Pitfalls and Limitations in Non–Small Cell Lung Cancer Staging

The Superiority of Fibroblast Activation Protein Inhibitor (FAPI) PET/CT Versus FDG PET/CT in the Diagnosis of Various Malignancies

Cancer represents a major cause of death worldwide and is characterized by the uncontrolled proliferation of abnormal cells that escape immune regulation. It is now understood that cancer-associated fibroblasts (CAFs), which express specific fibroblast activation protein (FAP), are critical participants in tumor development and metastasis. Researchers have developed various FAP-targeted probes for imaging of different tumors from antibodies to boronic acid-based inhibitor molecules and determined that quinoline-based FAP inhibitors (FAPIs) are the most appropriate candidate as the radiopharmaceutical for FAPI PET/CT imaging. When applied clinically, FAPI PET/CT yielded satisfactory results. Over the past few years, the utility and effectiveness of tumor detection and staging of FAPI PET/CT have been compared with FDG PET/CT in various aspects, including standardized uptake values (SUVs), rate of absorbance and clearance. This review summarizes the development and clinical application of FAPI PET/CT, emphasizing the diagnosis and management of various tumor types and the future prospects of FAPI imaging.

Comparison of 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT in patients with non-small cell lung cancer

AIM

In this study, we aimed to compare the diagnostic accuracy of 18 F-fluorodeoxyglucose ( 18 F-FDG) and Gallium-68 labeled fibroblast activator protein inhibitor ( 68 Ga-FAPI)-04 PET/CT in the tumor-node-metastasis (TNM) staging of patients with nonsmall cell lung cancer (NSCLC) and investigate whether adenocarcinoma (ADC) and squamous cell cancer (SCC) exhibit different uptake patterns on 68 Ga-FAPI-04 PET/CT.

MATERIALS AND METHOD

Twenty-nine patients with a histopathologically-confirmed diagnosis of NSCLC, who had no history of previous radiation therapy or chemotherapy and underwent 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT imaging between January 2021 and December 2021 were included in this retrospective study. Staging was performed using the 8th edition of the TNM staging system on both 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT images. Standardized uptake value (SUV) max and tumor-to-background ratios (TBR) were calculated on primary lesions and metastases.

RESULTS

There was no statistically significant difference in primary lesions in terms of SUV max and TBR values. However, 68 Ga-FAPI-04 PET/CT was significantly superior to 18 F-FDG PET/CT in terms of the number of lymph nodes and bone metastases revealed. The SUV max and TBR values of lymph nodes, hepatic lesions and bone lesions were significantly higher on 68 Ga-FAPI-04 PET/CT than on 18 F-FDG PET/CT. 68 Ga-FAPI-04 PET/CT changed the disease stage of three patients (10.9%). The diagnostic accuracy of 68 Ga-FAPI-04 PET/CT was 100%, whereas the diagnostic accuracy of 18 F-FDG PET/CT was 89.6% ( P  = 0.250).

CONCLUSION

Although 68 Ga-FAPI-04 PET/CT detected more lesions and higher diagnostic accuracy than 18 F-FDG PET/CT in NSCLC, neither method was statistically superior to each other in terms of diagnostic accuracy in TNM staging.

Survival after surgery for clinical stage I non-small-cell lung cancer with interstitial pneumonia

OBJECTIVES

To evaluate the surgical outcomes after surgery in patients with stage I lung cancer and idiopathic interstitial pneumonia (IIP).

MATERIAL AND METHODS

This retrospective cohort study was conducted in 2131 patients with clinical stage I non-small-cell lung cancer (NSCLC) who underwent pulmonary resection between 2009 and 2018. Based on computed tomography (CT) findings, 233 patients had IIP. Lobectomy was performed in 180 patients with IIP and 1227 patients without IIP. Surgical outcomes, recurrence sites, and cause of death were investigated. In addition, we measured the distance between the tumor and hilum in patients with IIP and assessed the feasibility of sublobar resection.

