Accuracy and Cost-Effectiveness of [18F]-2-Fluoro-Deoxy-D-Glucose-Positron Emission Tomography Scan in Potentially Resectable Non-small Cell Lung Cancer

Synthetic 18F labeled biomolecules that are selective and promising for PET imaging: major advances and applications

The concept of positron emission tomography (PET) based imaging was developed more than 40 years ago. It has been a widely adopted technique for detecting and staging numerous diseases in clinical settings, particularly cancer, neuro- and cardio-diseases. Here, we reviewed the evolution of PET and its advantages over other imaging modalities in clinical settings. Primarily, this review discusses recent advances in the synthesis of 18F radiolabeled biomolecules in light of the widely accepted performance for effective PET. The discussion particularly emphasizes the 18F-labeling chemistry of carbohydrates, lipids, amino acids, oligonucleotides, peptides, and protein molecules, which have shown promise for PET imaging in recent decades. In addition, we have deliberated on how 18F-labeled biomolecules enable the detection of metabolic changes at the cellular level and the selective imaging of gross anatomical localization via PET imaging. In the end, the review discusses the future perspective of PET imaging to control disease in clinical settings. We firmly believe that collaborative multidisciplinary research will further widen the comprehensive applications of PET approaches in the clinical management of cancer and other pathological outcomes.

Correlation analysis between unenhanced and enhanced CT radiomic features of lung cancers presenting as solid nodules and their efficacy for predicting hilar and mediastinal lymph node metastases

Objectives

If hilar and mediastinal lymph node metastases occur in solid nodule lung cancer is critical for tumor staging, which determines the treatment strategy and prognosis of patients. We aimed to develop an effective model to predict hilar and mediastinal lymph node metastases by using texture features of solid nodule lung cancer.

Methods

Two hundred eighteen patients with solid nodules on CT images were analyzed retrospectively. The 3D tumors were delineated using ITK-SNAP software. Radiomics features were extracted from unenhanced and enhanced CT images based on AK software. Correlations between radiomics features of unenhanced and enhanced CT images were analyzed with Spearman rank correlation analysis. According to pathological findings, the patients were divided into no lymph node metastasis group and lymph node metastasis group. All patients were randomly divided into training group and test group at a ratio of 7:3. Valuable features were selected. Multivariate logistic regression was used to build predictive models. Two predictive models were established with unenhanced and enhanced CT images. ROC analysis was used to estimate the predictive efficiency of the models.

Results

A total of 7 categories of features, including 107 features, were extracted. There was a high correlation between the 7 categories of features from unenhanced CT images and enhanced CT images (all r > 0.7, p < 0.05). Among them, the shape features had the strongest correlation (mean r = 0.98). There were 5 features in the enhanced model and the unenhanced model, which had important predicting significance. The AUCs were 0.811 and 0.803, respectively. There was no significant difference in the predictive performance of the two models (DeLong's test, p = 0.05).

Conclusion

Our study models achieved higher accuracy for predicting hilar and mediastinal lymph node metastasis of solid nodule lung cancer and have some value in promoting the staging accuracy of lung cancer. Our results show that CT radiomics features have potential to predict hilar and mediastinal lymph node metastases in solid nodular lung cancer. In addition, enhanced and unenhanced CT radiomics models had comparable predictive power in predicting hilar and mediastinal lymph node metastases.

Perforation of small intestine secondary to metastatic lung adenocarcinoma: A case report

RATIONALE

About 50% of patients with a diagnosis of nonsmall cell lung carcinoma exhibit metastatic disease at the time of diagnosis. The preferential sites of extrapulmonary spread are the lymph nodes, liver, brain, adrenal glands, and bones; gastrointestinal tract perforation secondary to metastatic lung cancer is extremely rare.

PATIENT CONCERNS

A 60-year-old male nonsmoker patient presented with a 20-day history of facial, neck, and right upper limb edema. Physical examination revealed a 3.5 cm mass in his right chest. Computed tomography (CT) revealed a 4 cm mass near the right lung hilum.

DIAGNOSIS

Biopsy of the right chest wall mass revealed low differentiated lung adenocarcinoma. Additionally, retroperitoneal lymphadenopathy, pericardial effusion, metastases in the mediastinum, bilateral adrenal gland, and right thoracic wall nodule, as well as multiple bone metastases were also found.

INTERVENTIONS

Since the patient was diagnosed with multiple metastatic lung cancer, chemotherapy was started. One week after chemotherapy, he experienced a sudden acute abdominal pain. Abdominal CT examination indicated the possibility of intestinal perforation. Hence, the patient underwent an emergency operation. During the surgical procedure, 2 perforations of size 1×1 cm were discovered at 110 cm and 140 cm of the jejunum from Treitz's ligament. Then, an intestinal resection and end-to-end anastomosis were performed. The pathological diagnosis of the resected specimen revealed that it was a metastatic lung adenocarcinoma of small intestine.

OUTCOMES

The patient died 10 days after operation and 19 days following the cancer diagnosis due to septic shock.

LESSONS

Gastrointestinal tract metastasis from the lung is uncommon, but the survival rate is extremely low; therefore, it should be considered as a possibility in patients who present with any of the gastrointestinal symptoms.

Dosimetric evaluation of the feasibility of stereotactic body radiotherapy for primary lung cancer with lobe-specific selective elective nodal irradiation

More than 10% of all patients treated with stereotactic body radiotherapy (SBRT) for primary lung cancer develop regional lymph node recurrence. We evaluated the dosimetric feasibility of SBRT with lobe-specific selective elective nodal irradiation (ENI) on dose-volume histograms. A total of 21 patients were treated with SBRT for Stage I primary lung cancer between January 2010 and June 2012 at our institution. The extents of lobe-specific selective ENI fields were determined with reference to prior surgical reports. The ENI fields included lymph node stations (LNS) 3 + 4 + 11 for the right upper lobe tumors, LNS 7 + 11 for the right middle or lower lobe tumors, LNS 5 + 11 for the left upper lobe tumors, and LNS 7 + 11 for the left lower lobe tumors. A composite plan was generated by combining the ENI plan and the SBRT plan and recalculating for biologically equivalent doses of 2 Gy per fraction, using a linear quadratic model. The V20 of the lung, D(1cm3) of the spinal cord, D(1cm3) and D(10cm3) of the esophagus and D(10cm3) of the tracheobronchial wall were evaluated. Of the 21 patients, nine patients (43%) could not fulfill the dose constraints. In all these patients, the distance between the planning target volume (PTV) of ENI (PTVeni) and the PTV of SBRT (PTVsrt) was ≤2.0 cm. Of the three patients who developed regional metastasis, two patients had isolated lymph node failure, and the lymph node metastasis was included within the ENI field. When the distance between the PTVeni and PTVsrt is >2.0 cm, SBRT with selective ENI may therefore dosimetrically feasible.

