Early detection of disease progression after palliative chemotherapy in NSCLC patients by (18)F-FDG-PET

We investigated whether 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is capable of detecting renewed disease progression earlier than computed tomography (CT) in patients with inoperable non-small cell lung cancer (NSCLC) who have undergone chemotherapy as part of a palliative treatment plan.

18 patients were studied retrospectively. Three FDG-PET/CT scans for initial and follow-up diagnostic purposes were evaluated. Palliative chemotherapy was administered between the first FDG-PET/CT scan (t0) and the second (t1), followed by a treatment-free interval between the second FDG-PET/CT scan (t1) and the third (t2). Maximum standardized uptake values (SUVmax) and largest diameters of lesions were determined for PET scans and the corresponding CTs. Lesion-based and patient-based assessments were performed, as were assessments according to RECIST/PERCIST.

82 lesions were identified in 18 patients. In interval t1-t2, the increase in diameter in the lesion-based evaluation was 5.0% (non-significant), while the patient-based evaluation showed a non-significant reduction of 2.8%. Considering PET, both the lesion-based and patient-based evaluations found a significant increase in SUVmax by a median of 30.4 % and 45.8 %, respectively. PERCIST criteria at time point t2 identified ten more patients with progression than did RECIST.

In patients with NSCLC, renewed progression during the treatment-free interval after palliative chemotherapy can be detected earlier with PET than with CT. Thus, FDG-PET appears to be a useful diagnostic imaging procedure regarding this aspect. Its clinical relevance should be investigated in further studies.