RESULTS

The overall survival and cancer-specific survival of patients with IIP were significantly poorer than those of non-IIP patients. The five-year overall survival rates of patients with clinical stage IA/IB lung cancer with and without IIP were 58.1%/47.3% and 88.8%/68.9%, respectively. Furthermore, 9.4% of patients with IIP and 0.9% of patients without IIP died from respiratory-related causes within 2 years after surgery. Multivariate analyses revealed that volume capacity <80% (odds ratio: 3.259), usual interstitial pneumonia pattern by CT finding (odds ratio: 1.891), and nodal metastasis (odds ratio: 3.304) were prognostic factors for overall survival in patients with IIP. Unexpected nodal metastases were observed in 22.3% of patients with IIP. By CT judgment, sublobar resection was not feasible in 68% of patients with IIP who underwent lobectomy.

CONCLUSIONS

The overall survival of patients with early NSCLC after pulmonary resection with IIP was poor; this is related to the high prevalence of cancer-specific and respiratory-related deaths. Sublobar resection is not always feasible, the procedure on patients with IIP should be selected carefully according to the characteristics of each case. Nodal dissection should be performed to evaluate for metastasis, regardless of the extent of lung resection.

Impact of 18F-FDG PET/CT, CT and EBUS/TBNA on preoperative mediastinal nodal staging of NSCLC

BACKGROUND

Staging of non-small-cell lung cancer (NSCLC) is a multidisciplinary process involving imaging, endoscopic and surgical techniques. This study aims at investigating the diagnostic accuracy of ¹⁸F-FDG PET/CT, CT scan, and endobronchial ultrasound/transbronchial needle aspirate (EBUS/TBNA) in preoperative mediastinal lymph nodes (MLNs) staging of NSCLC.

METHODS

We identified all patients who were diagnosed with NSCLC at the King Hussein Cancer Center in Amman, Jordan, between July 2011 and December 2017. We collected their relevant clinical, radiological, and histopathological findings. The per-patient analysis was performed on all patients (N = 101) and then on those with histopathological confirmation (N = 57), followed by a per-lymph-node-station basis overall, and then according to distinct N-stage categories.

RESULTS

¹⁸F-FDG PET/CT, in comparison to CT, had a better sensitivity (90.5% vs. 75%, p = 0.04) overall and in patients with histopathological confirmation (83.3% vs. 54.6%), and better specificity (60.5% vs. 43.6%, p = 0.01) overall and in patients with histopathological confirmation in MLN staging (60.6% vs. 38.2%). Negative predictive value of mediastinoscopy, EBUS/TBNA, and ¹⁸F-FDG PET/CT were (87.1%), (90.91%), and (83.33%) respectively. The overall accuracy was highest for mediastinoscopy (88.6%) and EBUS/TBNA (88.2%), followed by ¹⁸F-FDG PET/CT (70.2%). Dividing patients into N1 disease vs. those with N2/N3 disease yielded similar findings. Comparison between ¹⁸F-FDG PET/CT and EBUS/TBNA in patients with histopathological confirmation shows 28 correlated true positive and true negative findings with final N-staging. In four patients, ¹⁸F-FDG PET/CT detected metastatic MLNs that would have otherwise remained undiscovered by EBUS/TBNA alone. Lymph nodes with a maximal standardized uptake value (SUVmax) more than 3 were significantly more likely to be true-positive.

CONCLUSION

Multimodality staging of the MLNs in NSCLC is essential to provide accurate staging and the appropriate treatment. ¹⁸F-FDG PET/CT has better overall diagnostic utility when compared to the CT scan. The NPV of ¹⁸F-FDG PET/CT in MLNs is reliable and comparable to the NPV of EBUS/TBNA. SUVmax of MLNs can help in predicting metastases, but nevertheless, a positive ¹⁸F-FDG PET/CT MLNs particularly if such a result would change the treatment plan, should be verified histopathologically.