Abnormal FDG Uptake in the Pericardial Adipose Tissue Mimicking Malignancy

Focal mediastinal F-18 FDG uptake may be from potential adenopathy requiring biopsy confirmation or benign active brown adipose tissue to be left untouched. Knowledge of this potential pitfall and precise localization with fusion PET/CT are important in preventing misinterpretation as malignancy. Our case report is important in the aspect that CT was not able to confirm the uptake as benign finding, which led to invasive biopsy and biopsy confirmed it to be a benign brown adipose tissue.

Nomogram to Predict Occult N2 Lymph Nodes Metastases in Patients With Squamous Nonsmall Cell Lung Cancer

For nonsmall cell lung cancer (NSCLC) patients without distant metastases, occult involvement of N2 lymph nodes would be of the utmost importance in determining both treatment and survival. The key to optimal treatment strategies relied on accurate diagnosis, in particular accurate clinical tumor staging. Patients with clinical N0 or N1 staging preoperatively had a sizeable risk to have occult N2 lymph nodes metastases.From November 2004 to March 2007, the entire database in a tertiary hospital of all patients with a pathologic diagnosis of squamous NSCLC underwent anatomical pulmonary resection and systematic mediastinal lymph node dissection were retrospectively collected and reviewed. A nomogram was developed on the basis of a multivariable logistic regression model with a combination of all potential variables. In order to surmount the potential of overestimating predictive performance, both bootstrapping for internal validation and an independent external validation set were employed.A nomogram incorporating the significant risk factors was created to predict the probability of occult N2 lymph nodes metastases. The calibration plot for the probability of occult N2 lymph nodes metastases showed an optimal agreement between the predicted probabilities by nomogram and actual observed probabilities. An objective and accurate nomogram predictive model for occult N2 lymph nodes metastases was drawn up and validated internally and externally in patients with squamous NSCLC.The nomogram model, as a robust tool in predicting occult N2 lymph nodes involvement, could be involved in a cost-effective application of specific diagnostic and therapeutic strategies.

Clinical significance of Ki-67 and p53 expression in curatively resected non-small cell lung cancer

The aim of this study is to explore the association of Ki-67 and p53 expression with prognosis in non-small cell lung cancer (NSCLC) patients who underwent curative resection. We retrospectively identified 116 consecutive patients with stages I-III NSCLC who underwent curative resection at a single center from January 2007 to December 2012. Ki-67 and p53 expression was assessed by immunohistochemistry. Data on clinicopathologic features and survival were collected retrospectively. Ki-67 expression in 109 samples and p53 expression in 115 patients were analyzed. According to the results, 108 patients (99 %) showed at least some expression of Ki-67. The median Ki-67 expression level was 30 %. Positive p53 expression was observed in 91 (79 %) patients. Higher Ki-67 expression (>40 %) was significantly more frequent in male (26 vs. 4 % in female, p=0.002), ever-smoker (31 vs. 10 % in never-smoker, p=0.024), and non-adenocarcinoma (30 vs. 11 % of adenocarcinoma, p=0.012) patients. In univariable analysis, median disease-free survival (DFS) was shorter with higher Ki-67 expression (16.1 vs. 61.9 months in those with lower Ki-67 expression, p=0.005), and p53 expression did not show an association with DFS. Among 42 patients with stage I NSCLC who did not receive adjuvant chemotherapy, DFS was significantly worse in patients with higher Ki-67 expression (2-year DFS rate 57 vs. 88 %, p=0.018). In a Cox regression model, higher Ki-67 expression (>40 %) was a significant independent prognostic factor associated with poorer DFS (HR 2.9, 95 % CI 1.3-6.2) along with TNM stage and age. Higher Ki-67 expression (>40 %) showed an independent association with shorter DFS in NSCLC patients who underwent curative resection.

New CT criteria for nodal staging in non-small cell lung cancer

OBJECTIVE

The purpose of our study was to develop a simple noninvasive technique for nodal staging using routine preoperative computed tomography (CT).

MATERIALS AND METHODS

The institutional review board approved this retrospective study, and written informed consent to perform the initial and follow-up CT studies was obtained from all patients. Preoperative CT findings (n=218 patients with resectable non-small cell lung cancer) and pathological diagnoses after surgical resection were evaluated. Using CT images, lymph node section area, circumference, and lesion attenuation values (LAVs) were drawn freehand, and the short axis (SA) and long axis (LA) were measured using caliper software. Receiver operating characteristic (ROC) curves were then used to analyze the section area, circumference, and LAVs.

RESULTS

Based on ROC curves, two cut-off values, lymph node section area >30 mm(2) and circumference >25 mm, showed greater sensitivity for nodal staging than the conventional criterion of lymph node SA ≥10 mm or the LA, SA/LA ratio or LAVs. Using lymph node section area >30 mm(2) for diagnosis, the sensitivity, specificity, and accuracy of nodal staging were 90.5%, 56.3%, and 58.3%, respectively. Using lymph node circumference >25 mm, the values were 76.2%, 70.4%, and 70.8%, respectively.

CONCLUSION

Lymph node section area >30 mm(2) and circumference >25 mm can serve as supportive criteria used by radiologists and surgeons to determine nodal staging. If these CT criteria are met, use of a more sensitive procedure such as positron emission tomography or mediastinoscopy is recommended.

CONCISE ABSTRACT

CT is used routinely during preoperative management of lung cancer. Based on ROC analyses, the cut-off values for surface area, circumference, the SA/LA ratio, and LAVs for diagnosis of lymph node metastasis were 30 mm(2), 25 mm, 0.65, and 50 Hounsfield units, respectively. Our findings indicate that lymph node surface area >30 mm(2) and circumference >25 mm are supportive criteria that can be used by radiologists and thoracic surgeons to determine nodal staging and surgical indications.

Is18F FDG PET-CT cost effective in lung cancer?

