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Abstract BACKGROUND After radiation therapy (RT) for brain metastases (BM), differentiating radiation necrosis from tumor recurrence remains challenging. PURSUE (NCT04410367) evaluated various measures of lesion 18F-fluciclovine uptake to establish image interpretation criteria (IIC) for 18F-fluciclovine-PET to accurately diagnose recurrent BM. METHODS Patients with solid tumor BM and a previously irradiated ‘reference’ lesion equivocal for recurrence on MRI who were scheduled for craniotomy underwent 18F-fluciclovine-PET (185 MBq) <42 days post-MRI and 1-21 days pre-craniotomy. Lesion 18F-fluciclovine uptake was qualitatively rated as ‘mild’ (up to blood pool), ‘moderate’ (above blood pool to parotid gland), or ‘marked’ (above parotid gland) by three independent blinded readers. The primary endpoint was diagnostic performance of different uptake thresholds on qualitative reads vs central histopathology. Secondary endpoints included diagnostic performance, based on different thresholds, of quantitative (e.g., lesion standardized uptake value [SUV]) and dynamic measures. IIC were determined by committee and subsequently used to assess the diagnostic performance of 18F-fluciclovine. RESULTS All 23 reference lesions from 23 enrolled patients underwent histopathological analysis; 10 (43%) were pathologically-confirmed BM recurrence. The highest performing qualitative measure was ‘marked’, rendering 92-100% sensitivity and 40-80% specificity across readers. SUVmax was a reader-independent, high-performing quantitative metric (AUC 0.87, SUVmax threshold 4.8, 80% sensitivity, 85% specificity). Dynamic measures did not add diagnostic value. Thus, IIC was established as: “Lesions with 18F-fluciclovine uptake of SUVmax equal to or greater than 4.8, or visually greater than the parotid gland, should be considered suspicious for recurrence. Otherwise, recurrence should be considered unlikely.” Application of the IIC resulted in 80% sensitivity, 77-85% specificity, 73-80% PPV, and 83-85% NPV across the readers. CONCLUSIONS PURSUE is the first prospective, multicenter trial to establish IIC for 18F-fluciclovine-PET for suspected recurrent BM after RT, verified by histopathology. Finalized IIC demonstrated excellent diagnostic performance for 18F-fluciclovine and will help evaluate 18F-fluciclovine-PET in future studies.

2001 Background: Differentiating radiation necrosis from tumor progression remains one of the most commonly encountered and clinically challenging scenarios after radiation therapy (RT) for brain metastases (BM). PURSUE (NCT04410367) evaluated the diagnostic performance of 18F-fluciclovine, an amino acid PET radiopharmaceutical, based on various lesion metrics, to establish image interpretation criteria (IIC) for suspected recurrent BM after RT. Methods: Patients with solid tumor BM were enrolled across 7 US sites if they had a previously irradiated ‘reference’ lesion equivocal on MRI for recurrence and were planned for craniotomy. 18F-Fluciclovine PET (185 MBq) took place <42 days post-MRI and 1-21 days pre-craniotomy. The primary endpoint was the diagnostic performance (sensitivity, specificity, positive-, and negative-predictive value [PPV/NPV]) of different thresholds of lesion 18F-fluciclovine uptake on qualitative, visual reads vs central histopathological analysis. Lesion 18F-fluciclovine uptake was assessed qualitatively by 3 independent blinded readers who visually rated the uptake as ‘mild’ (up to blood pool), ‘moderate’ (above blood pool to parotid), or ‘marked’ (above parotid). Secondary endpoints included the diagnostic performance based on different thresholds of quantitative (e.g., lesion SUV) and dynamic measures of uptake. A committee, including 2 expert imaging physicians independent to PURSUE, reviewed all data in round-table meetings to establish the IIC, which were subsequently used to assess diagnostic performance. Results: All 23 reference lesions in 23 subjects underwent histopathological analysis, with 10 (43%) confirmed as recurrent tumor. The highest performing qualitative measure was ‘marked’, rendering a sensitivity of 92-100%, with variable specificity of 40-80% across readers. SUVmax was a reader-independent, high-performing quantitative metric on ROC analysis (AUC 0.87, SUVmax threshold 4.8 conferring a sensitivity of 80% and specificity of 85%). Dynamic measures did not provide added diagnostic value. After analyzing these metrics, the committee established IIC as: Lesions with 18F-fluciclovine uptake of a SUVmax equal to or greater than 4.8, or visually greater than the parotid gland, should be considered suspicious for recurrence. Otherwise, recurrence should be considered unlikely. Application of the IIC resulted in a sensitivity of 80%, specificity of 77-85%, PPV of 73-80%, and NPV of 83-85% across the readers. Conclusions: This is the first prospective multicenter trial to evaluate PET characteristics of suspected recurrent BM after RT, verified by histopathology. Qualitative and quantitative IIC show 18F-fluciclovine to be a high-performing diagnostic tool. These IIC will help evaluate the diagnostic performance of 18F-fluciclovine PET in future trials. Clinical trial information: NCT04410367 .

