Imaging Features and Metastatic Patterns of Advanced <i>ALK</i>-Rearranged Non-Small Cell Lung Cancer.

Abstract

<b>OBJECTIVE.</b><i>ALK</i> rearrangements are an established targetable oncogenic driver in non-small cell lung cancer (NSCLC). The goal of this study was to determine the imaging features of the primary tumor and metastatic patterns in advanced <i>ALK</i>-rearranged (<i>ALK</i>+) NSCLC that may be different from those in <i>EGFR</i>-mutant (<i>EGFR</i>+) or <i>EGFR/ALK</i> wild-type (<i>EGFR</i>-/<i>ALK</i>-) NSCLC. <b>MATERIALS AND METHODS.</b> Patients with advanced <i>ALK</i>+, <i>EGFR</i>+, or <i>EGFR-/ALK-</i> NSCLC were retrospectively identified. Two radiologists concurrently assessed the imaging features of the primary tumor and the distribution of metastases in these patients. <b>RESULTS.</b> We identified a cohort of 333 patients with metastatic NSCLC (119 <i>ALK+</i> cases, 116 <i>EGFR+</i> cases, and 98 <i>EGFR</i>-/<i>ALK</i>- cases). Compared with <i>EGFR</i>+ and <i>EGFR</i>-/<i>ALK</i>- NSCLC, the primary tumor in <i>ALK</i>+ NSCLC was more likely to be located in the lower lobes (53% of <i>ALK+</i>, 34% of <i>EGFR+</i>, and 36% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.05), less likely to be subsolid (1% of <i>ALK</i>+, 11% of <i>EGFR+</i>, and 8% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.02), and less likely to have air bronchograms (7% of <i>ALK+</i>, 28% of <i>EGFR+</i>, and 29% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.01). Compared with <i>EGFR</i>+ and <i>EGFR</i>-/<i>ALK</i>- tumors, <i>ALK</i>+ tumors had higher frequencies of distant nodal metastasis (20% of <i>ALK+</i> tumors vs 2% of <i>EGFR+</i> and 9% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.05) and lymphangitic carcinomatosis (37% of <i>ALK+</i> tumors vs 12% of <i>EGFR+</i> and 12% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.01), but <i>ALK</i>+ tumors had a lower frequency of brain metastasis compared with <i>EGFR</i>+ tumors (24% vs 41%; <i>p</i> = 0.01). Although there was no statistically significant difference in the frequencies of bone metastasis among the three groups, sclerotic bone metastases were more common in the <i>ALK</i>+ tumors (22% vs 7% of <i>EGFR+</i> tumors and 6% of <i>EGFR</i>-/<i>ALK</i>- tumors; <i>p</i> < 0.01). <b>CONCLUSION.</b> Advanced <i>ALK</i>+ NSCLC has primary tumor imaging features and patterns of metastasis that are different from those of <i>EGFR</i>+ or <i>EGFR</i>-/<i>ALK</i>- wild type NSCLC at the time of initial presentation.