Prognostic significance of preoperative ¹⁸F-FDG PET/CT in uterine leiomyosarcoma

Bladder leiomyoma and the utility of 18F-Fluorodeoxyglucose-Positron Emission Tomography - a Case Report

Bladder leiomyomas are rare neoplasms and various diagnostic methods are available to assist in confirming diagnosis preoperatively. Presented here is a case of bladder leiomyoma in a 41-year-old female who presented with urinary symptoms and right thigh pain. Imaging revealed a soft tissue density mass in the bladder wall. However concerns of a leiomyosarcoma remained. An 18F-fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) demonstrated low FDG uptake and absence of metastatic lesions. In combination with operative findings, the tumor allowed for localized resection instead of more invasive partial cystectomy. Therefore, FDG-PET might be used to support the diagnosis of leiomyoma and potentially facilitate a less aggressive surgical management.

Metastatic Pattern of Truncal and Extremity Leiomyosarcoma: Retrospective Analysis of Predictors, Outcomes, and Detection

Leiomyosarcomas (LMS) are a heterogenous group of malignant mesenchymal neoplasms with smooth muscle origin and are classified as either non-uterine (NULMS) or uterine (ULMS). Metastatic pattern, prognostic factors, and ideal staging/surveillance studies for truncal and extremity LMS have not been defined. A retrospective analysis of patients diagnosed with histopathology-confirmed truncal or extremity LMS between 2009 and 2019 was conducted. Data collected included demographics, tumor characteristics, staging, surveillance, and survival endpoints. The primary site was defined as: (1) extremity, (2) flank/Pelvis, or (3) chest wall/Spine. We identified 73 patients, 23.3% of which had metastatic LMS at primary diagnosis, while 68.5% developed metastatic disease at any point. The mean metastatic-free survival from primary diagnosis of localized LMS was 3.0 ± 2.8 years. Analysis of prognostic factors revealed that greater age (≥50 years) at initial diagnosis (OR = 3.74, p = 0.0003), higher tumor differentiation scores (OR = 12.09, p = 0.002), and higher tumor necrosis scores (OR = 3.65, p = 0.026) were significantly associated with metastases. Older patients (≥50 years, OR = 4.76, p = 0.017), patients with larger tumors (≥5 cm or ≥10 cm, OR = 2.12, p = 0.02, OR = 1.92, p = 0.029, respectively), higher differentiation scores (OR = 15.92, p = 0.013), and higher necrosis scores (OR = 4.68, p = 0.044) show worse survival outcomes. Analysis of imaging modality during initial staging and during surveillance showed greater tumor detection frequency when PET imaging was employed, compared to CT imaging (p < 0.0001). In conclusion, truncal and peripheral extremity LMS is an aggressive tumor with high metastatic potential and mortality. While there is a significant risk of metastases to lungs, extra-pulmonary tumors are relatively frequent, and broad surveillance may be warranted.

Differentiating uterine sarcoma from leiomyoma: BET1T2ER Check!

Although rare, uterine sarcoma is a diagnosis that no one wants to miss. Often benign leiomyomas (fibroids) and uterine sarcomas can be differentiated due to the typical low T2 signal intensity contents and well-defined appearances of benign leiomyomas compared to the suspicious appearances of sarcomas presenting as large uterine masses with irregular outlines and intermediate T2 signal intensity together with possible features of secondary spread. The problem is when these benign lesions are atypical causing suspicious imaging features. This article provides a review of the current literature on imaging features of atypical fibroids and uterine sarcomas with an aide-memoire BET¹T²ER Check! to help identify key features more suggestive of a uterine sarcoma.

