Osseous Metastases Research Articles

SAT537 Thyroid Cancer Mimicking Acute Coronary Syndrome

Abstract Disclosure: N.M. Rodrigues: None. B. Alexander: None. J. Palacios Merchan: None. Background: The use of thyrotropin –alpha for preparation of remnant ablation is associated with superior short-term quality of life and similar rates of remnant ablation as thyroid hormone withdrawal. Usually treatment with thyrotropin-alpha is well tolerated, but we need to be aware of the potential side effects. Clinical case: 61-year-old Hispanic female with multinodular goiter, underwent total thyroidectomy for compressive symptoms. The pathology report showed 4 cm invasive papillary carcinoma, well-differentiated follicular variant, with invasion of an adjacent parathyroid gland. The margins were negative, and no nodal involvement was noted. Due to the extra thyroidal extension, the plan was to undergo radioactive iodine ablation. She received two doses of thyrotropin-alpha. On the following day, 24 hours after the second thyrotropin-alpha, she complained of severe left sided chest pain and went to the emergency room. Initial workup for acute coronary syndrome was negative. CT angiography done to rule out aortic dissection showed diffuse multifocal bilateral pulmonary nodules and a 2.4 cm lytic lesion on the superior aspect of the manubrium suggesting osseous metastasis. She had severe tenderness to palpation of her chest - mostly of the sternum. We decided to perform a whole-body scan to determine if the lesions were iodine avid. Due to down trending TSH at 25 microIU/mL, she received another dose of thyrotropin-alpha. Her TSH subsequently increased to 209.4 microIU/mL with a thyroglobulin level of 2250 ng/mL. Whole body scan showed evidence of metastatic disease to the lungs bilaterally and bone metastatic lesions in the manubrium and left proximal femur. . The pain did not improve with morphine but responded well to oral diclofenac. One week later, she again received two doses of thyrotropin-alpha in preparation for radioactive iodine ablation with 200 mCi of I-131 due to the metastatic lesions. She started taking prednisone 50 mg daily for 1 week before the thyrotropin- alpha injection and continued prednisone 25 mg for five additional days. She remained asymptomatic during the radioactive iodine treatment. Conclusion: Thyrotropin-alfa has a manufacturer warning that it can lead to an increase in tumor burden resulting in severe pain and inflammation, especially at the metastatic sites. Even though imaging to look for metastasis is usually not part of the protocol before radioactive iodine ablation, it could be considered in patients with high-risk features on the surgical pathology report. This could prevent possible complications related to thyrotropin-alpha by identifying patients at risk. It is recommended that patients with cancer near their trachea, in their central nervous system, or in their lungs receive treatment with glucocorticoids to reduce inflammation. This pretreatment is shown to be very effective in preventing these complications. Presentation Date: Saturday, June 17, 2023

Comparison of Diagnostic Value between 99mTechnetium-Methylene Diphosphate Bone Scan and 99mTechnetium-Prostate-specific Membrane Antigen Scan in Patients with Prostate Cancer with Osseous Metastases.

Prostate cancer (PCa) ranks as the second most prevalent cancer among men globally. The utilization of efficient and cost-effective diagnostic and therapeutic approaches holds paramount importance in the diagnosis and treatment of these patients, significantly impacting treatment outcomes. This study focuses on the investigation and comparison of two commonly employed scans within the treatment process for these patients. In this prospective study, which spanned over 2 years, 40 patients diagnosed with PCa underwent examination using two scans: 99m Technetium-Prostate-specific Membrane Antigen (99mTC-PSMA) Scan and between Technetium-Methylene Diphosphate (99mTC-MDP) Bone Scan. The findings of these scans were then compared with each other, as well as with the results obtained from magnetic resonance imaging and the prostate-specific antigen level. The analysis of the results was conducted utilizing SPSS 22 software, and descriptive statistical methods were employed to present the findings. In this prospective study, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the 99mTC-MDP Bone Scan were found to be 88.2%, 83.3%, 96.7%, 55.5%, and 87.5%, respectively. Similarly, for the 99mTC-PSMA Scan, the corresponding values were 94.1%, 83.3%, 96.4%, 83.3%, and 92.5%, respectively. Based on the findings of this study, it can be concluded that the diagnostic accuracy of the 99mTC-PSMA Scan is marginally higher compared to the 99mTC-MDP Bone Scan. Therefore, for patients who are limited to only one scan, the 99mTC-PSMA Scan appears to be the preferable choice.

