[18F-FDG PET and bone scintigraphy to search for bone metastasis of lung cancer]

Is there any significance of lung cancer histology to compare the diagnostic accuracies of (18)F-FDG-PET/CT and (99m)Tc-MDP BS for the detection of bone metastases in advanced NSCLC?

Aim of the study

Bone scintigraphy (BS) and fluorine-18 deoxyglucose positron emission tomography computed tomography (¹⁸F-FDG-PET/CT) are widely used for the detection of bone involvement. The optimal imaging modality for the detection of bone metastases in histological subgroups of non-small cell lung cancer (NSCLC) remains ambiguous. The aim of this study was to compare the efficacy of ¹⁸F-FDG-PET/C and 99mTc-methylene diphosphonate (^99mTc-MDP) BS in the detection of bone metastases of patients in NSCLC. Specifically, we compared the diagnostic accuracies of these imaging techniques evaluating bone metastasis in histological subgroups of NSCLC.

Material and methods

Fifty-three patients with advanced NSCLC, who had undergone both ¹⁸F-FDG-PET/CT and BS and were eventually diagnosed as having bone metastasis, were enrolled in this retrospective study.

Results

The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ¹⁸F-FDG-PET/CT and BS were 90.4%, 99.4%, 98.1%, 96.6%, 97.0% and 84.6%, 93.1%, 82.5%, 93.2, 90.8%, respectively. The κ statistics were calculated for ¹⁸F-FDG-PET/CT and BS. The κ-value was 0.67 between ¹⁸F-FDG-PET/CT and BS in all patients. On the other hand, the κ-value was 0.65 in adenocarcinoma, and 0.61 in squamous cell carcinoma between ¹⁸F-FDG-PET/CT and BS. The κ-values suggested excellent agreement between all patients and histological subgroups of NSCLC.

Conclusions

¹⁸F-FDG-PET/CT was more favorable than BS in the screening of metastatic bone lesions, but the trend did not reach statistical significance in all patients and histological subgroups of NSCLC. Our results need to be validated in prospective and larger study clinical trials to further clarify this topic.

[PET in primary pulmonary or pleural cancer]

In our hospital as in many others, primary lung cancer is the most frequent indication for FDG PET. Studies have assessed the clinical utility of this imaging modality in characterizing solitary pulmonary nodules or masses, initial staging, defining tumor volume in radiotherapy and searching for recurrence of or restaging non-small cell carcinoma; studies are currently underway to evaluate its use in early assessment of chemotherapy response. Small cell lung cancer has a high FDG uptake and PET/CT can be useful for rapid staging. False negative results may be due to pure bronchioloalveolar carcinomas and endocrine tumors. FDG-PET will certainly play a more important role in the diagnosis and follow-up of pleural cancers in the future. An unexpected positive FDG PET focus should be considered as a warning, but histological proof should precede any irrevocable decisions.