Prognostic relevance of the hexosamine biosynthesis pathway activation in leiomyosarcoma

Metabolic reprogramming of tumor cells and the increase of glucose uptake is one of the hallmarks of cancer. In order to identify metabolic pathways activated in leiomyosarcoma (LMS), we analyzed transcriptomic profiles of distinct subtypes of LMS in several datasets. Primary, recurrent and metastatic tumors in the subtype 2 of LMS showed consistent enrichment of genes involved in hexosamine biosynthesis pathway (HBP). We demonstrated that glutamine-fructose-6-phosphate transaminase 2 (GFPT2), the rate-limiting enzyme in HBP, is expressed on protein level in a subset of LMS and the expression of this enzyme is frequently retained in patient-matched primary and metastatic tumors. In a new independent cohort of 327 patients, we showed that GFPT2 is associated with poor outcome of uterine LMS but not extra-uterine LMS. Based on the analysis of a small group of patients studied by ¹⁸F-FDG-PET imaging, we propose that strong expression of GFPT2 in primary LMS may be associated with high metabolic activity. Our data suggest that HBP is a potential new therapeutic target in one of the subtypes of LMS.

18F-FDG and 68Ga-DOTATOC PET/CT Findings in a Case of Abdominal Leiomyosarcoma

ABSTRACT

We report the case of a 58-year-old man with mesenteric nodule at CT performed for abdominal pain. In the suspicion of neoplastic disease, he underwent 18F-FDG PET/CT that did not show abnormal uptake. The nodule was monitored alternating CT and MRI. Two years after the first detection, MRI revealed an increase in size, and 18F-FDG PET/CT was repeated for metabolic evaluation, showing increased metabolic activity. In suspicion of neuroendocrine tumor, for anatomical site, slow growth, and clinical symptoms, 68Ga-DOTATOC PET/CT was performed showing focal uptake, indicating high expression of somatostatin receptors. The final pathology report was consistent with high-grade leiomyosarcoma.

How to differentiate uterine leiomyosarcoma from leiomyoma with imaging

Uterine leiomyomas, the most frequent benign myomatous tumors of the uterus, often cannot be distinguished from malignant uterine leiomyosarcomas using clinical criteria. Furthermore, imaging differentiation between both entities is frequently challenging due to their potential overlapping features. Because a suspected leiomyoma is often managed conservatively or with minimally invasive treatments, the misdiagnosis of leiomyosarcoma for a benign leiomyoma could potentially result in significant treatment delays, therefore increasing morbidity and mortality. In this review, we provide an overview of the differences between leiomyoma and leiomyosarcoma, mainly focusing on imaging characteristics, but also briefly touching upon their demographic, histopathological and clinical differences. The main indications and limitations of available cross-sectional imaging techniques are discussed, including ultrasound, computed tomography, magnetic resonance imaging (MRI) and positron emission tomography/computed tomography. A particular emphasis is placed on the review of specific MRI features that may allow distinction between leiomyomas and leiomyosarcomas according to the most recent evidence in the literature. The potential contribution of texture analysis is also discussed. In order to help guide-imaging diagnosis, we provide an MRI-based diagnostic algorithm which takes into account morphological and functional features, both individually and in combination, in an attempt to optimize radiologic differentiation of leiomyomas from leiomyosarcomas.

Role of 18F-FDG PET/CT in restaging and follow-up of patients with uterine sarcomas

PURPOSE

Uterine sarcomas are rare tumors with poor prognosis due to the high recurrence rates. The current role of ¹⁸F-FDG PET/CT in the post-therapy surveillance is not established yet.

MATERIALS AND METHODS

Forty-one women with uterine sarcoma underwent 73 ¹⁸F-FDG PET/CT for restaging in suspected recurrence or during follow-up in asymptomatic patients. Histopathology results and/or clinical/imaging follow-up for at least 12 months were considered the reference standard. The diagnostic accuracy and clinical impact of ¹⁸F-FDG PET/CT was calculated.