Medical advances are often technology driven. One of the new technologies used in imaging is the positron emission tomography (PET)-computed tomography (CT) scanner, which combines the advantages of the functional imaging of PET with CT. This enables both functional and anatomical data to be acquired at the same time. However, such technology is expensive and not always widely available. In the assessment of patients suffering from non-small-cell lung cancer the only curative treatment is surgery or radical radiotherapy, but this is only possible if disease is limited to the affected lung and local nodes. Imaging with CT has not been reliable in determining disease load and many patients undergo futile thoracotomies, which are both expensive and also carry a significant morbidity. In this clinical scenario there is evidence that (18)F fluorodeoxyglucose PET-CT is the best discriminator of disease load and, if used in the correct clinical setting, will not only reduce the number of futile operations but also reduce costs.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

Methods for staging non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Correctly staging lung cancer is important because the treatment options and prognosis differ significantly by stage. Several noninvasive imaging studies and invasive tests are available. Understanding the accuracy, advantages, and disadvantages of the available methods for staging non-small cell lung cancer is critical to decision-making.

METHODS

Test accuracies for the available staging studies were updated from the second iteration of the American College of Chest Physicians Lung Cancer Guidelines. Systematic searches of the MEDLINE database were performed up to June 2012 with the inclusion of selected meta-analyses, practice guidelines, and reviews. Study designs and results are summarized in evidence tables.

RESULTS

The sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were approximately 55% and 81%, respectively, confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis. For PET scanning, estimates of sensitivity and specificity for identifying mediastinal metastasis were approximately 77% and 86%, respectively. These findings demonstrate that PET scanning is more accurate than CT scanning, but tissue biopsy is still required to confirm PET scan findings. The needle techniques endobronchial ultrasound-needle aspiration, endoscopic ultrasound-needle aspiration, and combined endobronchial ultrasound/endoscopic ultrasound-needle aspiration have sensitivities of approximately 89%, 89%, and 91%, respectively. In direct comparison with surgical staging, needle techniques have emerged as the best first diagnostic tools to obtain tissue. Based on randomized controlled trials, PET or PET-CT scanning is recommended for staging and to detect unsuspected metastatic disease and avoid noncurative resections.

CONCLUSIONS

Since the last iteration of the staging guidelines, PET scanning has assumed a more prominent role both in its use prior to surgery and when evaluating for metastatic disease. Minimally invasive needle techniques to stage the mediastinum have become increasingly accepted and are the tests of first choice to confirm mediastinal disease in accessible lymph node stations. If negative, these needle techniques should be followed by surgical biopsy. All abnormal scans should be confirmed by tissue biopsy (by whatever method is available) to ensure accurate staging. Evidence suggests that more complete staging improves patient outcomes.

Diagnostic imaging in the preoperative management of lung cancer

Surgical resection is the accepted standard of care for patients with non-small cell lung cancer (NSCLC). Several imaging modalities play central roles in the detection and staging of the disease. The aim of this review is to evaluate the utility of computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and PET/CT for NSCLC staging. Radiographic staging refers to the use of CT as a non-invasive diagnostic technique. However, while the vast majority of patients undergo only CT, CT is a notoriously inaccurate means of tumor and nodal staging in many situations. PET/CT clearly improves the staging, particularly nodal staging, compared to CT or PET alone. In addition, as a result of the increased soft-tissue contrast, MRI is superior to CT for distinguishing between tissue characteristics. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), which is a minimally invasive technique, also has pathological diagnostic potential. Extensive research and the resultant improvements in the understanding of genetics, histology, molecular biology and oncology are transforming our understanding of lung cancer, and it is clear that imaging modalities such as CT, MRI, PET and PET/CT will have an important role in its preoperative management. However, thoracic surgeons should also be aware of the limitations of these techniques.

Serum C-reactive protein and procalcitonin levels in non-small cell lung cancer patients

Aim of the study

The basic uses of C-reactive protein (CRP) and procalcitonin (PCT) in clinical practice are in the diagnosis and follow-up of infectious disease. The fact that CRP already achieves high levels in cases with lung cancer, however, limits its diagnostic specificity. Procalcitonin may be an important marker in the differential diagnosis of lung cancer patients who have fever and high CRP levels. Our objective in this study was to determine the levels of CRP and PCT in patients with newly diagnosed non-infectious non-small cell lung cancer (NSCLC) and to relate these results to patient and disease characteristics.

Material and methods

Serum CRP and PCT levels were measured in 79 histopathologically proven NSCLC patients and 20 healthy controls. Results were compared with demographic and clinical variables in patients with NSCLC.

Results

Serum CRP concentrations were significantly higher in NSCLC patients compared to the control group [38.30 (7.79–185) mg/dl vs. 7.79 (3.36–26.10) mg/dl; p < 0.001]. There was no significant difference between the two groups in PCT levels (p > 0.05). A mild, positive correlation was found between CRP level and tumor diameter. When comparing CRP levels in the lung cancer patients grouped according to age, sex, smoking status, clinical TNM staging and performance status (PS), the only significant difference found was that for PS score.

Conclusions

High serum CRP levels in non-infectious NSCLC patients are mainly related to PS status and weakly to tumor size. Adding serum PCT measurement may contribute to exclusion of infections in patients with NSCLC.

Use of Positron Emission Tomography in Initial Staging of Nonsmall Cell Lung Carcinoma: A Regional Teaching Hospital Experience

The ability to accurately diagnose mediastinal lymph node involvement is significantly important in patients with nonsmall cell lung cancer (NSCLC). Positron emission tomography (PET) imaging has become a standard technique to assess lymph node involvement in patients with NSCLC. The purpose of this study is to evaluate the accuracy of PET scan imaging as a mediastinal staging tool in patients with NSCLC at our regional teaching institution. We performed a single-institution, retrospective review of patients diagnosed with NSCLC from January 1, 2006, through December 31, 2007. We included only those patients who underwent computed tomography (CT), PET, and pathologic assessment of mediastinal lymph nodes. Using pathologic assessment as the criterion standard, the overall accuracy, sensitivity, specificity, and positive and negative predictive values of CT and PET were calculated. One hundred seventeen patients were identified for inclusion in the study. The overall accuracy was 81.2 per cent for CT and 91.5 per cent for PET. Sensitivity was 42.1 per cent for CT and 52.6 per cent for PET. Specificity was 88.8 per cent for CT and 99.0 per cent for PET. Positive predictive values were 42.1 per cent for CT and 90.9 per cent for PET; negative predictive values were 88.8 per cent for CT and 91.5 per cent for PET. False-negative result rates were 9.4 per cent for CT and 7.7 per cent for PET; false-positive result rates were 9.4 per cent for CT and 0.9 per cent for PET. Our analysis confirms the use of PET scan imaging in the staging of patients with NSCLC at a regional teaching institution.

