ALK– Versus EGFR-positive NSCLC: CT Imaging and Clinical Characteristics

In a retrospective study of Asian patients with non-small cell lungcancer (NSCLC), there were differences in computed tomography (CT) findings depending on if a disease was characterized by an ALK gene rearrangement or an activating EGFR mutation.

Upfront molecular testing for ALK and EGFR alterations is recommended for all patients with a diagnosis of advanced NSCLC characterized by a non squamous histology. However, clinical features and imaging-related characteristics associated with particular molecular forms of advanced NSCLC may provide useful information related to raising clinical suspicion for a particular molecular subtype of the disease.

In particular, ALK and EGFR alterations are generally considered to be mutually exclusive, and previous reports on imaging results related to ALK-positive NSCLC have been conflicting.

Related Articles.

• Overall Survival in Patients With Stage IV ALK-Positive Non-Small Cell Lung Cancer Treated With Crizotinib.
• Genomic Profiling Using Guardant 360 Cell-Free DNA-Based Assay vs Tumor-Based Genotyping Assays in Advanced NSCLC.

This study included 201 patients with NSCLC characterized by the type of mutation found; patients were classified according to the following molecular subgroups: ALK (21 patients), EGFR (124 patients), and non-ALK/EGFR(56 patients). Compared with patients in the EGFR subgroup, CT findings for patients in the ALK subgroup were more likely to be characterized by a large mass (P =.0155), a solid mass (P =.0048), no air bronchogram (P =.0148), a central location (P =.0322), and lymphadenopathy (P =.0353).

Compared with the non-ALK/EGFR subgroup, patients in the ALK subgroup were less likely to have coexisting emphysema (P =.0135),more likely to be female (P =.0043),and a light or never-smoker (P =.0039).In addition, patients with disease characterized by an ALK alteration were more likely to be younger compared with those in the EGFR subgroup (P =.0156). Following multivariate analysis including all CT and clinical variables, air bronchogram, emphysema,and a central location were independently associated with ALK status.

Limitations of this study, as noted by the study authors, included its retrospective design, and the small number of patients in the ALK subgroup.

Reference

1. Mori M, Hayashi H, Fukuda M, et al. Clinical and computed tomographycharacteristics of non-small cell lungcancer with ALK generearrangement: Comparison with EGFR mutation and ALK/EGFR-negative lung cancer [published online February 27, 2019]. Thorac Cancer. doi:10.1111/1759-7714.13017