RESULTS

Thirty-three ¹⁸F-FDG PET/CT were positive, while the remaining 40 studies were negative. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ¹⁸F-FDG PET/CT were 88%, 98%, 97%, 91% and 93%, respectively. Considering patients with clinical or radiological suspicion of recurrence (n=47) and those during follow-up (n=26), sensitivity, specificity, PPV, NPV and accuracy of ¹⁸F-FDG PET/CT were 89%, 100%, 100%, 86% and 94%, and 80%, 95%, 80%, 95% and 92%, respectively. ¹⁸F-FDG PET/CT had a positive clinical impact in 9/73 (12%) studies and changed the clinical management in 8/41 (20%) patients.

CONCLUSIONS

¹⁸F-FDG PET/CT seems to be an accurate method for detection and localization of local and distant recurrence in patients with uterine sarcoma with good sensitivity and specificity and significant impact on clinical decision making.

FDG-PET Assessment of Other Gynecologic Cancers

PET and PET/computed tomography play a role in the staging, monitoring of response to therapy, and surveillance for cervical and ovarian cancers. Currently, it is also an integral part of the assessment of patients with endometrial cancer and other gynecologic malignancies, such as vaginal and vulvar cancers and uterine sarcomas. In this article, we discuss in detail and highlight the potential role of PET and PET/computed tomography in evaluating these gynecologic malignancies using illustrative cases with relevant imaging findings.

Presurgical Identification of Uterine Smooth Muscle Malignancies through the Characteristic FDG Uptake Pattern on PET Scans

The unidentified presence of uterine smooth muscle malignancies poses a tremendous risk in women planning surgery for presumed benign leiomyomas. We sought to investigate whether preoperative FDG PET may be useful to identify leiomyosarcomas (LMS) and smooth muscle tumors of uncertain malignant potential (STUMP). Methods. We investigated patients with rapidly growing uterine masses which were suspected of being malignant on ultrasound or MRI. Among the 21 patients who underwent FDG PET, we identified 7 LMS, 1 STUMP, and 13 leiomyomas. PET-derived parameters and FDG uptake patterns were analyzed retrospectively. Results. The SUV_max values of LMS/STUMP (range: 3.7–11.8) were significantly higher than those observed in leiomyomas (range: 2.0–9.4; P=0.003) despite a significant overlap. The metabolic tumor/necrosis ratio was significantly higher in LMS/STUMP than in leiomyomas (P < 0.001), with no significant intergroup overlaps. All LMS/STUMP revealed a characteristic pattern of FDG uptake, identifying a specific “hollow ball” sign (corresponding to areas of coagulative tumor necrosis). In contrast, this sign was invariably absent in patients with leiomyomas. Conclusion. The characteristic FDG uptake pattern instead of SUV on PET images allows identifying LMS/STUMP in patients with rapidly growing uterine masses, avoiding the deleterious consequences of regular surgery for presumed benign leiomyomas.

Identification of key genes and pathways in uterine leiomyosarcoma through bioinformatics analysis

Uterine leiomyosarcoma (uLMS) is a rare but malignant gynaecological tumour with a poor survival outcome. The present study was aimed at identifying the key genes and pathways in the development of uLMS through bioinformatics analysis. To minimize the frequency of false-positive results of the bioinformatics analysis, 3 microarrays including GSE764, GSE64763 and GSE68312 were downloaded from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were screened out using the online tool GEO2R. Then, Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery. Finally, a protein-protein interaction (PPI) network of the DEGs was constructed using Cytoscape, and module analysis was conducted using the plug-in MCODE. A total of 95 DEGs including 21 upregulated genes and 74 downregulated genes were identified. The upregulated DEGs were annotated with 'DNA metabolic process', 'nucleobase-containing compound biosynthetic process' and 'cellular macromolecule biosynthetic process', while the downregulated DEGs were annotated with 'cellular response to chemical stimulus', 'movement of cell or subcellular component' and 'response to inorganic substances'. The results of the PPI network analysis demonstrated that matrix metallopeptidase 9, apolipoprotein E, cyclin E1 and syndecan 1 were the predominant upregulated genes in uLMS. Additionally, the genes in the main module were enriched in 'proteoglycans in cancer', 'p53 signalling pathway' and 'extracellular matrix-receptor interaction'. The key genes and pathways identified in the present study may provide valuable clues for clarifying the molecular mechanism underlying the development of uLMS and demonstrate promise for use as diagnostic markers and therapeutic targets.

