RADT-24. SYNTHETIC TREATMENT OF CENTRAL NERVOUS SYSTEM EWING/PRIMITIVE NEUROECTODERMAL TUMOR (EWING/PNET): A CASE REPORT

Ewing/PNET is a rare tumor of the central nervous system. After the standard treatment, there’re still 86.7% of patients had recurrence and no standard treatment after recurrence. Here we report a case of Ewing/PNET with a good survival after synthetic treatment to provide evidence for future clinical strategies. A 23-year-old male underwent resection of the left frontal tumor on April 28, 2017, the pathological diagnosis was Ewing/PNET. He received whole brain radiotherapy 36Gy in 18 fractions, and tumor bed boost to 56Gy in 28 fractions, with 3 courses of Nedaplatin adjuvant chemotherapy. The tumor recured 23 months after the surgery. The patient underwent the second resection, followed by 4 courses of ADM+VCR+CTX/IE chemotherapy. However, 27 months after the first surgery, the tumor evaluation progressive resection of recurrent tumors in the anterior cranial base-ethmoid sinus. During the chemotherapy, MRI showed that tumor still increased. There was a mass in the root of the forehead and nose. After the third recurrence, the patient received re-radiotherapy (50Gy in 25 fractions) 29 months later after the first RT. The tumor was significantly reduced after radiotherapy. Physical examination showed that the sense of smell continued to weaken, the visual acuity was the same as before. 8 courses of VIT (Irinotecan, vincristine, temozolomide) were followed by second RT, tumor was assessed every 2 courses. 44 months after the first surgery, he suffered a third recurrence in spina cord. And then he received rescue RT (20Gy in 10 fractions) in the recurrent tumor. The tumor was reduced after local radiotherapy. He was undergoing follow-up till May 2021, And the OS is 49 months. In conclusion, the incidence of this disease is low, especially in adults. However, the prognosis is poor. Early detection, early operation, combined with radiotherapy and chemotherapy are promising to improve the efficacy of Ewing/PNET.

NIMG-28. PROSPECTIVE HISTOPATHOLOGY-VALIDATED MACHINE LEARNING FOR DISTINGUISHING TRUE PROGRESSION FROM TREATMENT-RELATED CHANGES IN GLIOBLASTOMA PATIENTS

PURPOSE Decision making about the best course of treatment for glioblastoma patients becomes challenging when a new enhancing lesion appears in the vicinity of the surgical bed on follow-up MRI (after maximal safe tumor resection and chemoradiation), raising concerns for tumor progression (TP). Literature indicates 30-50% of these new lesions describe primarily treatment-related changes (TRC). We hypothesize that quantitative analysis of specific and sensitive features extracted from multi-parametric MRI (mpMRI) via machine learning (ML) techniques may yield non-invasive imaging signatures that distinguish TP from TRC and facilitate better treatment personalization. METHODS We have generated an ML model on a retrospective cohort of 58 subjects, and prospectively evaluated on an independent cohort of 58 previously unseen patients who underwent second resection for suspicious recurrence and had availability of advanced mpMRI (T1, T1-Gd, T2, T2-FLAIR, DTI, DSC). The features selected by our retrospective model, representing principal components analysis of intensity distributions, morphological, statistical, and texture descriptors, were extracted from the mpMRI of the prospective cohort. Integration of these features revealed signatures distinguishing between TP, mixed response, and TRC. Independently, a board-certified neuropathologist evaluated the resected tissue by blindly classifying it in the above three categories, based on mitotic figures, pseudopalisading necrosis, geographic necrosis, dystrophic calcification, vascular changes, and Ki67. RESULTS Tissues classified as TRC by the neuropathologist were associated with imaging phenotypes of lower angiogenesis (DSC-derived features), lower cellularity (DTI-derived features), and higher water concentration (T2, T2-FLAIR features). Our ML model characterized TP with 78% accuracy (sensitivity:86%, specificity:70%, AUC:0.80 (95%CI, 0.68-0.92)) and TRC with 81% accuracy (sensitivity:80%, specificity:81%, AUC:0.87 (95%CI, 0.72-1.00)). CONCLUSION Our proposed ML model reveals distinct non-invasive markers of TP and TRC, directly associated with histopathological changes in prospective glioblastoma patients. Reliable stratification of TP and TRC entities may help to noninvasively determine whether the course of treatment should change.