Diffuse Leptomeningeal Glioneuronal Tumors: A Case Series of Five Patients with Parenchymal Forms and an Analysis of the Diagnostic Challenges, Treatment Options and Outcomes.

Diffuse leptomeningeal glioneuronal tumors (DL-GNT) are rare glioneuronal neoplasms with oligodendroglioma-like cells. These tumors can present as a dominant intracranial mass or as a solitary spinal cord mass without leptomeningeal involvement. In this study, we aimed to determine the magnetic resonance imaging and histopathological features, treatment modalities, and clinical outcomes of the parenchymal forms of DL-GNTs. This is a retrospective three-center case series study of 5 patients with a confirmed parenchymal form of DLGTs, out of which 4 patients were adults. Brain and spinal cord MR imaging were performed in all patients at either 1.5 or 3T. The patients' age ranged from 5 years to 50 years with a mean age of 27.6 years at presentation. Four of the tumors were located in the frontal lobe, and one in the tectum. They were usually solid-cystic enhancing tumors as the other mixed neuronal-glial tumors. All of the tumors had an extension to the superficial surface of a cerebral hemisphere. One had systemic bone metastases. The clinical signs and symptoms of the parenchymal form varied based on the location of the mass, in contrast to the leptomeningeal form associated with hydrocephalus. In one case, the tumor's initial grade was defined as intermediate. The initial histopathology of the two cases was low-grade and no upgrade occurred in the follow-up period. In two cases, although the tumors were low grade initially, they progressed to an anaplastic form in the follow-up period. The parenchymal form of DL-GNTs is common in adults. Extension to the superficial surface of a cerebral hemisphere is a distinctive imaging feature. Systemic osseous metastasis may occur. Due to the presence of common histopathological features, including the biphasic composition of glial and neuronal cell elements and oligodendroglioma-like cells, a proposed classification approach might be more beneficial for the histopathological and imaging description, and management of the glioneuronal tumors with oligodendroglioma-like features.

P11.40.A GLIOBLASTOMA WITH OSSEOUS METASTASES: A SINGLE INSTITUTION CASE SERIES

Abstract BACKGROUND Although glioblastoma (GBM) is the most common malignant primary brain tumor in adults, extracranial metastasis is rare, occurring in <2% of cases. This rarity has been attributed to the blood brain barrier, immunologic factors, lack of traditional lymphatics in the brain, and the poor prognosis of GBM, limiting its opportunity to metastasize. When GBM does metastasize, bone is the most common destination. GBM may spread hematogenously to bone, especially to vertebral bodies via the surrounding venous plexus. In this single-institution study, we review the clinical characteristics of GBM patients with osseous metastases and evaluate potential risk factors and prognostic significance. MATERIAL AND METHODS Using an institutional database, we identified and retrospectively analyzed 6 GBM patients with osseous metastases and studied their demographics, tumor genetics, clinical courses, and outcomes. RESULTS Five of 6 (83%) GBM patients with osseous metastases were male, with a median age of 46 years at GBM diagnosis (range: 20-84). All patients had IDH wild type and MGMT unmethylated GBM with mutations in TP53. Two patients (33%) were initially diagnosed with gliosarcoma. All patients were treated with surgical resection followed by radiation with concurrent and adjuvant temozolomide. Five patients (83%) received bevacizumab for vasogenic edema (n=4) or intracranial tumor progression (n=1) prior to bone metastasis diagnosis. Bone metastases were diagnosed a median of 12.2 months (range: 5.3-35.2) after GBM diagnosis and 4.8 months after starting bevacizumab (range: 3.5-13.2). Two patients (33%) received immune checkpoint inhibitor therapy and two patients (33%) received tumor-treating fields prior to bone metastasis discovery. Bone metastases were symptomatic in 2 patients, presenting with back pain (n=1) and leg weakness and urinary incontinence (n=1). Three patients (50%) had concurrent metastases to other organs. Osseous metastases were biopsy-confirmed in 3 (50%) cases, while the other 3 patients had no known alternative malignancy to explain their bone metastases. After osseous metastasis discovery, the median survival was 27 days (range: 13-225). CONCLUSION Most of our GBM patients with osseous metastases were male and most, but not all, were young at GBM diagnosis. Tumor genetics common to all patients included IDH wild type, MGMT unmethylated status, and TP53 mutation, which may be important for osseous metastasis. Most patients received bevacizumab, which may be associated with earlier metastasis. While rare, metastatic GBM should be within the differential for GBM patients with bone pain or progressive neurologic symptoms, as osseous metastases portend a dismal prognosis in an already aggressive malignancy.