Preoperative [18F]FDG PET/CT tumour heterogeneity index in patients with uterine leiomyosarcoma: a multicentre retrospective study

PURPOSE

We investigated the prognostic value of the tumour heterogeneity index determined on preoperative [¹⁸F]FDG PET/CT in patients with uterine leiomyosarcoma (LMS).

METHODS

We retrospectively reviewed patients with uterine LMS who underwent preoperative [¹⁸F]FDG PET/CT scans at three tertiary referral hospitals. The PET/CT parameters maximum standardized uptake value of the primary tumour (SUV_max), metabolic tumour volume (MTV) and total lesion glycolysis were assessed. The negative values of the MTV linear regression slope (nMLRS) according to the SUV thresholds of 2.5 and 3.0 were determined as the tumour heterogeneity index. The value of PET/CT-derived parameters in predicting progression-free survival (PFS) and overall survival (OS) were determined in regression analyses.

RESULTS

Clinicopathological and PET/CT data from 16 patients were reviewed. The median postsurgical follow-up was 21 months (range 4-82 months), and 12 patients (75.0%) experienced recurrence. Tumour size (P = 0.017), SUV_max (P = 0.019), MTV (P = 0.016) and nMLRS (P = 0.008) were significant prognostic factors for recurrence. MTV (P = 0.048) and nMLRS (P = 0.045) were significant prognostic factors for patient survival. nMLRS was correlated with clinicopathological parameters including tumour size (Pearson's correlation coefficient γ = 0.825, P < 0.001) and lymph node metastasis (γ = 0.721, P = 0.004). Patient groups categorized according to the nMLRS cut-off value showed significant differences in PFS (P = 0.033) and OS (P = 0.044).

CONCLUSION

The preoperative tumour heterogeneity index obtained using the MTV linear regression slope may be a novel and useful prognostic marker in uterine LMS.

Utility of 18F-fluorodeoxyglucose-positron emission tomography in the differential diagnosis of benign and malignant gynaecological tumours

INTRODUCTION

Positron emission tomography/computed tomography (PET/CT) involving 18F-fluorodeoxyglucose (FDG) is widely used for systemic cancer and recurrence diagnosis. However, the differential diagnosis of benign and malignant gynaecological tumours according to FDG accumulation is unclear. This study aimed to investigate the intensity of FDG uptake/metabolic activity for the differential diagnosis of benign and malignant gynaecological tumours.

METHODS

This study included seven patients with physiological phenomena, 34 with benign tumours, 13 with borderline malignant tumours and 119 with malignant tumours who underwent 18F-FDG PET/CT. We assessed the maximum standardized uptake value (SUVmax) and determined its utility in the diagnosis of benign and malignant tumours using a receiver operating characteristic (ROC) curve analysis.

RESULTS

Among the 63 patients with ovarian tumours, the mean SUVmax of 22 patients with benign ovarian tumours was 2.48 and the mean SUVmax of 41 patients with malignant ovarian tumours was 10.98 (P < 0.001). In the ROC curve analysis, the area under the curve (AUC) was 0.977, with a 95% confidence interval of 0.947-1.000. With a cut-off value of 3.97 for the optimal SUVmax, the sensitivity and specificity were 95.1% and 86.4%, respectively. In addition, the AUC was 0.911 (95% CI: 0.768-1.000) for the assessment of uterine myomas and sarcomas. With a cut-off value of 10.62 for the optimal SUVmax, the sensitivity and specificity were 91.7% and 86.7% respectively.

CONCLUSIONS

The SUVmax value helps differentiate benign and malignant ovarian tumours, as well as uterine myomas and uterine sarcomas.