Prospective comparative study of intraoperative balloon electronic brachytherapy versus resection with multidisciplinary adjuvant therapy for recurrent glioblastoma

Background: Intraoperative balloon electronic brachytherapy (IBEB) may provide potential benefit for local control of recurrent cerebral glioblastomas (GBMs). Methods: This is a preliminary report of an open-label, prospective, comparative cohort study conducted in two neurosurgical centers with ongoing follow-up. At recurrence, patients at one center (n = 15) underwent reresection with IBEB while, at the second center (n = 15), control subjects underwent re-resection with various accepted second-line adjuvant chemoradiotherapy options. A comparative analysis of overall survival (OS) and local progression-free survival (LPFS) following re-resection was performed. Exploratory subgroup analysis based on postoperative residual contrast-enhanced volume status was also done. Results: In the IBEB group, median LPFS after re-resection was significantly longer than in the control group (8.0 vs. 6.0 months; log rank χ2 = 4.93, P = 0.026, P < 0.05). In addition, the median OS after second resection in the IBEB group was also significantly longer than in the control group (11.0 vs. 8.0 months; log rank χ2 = 4.23, P = 0.04, P < 0.05). Conclusion: These hypothesis-generating results from a small cohort of subjects suggest putative clinical benefit in OS and LPFS associated with maximal safe re-resection of recurrent GBM with IBEB versus re-resection and standard adjuvant therapy, a hypothesis that deserves further testing in an appropriately powered clinical trial.

Discrepancy between German S3 Guideline Recommendations and Daily Urologic Practice in the Management of Nonmuscle Invasive Bladder Cancer: Results of a Binational Survey

<b><i>Introduction:</i></b> Guideline recommendations are meant to help minimize morbidity and to improve the care of nonmuscle invasive bladder cancer (NMIBC) patients but studies have suggested an underuse of guideline-recommended care. The aim of this study was to evaluate the level of adherence of German and Austrian urologists to German guideline recommendations. <b><i>Methods:</i></b> A survey of 27 items evaluating diagnostic and therapeutic recommendations (15 cases of strong consensus and 6 cases of consensus) for NMIBC was administered among 14 urologic training courses. Survey construction and realization followed the checklist for reporting results of internet e-surveys and was approved by an internal review board. <b><i>Results:</i></b> Between January 2018 and June 2019, a total of 307 urologists responded to the questionnaire, with a mean response rate of 71%. The data showed a weak role of urine cytology (54%) for initial diagnostics although it is strongly recommended by the guideline. The most frequently used supporting diagnostic tool during transurethral resection of the bladder was hexaminolevulinate (95%). Contrary to the guideline recommendation, 38% of the participants performed a second resection in the case of pTa low-grade NMIBC. Correct monitoring of Bacille Calmette-Guérin (BCG) response with cystoscopy and cytology was performed by only 34% of the urologists. <b><i>Conclusions:</i></b> We found a discrepancy between certain guideline recommendations and daily routine practice concerning the use of urine cytology for initial diagnostics, instillation therapy with a low monitoring rate of BCG response, and follow-up care with unnecessary second resection after pTa low-grade NMIBC in particular. Our survey showed a moderate overall adherence rate of 73%. These results demonstrate the need for sharpening awareness of German guideline recommendations by promoting more intense education of urologists to optimize NMIBC care thus decreasing morbidity and mortality rates.

Recurrence after Curative Resection for Intrahepatic Cholangiocarcinoma: How to Predict the Chance of Repeat Hepatectomy?