The role of prostate-specific antigen in the osteoblastic bone metastasis of prostate cancer: a literature review.

Prostate cancer is the only human malignancy that generates predominantly osteoblastic bone metastases, and osteoblastic bone metastases account for more than 90% of osseous metastases of prostate cancer. Prostate-specific antigen (PSA) plays an important role in the osteoblastic bone metastasis of prostate cancer, which can promote osteomimicry of prostate cancer cells, suppress osteoclast differentiation, and facilitate osteoblast proliferation and activation at metastatic sites. In the meantime, it can activate osteogenic factors, including insulin-like growth factor, transforming growth factor β2 and urokinase-type plasminogen activator, and meanwhile suppress osteolytic factors such as parathyroid hormone-related protein. To recapitulate, PSA plays a significant role in the osteoblastic predominance of prostate cancer bone metastasis and bone remodeling by regulating multiple cells and factors involved in osseous metastasis.

1303 The Role of Cemiplimab in the Management of Locally Advanced and Metastatic Squamous Cell Skin Cancers: A Case Report

Abstract This case report discusses the use of cemiplimab, an immune checkpoint inhibitor, as a single agent for management of locally advanced basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) in a 79-year-old male patient. The patient was initially referred to plastic surgery for facial lacerations closure after a fall and was incidentally found to have suspicious lesions on his central forehead, right lateral canthus, mid-face, & anterior shoulder. He had history of skin lesions treated with photodynamic therapy, and recent palliative radiotherapy and fixation of a right humerus pathological fracture. Biopsy of the lesions confirmed locally advanced BCC and SCC malignancies, and underwent staging imaging, which showed evidence of osseous metastasis and lymphadenopathy. The patient was offered operative treatment with hemi-maxillectomy, orbital exenteration, and neck and axillary dissection but opted for immunotherapy drug with cemiplimab in accordance with National Institute for Health and Care Excellence (NICE) guidelines for treatment. The patient's skin lesions improved significantly after 3 rounds of treatment with shrinkage of the right lateral canthus and right midface lesions, apparent resolution of the forehead lesion, and improvement in the chronic shoulder wound, and no palpable regional lymphadenopathy. This case report adds to the growing body of evidence supporting the use of checkpoint inhibitors for SCCs and BCCs, particularly in cases where surgery and radiotherapy are not suitable. It also discusses current guidelines and socio-economic implications of this treatment. Overall, further research/trials are needed to determine optimal management strategies and improve outcomes for patients with SCC and BCC.

A Pilot Study of F-18 Fluciclovine-PET/CT as a Diagnostic Tool for Bone Metastases in Patients With Castrate Resistant Prostate Adenocarcinoma and Correlative Analysis of Blood and Bone Molecular Testing (The FACT Study).

Suspicious F-18 fluciclovine PET/CT findings for osseous metastases from prostate cancer (PC) were targeted for core needle biopsy. We correlated the maximum standardized uptake value (SUVmax) of biopsied lesions, with biopsy results, other diagnostic outcomes, and blood and tissue molecular analysis (TMA). Patients with castrate resistant prostate cancer (CRPC) were recruited from a university oncology clinic. SUVmax, histology, blood, and TMA were correlated. Fifteen patients were enrolled and 12 underwent bone biopsies. Fifty percent of bone biopsies demonstrated malignancy. Higher SUVmax was associated with positive biopsies for adenocarcinoma (P = .003), and lesions with SUVmax ≥ 5.1 were all positive for malignancy. Significant correlation between blood and somatic TMA (P = .002) was also found. Higher uptake of F-18 fluciclovine was associated with higher predictive value for osseous metastasis on biopsy. There was a significant correlation between blood and TMA.

