Primary Pulmonary Lymphoepithelioma-like Carcinoma on FDG PET/CT

68Ga-DOTATATE PET/CT in Primary Pulmonary Lymphoepithelioma-Like Carcinoma

ABSTRACT

Primary pulmonary lymphoepithelioma-like carcinomas (LELCs) are extremely rare tumors with better prognosis than other types of lung malignancies. In this case, we present 18F-FDG and 68Ga-DOTATATE PET/CT findings in a 52-year-old woman with pathologically confirmed pulmonary LELC. The pulmonary LELC presented mild 18F-FDG but avid 68Ga-DOTATATE uptake, indicating that the somatostatin receptor 2 may be highly expressed in LELCs. Therefore, 68Ga-DOTATATE PET/CT is a useful tool for tumor detection and initial staging in patients with LELCs.

Pulmonary Lymphoepithelioma-Like Carcinoma: A Mini-Review

Pulmonary lymphoepithelioma-like carcinoma (PLELC) is a rare and distinct subtype of non-small-cell lung carcinoma associated with Epstein–Barr virus (EBV) infection. We systematically reviewed the recent research that expands our knowledge about PLELC, with main focus on its genetic profile, tumor-infiltrating environment, PD-L1 expression, circulating EBV-DNA, clinical utility of 18F-FDG PET/CT, and treatment strategy. A low frequency of typical driver mutations and widespread existence of copy number variations was detected in PLELC. Persistent EBV infection may trigger intense infiltration of lymphocytes, representing enhanced tumor immunity and possibly resulting in a better prognosis. Circulating EBV-DNA in the plasma of patients with PLELC may predict disease progression and response to therapy. PLELC is 18F-FDG avid, and 18F-FDG PET may help refine palliation strategies and subsequently improve the prognosis. Most of the reported patients present at early and resectable stage, and surgical resection with curative intent is the preferred approach. There is currently no consensus on the regimen of chemotherapy for patients with advanced stages. EGFR-targeted therapies seem to have no therapeutic effect, and the clinical impact of PD-1/PD-L1 therapy is uncertain but worthy of further research.

Metabolic tumor volume predicts overall survival in patients with primary pulmonary lymphoepithelioma-like carcinoma

Pretreatment tumor metabolic burden, measured using fluorine-18 fluorodeoxyglucose positron emission tomography/computerized tomography (¹⁸F-FDG PET/CT), has been demonstrated to predict outcomes in various types of malignancies. Additionally, Epstein-Barr virus (EBV) serum titer is associated with stages of pulmonary lymphoepithelioma-like carcinoma (LELC). The present study aimed to investigate the prognostic value of the functional parameters of ¹⁸F-FDG PET/CT in pulmonary LELC and their association with serum EBV DNA. The present retrospective study analyzed data from 71 patients with pulmonary LELC; among these, 32 patients with pulmonary LELC underwent pretreatment ¹⁸F-FDG PET/CT staging between January 2008 and December 2016. EBV viral load and functional parameters of ¹⁸F-FDG PET/CT were used for survival analysis. Multivariate analysis identified tumor stage IV as a significant predictor of poor progression-free survival [hazard ratio (HR), 4.85; P=0.049], whereas elevated total metabolic tumor volume (MTV ≥72.6 ml) independently predicted worse overall survival (OS; HR, 12.59; P=0.024). Pretreatment serum EBV DNA titer was significantly positively associated with total MTV (P=0.0337) and total lesion glycolysis (TLG; P=0.0093), but could not predict outcomes. Total MTV was an independent predictor of OS, and may guide clinical management for pulmonary LELC.

Prognostic Value and Clinical Impact of Pretreatment FDG PET in Pulmonary Lymphoepithelioma-Like Carcinoma

PURPOSE

Compared with other forms of non-small cell lung cancer, pulmonary lymphoepithelioma-like carcinoma (LELC) is rarer and portends better outcomes. We sought to investigate the prognostic role and clinical impact of pretreatment F-FDG PET in pulmonary LELC.

METHODS

A total of 71 patients with pulmonary LELC were identified through a retrospective review of clinical records. Of them, 41 underwent F-FDG PET for primary staging. Outcomes were assessed using the Kaplan-Meier method and Cox regression models with a forward stepwise selection procedure. Staging changes served as the main outcome measure for assessing the impact of F-FDG PET. For the purpose of analyses, all patients were restaged according the American Joint Committee on Cancer Staging Manual eighth edition.

RESULTS

Stage and pretreatment F-FDG PET were significantly independent predictors of overall survival (OS) on multivariate analysis. Five-year OS rates for patients with stages I-II, III-IVA, and IVB were 92.3%, 70.4%, and 20.0%, respectively. The use of F-FDG PET for staging purposes was associated with a better OS (P = 0.003). Specifically, the 5-year OS rates for patients who were staged with and without F-FDG PET were 85.4% and 49.7%, respectively (P = 0.012). F-FDG PET resulted in a disease upstage in 28.6% of patients with CT-defined stages III-IVA; of them, 14.3% were upstaged to IVB disease.

CONCLUSIONS

The American Joint Committee on Cancer eighth edition stage and pretreatment F-FDG PET were independent prognostic factors for OS in patients with pulmonary LELC. F-FDG PET imaging resulted in a better disease staging with a corresponding optimization of therapeutic interventions, which ultimately improved survival outcomes.