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e24089 Background: Little is known about risk and protective factors for dementia in cancer survivors. With increasing longevity due to improved cancer therapy, it’s prudent to study factors contributing to cognitive impairment in this patient population. Methods: We performed multivariable cox regression analyses to assess established risk factors for all-cause dementia (age, education, APOE4-status, social and physical activity engagement) in breast and prostate cancer survivors. Patients 50+ years old with pathology-confirmed cancer diagnosis at Mayo Clinic were identified from a longitudinal, population-based cohort – Mayo Clinic Study of Aging. Analyses were controlled for age, APOE4-status, education, and cancer treatment. Results: We included a total of 209 patients with breast cancer (mean age 75.4 years, 24% APOE4-positive, median follow-up 6.8 years) and 352 with prostate cancer (mean age 77 years, 26% APOE4-positive, median follow-up 6.4 years). 31 patients with breast cancer (15%) and 66 patients with prostate cancer (20%) were diagnosed with dementia at last follow-up. Older age was associated with increased risk for dementia (5-year increase – breast: hazard ratio (HR) 1.9 [95%CI 1.3-2.7, p = 0.001]; prostate: HR 2.4 [95%CI 1.8-3.2, p < 0.0001]). APOE4-positivity was associated with increased dementia risk in breast (HR 3.6 [95%CI 1.6-7.8, p < 0.002]), but not prostate cancer (HR 1.2 [95%CI 0.7-2.0, p = 0.5]). More education was associated with lower dementia risk in prostate cancer (education year: HR 0.91 [95%CI 0.84-0.98, p < 0.02]; education years > 12: HR 0.26 [95%CI 0.1-0.6, p < 0.001]). Physical activity engagement in mid-life was associated with lower dementia risk (prostate: HR 0.56 [95%CI 0.4-0.8, p < 0.005]; breast: HR 0.48 [95%CI 0.3-0.9, p < 0.02]). Conclusions: In this longitudinal, population-based study we found that some risk and protective factors for dementia in cancer survivors vary by cancer type. While advanced age is an expected dementia risk factor, there were mixed results for APOE4-positivity (increased risk only in breast cancer) and education (only protective in prostate cancer). Our results support further study into factors influencing dementia risk by cancer type in hopes of identifying preventative strategies.

e17057 Background: Results from the VISION trial (NCT03511664) led to the approval of lutetium-177 (177Lu)–PSMA-617 for the treatment of metastatic castration-resistant prostate cancer (mCRPC). This trial excluded patients with baseline cytopenias, thus safety in this frequently encountered patient population is unknown. We aimed to use real-world data to describe the tolerability of radioligand therapy in those with poorer bone marrow reserve. Methods: We retrospectively reviewed the records of all patients, who received a first dose of 177Lu–PSMA-617 at Mayo Clinic in the interval of April 26, 2022, to December 1, 2022. Patients were categorized as having poor marrow reserve on the basis of pre-treatment hematologic parameters, including: (1) an anemia cohort with hemoglobin (Hg) less than 9 g/dL, (2) a thrombocytopenia cohort with platelets (Plt) less than 100 x 109/L, (3) a leukopenia cohort with white blood cell count (WBC) less than 2.5 x 109/L, and (4) a multiple cytopenia cohort. These were exclusionary parameters from the VISION trial. Longitudinal laboratory data and clinical outcomes were collected and analyzed using descriptive statistics. Results: At data cutoff, 185 patients had received one or more doses of 177Lu, including 26 (14%) with at least one baseline cytopenia prior to their first cycle of treatment. In total, there were 19 (73%) patients with anemia, 3 (12%) with thrombocytopenia, 2 (8%) with leukopenia, and 2 (8%) with multiple cytopenias at baseline. The median number of cycles received thus far is 3, including 14 (54%) who are still receiving therapy and 12 (46%) who have permanently discontinued treatment. Median longitudinal changes in blood counts for the anemia cohort are presented in Table 1. Reasons for treatment discontinuation include: toxicity (n = 2), disease progression (n = 5), death (n = 4), or other (n = 1). Dose reductions or treatment delays for worsening myelosuppression were utilized in 3 (12%) and 5 (19%) patients, respectively. Transfusions of packed red blood cells or platelets were required for 16 (62%) patients. A total of 6 (23%) received care in the emergency department or were hospitalized. Conclusions: Treatment discontinuation for toxicity was rare among men with mCRPC and baseline cytopenias, while receiving 177Lu; however, these patients have an overall poor prognosis. [Table: see text]