SDPS-08 OSSEOUS METASTASES IN H3G34-MUTANT DIFFUSE HEMISPHERIC GLIOMAS

Abstract Subset of patients with H3G34 gliomas may present with extra-CNS metastasis further complicating both diagnosis and treatment. We describe a case of a 19-year-old female presenting initially with focal motor seizure in right leg along with leg pain. MRI of the leg showed an ill-defined right distal femur expansile osteolytic lesion with central fluid signal, thick rim enhancement, endosteal scalloping, cortical invasion, and smooth enhancing periosteal reaction/soft tissue extension associated with surrounding enhancing marrow signal abnormality worrisome for lesion extension. Contrast brain MRI exhibited multiple frontal and partial lobe T2 FLAIR hyperintense lesions. The largest lesion demonstrated contrast enhancement, internal foci of restricted diffusion, and a focus of intratumoral hemorrhage. A whole-body PET/CT showed intensely FDG-avid lytic lesion in the right distal femur, with FDG activity along the biopsy tract. Hypermetabolic lytic metastases to the right femoral head and mid-sacral body were also observed. A craniotomy with brain lesion biopsy two months later indicated preliminary histopathology of malignant small round blue cell neoplasm. A biopsy from the distal right femur was non-diagnostic of malignancy but a sacral bone biopsy reported malignant small blue cell neoplasm, consistent with involvement by the patient's known cranial neoplasm. Final pathological diagnosis including molecular diagnostics was consistent with WHO grade 4 IDH-wildtype H3G34 mutant diffuse hemispheric glioma with osseous metastases. Patient was treated with chemoradiotherapy with temozolomide (TMZ). Following the sixth cycle of TMZ, MRI brain imaging was stable. Apart from holocephalic headaches, the patient had no significant medication side effects and was seizure-free. A second whole-body PET scan showed improvement and interval decrease in FDG uptake of the sacrum and right femoral head. Given the stress that patients with H3G34 can experience and the poor prognosis, it is imperative to expand our knowledge and ascertain accurate screening and diagnostic methodologies.

Osseous Metastases in Thyroid Cancer: Unveiling Risk Factors, Disease Outcomes, and Treatment Impact.

Bone is the second most common site of metastasis in patients with thyroid cancer (TC) and dramatically impacts overall survival and quality of life with no definitive cure, yet there is no extensive study of the demographic and clinical risk factors in the recent literature. Data regarding 120,754 TC patients with bone metastasis were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate analyses were used to identify the risk factors of bone metastasis occurring in various histologies of TC. Cox regression was performed to analyze the influence of bone metastasis on overall survival. Hazard ratios were computed to analyze the association between bone metastasis and the primary outcomes. Of the 120,754 records collected from the SEER database from 2000 to 2019, 976 (0.8%) presented with bone metastasis, with occurrence being the greatest in patients of age ≥ 55 years (OR = 5.63, 95%CI = 4.72-6.71), males (OR = 2.60, 95%CI = 2.27-2.97), Blacks (OR = 2.38, 95%CI = 1.95-2.9) and Asian or Pacific Islanders (OR = 1.90, 95%CI = 1.58-2.27), and single marital status. TC patients presenting with bone metastasis (HR = 2.78, 95%CI = 2.34-3.3) or concurrent bone and brain metastases (HR = 1.62, 95%CI = 1.03-2.55) had a higher mortality risk. Older age, gender, race, and single marital status were associated with bone metastasis and poorer prognosis in TC patients at initial diagnosis. Understanding such risk factors can potentially assist clinicians in making early diagnoses and personalized treatment plans, as well as researchers in developing more therapeutic protocols.

DIPG-44. DIFFUSE MIDLINE GLIOMA WITH EXTRACRANIAL METASTASIS

Abstract Diffuse midline gliomas (DMGs) are malignant infiltrative gliomas enriched in the pediatric population and characterized by loss of the H3 K27me3 epigenetic marker, most frequently via mutation of the H3F3A gene. Few cases of extracranial DMG metastasis with redemonstrated H3F3A p.K28M (K27M) mutation in metastatic tissue are reported in the literature. Here, we report two such patients, both females (ages 12 and 15), with DMG and extracranial metastasis who died 5 years after initial diagnosis. The first patient with thalamic DMG underwent biopsy, radiation, chemotherapy, and subsequent decompression of spinal metastasis. Initial tumor biopsy demonstrated mutation in BRAF p.V600E, H3F3A K27M, and TERT promoter. The epidural spinal metastasis had mutations in BRAF p.V600E, H3F3A, TERT, and TP53. The second patient with brainstem DMG, diagnosed by radiographic appearance, underwent conventional external beam radiation therapy, chemotherapy including panobinostat and direct delivery of radioimmunotherapy, intra-arterial delivery of bevacizumab, and subsequent decompression of spinal metastasis. The histology and molecular profile for the spinal metastasis was consistent with DMG H3 K27M-mutant, with mutations in BRAF p.G464V, PTPN11 p.R498L, PDGFRA, and KIT. Bone marrow biopsy demonstrated atypical extrinsic cells with strong and diffuse immunolabeling for OLIG2. Autopsy revealed solid organ and osseous metastases. Both patients significantly exceeded the median life expectancy for DMG, raising the possibility that prolonged overall survival permitted progression to a rarely observed disseminated state of disease. There was absence of TP53/p53 modulating pathway mutation seen in classic DMG in the thalamic biopsy of the first patient, as well as the metastatic disease for the second patient, which may contribute to the prolonged survival observed. Molecular analysis of metastatic disease is important, as clinically and prognostically relevant alterations that vary from the primary site of disease may be detected, which shed light on clonal evolution patterns and further our understanding of disease biology.