(1) Background: Tumor recurrence after liver resection (LR) for intrahepatic cholangiocarcinoma (ICC) is common. Repeat liver resection (RLR) for recurrent ICC results in good survival outcomes in selected patients. The aim of this study was to investigate factors affecting the chance of resectability of recurrent ICC. (2) Methods: LR for ICC performed between January 2001 and December 2020 were retrospectively reviewed. Patients who had undergone first LR were considered for the study. Data on recurrences were analyzed. A logistic regression model was used for multivariable analysis of factors related to RLR rate. (3) Results: In total, 140 patients underwent LR for ICC. Major/extended hepatectomies were required in 105 (75%) cases. The 90-day mortality was 5.7%, Clavien–Dindo grade 3, 4 complications were 9.3%, N+ disease was observed in 32.5%, and the median OS was 38.3 months. Recurrence occurred in 91 patients (65%). The site of relapse was the liver in 53 patients (58.2%). RLR was performed in 21 (39.6%) patients. Factors that negatively affected RLR were time to recurrence ≤12 months (OR 7.4, 95% CI 1.68–33.16, p = 0.008) and major hepatectomy (OR 16.7, 95% CI 3.8–73.78, p < 0.001) at first treatment. Survival after recurrence was better in patients who underwent RLR as compared with not resected patients (31 vs. 13.2 months, p = 0.02). (4) Conclusions: Patients with ICC treated at first resection with major hepatectomy and those who recurred in ≤12 months had significantly lower probability to receive a second resection for recurrence.

Case Report: A Rare Case of Nasal Forehead Mass in Kimura's Disease

Background: Kimura's disease is a rheumatic immune disease and head and neck lymph nodes are often involved. A mass occurring in the nasal forehead is rare. Good prognosis after surgical resection by glucocorticoid therapy is more rare.Case Summary: We report the rare case of a nasal forehead mass in a 45-year-old male patient with Kimura's disease. The patient underwent resection of the mass in October 2018 in a local hospital and the postoperative pathology was unclear. He then underwent a second resection in our department in December 2019 mainly because growth of the mass was affecting his appearance. Postoperative pathology confirmed that the patient had Kimura's disease, and he accepted systemic treatment with prednisone. We followed the patient for 10 months after surgery. He is now recovering well and continues to be closely monitored during follow-up.Conclusion: It is rare that the painless mass in the nasal forehead is diagnosed as a Kimura's disease.After completely resection of the mass and systemic treatment with prednisone, the patient had a good outcome. We provide experience for the treatment of Kimura's disease in nasal forehead.

MRI after Whoops procedure: diagnostic value for residual sarcoma and predictive value for an incomplete second resection

Objective To determine the value of MRI for the detection and assessment of the anatomic extent of residual sarcoma after a Whoops procedure (unplanned sarcoma resection) and its utility for the prediction of an incomplete second resection. Materials and methods This study included consecutive patients who underwent a Whoops procedure, successively followed by gadolinium chelate-enhanced MRI and second surgery at a tertiary care sarcoma center. Results Twenty-six patients were included, of whom 19 with residual tumor at the second surgery and 8 with an incomplete second resection (R1: n = 6 and R2: n = 2). Interobserver agreement for residual tumor at MRI after a Whoops procedure was perfect (κ value: 1.000). MRI achieved a sensitivity of 47.4% (9/19), a specificity of 100% (7/7), a positive predictive value of 100% (9/9), and a negative predictive value of 70.0% (7/17) for the detection of residual tumor. MRI correctly classified 2 of 19 residual sarcomas as deep-seated (i.e., extending beyond the superficial muscle fascia) but failed to correctly classify 3 of 19 residual sarcomas as deep-seated. There were no significant associations between MRI findings (presence of residual tumor, maximum tumor diameter, anatomic tumor extent, tumor margins, tumor spiculae, and tumor tail on the superficial fascia) with an incomplete (R1 or R2) second resection. Conclusion Gadolinium chelate-enhanced MRI is a reproducible method to rule in residual sarcoma, but it is insufficiently accurate to rule out and assess the anatomic extent or residual sarcoma after a Whoops procedure. Furthermore, MRI has no utility in predicting an incomplete second resection.

Gamma Knife for Recurrent Ameloblastoma with Cavernous Sinus Metastasis: A Case Report

Ameloblastoma (AME) is a rare, benign intraosseous progressively growing odontogenic tumor. Due to its invasive behavior, the rate of recurrence is high. Recurrent AME tends to transform malignantly and metastatic. Lung is the most common sites of AME metastasis, followed by lymph nodes. Here we present a case of AME with intracranial metastasis. A 26-year-old woman who had recurrent AME in the left jaw. After the second resection, AME metastasis to the cavernous sinus, sellar and suprasellar regions. Because the metastatic tumor was unresectable, she received Gamma Knife instead. After 3 years follow-up, the tumor was well controlled. In conclusion, Gamma Knife can be a feasible option for unresectable Oligometastatic AME.

