Diagnostic value of 18F-FDG PET/CT for cutaneous extranodal natural killer/T-cell lymphoma, nasal type

68Ga-FAPI PET imaging monitors response to combined TGF-βR inhibition and immunotherapy in metastatic colorectal cancer

BACKGROUNDImproving and predicting tumor response to immunotherapy remains challenging. Combination therapy with a transforming growth factor-β receptor (TGF-βR) inhibitor that targets cancer-associated fibroblasts (CAFs) is promising for the enhancement of efficacy of immunotherapies. However, the effect of this approach in clinical trials is limited, requiring in vivo methods to better assess tumor responses to combination therapy.METHODSWe measured CAFs in vivo using the 68Ga-labeled fibroblast activation protein inhibitor-04 (68Ga-FAPI-04) for PET/CT imaging to guide the combination of TGF-β inhibition and immunotherapy. One hundred thirty-one patients with metastatic colorectal cancer (CRC) underwent 68Ga-FAPI and 18F-fluorodeoxyglucose (18F-FDG) PET/CT imaging. The relationship between uptake of 68Ga-FAPI and tumor immunity was analyzed in patients. Mouse cohorts of metastatic CRC were treated with the TGF-βR inhibitor combined with KN046, which blocks programmed death ligand 1 (PD-L1) and CTLA-4, followed by 68Ga-FAPI and 18F-FDG micro-PET/CT imaging to assess tumor responses.RESULTSPatients with metastatic CRC demonstrated high uptake rates of 68Ga-FAPI, along with suppressive tumor immunity and poor prognosis. The TGF-βR inhibitor enhanced tumor-infiltrating T cells and significantly sensitized metastatic CRC to KN046. 68Ga-FAPI PET/CT imaging accurately monitored the dynamic changes of CAFs and tumor response to combined the TGF-βR inhibitor with immunotherapy.CONCLUSION68Ga-FAPI PET/CT imaging is powerful in assessing tumor immunity and the response to immunotherapy in metastatic CRC. This study supports future clinical application of 68Ga-FAPI PET/CT to guide precise TGF-β inhibition plus immunotherapy in CRC patients, recommending 68Ga-FAPI and 18F-FDG dual PET/CT for CRC management.TRIAL REGISTRATIONCFFSTS Trial, ChiCTR2100053984, Chinese Clinical Trial Registry.FUNDINGNational Natural Science Foundation of China (82072695, 32270767, 82272035, 81972260).

Extranodal NK-/T-cell lymphoma, nasal type: what advances have been made in the last decade?

Extranodal NK-/T-cell lymphoma (ENKTCL) is a rare and highly aggressive malignancy with significant racial and geographic variations worldwide. In addition to the formerly "nasal-type" initial description, these lymphomas are predominantly extranodal in origin and typically cause vascular damage and tissue destruction, and although not fully understood, Epstein-Barr virus (EBV) has an important role in its pathogenesis. Initial assessment must include a hematopathology review of representative and viable tumor areas without necrosis for adequate immunohistochemistry studies, including EBV-encoded small RNA (EBER) in situ hybridization (ISH). Positron emission tomography with 18-fluorodeoxyglucose (¹⁸F-FDG-PET/CT) for accurate staging is essential, and most patients will have localized disease (IE/IIE) at diagnosis. Apart from other T-cell malignancies, the best treatment even for localized cases is combined modality therapy (chemotherapy plus radiotherapy) with non-anthracycline-based regimens. For advanced-stage disease, l-asparaginase-containing regimens have shown improved survival, but relapsed and refractory cases have very poor outcomes. Nowadays, even with a better understanding of pathogenic pathways, up-front therapy is completely based on chemotherapy and radiotherapy, and treatment-related mortality is not low. Future strategies targeting signaling pathways and immunotherapy are evolving, but we need to better identify those patients with dismal outcomes in a pre-emptive way. Given the rarity of the disease, international collaborations are urgently needed, and clinical trials are the way to change the future.

Multimodality imaging evaluation of primary testicular extranodal natural killer/T-cell lymphoma: two case reports

Background

Extranodal natural killer/T-cell lymphoma (ENKTCL) is a distinct pathological entity and accounts for ~10% of T-cell lymphomas. The histological features of ENKTCL include angiodestruction and coagulative necrosis and the association with EBV infection. ENKTCL is typically aggressive and mainly affects the nasal cavity and nasopharyngeal region. However, some patients can present with distant nodal or extranodal involvement such as the Waldeyer ring, gastrointestinal tract, genitourinary organs, lung, thyroid, skin, and testes. Compared to ENKTCL of nasal type, primary testicular ENKTCL is very rare and has a lower age of onset and faster clinical progression, with tumor cell dissemination occurring early in the disease.