Stroke-like presentation of acute toxic leukoencephalopathy due to capecitabine treatment with extensive intramyelinic edema.

Stroke-like presentation of acute toxic leukoencephalopathy due to capecitabine treatment with extensive intramyelinic edema.

Accuracy of MRI scans in predicting intra-articular joint involvement in high-grade sarcomas around the knee.

Intra-articular (IA) tumours around the knee are treated with extra-articular (EA) resection, which is associated with poor functional outcomes. We aim to evaluate the accuracy of MRI in predicting IA involvement around the knee. We identified 63 cases of high-grade sarcomas in or around the distal femur that underwent an EA resection from a prospectively maintained database (January 1996 to April 2020). Suspicion of IA disease was noted in 52 cases, six had IA pathological fracture, two had an effusion, two had prior surgical intervention (curettage/IA intervention), and one had an osseous metastasis in the proximal tibia. To ascertain validity, two musculoskeletal radiologists (R1, R2) reviewed the preoperative imaging (MRI) of 63 consecutive cases on two occasions six weeks apart. The radiological criteria for IA disease comprised evidence of tumour extension within the suprapatellar pouch, intercondylar notch, extension along medial/lateral retinaculum, and presence of IA fracture. The radiological predictions were then confirmed with the final histopathology of the resected specimens. The resection histology revealed 23 cases (36.5%) showing IA disease involvement compared with 40 cases without (62%). The intraobserver variability of R1 was 0.85 (p < 0.001) compared to R2 with κ = 0.21 (p = 0.007). The interobserver variability was κ = 0.264 (p = 0.003). Knee effusion was found to be the most sensitive indicator of IA involvement, with a sensitivity of 91.3% but specificity of only 35%. However, when combined with a pathological fracture, this rose to 97.5% and 100% when disease was visible in Hoffa's fat pad. MRI imaging can sometimes overestimate IA joint involvement and needs to be correlated with clinical signs. In the light of our findings, we would recommend EA resections when imaging shows effusion combined with either disease in Hoffa's fat pad or retinaculum, or pathological fractures.

Incidence of metachronous peritoneal metastases for intrahepatic cholangiocarcinoma after curative resection: A single center cohort analysis.

e16199 Background: The impact of metachronous peritoneal metastases (m-pm) on survival after curative resection for intrahepatic cholangiocarcinoma (iCCA) is poorly understood, while there is some knowledge to the occurrence of pulmonary and hepatic metastases. Studies are needed to analyze the impact of advanced metastatic disease for m-pm for iCCA after curative resection. Methods: At the Charité - Universitätsmedizin Berlin, a total of 1979 patients with the general diagnosis of cholangiocellular carcinoma were discussed in interdisciplinary tumor conferences from 2010 to 2022. Results: At the Charité - Universitätsmedizin Berlin, a total of 1979 patients with the general diagnosis of cholangiocellular carcinoma were discussed in interdisciplinary tumor conferences from 2010 to 2022. iCCA was present in 269 cases and proven histopathological results were documented at our hospital in 227 patients. Out of these, 209 patients underwent curative resection, while no advanced tumor disease leading to termination of the indicated operation were found. Two patients presented limited synchronous peritoneal metastases (s-pm) intraoperatively. The postoperative histopathological result presented N0-status in 113 patients and N+-status in 96 patients. Metachronous metastases were diagnosed in 17 patients after 103 months on average with a mean overall survival (OS) of 108 months. Regarding postoperative complications &gt;3b Clavien-Dindo after the initial surgery one patient died in the early postoperative follow-up within the first 30 days. Complete radical resection (R0) was achieved in 133 patients, while R1-status was recorded in 28 patients. Furthermore seven m-pm patients additionally presented hepatic metastases, five m-pm patients pulmonary metastases, while one m-pm patient showed simultaneous hepatic and pulmonal metastases and one other m-pm patient developed even hepatic, pulmonal and osseous metastases. Neoadjuvant oncologic therapy was performed in two patients, adjuvant therapy was applied in six patients prior to the diagnosis of m-pm. Again, a total of five patients received palliative therapy after diagnosis of m-pm. Nevertheless, one patient underwent pulmonary metastectomy. Conclusions: The primary aim regarding the two s-pm patients was immediate postoperative surgical outcome without complications (&gt;3a according to Clavien-Dindo) and was feasible, regarding the prognostic impact of s-pm for surgical resectability; curative resection seems to be an option. The primary aim for m-pm was OS, while promising outcomes were shown in this study.

