[Value of positron emission tomography with 18-fluorodeoxyglucose (FDG-PET) in diagnosis of recurrent bronchial carcinoma]

Usefulness of fluoro-2-deoxyglucose positron emission tomography for investigating unexplained rising carcinoembryonic antigen levels that occur during the postoperative surveillance of lung cancer patients

BACKGROUND

Positron emission tomography with 18-fluorodeoxyglucose (FDG-PET) has been useful for the detection of recurrent lung cancer. However, such technology is expensive and is not always widely available. In this study, we evaluated the selected use of FDG-PET for lung cancer patients with re-elevated levels of serum carcinoembryonic antigen (CEA) after curative surgery.

METHODS

Among 327 patients who underwent curative resection for primary lung cancer from May 2002 through March 2007, 199 had adenocarcinoma, of whom 78 (39%) had elevated levels of serum CEA before treatment. After surgery, the level was monitored every 1 to 3 months. Re-elevation of CEA was recognized in 39 (50%) patients, 22 of whom underwent FDG-PET and were included in this study. FDG-PET images were visually inspected, and abnormally increased FDG uptake was interpreted as recurrence. The sensitivity, specificity, positive predictive value, and negative predictive value of PET in detecting recurrent lung cancer were determined.

RESULTS

FDG-PET correctly identified 14 out of 15 relapses and gave true negative results in six out of seven remissions, i.e., one false-negative and one false-positive were observed. The sensitivity, specificity, positive predictive value, and negative predictive value were 93%, 86%, 93%, and 86%, respectively.

CONCLUSION

In 64% of the patients with unexplained increased CEA levels, FDG-PET provided decisive diagnostic clues guiding further diagnostic and therapeutic interventions. The selected use of FDG-PET for patients with re-elevated serum CEA levels after surgery can be a practical and effective mode of surveillance for detecting recurrent lung cancer.

Diagnostic performance and prognostic impact of FDG-PET in suspected recurrence of surgically treated non-small cell lung cancer

PURPOSE

The differentiation of recurrent lung cancer and post-therapeutic changes remains a problem for radiological imaging, but FDG-PET allows biological characterisation of tissues by visualising glucose metabolism. We evaluated the diagnostic performance and prognostic impact of FDG-PET in cases of suspected relapse of lung cancer.

METHODS

In 62 consecutive patients, 73 FDG-PET scans were performed for suspected recurrence after surgical therapy of lung cancer. FDG uptake by lesions was measured as the standardised uptake value (SUV). PET results were compared with the final diagnosis established by biopsy or imaging follow-up. SUV and clinical parameters were analysed as prognostic factors with respect to survival.

RESULTS

FDG-PET correctly identified 51 of 55 relapses and gave true negative results in 16 of 18 remissions (sensitivity, specificity, accuracy: 93%, 89%, 92%). SUV in recurrent tumour was higher than in benign post-therapeutic changes (10.6+/-5.1 vs 2.1+/-0.6, p<0.001). Median survival was longer for patients with lower FDG uptake in recurrent tumour (SUV<11: 18 months, SUV > or = 11: 9 months, p<0.01). Long-term survival was observed mainly after surgical re-treatment (3-year survival rate 38%), even if no difference in median survival for surgical or non-surgical re-treatment was detected (11 vs 12 months, p=0.0627). For patients subsequently treated by surgery, lower FDG uptake predicted longer median survival (SUV<11: 46 months, SUV> or = 11: 3 months, p<0.001). SUV in recurrent tumour was identified as an independent prognostic factor (p<0.05).

CONCLUSION

FDG-PET accurately detects recurrent lung cancer. SUV in recurrent tumour is an independent prognostic factor. FDG-PET helps in the selection of patients who will benefit from surgical re-treatment.

Positron-emission tomography in prognostic and therapeutic assessment of lung cancer: systematic review

Positron-emission tomography (PET) with 18-fluorodeoxyglucose has a role in the diagnosis and staging of lung cancer, but is also appealing for assessment of prognosis and treatment. A systematic search of the published work shows good evidence that [(18)F]FDG uptake on PET has independent prognostic value in newly diagnosed non-small-cell lung cancer. PET is a sensitive method of measuring the biological effects of anticancer therapy, but until better standardisation and large-scale experience is available, it should only be used for additional assessments of early response in clinical trials. Further studies are needed to define the role of [(18)F]FDG-PET in restaging after induction therapy in multimodality approaches for locally advanced lung cancer. The assessment of prognosis by [(18)F]FDG-PET is less substantiated in treated lung cancer than in newly diagnosed patients. Good prospective evidence documents the effectiveness of [(18)F]FDG-PET over CT in the correct identification of recurrent lung cancer.

Value of whole-body FDG PET in management of lung cancer

18F-fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT. FDG PET imaging is sensitive to the detection of lung cancer in patients who have indeterminate lesions on CT, whereas low grade malignancy such as bronchioloalveolar carcinoma and carcinoid may be negative on FDG PET. The specificity of PET imaging is less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. This possibility should be kept in mind in the analysis of PET studies of glucose metabolism aimed at differentiating malignant from benign solitary pulmonary nodules. FDG uptake is considered to be a good marker of cell differentiation, proliferative potential, aggressiveness, and the grade of malignancy in patients with lung cancer. FDG PET accurately stages the distribution of lung cancer. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymphnode status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies. Whole-body FDG PET is also useful for the detection of recurrence. Several studies have indicated that the degree of FDG uptake in primary lung cancer can be used as an independent prognostic factor. Thus, whole-body FDG PET is clinically very useful in the management of lung cancer.