A metastatic jejunal tumor from squamous cell carcinoma of the lung found in an intestinal perforation

An 85-year-old male with advanced squamous cell carcinoma of the lung, who was diagnosed about 10 years prior to his current presentation, suddenly complained of abdominal pain and underwent an abdominal computed tomography scan, which revealed free air and massive ascites. He was admitted to our hospital for acute peritonitis and emergency surgery was performed. During the surgical procedure, a perforation of the jejunum was diagnosed and repaired. He was diagnosed to have a metastatic tumor originating from a squamous cell carcinoma of the lung. He improved and was transferred to the former hospital on the 27th postoperative day. Jejunal metastasis from squamous cell carcinoma of the lung is rare, and the prognosis of peritonitis due to a perforated intestinal metastasis from lung cancer is poor. There have been 10 reports of jejunal metastasis of squamous cell carcinoma of the lung reported in Japan between 2000 and 2011. Therefore, when patients with advanced lung cancer present with acute abdomen, it is necessary to keep in mind the possibility of a gastrointestinal metastatic tumor.

Clinical impact of FDG PET-CT in patients with potentially operable metastatic colorectal cancer

AIM

To assess the clinical impact of 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography-computed tomography (PET-CT) in patients with potentially resectable metastatic colorectal cancer.

MATERIALS AND METHODS

One hundred and two patients with potentially resectable metastatic colorectal cancer underwent FDG PET-CT in addition to conventional imaging over an 18-month period. The findings were compared to conventional imaging, with histological or clinico-radiological validation. The impact on subsequent management was evaluated using information from clinico-radiological databases.

RESULTS

Of 102 patients (mean age 67 years, range 27-85 years), 94 had liver, five had isolated lung, and three had limited peritoneal metastases. In 31 patients (30%) PET-CT had a major impact on subsequent management, by correctly clarifying indeterminate lesions on conventional imaging as inoperable metastatic disease in 16 patients, detecting previously unsuspected metastatic disease in nine patients, identifying occult second primary tumours in three patients, and correctly down-staging three patients. PET-CT had a minor impact in 12 patients (12%), no impact in 49 cases (48%), and a potentially negative impact in 10 cases (10%). Following PET-CT, 36 (35%) patients were no longer considered for surgery. Of those remaining operative 45 of 66 (68%) underwent potentially curative metastatic surgery. In this cohort PET-CT saved 16 futile laparotomies.

CONCLUSION

FDG PET-CT has a valuable role in selected patients with metastatic colorectal cancer by improving staging accuracy and characterizing indeterminate lesions and helps triage patients to the appropriate treatment.

Colonic metastasis from primary lung adenocarcinoma: case report and review of the literature

We report a rare case of a 38-year-old woman with metastatic colonic adenocarcinoma from primary lung adenocarcinoma detected by PET/CT. She underwent colonoscopy and adenocarcinoma was diagnosed in the pathology report, which was the same as that for lymph node biopsy from a left supraclavicular lymph node. We used immunohistochemistry to diagnose primary adenocarcinoma of the lung with colonic metastasis. Owing to mutation in exon 19 of EGFR gene, targeted therapy was given to her with a prescription of oral gefitinib for 1 month as first-line treatment. It was chosen to further treat the patient with chemotherapy and radiotherapy. As the patient was suffering from increasing coughing and sputum, radiotherapy and chemotherapy were subsequently cancelled. Since the general condition of the patient was relatively poor, Tarceva was therefore prescribed. The patient had lived for 5 more months since the diagnosis of metastatic colonic adenocarcinoma.

[What is the role of FDG-PET in thoracic oncology in 2010?]

18F-Fluorodeoxyglucose-Positron Emission Tomography (FGD-PET) has been considered to have a major impact on the management of lung malignancies since the beginning of this century. Its value has been demonstrated by many publications, meta-analysis and European/American/Japanese recommendations. PET combined with computed tomography has provided useful information regarding the diagnosis and staging of lung cancer and allows for the delivery of adaptive radiotherapy. In its more common uses, PET has been shown to be cost-effective. With the widespread use of new radiotracers, PET will play an increasing role in the evaluation of response to treatment.

Economic evaluation of PET and PET/CT in oncology: evidence and methodologic approaches

PET and PET/CT have changed the diagnostic algorithm in oncology. Health care systems worldwide have recently approved reimbursement for PET and PET/CT for staging of non-small cell lung cancer and differential diagnosis of solitary pulmonary nodules because PET and PET/CT have been found to be cost-effective for those uses. Additional indications that are covered by health care systems in the United States and several European countries include staging of gastrointestinal tract cancers, breast cancer, malignant lymphoma, melanoma, and head and neck cancers. Regarding these indications, diagnostic effectiveness and superiority over conventional imaging modalities have been shown, whereas cost-effectiveness has been demonstrated only in part. This article reports on the current knowledge of economic evaluations of PET and PET/CT in oncologic applications. Because more economic evaluations are needed for several clinical indications, we also report on the methodologies for conducting economic evaluations of diagnostic tests and suggest an approach toward the implementation of these tests in future clinical studies.

Incidental PET/CT findings in the cancer patient: how should they be managed?

BACKGROUND

Despite a paucity of evidence-based guidelines, the use of PET/CT (positron emission tomography/computed tomography) in the management of cancer patients is increasing. As widespread clinical application increases, unexpected radiographic findings are occasionally identified. These incidental findings are often suspicious for a second primary malignancy. The purpose of this study was to determine the clinical impact of these incidental PET/CT findings.

METHODS

A query of our prospectively acquired Nuclear Medicine database was performed to identify patients with a known malignancy being staged or serially imaged with PET/CT. Patients with incidental findings suggestive of a second primary malignancy were selected. Statistical analysis was performed to determine the ability of PET/CT to identify a second primary malignancy. All PET/CT were interpreted by board certified nuclear radiologists.