FDG PET/CT and NaF PET/CT imaging quantification of osseous metastatic lesions in patients with metastatic genitourinary (mGU) cancer and their association with survival outcomes.

e16573 Background: Identifying osseous lesions and quantifying their response to therapy is challenging. 18F-fluorodeoxyglucose (FDG) and 18F-sodium Fluoride (NaF) PET/CT are both functional imaging modalities with increased sensitivity and specificity for detecting osseous lesions. This study analyzed the association of baseline FDG PET/CT and NaF PET/CT semi-quantitative parameters of bone lesions with or without additional visceral metastasis with survival for patients (pts) with non-prostate mGU malignancies treated on a phase I study with Cabozantinib (Cabo), Nivolumab (Nivo) +/- Ipilimumab (Ipi). Methods: Patients underwent sequential FDG PET/CT and NaF PET/CT scans at baseline. Semi-quantitative imaging parameters were measured including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for FDG and fluoride uptake tumor volume (FTV) and total lesion fluoride uptake (TLF) for NaF. Total bone lesion number was captured for all scans. Bone lesion CT characteristics were grouped into 4 categories (0 = normal, 1 = osteolytic, 2 = osteoblastic and 3 = mixed). Semi-quantitative parameters were divided to create two equally sized groups (low vs high) and the association of imaging parameters and survival was determined with Kaplan-Meier curves. Results: We analyzed 40 pts with non-prostate mGU cancers and osseous metastases with or without additional visceral metastasis. Thirty-four (85%) were males; median age was 56 (range 23-81); Histologically, 19 (48%) had urothelial carcinoma, 8 renal carcinoma, 5 testicular, 2 penile cancer, 2 renal medullary, 2 urachal/adenocarcinoma, 1 mucinous and 1 bladder clear cell. Eighteen pts had mixed bone lesion CT characteristic, 8 osteolytic, 4 osteoblastic and 10 normal. A total of 111 osseous lesions were detected on FDG PET/CT while 251 lesions were detected on NaF PET/CT. FDG PET/CT low vs high SUVmax and low vs high TLG were associated with improved OS [25 months(mo) (95% CI: 14.0 – not estimable) vs 8.8 mo (2.9-25.4), p = 0.034], and [25.4mo (17.0 – not estimable) vs 8.8 mo (2.9 -24.9), p = 0.018], respectively. There was no difference in OS for pts with bone only disease compared to pts with bone and visceral disease [21mo (8.4-37.2 vs 14 mo (3.2-25.4), p = 0.12] though there was a difference in PFS [13.4mo (4.8-18.3) vs 4.5 mo (1.7-5.8), p = 0.044]. There were no NaF PET/CT semi-quantitative parameters that were associated with survival outcomes, and CT characterization of osseous lesions was also not found to be associated with survival outcomes. Conclusions: FDG PET/CT semi-quantitative parameters showed potential prognostic capabilities in pts with non-prostate mGU malignancies with bone +/- visceral metastases treated on a phase I study with CaboNivo +/- Ipi. Additional parameters and histologic subsets will be presented.

Novel MRI scoring system to assess osseous malignancy in patients with soft tissue sarcoma following radiotherapy.

11561 Background: Although radiotherapy is an important component of STS management, radiation induced changes such as radiation osteitis are commonly identified on magnetic resonance imaging (MRI). These imaging findings may be concerning for malignancy and sometimes require biopsy for investigation. This study proposes a novel MRI scoring system to assess osseous lesions and predict potential for malignancy based on MRI score in STS patients who received radiotherapy. Methods: The MRI score consisted of 3 parameters: morphology, signal intensity, and progression. Interobserver reliability between the total score of MRI examinations scored by two senior musculoskeletal radiologists were analyzed with Cohen’s kappa coefficient. Receiver operating curve (ROC) analysis was performed to determine a predictive MRI score for malignancy. Results: 156 MRI’s from 30 STS patients who received radiotherapy were retrospectively reviewed. Two (6.7%) patients developed regional osseous metastasis identified on MRI. The kappa coefficient of the scoring system was 0.785 demonstrating substantial interobserver agreement (p&lt;0.001). ROC analysis demonstrated that the optimal cut-off value for malignant lesion on MRI was 5.5 (area under the curve 0.998 (95% CI 0.993-1.000) p&lt;0.001). Conclusions: This novel MRI scoring system recommends lesions with a score of six and above to be biopsied to distinguish if malignancy is present. We believe this scoring system can be utilized by multidisciplinary care teams to guide clinical recommendations for patients with STS and MRI findings concerning for malignancy versus radiation induced changes.[Table: see text]