Objectives Somatostatin receptor (SSTR) PET imaging is utilized with increasing frequency in the clinical management of neuroendocrine tumors. Incidental PET-avid CNS lesions are commonly noted and presumed to be meningiomas. However, SSTR PET lacks specificity for meningioma identification. This study aimed to clarify the role of SSTR-based imaging in the classification of incidental CNS lesions based on current clinical practice. Methods Patients who underwent both Ga-68-DOTATATE PET and brain MRI and had an incidental CNS lesion identified with a radiographic prediction of meningioma via one (discordant prediction) or both (concordant prediction) imaging modalities were retrospectively analyzed. Imaging indication, semiquantitative measures, and clinical history were recorded. Results Among 48 patients with a CNS lesion identified on both imaging modalities, most scans were performed for a history of neuroendocrine tumor (64.6%). Cases with concordant lesion-type prediction of meningioma between imaging modalities (N = 24) displayed a significantly higher SUV max (median 7.9 vs. 4.0; P = 0.008) and Krenning score (median 3.0 vs. 2.0; P = 0.005) on Ga-68-DOTATATE PET compared with cases with a discordant prediction of meningioma (N = 24). In cases with lower SUV max values, Ga-68-DOTATATE was more likely to discordantly predict meningioma without agreement by the corresponding MRI. Prior cranial radiation or use of somatostatin mimetics did not affect quantitative radiographic measures, and MRI-based tumor size was similar across groups. Conclusion Lesions with increased avidity may be more confidently predicted as meningioma in Ga-68-DOTATATE PET scans, whereas there is more discrepancy in prediction among low SUV cases.

AbstractBackgroundMeningiomas are the most common primary central nervous system (CNS) tumor in adults and CNS World Health Organization grade 2 (atypical) meningiomas show an intermediate risk of recurrence/progression. Molecular parameters are needed to better inform management following gross total resection (GTR).MethodsWe performed comprehensive genomic analysis of tumor tissue from 63 patients who underwent radiologically confirmed GTR of a primary grade 2 meningioma, including a CLIA-certified target next-generation sequencing panel (n = 61), chromosomal microarray (n = 63), genome-wide methylation profiling (n = 62), H3K27me3 immunohistochemistry (n = 62), and RNA-sequencing (n = 19). Genomic features were correlated with long-term clinical outcomes (median follow-up: 10 years) using Cox proportional hazards regression modeling and published molecular prognostic signatures were evaluated.ResultsThe presence of specific copy number variants (CNVs), including -1p, -10q, -7p, and -4p, was the strongest predictor of decreased recurrence-free survival (RFS) within our cohort (P &lt; .05). NF2 mutations were frequent (51%) but did not show a significant association with RFS. DNA methylation-based classification assigned tumors to DKFZ Heidelberg benign (52%) or intermediate (47%) meningioma subclasses and was not associated with RFS. H3K27 trimethylation (H3K27me3) was unequivocally lost in 4 tumors, insufficient for RFS analysis. Application of published integrated histologic/molecular grading systems did not improve prediction of recurrence risk over the presence of -1p or -10q alone.ConclusionsCNVs are strong predictors of RFS in grade 2 meningiomas following GTR. Our study supports incorporation of CNV profiling into clinical evaluation to better guide postoperative patient management, which can be readily implemented using existing, clinically validated technologies.

Abstract BACKGROUND Interpretation of serial magnetic resonance imaging (MRI) for glioblastoma following radiation therapy (RT) is complicated by difficulty differentiating tumor from treatment-related changes, even using updated RANO criteria. The incorporation of novel imaging such as 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (18F-DOPA) PET/CT to post-treatment serial imaging may improve prognostication and better facilitate future treatment decisions. METHODS The secondary analysis of a recent phase II prospective clinical trial of 18F-DOPA PET/CT-directed dose-escalated RT included patients with IDH-wildtype, MGMT-unmethylated glioblastoma who underwent post-treatment serial 18F-DOPA PET/CT surveillance. Quantitative features were extracted from pre-RT and post-RT serial PET/CT images, and robust prognostic features were selected using an in-house workflow. Both an automated machine learning (ML) algorithm and an interpretable ML algorithm were utilized to correlate surveillance PET image features with subsequent survival of greater than 12 months versus less than 12 months from the surveillance timepoint. Changes from pre-RT to post-RT PET/CT (delta model) were also assessed for association with post-RT survival and validated with a separate cohort. RESULTS Thirty-five patients with IDH-wildtype, MGMT-unmethylated glioblastoma who had at least one available (range: 1-14) post-treatment 18F-DOPA PET/CT were included. Twenty-four were used for model training, while 11 were used for validation. Ultimately, a five-feature post-RT model utilizing two shape, two texture, and one first-order radiomic feature was selected. For the delta model, five texture, two shape, and one first order radiomic feature were selected. The models show 90% accuracy in predicting survival &lt; 12 months post-surveillance on the training set, and 68%-73% accuracy (AUC 0.64-0.73) for the validation cohort. Delta features were significantly associated with overall survival (p &lt; 0.05). CONCLUSIONS Post-RT serial 18F-DOPA PET/CT imaging can help distinguish true tumor progression in patients with glioblastoma using a radiomics model. Tumor response evaluated for changes from pre-RT to post-RT 18F-DOPA PET/CT also predicted subsequent overall survival.