RESULTS

Of 3,814 PET/CT scans performed on 2,219 cancer patients at our institution from January 1, 2005, to December 29, 2008, 272 patients (12% of all patients) had findings concerning for a second primary malignancy. An invasive work-up was performed on 49% (133/272) of these patients, while 15% (40/272) had no further evaluation due to an advanced primary malignancy. The remaining 36% (99/272) had no further evaluation secondary to a low clinical suspicion determined by the treating team, a clinical plan of observation, or patients lost to follow-up. Of the 133 patients evaluated further, clinicians identified a second primary malignancy in 41 patients (31%), benign disease in 62 patients (47%), and metastatic disease from their known malignancy in 30 patients (23%). The most common sites for a proven second primary malignancy were: lung (N = 10), breast (N = 7), and colon (N = 5). Investigation of these lesions was performed using several techniques, including 24 endoscopies (6 malignant). A surgical procedure was performed in 74 patients (29 malignant), and a percutaneous biopsy was performed on 34 patients (12 malignant). The overall positive predictive value for PET/CT to detect a second primary malignancy was 31% in this subgroup. At a median follow-up of 22 months, 9 of 41 patients with a second primary were dead of a malignancy, 20 were alive with disease, and 12 had no evidence of disease.

CONCLUSION

Incidental PET/CT findings consistent with a second primary are occasionally encountered in cancer patients. In our data, approximately half of these findings were benign, a third were consistent with a second primary malignancy or a metastatic focus, and the remainder were never evaluated due to physician and patient decision. Advanced primary tumors are unlikely to be impacted by a second primary tumor suggesting that this subset of patients will not benefit from further investigation. Our data suggests that, despite the high rate of false positivity, incidental PET/CT findings should be investigated when the results will impact treatment algorithms. The timing and route of investigation should be dictated by clinical judgment and the status of the primary tumor. Further investigation will need to be performed to determine the long-term clinical impact of incidentally identified second primary malignancies.

Cost of a 5-year lung cancer survivor: symptomatic tumour identification vs proactive computed tomography screening

Background:

Our objective was to analyse the cost effectiveness of computed tomography (CT) screening for lung cancer in terms of the cost per long-term survivor, which has not been evaluated to date.

Methods:

Estimations were computed based on data from the Surveillance, Epidemiology, and End Results registries covering years 1999–2003. The design framework of our model allowed for the incorporation of multiple values taken from the epidemiological and clinical literature to be utilised for cost inputs, scope of patients screened, diagnostic staging, and survival percentages applied separately to two cohorts: age 40–79 and 60–79 years. This enabled the analysis of over 1400 scenarios, each containing a unique set of input values, for which the estimated cost per 5-year survivor (CP5YS) was compared between the symptom-detected and proactive screening approaches.

Results:

Estimated CP5YS were higher for the symptom-detected approach in all 729 scenarios analysed for the cohort ages 60–79 years, ranging from approximately $5800 to $116 700 increased cost per 5-year survivor (CP5YS). For the cohort ages 40–79 years, 75% of the 729 scenarios analysed showed increased CP5YS for the symptom-detected approach ranging from $5700 to $110 000 increased CP5YS. Total costs and total 5-year survivors were higher for the proactive screening method for all scenarios analysed across both cohorts with increases ranging from 50–256% and 98–309%, respectively.

Conclusion:

The predicted increase in long-term survival with CT screening and the potential for better utilisation of health-care dollars in terms of CP5YS, particularly when screening patients over the age of 60 years, are critically important considerations in directing effective future lung cancer management strategy.

Accuracy of helical computed tomography for the identification of lymph node metastasis in resectable non-small cell lung cancer

PURPOSE

The criteria for the diagnosis of lymph node metastasis (LNM) in non-small cell lung cancer were investigated using helical computed tomography (hCT). The conventional criterion (1-cm short axis threshold) is generally accepted; however, this criterion is based on conventional CT. New criteria for LNM were investigated because the resolution of hCT is better than that of conventional CT.

METHODS

Ninety-seven NSCLC patients examined with hCT were enrolled. Both the long axis (LA) and short axis (SA) of the nodes were measured using hCT.

RESULTS

Based on the receiver operating characteristic curves, the thresholds that gave optimal sensitivity and specificity for LNM were 13 mm for LA and 9 mm for SA. The LNM diagnosis was re-evaluated using the combination of cutoff values. When the LA was > or =13 mm and the SA was > or =9 mm, the sensitivity, specificity, and accuracy were 56.3%, 92.1%, and 88.1%, respectively. When the LA was > or =13 mm or SA was > or =9 mm, sensitivity, specificity, and accuracy were 75.0%, 74.7%, and 74.7%, respectively. These values were not so different from the conventional criterion recalculated from these data.

CONCLUSION

The new criteria are considered to be useful for making a LNM diagnosis. The conventional criteria for the LNM diagnosis might therefore be applicable even for hCT.

Assessing short-term effects and costs at an early stage of innovation: the use of positron emission tomography on radiotherapy treatment decision making

OBJECTIVES

Positron emission tomography (PET) is an innovative imaging tool. Associated with computed tomography (CT), it allows a better definition for the tumor volume for radiotherapy, compared with CT only. The aim of this study was to assess the effects of PET on resource allocation (costs and savings) and on the choice of the following treatment in radiotherapy.

METHODS

In 2004 and 2005, 209 patients were enrolled (97 patients with Hodgkin's disease and 112 with non-small cell lung cancer) in a national study conducted in eight hospitals. Two treatment decisions made on the basis of CT only or CT associated with PET, were compared in a prospective study where each subject was his/her own control. The direct medical cost of using PET was assessed by microcosting, using data collected from specific questionnaires. The costs of new tests and the costs and savings associated with changes in the chosen treatment were calculated on the basis of reimbursement rates.

RESULTS

The mean cost of using PET was approximately euro 800 per patient (50 percent for the radionuclide 18F-FDG [2-[18F]fluoro-2-deoxy-D-glucose]). Radiotherapy treatments were modified for 10 percent of patients with Hodgkin's disease versus 40 percent of patients with lung cancer. Overall, the use of PET induced both increases and decreases in the mean cost per patient: the net effect was a euro 425 and euro 931 cost increase in lung cancer and Hodgkin's disease, respectively.

CONCLUSIONS

The use of PET for radiotherapy decision making seems more valuable for lung cancer than for Hodgkin's disease, both in terms of costs and changes in radiotherapy treatment. This result might help policy makers for prioritization.