Predictive Value of Total Metabolic Tumor Burden Prior to Treatment in NSCLC Patients Treated with Immune Checkpoint Inhibition.

We aimed to assess the predictive value of the total metabolic tumor burden prior to treatment in patients with advanced non-small-cell lung cancer (NSCLC) receiving immune checkpoint inhibitors (ICIs). Pre-treatment 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (PET/CT) scans performed in two consecutive years for staging in adult patients with confirmed NSCLC were considered. Volume, maximum/mean standardized uptake value (SUVmax/SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were assessed per delineated malignant lesion (including primary tumor, regional lymph nodes and distant metastases) in addition to the morphology of the primary tumor and clinical data. Total metabolic tumor burden was captured by totalMTV and totalTLG. Overall survival (OS), progression-free survival (PFS) and clinical benefit (CB) were used as endpoints for response to treatment. A total of 125 NSCLC patients were included. Osseous metastases were the most frequent distant metastases (n = 17), followed by thoracal distant metastases (pulmonal = 14 and pleural = 13). Total metabolic tumor burden prior to treatment was significantly higher in patients treated with ICIs (mean totalMTV ± standard deviation (SD) 72.2 ± 78.7; mean totalTLG ± SD 462.2 ± 538.9) compared to those without ICI treatment (mean totalMTV ± SD 58.1 ± 233.8; mean totalTLG ± SD 290.0 ± 784.2). Among the patients who received ICIs, a solid morphology of the primary tumor on imaging prior to treatment was the strongest outcome predictor for OS (Hazard ratio HR 28.04, p < 0.01), PFS (HR 30.89, p < 0.01) and CB (parameter estimation PE 3.46, p < 0.01), followed by the metabolic features of the primary tumor. Interestingly, total metabolic tumor burden prior to immunotherapy showed a negligible impact on OS (p = 0.04) and PFS (p = 0.01) after treatment given the hazard ratios of 1.00, but also on CB (p = 0.01) given the PE < 0.01. Overall, biomarkers on pre-treatment PET/CT scans showed greater predictive power in patients receiving ICIs, compared to patients without ICI treatment. Morphological and metabolic properties of the primary tumors prior to treatment in advanced NSCLC patients treated with ICI showed great outcome prediction performances, as opposed to the pre-treatment total metabolic tumor burdens, captured by totalMTV and totalTLG, both with negligible impact on OS, PFS and CB. However, the outcome prediction performance of the total metabolic tumor burden might be influenced by the value itself (e.g., poorer prediction performance at very high or very low values of total metabolic tumor burden). Further studies including subgroup analysis with regards to different values of total metabolic tumor burden and their respective outcome prediction performances might be needed.

Radiation osteitis: incidence and clinical impact in the setting of radiation treatment for soft tissue sarcoma.

Radiotherapy is an important component of soft tissue sarcoma management. Radiation osteitis is a common radiographic finding identified in the setting of radiotherapy on magnetic resonance imaging (MRI). This study aims to identify the incidence of radiation osteitis in patients who received radiotherapy for soft tissue sarcoma and if a further workup, including a biopsy, was performed for concerning MRI findings. Medical records of patients with soft tissue sarcoma who received radiotherapy from 2008 to 2020 were retrospectively reviewed. Patients with at least one MRI of the sarcoma site following radiotherapy and information regarding radiotherapy treatments were included. MRIs of these patients were reviewed for the presence of radiation osteitis by two musculoskeletal radiologists. The clinical course of these patients including biopsy for concerning MRI findings, local recurrence, and metastasis was recorded. Thirty soft tissue sarcoma patients who received radiation for soft tissue sarcoma were included. Radiation osteitis was present in 18 patients. The time to osteitis present on MRI following radiotherapy completion was a median of 4.5 months. Biopsy for concerning MRI findings was performed in eight patients, five for local recurrence, and three for regional osseous metastasis. Three patients had confirmed osseous metastases. Although radiation osteitis is often a benign imaging finding, it can be difficult to discern these lesions from potentially malignant sites of disease. We recommend multidisciplinary management of soft tissue sarcoma at sarcoma centers to appropriately identify benign from malignant lesions and decide the necessity of a biopsy.

