Comparative analysis of clinicoradiologic characteristics of lung adenocarcinomas with ALK rearrangements or EGFR mutations.

OBJECTIVE

To compare the clinicoradiologic features of tumours with echinoderm anaplastic lymphoma kinase (ALK) rearrangements, epidermal growth factor receptor (EGFR) mutations, or wild type (WT) for both genes in a cohort of patients with lung adenocarcinoma to identify useful characteristics of different gene statuses.

METHODS

In 346 lung adenocarcinoma patients, ALK rearrangements were confirmed with fluorescence in situ hybridisation, and EGFR mutations were determined by pyrosequencing assay. Patients were divided into three groups: ALK rearrangement (ALK+ group, n = 48), EGFR mutation (EGFR+ group, n = 166), and WT for both genes (WT group, n = 132). Chest computed tomography (CT) examinations were performed in all patients. The percentages of ground-glass opacity volume (pGGO) and tumour shadow disappearance rate (TDR) were measured using semi-automated nodule assessment software.

RESULTS

The pGGO was significantly lower in the ALK+ group (25.1 % ± 24.3) than in the EGFR+ group (37.2 % ± 25.7, p < 0.001) and the WT group (36.1 % ± 24.6, p = 0.001). The TDR in the ALK+ group (17.3 % ± 25.1) was significantly lower than in the EGFR+ group (26.8 % ± 24.9, p = 0.002) and the WT group (25.7 % ± 24.6, p = 0.003).

CONCLUSIONS

Solid pattern with lower incidence of lobulated border, finely spiculated margins, pleural retraction, and bubble-like lucency on CT imaging are the main characteristics of ALK rearrangement tumours.

KEY POINTS

• EGFR/ALK testing is recommended for lung adenocarcinoma patients for EGFR/ALK-targeted TKI therapy. • EGFR /ALK testing is restricted by limited tissue samples and cost pressures. • Lower pGGO and TDR are the main clinicoradiological characteristics of ALK+ tumours. • pGGO and TDR are predictive factors for selecting patients for ALK/EGFR testing.