Molecular imaging: reporter gene imaging

Non-invasive in-vivo molecular genetic imaging developed over the past decade and predominantly utilises radiotracer (PET, gamma camera, autoradiography), magnetic resonance and optical imaging technology. Molecular genetic imaging has its roots in both molecular biology and cell biology. The convergence of these disciplines and imaging modalities has provided the opportunity to address new research questions, including oncogenesis, tumour maintenance and progression, as well as responses to molecular-targeted therapy. Three different imaging strategies are described: (1) "bio-marker" or "surrogate" imaging; (2) "direct" imaging of specific molecules and pathway activity; (3) "indirect" reporter gene imaging. Examples of each imaging strategy are presented and discussed. Several applications of PET- and optical-based reporter imaging are demonstrated, including signal transduction pathway monitoring, oncogenesis in genetic mouse models, endogenous molecular genetic/biological processes and the response to therapy in animal models of human disease. Molecular imaging studies will compliment established ex-vivo molecular-biological assays that require tissue sampling by providing a spatial and a temporal dimension to our understanding of disease development and progression, as well as response to treatment. Although molecular imaging studies are currently being performed primarily in experimental animals, we optimistically expect they will be translated to human subjects with cancer and other diseases in the near future.

Noninvasive staging of non-small cell lung cancer: ACCP evidenced-based clinical practice guidelines (2nd edition)

BACKGROUND

Correctly staging lung cancer is important because the treatment options and the prognosis differ significantly by stage. Several noninvasive imaging studies including chest CT scanning and positron emission tomography (PET) scanning are available. Understanding the test characteristics of these noninvasive staging studies is critical to decision making.

METHODS

Test characteristics for the noninvasive staging studies were updated from the first iteration of the lung cancer guidelines using systematic searches of the MEDLINE, HealthStar, and Cochrane Library databases up to May 2006, including selected metaanalyses, practice guidelines, and reviews. Study designs and results are summarized in evidence tables.

RESULTS

The pooled sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were 51% (95% confidence interval [CI], 47 to 54%) and 85% (95% CI, 84 to 88%), respectively, confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis. For PET scanning, the pooled estimates of sensitivity and specificity for identifying mediastinal metastasis were 74% (95% CI, 69 to 79%) and 85% (95% CI, 82 to 88%), respectively. These findings demonstrate that PET scanning is more accurate than CT scanning. If the clinical evaluation in search of metastatic disease is negative, the likelihood of finding metastasis is low.

CONCLUSIONS

CT scanning of the chest is useful in providing anatomic detail, but the accuracy of chest CT scanning in differentiating benign from malignant lymph nodes in the mediastinum is poor. PET scanning has much better sensitivity and specificity than chest CT scanning for staging lung cancer in the mediastinum, and distant metastatic disease can be detected by PET scanning. With either test, abnormal findings must be confirmed by tissue biopsy to ensure accurate staging.

Staging non-small cell lung cancer

Patients with newly diagnosed non-small cell lung cancer (NSCLC) need accurate tumor staging in order to direct appropriate therapy and establish prognosis; the tumor is usually staged using the TNM system. The major imaging modalities currently used for staging this disease are thoracic computed tomography (CT) (including the adrenal glands) and whole body fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning. CT is generally most useful in evaluating the T stage, i.e. local spread of the neoplasm, whereas PET is most helpful in assessing the N and M stages, i.e. regional and distant tumor spread, respectively. Integrated CT-PET imaging adds information compared to the use of either modality alone. PET findings frequently lead to upstaging the disease and thus prevent unindicated surgeries. Magnetic resonance imaging (MRI) is helpful in evaluating local extent of disease in patients with superior sulcus tumors and possible brachial plexus involvement. Staging accuracy using any of these imaging techniques is imperfect; therefore, pathologic confirmation of positive findings is recommended, whenever possible, before denying a patient potentially curative therapy.

Ensuring the right PET scan for the right patient

Guidelines issued by the National Institute for Clinical Excellence (NICE) in the England and Wales recommend that rapid access to (18)F-deoxyglucose positron emission tomography (FDG-PET) is made available to all appropriate patients with non-small-cell lung cancer (NSCLC). The clinical evidence for the benefits of PET scanning in NSCLC is substantial, showing that PET has high accuracy, sensitivity and specificity for disease staging, as well as pre-therapeutic assessment in candidates for surgery and radical radiotherapy. Moreover, PET scanning can provide important information to assist in radiotherapy treatment planning, and has also been shown to correlate with responses to treatment and overall outcomes. If the government cancer waiting time targets are to be met, rapid referral from primary to secondary healthcare is essential, as is early diagnostic referral within secondary and tertiary care for techniques such as PET. Studies are also required to explore new areas in which PET may be of benefit, such as surveillance studies in high-risk patients to allow early diagnosis and optimal treatment, while PET scanning to identify treatment non-responders may help optimise therapy, with benefits both for patients and healthcare resource use. Further studies are needed into other forms of lung cancer, including small-cell lung cancer and mesothelioma. In conclusion, PET scanning has the potential to improve the diagnosis and management of lung cancer for many patients. Further studies and refinement of guidelines and procedures will maximise the benefit of this important technique.

Advances in positron emission tomography technology have increased the need for surgical staging in non–small cell lung cancer

OBJECTIVES

Pretreatment staging of patients with non-small cell lung cancer is critically important in determining an appropriate treatment plan. As positron emission tomography (PET) and computed tomography (CT) are proven complementary modalities in clinical staging, recent advances in PET technology have brought forth integrated PET/CT as the new standard. We tested the hypothesis that improvements in PET technology have not increased the sensitivity or specificity of PET in the staging of non-small cell lung cancer to an extent that surgical staging is no longer required.

METHODS

This is a retrospective, single-institution review of 336 patients from 1995 to 2005 with biopsy-proven non-small cell lung cancer who underwent [18F] fluoro-2-deoxy-D-glucose-PET before mediastinal lymph node sampling by cervical mediastinoscopy or thoracotomy. Clinical records, histopathologic reports, and PET findings were reviewed. Data were analyzed by the Pearson chi2 test.

RESULTS

Within the study population, 210 patients had routine PET and 126 had integrated PET/CT. For detecting mediastinal metastases the sensitivities of PET versus integrated PET/CT were 61.1% versus 85.7% (P < .05), specificities were 94.3% versus 80.6% (P < .001), positive predictive values were 68.8% versus 55.8%, negative predictive values were 92.1% versus 95.2%, and overall accuracy was 88.6% versus 81.7%.

