Introduction: The fusion oncogene of echinoderm microtubule-associated protein like 4 (EML4) and anaplastic lymphoma kinase (ALK) defines a new molecular subset of non-small-cell lung cancer. We explored the EML4-ALK gene in a relatively large cohort and reviewed the clinicoradiologic background of the patients.
Methods: We studied 720 patients with lung adenocarcinoma. The clinicopathological characteristics of each patient were compared among the subgroups stratified by the EML4-ALK gene status. For radiographic evaluation, we scored the proportion of the ground-glass opacity (GGO) component and calculated the tumor disappearance rate (TDR) in each tumor in the cohort of 168 patients that were extracted by using a case-matching procedure.
Results: Twenty-eight (3.9%) patients harbored the EML4-ALK gene. Younger age (p=0.001), no or light history of smoking (p=0.05) and normal serum carcinoembryonic antigen (CEA) level (p=0.04) were characteristics of the patients with EML4-ALK. No significant difference was observed for overall and disease free survival between the two groups. All but one tumor in the EML4-ALK-positive group exhibited no GGO, whereas half of the tumors (69/140 patients) in the EML4-ALK-negative group exhibited some GGO (p=0.0004). The mean TDRs were 0.33 and 0.54, respectively, which was significantly lower in the positive group (p=0.0006).
Conclusions: We identified younger age, no or light history of smoking, and normal serum CEA as clinical features of patients with EML4-ALK-positive lung adenocarcinoma. In addition, EML4-ALK-positive tumors exhibited a solid pattern on CT. These features may be of value in predicting for patient selection for ALK inhibition therapy in the absence of genetic screening.
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