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) have been offered in clinical practice mainly for the management of oligometastatic and oligoprogressive patients, allowing the prescription of high total dose delivered in one or few sessions to small target volumes, minimizing the dose exposure of normal tissues. Due to the high delivered doses and the proximity of critical organs at risk (OAR) such as the spinal cord, the correct definition of the treatment volume becomes even more important in SBRT treatment, thus making it necessary to standardize the method of target definition and contouring, through the adoption of specific guidelines and specific automatic contouring tools. An automatic target contouring system for spine SBRT is useful to reduce inter-observer differences in target definition. In this study, an automatic contouring tool was evaluated. Methods Simulation CT scans and MRI data of 20 patients with spinal metastases were evaluated. To evaluate the advantage of the automatic target contouring tool (Elements SmartBrush Spine), which uses the identification of different densities within the target vertebra, we evaluated the agreement of the contours of 20 spinal target (2 cervical, 9 dorsal and 9 lumbar column), outlined by three independent observers using the automatic tool compared to the contours obtained manually, and measured by DICE similarity coefficient. Results The agreement of GTV contours outlined by independent operators was superior with the use of the automatic contour tool compared to manually outlined contours (mean DICE coefficient 0.75 vs 0.57, p = 0.048). Conclusions The dedicated contouring tool allows greater precision and reduction of inter-observer differences in the delineation of the target in SBRT spines. Thus, the evaluated system could be useful in the setting of spinal SBRT to reduce uncertainties of contouring increasing the level of precision on target delivered doses.