CONCLUSIONS

Improvements in PET technology have increased integrated PET/CT sensitivity at the cost of significantly decreased specificity. Although it may appear that integrated PET/CT incurs fewer false negative results, the dramatic increase in false positive results reinforces the notion that integrated PET/CT should be used only as an adjunct to clinical staging and that surgical staging remains the gold standard in non-small cell lung cancer.

Lung cancer

Lung cancer is the most frequently occurring cancer in the world, and in the United States it is the second most common cancer diagnosed. Accurate staging by imaging can have a significant impact on appropriate treatment and surgical options. Familiarity with the different histologic subtypes of lung cancer and the typical and atypical appearances of lung cancer is vital. Radiologists serve a critical role in the diagnosis, staging, and follow-up of patients with lung cancer.

Multi-Modality Molecular Imaging of Tumors

Noninvasive in vivo molecular-genetic imaging uses nuclear, magnetic resonance, and optical imaging techniques. Described and discussed are "direct" imaging of specific molecules and pathway activity, "indirect" reporter gene imaging, and "bio-marker" or "surrogate" imaging. Applications of PET- and optical-based reporter imaging are demonstrated, including imaging of oncogenesis in genetic mouse models, endogenous molecular-genetic-biological properties, and response to therapy in animal models of human disease. Molecular imaging studies complement established ex vivo molecular-biological assays that require tissue sampling by providing a spatial as well as temporal dimension to our understanding of oncogenesis, and the progression and treatment of cancer. Molecular imaging studies being performed in experimental animals will be translated to animals in the near future.

Gastro-intestinal metastasis of primary lung carcinoma: clinical presentations and outcome

Symptomatic gastro-intestinal (GI) metastasis in lung carcinomas is extremely rare and only a few case reports have been published. Here we review all of the cases of lung cancer from January 2003 to April 2005 in a tertiary teaching hospital in Taiwan. A total of six patients (1.77%, 6/339) with primary lung cancer demonstrated symptomatic gastro-intestinal metastasis. Three patients had squamous cell carcinoma, one had adenocarcinoma, and two had small cell carcinoma. Three patients with gastric metastasis were diagnosed via gastro-endoscopy while one with cecal involvement was diagnosed via colon fiberscopy. Two patients with small bowel perforation and intussusception were diagnosed via laparotomy. We presented these rare cases and made a review of the literature.

Plasma fibrinogen and serum C-reactive protein are associated with non-small cell lung cancer

OBJECTIVES

There is an association between coagulation and lung cancer. Therefore, pre-operative plasma fibrinogen and serum C-reactive protein (CRP) concentration were assessed to determine their association with tumour characteristics and to ascertain any role in patient selection for curative resection.

METHODS

These parameters were compared with tumour size, pTNM stage, and possibility of complete resection in 93 patients with non-small cell lung cancer who underwent surgical resection.

RESULTS

Plasma fibrinogen concentration (r(s)=0.34, P=0.001) and serum CRP concentration (r(s)=0.34, P=0.001) were positively correlated with maximum pathological tumour size. A higher plasma fibrinogen concentration was associated with squamous cell carcinoma versus adenocarcinoma (4.5+/-0.13 g/L versus 3.6+/-0.28 g/L; P=0.008), with a trend towards a similar association for CRP (P=0.06). Pathological T stage was also associated with mean plasma fibrinogen and serum CRP concentration (P=0.01 and 0.04, respectively), but pN stage was not associated with either parameter. Incomplete resection occurred in 23% of patients with plasma fibrinogen > 5 g/L or serum CRP > 40 mg/L (versus only 8% when fibrinogen < or = 5 g/L and CRP < or = 40 mg/L; P=0.09).

CONCLUSIONS

Plasma fibrinogen and serum CRP are associated with tumour characteristics. High values were associated with inability to achieve complete resection which may refine patient selection for thoracotomy when used with other staging modalities. Attempted resection may be justified in a patient of borderline fitness who has favourable plasma fibrinogen and serum CRP concentration, where a high resection rate is possible. As the relationship was with T stage rather than N stage it may be complimentary to PET scanning, which has only marginally better accuracy for T stage than CT scanning.

Two cases of pulmonary paragonimiasis on FDG-PET CT imaging

Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) is useful in cancer diagnosis owing to its sensitivity to the differences in glucose metabolic rate between benign and malignant diseases, especially in the lung. One pitfall in PET imaging of lung disease, however, is the overlap in metabolic rate of inflammatory and neoplastic entities. Paragonimiasis is a food-borne parasitic disease that causes the pulmonary and pleural inflammation. We present two cases of pulmonary paragonimiasis that showed high uptake suggestive of tumor on FDG-PET CT images, both confirmed on histopathology by visualization of Paragonimus westermani eggs in the involved tissues.

Cost-effectiveness of routine mediastinoscopy in computed tomography– and positron emission tomography–screened patients with stage I lung cancer

OBJECTIVE

Accurate preoperative staging is essential for the optimal management of patients with lung cancer. An important goal of preoperative staging is to identify mediastinal lymph node metastasis. Computed tomography and positron emission tomography may identify mediastinal lymph node metastasis with sufficient sensitivity to allow omission of mediastinoscopy. This study utilizes our experience with patients with clinical stage I lung cancer to perform a decision analysis addressing whether mediastinoscopy should be performed in clinical stage I lung cancer patients staged by computed tomography and positron emission tomography.

METHODS

We retrospectively reviewed our thoracic surgery database for cases between May 1999 and May 2004. Patients deemed clinical stage I by computed tomography and positron emission tomography were chosen for further study. Individual computed tomography, positron emission tomography, and operative and pathology reports were reviewed. The postresection pathologic staging and long-term survival were recorded. A decision model was created using TreeAgePro software and our observed data for the prevalence of mediastinal lymph node metastases and for the rate of benign nodules. Data reported in the literature were also utilized to complete the decision analysis model. A sensitivity analysis of key variables was performed.

RESULTS

A total of 248 patients with clinical stage I lung tumors were identified. One hundred seventy-eight patients (72%) underwent mediastinoscopy before resection, and 5/178 (3%) showed N2 disease. An additional 9 patients were found to have N2 metastasis in the final resected specimen, resulting in a total of 14/248 patients (5.6%) with occult mediastinal lymph node metastases. Benign nodules were found in 19/248 (8%) of patients. Decision analysis determined that mediastinoscopy added 0.008 years of life expectancy at a cost of 250,989 dollars per life-year gained. The outcome was sensitive to the prevalence of N2 disease in the population and the benefit of induction versus adjuvant therapy for N2 lung cancer. If the prevalence of N2 disease exceeds 10%, the sensitivity analysis predicts that mediastinoscopy would lengthen life at a cost of less than 100,000 dollars per life-year gained.

