Detection of non-aggressive stage IA lung cancer using chest computed tomography and positron emission tomography/computed tomography.

Objectives: In contrast to lung cancer with ground-glass opacity, the radiological investigation of solid lung cancer has not been well examined. The aim of this study was to explore chest computed tomography (CT) and positron emission tomography (PET)/CT findings with regard to outcomes after lung cancer surgery in order to radiologically classify clinical stage IA lung cancers by tumour aggressiveness.

Methods: Three hundred and fifteen clinical stage IA patients were analysed. Four groups were defined by tumour solidity on CT and by the standardized uptake value (SUV) index on PET-CT (tumour maximum SUV/mean right liver lobe SUV). We analysed the association between radiological findings and both pathological invasiveness and postoperative outcome.

Results: Group A (n = 84) had an SUV index <1.0 and non-solid tumours, Group B (n = 24) had an SUV index <1.0 and solid tumours, Group C (n = 54) had an SUV index ≥1.0 and non-solid tumours, while Group D (n = 153) had an SUV index ≥1.0 and solid tumours. Invasive lung cancer was found in 2/84 (2.4%) patients in Group A, 1/24 (4.2%) in Group B, 13/54 (24.1%) in Group C and 58/153 (37.9%) in Group D (P < 0.01). The 5-year recurrence-free rate was 100% in Groups A and B, 90.3% in C and 65.7% in D (P < 0.01). The cancer-specific survival rate was 100% in A and B, 94.6% in C and 81.7% in D (P < 0.01).

Conclusions: The present results suggest that preoperative PET/CT and thin-section CT findings provide important information for a selection of surgical procedures for clinical stage IA lung cancers. In clinical stage IA lung cancers displaying solid or non-solid density in thin-section findings, an SUV index <1.0 may be a better criterion for detecting non-aggressive lung cancer even in solid lung cancers.