IMMU-26. DISEASE CONTROL IN A PEDIATRIC PATIENT WITH NEWLY DIAGNOSED GLIOBLASTOMA MULTIFORME (GBM) AND SOMATIC HIGH MICROSATELLITE INSTABILITY (MSI-H) WITH PD-1 INHIBITOR NIVOLUMAB (NIVO) ONLY AND NO FOCAL RADIOTHERAPY (RT)

Immune checkpoint inhibitors that target programmed death receptor-1 (PD-1) have recently been shown to be a promising option for the management of recurrent mismatch repair (MMR) deficient GBM following radiotherapy. We report a case of a 9-year-old boy who presented with a 6 week history of frontal headaches and was found to have a left frontal lobe mass. Pathology obtained from a gross total resection (GTR) was consistent with classic GBM, WHO Grade IV. Neuroimaging four weeks following initial resection was remarkable for local recurrence. The patient underwent another GTR of the tumor at our center. While pathology again confirmed GBM, GlioSequencing of tumor tissue from second resection showed MSI-H, NF2 mutation p.R338H, NF1 mutations p.R2450* and pI193Yfs*11, TP53 mutations p.R213* and p.R273C, EGFR mutation, and multiple variants of uncertain significance. Germline testing was negative for MMR deficiency or other deleterious mutations. Parents opted to defer radiotherapy and consented to monotherapy treatment with Nivolumab (Opdivo, BMS pharmaceuticals, USA), a PD-1 inhibitor, at a dose of 3 mg/kg administered every two weeks. Our patient is now 22 months post-second resection and continues to receive Nivolumab without evidence of recurrent disease or adverse autoimmune effects from PD-1 blockade. He has remained in school with good academic performance and has exhibited no regression of functional status during the entirety of his treatment course. This case provides evidence of possible efficacy of PD-1 blockade without focal radiotherapy in this child with GBM and somatic MSI instability.

Intraoperative electrostimulation for awake brain mapping: how many positive interference responses are required for reliability?

OBJECTIVEThe purpose of this study was to characterize the reproducibility of language trials within and between brain mapping sessions.METHODSBrain mapping and baseline testing data from 200 adult patients who underwent resection of left-hemisphere tumors were evaluated. Data from 11 additional patients who underwent a second resection for recurrence were analyzed separately to investigate reproducibility over time. In all cases, a specific protocol of electrostimulation brain mapping with a controlled naming task was used to detect language areas, and the results were statistically compared with preoperative and intraoperative baseline naming error rates. All patients had normal preoperative error rates, controlled for educational level and age (mean 8.92%, range 0%–16.25%). Intraoperative baseline error rates within the normal range were highly correlated with preoperative ones (r = 0.74, p < 10−10), although intraoperative rates were usually higher (mean 13.30%, range 0%–26.67%). Initially, 3 electrostimulation trials were performed in each cortical area. If 2 of 3 trials showed language interference, 1 or 2 additional trials were performed (depending on results).RESULTSIn the main group of 200 patients, there were 82 single interferences (i.e., positive results in 1 of 3 trials), 227 double interferences (2/3), and 312 full interferences (3/3). Binomial statistics revealed that full interferences were statistically significant (vs intraoperative baseline) in 92.7% of patients, while double interferences were significant only in 38.5% of patients, those with the lowest error rates. On further testing, one-third of the 2/3 trials became 2/4 trials, which was significant in only one-quarter of patients. Double interference could be considered significant for most patients (> 90%) when confirmed by 2 subsequent positive trials (4/5). In the 11 patients who were operated on twice, only 26% of areas that tested positive in the initial operation tested positive in the second and showed the same type of interference and the same current threshold (i.e., met all 3 criteria).CONCLUSIONSElectrostimulation trials in awake brain mapping produced graded patterns of positive reproducibility levels, and their significance varied with the baseline error rates. The results suggest that caution is warranted when 2 of 3 trials are positive, although the need for additional trials depends on the individual patients’ baseline error rates. Reproducibility issues should be considered in the interpretation of data from awake brain mapping.