Is FDG-PET/CT used correctly in the combined approach for nodal staging in NSCLC patients?

BACKGROUND: The most widely accepted approach nowadays in nodal staging of non-small cell lung cancer (NSCLC) is the combined use of 18-Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) and endobronchial ultrasound-transbronchial needle aspiration (EBUS-TBNA). However, this approach may not be sufficient, especially for early stages. AIMS: Our aim was to assess whether more satisfactory results can be obtained with standardized uptake value maximum lymph node/standardized uptake value mean mediastinal blood pool (SUVmax LN/SUVmean MBP), SUVmax LN/Primary tumor, or a novel cut-off value to SUVmax in this special group. SUBJECTS AND METHODS: Patients with diagnosed NSCLC and underwent FDG-PET/CT were reviewed retrospectively. 168 LNs of 52 early stage NSCLC patients were evaluated. The LNs identified in surgery/pathology reports were found in the FDG-PET/CT images. Anatomic and metabolic parameters were measured. Statistical analysis was performed by using of MedCalc Statistical Software. RESULTS: Regardless of LNs size; sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of SUVmax >2.5 were 91.5%, 65.9%, 58.2%, and 95.1%, respectively. Optimum cut-off value of SUVmax was >4.0. Sensitivity, specificity, PPV, and NPV were found as 81.0%, 90.0%, 81.0%, and 90.0% respectively. Optimum cut-off value of SUVmax LN/SUVmean MBP was >1.71. Sensitivity, specificity, PPV, and NPV were found as 94.7%, 80.0%, 71.1%, and 96.7%, respectively. Optimum cut-off value of SUVmax LN/Primary tumor was >0.28. Sensitivity, specificity, PPV, and NPV were found as 81.1%, 85.1%, 72.9% and 90.1%, respectively. CONCLUSION: SUVmax LN/SUVmean MBP >1.71 has higher PPV than currently used, with similar NPV and sensitivity. This can provide increase in the accuracy of combined approach. In this way, faster nodal staging/treatment decisions, cost savings for healthcare system and time saving of medical professionals can be obtained.

Factors affecting the accuracy of 18F-FDG PET/CT in evaluating axillary metastases in invasive breast cancer.

BACKGROUND AND AIM: There are conflicting results of studies on accuracy of positron emission tomography (PET)/computed tomography (CT) for axillary staging. The aim of this study is to determine the factors affecting the efficacy of 18F-fluorodeoxyglucose (18F-FDG) PET/CT in detecting axillary metastases in invasive breast cancer. MATERIALS AND METHODS: Data of 232 patients with invasive breast cancer who underwent 18F-FDG PET/CT examination before surgery between January 2013 and September 2017 were reviewed retrospectively. Histopathological examination of axillary lymph nodes (ALNs) was used as a reference to assess the efficacy of 18F-FDG PET/CT in detecting axillary metastases. RESULTS: While 134 (57.8%) patients had axillary metastases as detected in 18F-FDG PET/CT scans, histopathologically axillary metastases were detected in 164 (70.7%) patients. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of 18F-FDG PET/CT in detection of axillary metastasis were 72.56%, 77.94%, 88.8%, 54%, and 74.1%, respectively. The false-negative and false-positive rates were 27.4% and 22%, respectively. In univariate analysis, patients' age, estrogen receptor positivity, higher ALN SUVmax, greater tumor size, and lymph node size determined by 18F-FDG PET/CT were all significantly associated with accuracy of 18F-FDG PET/CT for axillary metastasis. In multivariate analysis, tumor size determined by 18F-FDG PET/CT and ALN SUVmax were independent variables associated with axillary metastasis. The accuracy of 18F-FDG PET/CT for axillary metastasis was higher in patients with a larger tumor (≥19.5 mm) and a higher ALN SUVmax (≥3.2). CONCLUSION: 18F-FDG PET/CT should not be routinely used for axillary staging, especially in patients with small tumors. It cannot eliminiate the necessity of sentinel lymph node biopsy. When it is used, both visual information and optimal cut-off value of axillary node SUVmax should be taken into consideration.