Case report

Case 1: A 23-year-old man presented with 1 month of right testicular pain and swelling. Enhancement CT revealed increased density in the right testis, uneven increased enhancement, discontinuity of the local envelope, and multiple trophoblastic vessels in the arterial phase. Testicular ENKTCL was diagnosed by post-operative pathology. The patient underwent a follow-up ¹⁸F-FDG PET/CT imaging 1 month later and found elevated metabolism in the bilateral nasal, left testicular, and right inguinal lymph nodes. Unfortunately, the patient received no further treatment and died 6 months later. Case 2: A 2-year-old male child presented with an enlarged right testicle, MRI showed a mass in the right epididymis and testicular area, which showed low signal on T1WI, high signal on T2WI and DWI, and low signal on ADC. Meanwhile, CT showed soft tissue in the lower lobe of the left lung and multiple high-density nodules of varying sizes in both lungs. Based on the post-operative pathology, the lesion was diagnosed with primary testicular ENKTCL. The pulmonary lesion was diagnosed as hemophagocytic lymphohistiocytosis associated with EBV infection. The child was given SMILE chemotherapy, but pancreatitis was induced during chemotherapy, then he died 5 months later after chemotherapy.

Conclusion

Primary testicular ENKTCL is very rare in clinical practice, typically presenting as a painful testicular mass, which can mimic inflammatory lesions and cause diagnostic challenges. ¹⁸F-FDG PET/CT plays pivotal roles in the diagnosis, staging, evaluation of treatment outcomes and prognosis evaluation in patients with testicular ENKTCL, and it is helpful to assist clinical practice to better formulate individualized treatment plans.

The role of 18F-FDG PET/CT in primary cutaneous lymphoma: an educational review

INTRODUCTION

Primary cutaneous lymphoma (PCL) is a cutaneous non-Hodgkin's lymphoma that originates in the skin and lacks extracutaneous spread upon initial diagnosis. The clinical management of secondary cutaneous lymphomas is different from that of PCLs, and earlier detection is associated with better prognosis. Accurate staging is necessary to determine the extent of disease and to choose the appropriate treatment. The aim of this review is to investigate the current and potential roles of ¹⁸F- fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET/CT) in the diagnosis, staging, and monitoring of PCLs.

METHODS

A focused review of the scientific literature was performed using inclusion criteria to filter results pertaining to human clinical studies performed between 2015 and 2021 that analyzed cutaneous PCL lesions on ¹⁸F PET/CT imaging.

RESULTS & CONCLUSION

A review of 9 clinical studies published after 2015 concluded that ¹⁸F-FDG PET/CT is highly sensitive and specific for aggressive PCLs and proved valuable for identifying extracutaneous disease. These studies found ¹⁸F-FDG PET/CT highly useful for guiding lymph node biopsy and that imaging results influenced therapeutic decision in many cases. These studies also predominantly concluded that ¹⁸F-FDG PET/CT is more sensitive than computed tomography (CT) alone for detection of subcutaneous PCL lesions. Routine revision of nonattenuation-corrected (NAC) PET images may improve the sensitivity of ¹⁸F-FDG PET/CT for detection of indolent cutaneous lesions and may expand the potential uses of ¹⁸F-FDG PET/CT in the clinic. Furthermore, calculating a global disease score from ¹⁸F-FDG PET/CT at every follow-up visit may simplify assessment of disease progression in the early clinical stages, as well as predict the prognosis of disease in patients with PCL.

The prevalence and prognosis of next-generation therapeutic targets in metastatic castration-resistant prostate cancer

