The Management Impact of Clinically Significant Incidental Lesions Detected on Staging FDG PET-CT in Patients with Non-small Cell Lung Cancer (NSCLC): an Analysis of 649 Cases

Unlabelled: To evaluate FDG PET-CT in the detection of unexpected pre-malignancy or second malignancy at the initial staging of patients with histologically proven non-small cell lung cancer (NSCLC) and its impact on management.

Methods: Staging FDG PET-CT scans acquired between February 2006 and July 2010 in 649 patients (M=389; F=260) with NSCLC were reviewed for the presence of unexpected pre-malignancy or second primary. A "True-Positive" lesion represented a second primary or pre-malignant lesion. A "False-Positive" lesion was due to benign causes or an atypical site of metastasis from NSCLC.

Results: 77 (12%) patients were identified on PET-CT as having a potential pre-malignancy or second primary. 39 out of 77 (51%) patients had diagnostic verification where histopathology served as reference standard in 33 patients (85%) and the rest had endoscopy and progress PET-CT scans. 20 patients (3.1%) had a second primary (n=11) or pre-malignant lesions comprising dysplastic colorectal polyps (n=9), and additional therapy and/or management change for the index tumour was instigated in 17 patients (85%). In patients with a second primary, 3 (27%) patients had a high impact change in management from an initial curative intent to palliative.

Conclusion: Staging FDG PET-CT is highly valuable in identifying second primary cancers or pre-malignant lesions in patients with NSCLC. When a second primary is detected on PET-CT, there is a high impact change in management in 27% of patients.