Recent and Current Advances in FDG-PET Imaging within the Field of Clinical Oncology in NSCLC: A Review of the Literature

Lung cancer is the leading cause of cancer-related deaths around the world, the most common type of which is non-small-cell lung cancer (NSCLC). Computed tomography (CT) is required for patients with NSCLC, but often involves diagnostic issues and large intra- and interobserver variability. The anatomic data obtained using CT can be supplemented by the metabolic data obtained using fluorodeoxyglucose F 18 (FDG) positron emission tomography (PET); therefore, the use of FDG-PET/CT for staging NSCLC is recommended, as it provides more accuracy than either modality alone. Furthermore, FDG-PET/magnetic resonance imaging (MRI) provides useful information on metabolic activity and tumor cellularity, and has become increasingly popular. A number of studies have described FDG-PET/MRI as having a high diagnostic performance in NSCLC staging. Therefore, multidimensional functional imaging using FDG-PET/MRI is promising for evaluating the activity of the intratumoral environment. Radiomics is the quantitative extraction of imaging features from medical scans. The chief advantages of FDG-PET/CT radiomics are the ability to capture information beyond the capabilities of the human eye, non-invasiveness, the (virtually) real-time response, and full-field analysis of the lesion. This review summarizes the recent advances in FDG-PET imaging within the field of clinical oncology in NSCLC, with a focus on surgery and prognostication, and investigates the site-specific strengths and limitations of FDG-PET/CT. Overall, the goal of treatment for NSCLC is to provide the best opportunity for long-term survival; therefore, FDG-PET/CT is expected to play an increasingly important role in deciding the appropriate treatment for such patients.

Role of FDG PET/CT in the Eighth Edition of TNM Staging of Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer-related mortality in the United States, and accurate staging plays a vital role in determining prognosis and treatment. The recently revised eighth edition of the TNM staging system for lung cancer defines new T and M descriptors and updates stage groupings on the basis of substantial differences in survival. There are new T descriptors that are based on the findings at histopathologic examination, and T descriptors are reassigned on the basis of tumor size and extent. No changes were made to the N descriptors in the eighth edition of the TNM staging of lung cancer, because the four N categories that are based on the location of the diseased nodes can be used to consistently predict prognosis. The eighth edition includes a new M1b descriptor for patients with a single extrathoracic metastatic lesion in a single organ (M1b), because they have better survival and different treatment options, compared with those with multiple extrathoracic lesions (M1c). Examination with fluorine 18 fluorodeoxyglucose (FDG) PET/CT is the standard of care and is an integral part of the clinical staging of patients with lung cancer. To provide the treating physicians with accurate staging information, radiologists and nuclear medicine physicians should be aware of the updated classification system and should be cognizant of the site-specific strengths and limitations of FDG PET/CT. In this article, the eighth edition of the TNM staging system is reviewed, as well as the role of FDG PET/CT in the staging of non-small cell lung carcinoma. ^©RSNA, 2018.

The Role of Fluorodeoxy-D-glucose Positron Emission Tomography/Computed Tomography in Nodal Staging of Nonsmall Cell Lung Cancer in Sequential Surgical Algorithm

With nonsmall cell lung cancer (NSCLC), accurate mediastinal nodal staging is crucial to determine whether a patient is or is not a surgical candidate. Traditionally, computed tomography (CT) and fluorodeoxy-D-glucose (FDG) positron emission tomography (PET)/CT are the initial steps followed by tissue sampling through mediastinoscopy and/or thoracotomy, which are invasive procedures. There is controversy regarding the possibility of omission of the invasive diagnostic procedures and solely relying on noninvasive presurgical staging CT and FDG PET/CT results. Eighty-three patients who had PET/CT, mediastinoscopy, and thoracotomy for NSCLC were analyzed. For all lymph nodes that may be sampled by mediastinoscopy, PET/CT sensitivity was 80%, specificity was 86%, positive predictive value was 47%, and negative predictive value (NPV) was 97%; and for those in this group whose clinical stage was T1/T2 M0, sensitivity was 100% and specificity was 84%. For lymph nodes accessible only at thoracotomy, sensitivity was 42% and specificity was 88%. FDG PET/CT is accurate in assessing stations 2R/L, 4R/L, and 7 nodes and has the potential to replace mediastinoscopy in the treatment algorithm of T1/T2 M0 disease. A negative PET/CT may potentially prevent the patient from invasive mediastinoscopy given its high NPV. However, a patient with positive PET/CT should undergo tissue biopsy with pathology confirmation.