The success of the PROfound, IPATential150, and TheraP trials promoted the transition from sequential treatment to therapeutic targets (TTs)-guided precision treatment in metastatic castration-resistant prostate cancer (mCRPC). The objective of this study was to evaluate the prevalence and prognostic value of TTs from these three trials. All included Chinese mCRPC patients underwent circulating tumor DNA (ctDNA) sequencing, PTEN status assessment, and dual-tracer [⁶⁸ Ga-prostate-specific membrane antigen (PSMA) and ¹⁸ F-fluorodexyglucose (FDG)] positron emission tomography/computed tomography (PET/CT). Previous treatment with cabazitaxel, Lu-PSMA or olaparib was unallowed. Patients with known significant sarcomatoid or spindle cell or neuroendocrine small cell components were also excluded. TTs were defined as positive as follows: (a) high PSMA and no PSMA-/FDG+ disease on dual-tracer PET/CT scans; (b) defects in homologous recombination repair (HRR) genes in ctDNA; and (c) loss of PTEN immunohistochemistry staining in tumor tissue. The prevalence and prognostic value on progression-free survival (PFS) of TTs were evaluated. A total of 106 consecutive mCRPC patients were included. The prevalence of positive PET/CT, HRR defect, and PTEN loss was 30%, 29% and 16%, respectively. Sixty-three patients had at least one TT. Metastatic volume (odds ratio = 5.0; P = 0.017) was the only independent factor of positive TT in multivariate analysis. Seventy-four patients received abiraterone after TT screening. Patients with positive PET/CT (P = 0.011) and HRR defect (P = 0.002) had a significantly shorter PFS after receiving abiraterone than patients with negative TTs. However, PTEN status was unrelated to PFS, which may be due to a less number of patients with PTEN loss (P = 0.952). Overall, patients with any positive TTs had a significantly shorter PFS after abiraterone than patients with negative TTs (P = 0.009). Nearly 60% of Chinese patients with mCRPC who had a poor prognosis on abiraterone were candidates for precision treatments based on the specific criteria of TTs.

Extranodal NK/T-Cell Lymphoma With Widespread Cutaneous and Subcutaneous Involvement on 18 F-FDG PET/CT

ABSTRACT

Nasal-type extranodal natural killer/T-cell lymphoma is an aggressive rare type of lymphoma that mostly affects the nasal cavity and adjacent areas. However, some patients can present with distant nodal or extranodal involvement including the Waldeyer ring, gastrointestinal tract, genitourinary organs, lung, thyroid, skin, or adrenal glands. Herein, we present a unique case of extranodal natural killer/T-cell lymphoma with widespread cutaneous and subcutaneous involvement on 18 F-FDG PET/CT.

Diffuse large B-cell lymphoma with low 18F-fluorodeoxyglucose avidity features silent B-cell receptor signaling

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of aggressive lymphomas exhibiting increased glucose uptake. However, some DLBCLs featuring relatively low ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake denoted by the maximum standardized uptake value (SUV_max) on PET/CT have been identified. The biologic correlates of such a heterogeneity have remained largely unknown. Herein, we immunohistochemically detected and found low FDG-avid DLBCL cases featuring lower expression of some key molecules involved in B-cell receptor (BCR) signaling (pSYK) and glucose metabolism (GLUT1 and HK2). Besides, BCR-deficient DLBCL xenografts were found displaying lower SUV_max and expressions of pSYK, GLUT1, and HK2. Further immunoblotting demonstrated expressions of GLUT1 and HK2 in BCR-dependent DLBCLs could be down-regulated by a chemical SYK inhibition, whereas the inhibitory effects were not observed in BCR-deficient tumors. These findings suggest low FDG-avid DLBCLs display a silent BCR signaling and PET/CT might be utilized to tailor the BCR signaling-inhibitory treatment.

Clinical value of 18F-FDG-PET/CT in staging cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin malignancy. Computed tomography (CT) and/or MRI are commonly used for staging, however, the role of fluorine-18-fluorodeoxyglucose (F-FDG)-PET is not clearly established. In this study, we evaluated F-FDG-PET/CT imaging for initial staging of cSCC.

PATIENTS AND METHODS

F-FDG-PET/CT scans performed in patients with newly diagnosed cSCC were reviewed retrospectively. Images were visually assessed for lesions and F-FDG uptake [standardized uptake value (SUV)] in primary and secondary sites was measured. Suspected lesions on F-FDG-PET/CT were correlated with histopathology when available, follow-up imaging or clinical data in others.

RESULTS

Twenty-three cSCC patients who underwent F-FDG-PET/CT at diagnosis were evaluated. Primary sites were in head/neck (n=21), chest (n=1), and foot (n=1). All patients had F-FDG-positive scans with a total of 51 F-FDG-positive lesions. All primary lesions (n=24) were F-FDG-positive (SUV: 2.3-22.8; mean 10.2), and additional 27 F-FDG-positive lesions, including 21 nodes, four cutaneous, one osseous and one lung lesion, were noted in 13 patients. Mean size of F-FDG-positive nodes was 0.9 cm (range: 0.4-2.5 cm), predominantly clinically impalpable. Pathology was available for 40/51 lesions; 31 sites positive for malignancy. SUV (mean±SD) was 9.2±6.2 for malignant and 2.7±1.2 for benign lesions. Sensitivity, positive predictive value, and accuracy of F-FDG-PET/CT scan were 100, 77.5, and 77.5%, respectively. F-FDG detected seven additional lesions in three patients, compared to CT/MRI. Overall, staging F-FDG-PET/CT detected nine prior unknown lesions in five patients that were proven metastatic disease by histopathology or follow-up; F-FDG-PET/CT modified management in 5/23 (21.7%) patients.

