Clinical value of PET/CT in identifying patients with oligometastatic/oligoprogressive disease among first-line tyrosine kinase inhibitor-treated advanced EGFR-mutant non-small cell lung cancer: Implications from survival comparisons.

Abstract

Local therapy (LT) could potentially prolong the survival of patient with advanced epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) receiving tyrosine kinase inhibitors (TKIs) and harboring oligometastatic/oligoprogressive disease (OMD/OPD). However, the optimal imaging method for identifying patients with OMD/OPD remains controversial. The objective of this study was to investigate the clinical value of incorporating PET/CT in detecting patients with OMD/OPD. Consecutive cases with metastatic EGFR-mutant NSCLC undergoing first-line EGFR-TKI treatment were retrospectively screened and those receiving baseline PET/CT and brain magnetic resonance imaging (MRI) or complete conventional imaging (CIM), including brain MRI, chest computed tomography (CT), abdomen ultrasound or CT and bone scintigraphy were included. OMD/OPD was defined as metastases/progressions documented at a maximum of five lesions and three organs, otherwise was defined as multiple metastatic/progressive disease (MMD/MPD). Progression-free survival (PFS) and overall survival (OS) were analyzed. Of the 392 patients evaluated, baseline OMD was detected in 22.7% (53/233) of patients by PET/CT and in 18.2% (29/159) of patients by CIM (p = 0.171). Among the patients evaluated with baseline PET/CT, patients with OMD had longer PFS (p = 0.016) and tendency of improved OS (p = 0.058) than those with MMD. However, this result was not observed with patients evaluated using baseline CIM. With a median follow-up of 24.2 (range, 1.1-124.6) months, 297 patients had their first disease progression (FPD), of whom 164 (55.2%) had adequate imaging scans to analyze the tumor distributions at FPD comprehensively. OPD was detected in 63.0% (34/54) and 35.0% (39/110) of patients among the PET/CT and CIM assessed group (p = 0.003), respectively. Among the PET/CT assessed group, patients with OPD had significantly longer post-progressive overall survival (OS2) than those with MPD (p = 0.011). However, no significant difference of OS2 in the CIM assessed group was found. Patients with OMD/OPD, evaluated by PET/CT but not CIM, generally had more favorable survival outcomes than those with MMD/MPD among patients with metastatic NSCLC undergoing first-line EGFR-TKI treatment. PET/CT seems to affect the survival of patients under first-line EGFR-TKI treated metastatic NSCLC with OMD/OPD.