A Retrospective Multicenter Analysis of the Incidence of Bone-Only Disease at PSMA PET/CT in Castration Resistant Prostate Cancer Patients.

PSMA PET/CT has unprecedented accuracy for localization of initial or recurrent prostate cancer (PC), which can be applied in a metastasis-directed therapy approach. PSMA PET/CT (PET) also has a role in the selection of patients for metastasis-directed therapy or radioligand therapy and therapy assessment in CRPC patients. The purpose of this multicenter retrospective study was to determine the incidence of bone-only metastasis in CRPC patients who underwent PSMA PET/CT for restaging, as well as identifying potential predictors of bone-only PET positivity. The study analyzed data from 179 patients from two centers in Essen and Bologna. Results showed that 20.1% of the patients had PSMA uptake only in the bone, with the most frequent lesions located in the vertebrae, ribs, and hip bone. Half half of the patients showed oligo disease in bone and may benefit from a bone-metastasis-directed therapy. Initial positive nodal status and solitary ADT were shown to be negative predictors of osseous metastasis. The role of PSMA PET/TC in this patient population needs to be further explored in terms of its role in the evaluation and adoption of bone-specific therapies.

Rare paratesticular localization of dedifferentiated liposarcoma: Case report and review of the literature.

Dedifferentiated liposarcoma is defined as a malignant tumor that changes its shape from a well-differentiated liposarcoma to a non-liposarcomatous form. Most paratesticular liposarcomas manifest as an inguinal, painless, slow-growing mass. The standard treatment is extensive surgical excision, radiotherapy being proposed for cases with positive margins, those with recurrence, or in cases of the existence of unfavorable prognostic factors. We present the case of a young patient diagnosed initially with left hydrocele, which after 2 years proved to mask a differentiated liposarcoma of the spermatic cord. The initial clinical manifestations were represented by the increase in volume of the left groin-scrotal region and pain at this level. Microscopic examination in hematoxylin-eosin staining highlighted the presence of lipoblasts and fibroblasts in association with areas of hemorrhage and tumor necrosis. The performed immunohistochemical tests confirmed the diagnosis of dedifferentiated liposarcoma. To support and confirm the presence of the mouse double minute 2 homolog gene mutation, chromogenic in situ hybridization analysis was performed. The initial treatment was the surgical one. After 2 weeks, the patient received zolendronic acid for hypercalcemia which was caused by the osseous metastasis. The patient died secondary to acute renal failure caused by hypercalcemia despite the treatment received. This case underlines the importance of both the correct management of oncological patients, as well as immunohistochemical and genetic tests in the identification of prognostic factors, with the ultimate goal of administering an appropriate oncological treatment.

Prognosis of thyroid carcinoma patients with osseous metastases: an SEER-based study with machine learning.

Osseous metastasis (OM) is the second most common site of thyroid cancer distant metastasis and presents a poor prognosis. Accurate prognostic estimation for OM has clinical significance. Ascertain the risk factors for survival and develop an effective model to predict the 3-year, 5-year overall survival (OS) and cancer-specific survival (CSS) for thyroid cancer patients with OM. We retrieved the information of patients with OMs between 2010 and 2016 from the Surveillance, Epidemiology, and End Result Program. The Chi-square test, and univariate and multivariate Cox regression analyses were performed. Four machine learning (ML) algorithms, which were most commonly used in this field, were applied. A total of 579 patients having OMs were eligible. Advanced age, tumor size ≥ 40mm, combined with other distant metastasis were associated with worse OS in DTC OMs patients. Radioactive iodine (RAI) significantly improved CSS in both males and females. Among four ML models [logistic regression, support vector machines, extreme gradient boosting, and random forest (RF)], RF had the best performance [area under the receiver-operating characteristic curve: 0.9378 for 3-year CSS, 0.9105 for 5-year CSS, 0.8787 for 3-year OS, 0.8909 for 5-year OS]. The accuracy and specificity of RF were also the best. RF model shall be used to establish an accurate prognostic model for thyroid cancer patients with OM, not only from the SEER cohort but also intended for all thyroid cancer patients in the general population, which may be applicable in clinical practice in the future.