Purpose: To evaluate the CT and (18)fluorine FDG PET findings of large cell neuroendocrine carcinomas (LCNECs) of the lung and to evaluate whether CT and FDG PET findings can help predict the clinical outcome.

Material and methods: Thirty-one patients (Male:Female=29:2; mean age, 69 years) who underwent surgical resection of an LCNEC of the lung were included in this retrospective study. The tumours were assessed with respect to morphologic characteristics and the maximum standardised uptake value (SUVmax) on pre-operative CT and FDG PET. For patients undergoing curative resection (n=26), disease-free survival was evaluated using the Kaplan-Meier test. The prognostic significance was assessed using a multivariate Cox proportional hazards regression analysis.

Results: The mean tumour diameter was 3.8 ± 2.1cm. Eight tumours (25.8%) were located centrally in the lung, and 23 (74.2%) were located peripherally. The margins were lobulated in 29 patients (93.5%) and well defined in 20 (64.5%). The mean SUVmax was 9.0 ± 3.8. The five-year disease-free survival rate was 46.3%. The shorter disease-free survival was related to the TNM stage greater than stage I, no lobulated margin of a tumour, a SUVmax >12.9 of a tumour, a long diameter >5.6 cm of a tumour, or female gender (P=0.115, P=0.134, P=0.056, P=0.168, P=0.113, respectively). The multivariate analysis indicated that a long diameter >5.6 cm (hazard ratio, 9.265; 90% confidence interval (CI), 1.996-42.992; P=0.017), female gender (hazard ratio, 5.579; 90% CI, 1.398-22.264; P=0.041), no lobulated margin (hazard ratio, 9.955; 90% CI, 1.433-69.136; P=0.051), and SUVmax >12.9 (hazard ratio, 4.062; 90% CI, 1.235-13.368; P=0.053) were independent predictors of shorter disease-free survival.

Conclusions: LCNECs of the lung more commonly occurred peripherally and exhibited well-defined and lobulated margins on CT. The mean SUVmax was consistent with malignant tumours. Female gender, a larger tumour diameter, no lobulated margin, and higher SUVmax were poor prognostic factors.