CONCLUSION

F-FDG-PET/CT has high sensitivity in the detection of cSCC lesions, including small cutaneous and nodal disease, and has a potential role in initial staging and management.

Restaging [18F] fludeoxyglucose positron emission tomography/computed tomography scan in recurrent cutaneous squamous cell carcinoma: Diagnostic performance and prognostic significance

BACKGROUND

There are no specific recommendations for [¹⁸F] fludeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in assessing recurrent cutaneous squamous cell carcinoma (cSCC).

OBJECTIVE

To evaluate FDG-PET/CT in recurrent cSCC.

METHODS

FDG-PET/CT scans were retrospectively reviewed. Sites of abnormal uptake were noted and correlated with biopsy/histopathology studies, where available, and with follow-up imaging or clinical data in others. Comparison with available CT/magnetic resonance imaging was performed. The prognostic significance of PET/CT parameters was evaluated, and PET/CT-based change in management was recorded.

RESULTS

A total of 115 FDG-PET/CT scans were analyzed in 100 consecutive patients with cSCC. Of these, 96 (84%) scans were positive for recurrence, and 25 showed distant metastases. PET/CT detected unsuspected disease sites in 39 of 115 scans (34%), locoregional disease in 14, distant metastases in 11, both locoregional disease and distant metastases in 8, additional local cutaneous disease in 5, and second malignancy in 1. Comparison of 78 PET/CT scans with available CT/magnetic resonance imaging showed 37 additional abnormalities on 23 PET/CT scans, predominantly including skin/subcutaneous lesions and nodes. PET/CT led to change in management in 28% of patients. On univariate/multivariate analysis, increased number of FDG-positive lesions and lung metastases on PET/CT was associated with increased risk of death/disease progression.

LIMITATIONS

Retrospective study.

CONCLUSIONS

FDG-PET/CT was sensitive in detecting recurrent disease in cSCC, led to change in management for 28% of patients, and proved to be of prognostic value.

Positron emission tomography/computed tomography in the diagnosis, staging, and prognostic evaluation of natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTL) is a rare subtype of non-Hodgkin's lymphoma that is associated with Epstein-Barr virus infection. The clinicopathological features of NKTL are unique among lymphomas. NKTL is an aggressive disease with a poor prognosis in the absence of effective treatment. Accurate diagnosis and staging are essential to ensure an appropriate treatment strategy and accurate prognosis of NKTL. ¹⁸F-Fluorodexoyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a valuable technique in the diagnosis, staging, and prognostic evaluation of various types of malignant tumors, including NKTL. PET/CT imaging studies of patients with NKTL have shown that NKTL is ¹⁸F-FDG-avid and that PET/CT is superior to conventional methods in detecting cutaneous and extracutaneous lesions. We herein review recent PET/CT studies that have provided considerable insight into the diagnosis, staging, prognostic evaluation, and treatment effectiveness in patients with NKTL.

Prognostic significance of standardized uptake value on F18-FDG PET/CT in patients with extranodal nasal type NK/T cell lymphoma: A multicenter, retrospective analysis

OBJECTIVES

The purpose of this study was to evaluate the value of parameters assessed with F18-flurodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in predicting relapse free survival and overall survival in patients with extranodal nasal type NK/T cell lymphoma.

METHODS

Thirty-six patients with extranodal nasal type NK/T cell lymphoma, and who underwent PET/CT prior to curative treatment, were enrolled at five institutions. Volumes of interest covering the entire tumor volume were delineated on PET/CT images, and the maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured using thresholds of 40% of SUVmax. Furthermore, we compared the difference in F18-FDG avidity according to Epstein-Barr virus (EBV) infection status.

RESULTS

The SUVmax (p=0.041) and SUVmean (p=0.049) in patients who died were higher than the respective values of those who survived. A higher TLG (>45.8) was associated with relapse free survival (HR 7.856, p=0.034). Ann Arbor stage (III-IV, HR 14.12, p=0.004), and a higher SUVmax (>12.6, p=0.024) and SUVmean (>6.4, p=0.024) were associated with poor survival. However, neither the MTV nor the TLG (volumetric parameters) were significant predictors of death. The PET parameters SUVmax (p=0.181), SUVmean (p=0.237), MTV (p=0.636), and TLG (p=0.469) did not differ significantly between patients with and without EBV infections.

CONCLUSIONS

High TLG was the only significant predictive factor on relapse free survival. The SUVmax and SUVmean measured by F18-FDG PET/CT could be significant prognostic factors in patients with extranodal nasal type NK/T cell lymphoma.