CONCLUSION

Patients with clinical stage I lung cancer staged by computed tomography and positron emission tomography benefit little from mediastinoscopy. The survival advantage it confers is very small and is dependent on the prevalence of N2 metastasis and the unproven superiority of induction therapy over adjuvant therapy.

Quantitative assessment of SSTR2 expression in patients with non-small cell lung cancer using(68)Ga-DOTATOC PET and comparison with (18)F-FDG PET

PURPOSE

Dynamic PET studies with(68)Ga-DOTATOC were performed in patients with non-small cell lung cancer (NSCLC) to assess the somatostatin receptor 2 (SSTR2) expression. Furthermore, dynamic(18)F-fluorodeoxyglucose (FDG) studies were performed in the same patients to compare the SSTR2 expression with the tumour viability.

METHODS

The study population comprised nine patients, examined with both tracers on two different days within 1 week. Standardised uptake values (SUVs) were calculated and a two-tissue compartment model was applied to the data. Furthermore, a non-compartment model based on the fractal dimension (FD) was applied to the data.

RESULTS

The DOTATOC uptake was generally lower than the FDG uptake. Moderately enhanced DOTATOC uptake was noted in seven of the nine tumours. All kinetic parameters except k (4) were lower for DOTATOC than for FDG. The mean SUV was 2.018 for DOTATOC, in comparison to 5.683 for FDG. In particular, k (3) was highly variable for DOTATOC and showed an overlap with the normal lung tissue. The fractional blood volume V (B) was relatively low for both tracers, not exceeding 0.3. The highest significant logarithmic correlation was found for the FD of the two tracers (r=0.764, p=0.017). The logarithmic correlation for SUVs was also significant (r=0.646, p=0.060), as was that forV (B) (r=0.629, p=0.069). In contrast, none of the eight metastases which were positive on FDG PET showed any DOTATOC uptake.

CONCLUSION

The results demonstrated moderate (68)Ga-DOTATOC uptake in primary NSCLC but did not provide any evidence for SSTR2 expression in metastases. This may be caused by loss of the gene expression in metastases as compared with the primary tumours.

Positron emission tomographic scanning in the diagnosis and staging of non–small cell lung cancer 2 cm in size or less

OBJECTIVE

Several studies have suggested that positron emission tomography is more accurate than computed tomography for the staging of non-small cell lung cancer and can reduce the rate of unnecessary thoracotomy in patients with potentially resectable disease. However, there are few data on the utility of positron emission tomography in the diagnosis of patients with tumors of 2 cm or less in size.

METHODS

Patients with cT1/cT2 tumors of 2 cm or less in size were retrospectively reviewed. All had a computed tomographic scan, as well as a positron emission tomographic scan on a dedicated scanner, with a standard uptake value reported. A standard uptake value of 2.5 g/mL or greater was considered positive. The results of computed tomography and positron emission tomography were correlated with pathologic results after either resection (n = 60) or mediastinoscopy (n = 4).

RESULTS

Sixty-four patients (38 women; mean age, 66 years) had a mean tumor size of 1.4 cm (range, 0.7-2.0 cm). Forty-three patients had adenocarcinoma, 13 had adenocarcinoma-bronchioloalveolar carcinoma, 5 had squamous cell carcinoma, and 3 had other tumor types. Twenty-nine (45%) tumors had negative positron emission tomographic results. Both tumor size (>1 cm vs < or =1 cm) and cell type (adenocarcinoma-bronchioloalveolar carcinoma vs all other cell types) were significant predictors of positron emission tomography uptake in the primary tumor (P = .05 and .01, respectively). Nodal metastases were detected pathologically in 11 (17%) patients (5 N1 and 6 N2). Positron emission tomographic sensitivity and specificity for nodal metastases were only 45% and 89%, respectively. There was no statistically demonstrable survival difference between positron emission tomography-positive and positron emission tomography-negative tumors (3-year survival of 87% vs 100%, respectively).

CONCLUSION

Positron emission tomographic scanning has no demonstrable benefit in the diagnosis, staging, or prognosis of patients with tumors of 2 cm or less in size.

Accuracy of Helical Computed Tomography and [18F] Fluorodeoxyglucose Positron Emission Tomography for Identifying Lymph Node Mediastinal Metastases in Potentially Resectable Non–Small-Cell Lung Cancer

Purpose

Computed tomography (CT) and [18F] Fluorodeoxyglucose positron emission tomography (FDG-PET) are considered suitable methods for the noninvasive staging of the mediastinum. Our study was intended to estimate the efficacy of contrast-enhanced helical CT (hCT) and FDG-PET, alone and combined, in the diagnosis of lymph node mediastinal metastases.

Methods

This study was a prospective and blind comparison of the efficacy of hCT and FDG-PET with two alternative reference standards, mediastinoscopy, and mediastinoscopy plus thoracotomy plus a 6-month follow-up to diagnose lymph node mediastinal metastases in 132 consecutive patients with potentially resectable non–small-cell lung cancer (NSCLC). The metastatic disease was assessed histopathologically. Further clinical information was obtained postoperatively after a median follow-up of 42 months.

Results

The prevalence of cN2,3 is 0.28. For hCT the sensitivity and specificity are 0.86 (95% CI, 0.70 to 0.93) and 0.67 (95% CI, 0.56 to 0.75), for PET 0.94 (95% CI, 0.81 to 0.98) and 0.59 (95% CI, 0.49 to 0.68), and for hCT and PET combined in-parallel 0.97 (95% CI, 0.84 to 0.99) and 0.44 (95% CI, 0.34 to 0.53), which translate into a negative predicted probability of 0.98 (95% CI, 0.88 to 1.00). The crude diagnostic odds ratio of PET in the total sample studied is 13.1, in the subgroup hCT+ 11.04 (3.0 to 40 0.1), and in the hCT- 3.5 (0.5 to 21.5). Similar results were obtained for hCT stratified by PET.

Conclusion

hCT and PET perform similarly in the mediastinal staging of NSCLC, both tests are conditionally dependent and provide complementary information, and their diagnostic value mainly resides on the negative results.