AbstractObjectiveTo evaluate recurrence patterns and survival after recurrence among patients with sinonasal mucosal melanoma (SNMM).MethodsThis was a multi‐institutional retrospective review from seven U.S. institutions of patients with SNMM from 1991 to 2022. Recurrence was categorized as local, regional, distant, or multifocal. Kaplan‐Meier tests were used to evaluate disease‐free survival (DFS), overall survival (OS), and post‐recurrence survival (PRS) reported with standard errors (SE) and log‐rank testing used for comparison. Cox‐regression was further used, with hazard ratios (HR) and 95% confidence intervals (CI) reported.ResultsAmong 196 patients with SNMM, there were 146 patients with recurrence (74.5%). Among all patients, 60‐month DFS (SE) was 15.5% (2.9%), 60‐month OS (SE) was 44.7% (3.7%), mean age ± standard deviation at diagnosis was 69.7 ± 12.5 years, and 54.6% were female. In 26 patients who underwent primary treatment of the neck, 60‐month DFS did not differ from no treatment (p > 0.05). Isolated distant recurrence was most common (42.8%), followed by local (28.3%), multifocal (20.7%), and regional recurrence (8.3%). Among patients with regional recurrence in the neck, there was no 60‐month PRS benefit for patients undergoing salvage neck dissection or radiation (p > 0.05). Among patients with distant recurrence, only immunotherapy was associated with improved 12‐month PRS (HR = 0.32, 95% CI = 0.11–0.92, p = 0.034), and no treatment group was associated with improved 24‐ or 60‐month PRS (p > 0.05).ConclusionSNMM is associated with a high recurrence rate and poor survival. Primary treatment of the neck was not associated with reduced recurrence, and immunotherapy for treatment of distant recurrence was associated with increased 12‐month PRS.

AbstractBackgroundQuality of life (QOL) for individuals with sinonasal malignancy (SNM) is significantly under‐studied, yet it is critical for counseling and may impact treatment. In this study we evaluated how patient, treatment, and disease factors impact sinonasal‐specific and generalized QOL using validated metrics in a large cohort over a 5‐year posttreatment time frame.MethodsPatients with SNM who underwent definitive treatment with curative intent were enrolled in a prospective, multisite, longitudinal observational study. QOL was assessed using the 22‐item Sino‐Nasal Outcome Test (SNOT‐22) and University of Washington Quality of Life Questionnaire (UWQOL) instruments at pretreatment baseline and multiple follow‐ups through 5 years posttreatment. Multivariable modeling was used to determine demographic, disease, and treatment factors associated with disease‐specific and generalized physical and social/emotional function QOL.ResultsOne hundred ninety‐four patients with SNM were analyzed. All QOL indices were impaired at pretreatment baseline and improved after treatment. SNOT‐22 scores improved 3 months and UWQOL scores improved 6 to 9 months posttreatment. Patients who underwent open compared with endoscopic tumor resection had worse generalized QOL (p < 0.001), adjusted for factors including T stage. Pterygopalatine fossa (PPF) involvement was associated with worse QOL (SNOT‐22, p < 0.001; UWQOL Physical dimension, p = 0.02). Adjuvant radiation was associated with worse disease‐specific QOL (p = 0.03). Neck dissection was associated with worse generalized physical function QOL (p = 0.01). Positive margins were associated with worse generalized social/emotional function QOL (p = 0.01).ConclusionDisease‐specific and generalized QOL is impaired at baseline in patients with SNM and improves after treatment. Endoscopic resection is associated with better QOL. PPF involvement, adjuvant radiation, neck dissection, and positive margins were associated with worse QOL posttreatment.

Abstract BACKGROUND: Endpoints in clinical trials using novel treatments are evaluated by RANO criteria, which provide an estimate of tumor size from two-dimensional measurements along the most prominent axial slice. However, pediatric low-grade gliomas (pLGG) commonly have variegated shapes with solid and cystic components, potentially resulting in misevaluation of true tumor volume and thus, ultimately, trial outcome. OBJECTIVES: We aim to characterize treatment response through volumetric assessment of progressive/recurrent pLGGs treated with single-agent everolimus on PNOC001 clinical trial. We seek to identify clinically relevant criteria that provide added value to response assessment beyond 2D measurements. METHODS: In a cohort of 44 patients we performed 3D-segmentation of solid, cystic and whole tumor within our PACS-framework and compared results to previously carried-out central imaging review by RANO criteria which had yielded 15 PD, 27 SD, 2 PR and 0 CR. RESULTS: 8 tumors were solid only and 36 had a mixed solid-cystic appearance. When evaluating the entire tumor (i.e. solid and cystic components combined) and using the same RANO cutoff criteria, one case changed from PR to SD, one changed from SD to PR, 3 changed from SD to PD, and 7 changed from PD to SD, resulting in an overall discordance of 27% of cases. CONCLUSION: We propose that incorporation of volumetrics into response assessment provides additional and potentially more accurate information beyond RANO-based measurements. It is crucial to note that the above-reported changes represent numerical discrepancies as opposed to true-to-reality changes in clinical outcome. Determining representative thresholds for the deployment of volumetric measures in clinical trials will be critical. Future work will include data from the PNOC002 clinical trial and evaluate inter-reader agreement and reader discordance. With the availability of PACS-based 3D-tools in neuroradiology practice, well-defined volumetric criteria could be incorporated prospectively into treatment response analysis in clinical trials.