Detection of oligoprogressive disease in oncogene-addicted non-small cell lung cancer using PET/CT versus CT in patients receiving a tyrosine kinase inhibitor

Abstract

Objectives: In oncogene-addicted non-small cell lung cancer (NSCLC), oligoprogressive disease (OPD) can be treated with local ablative therapy (LAT) to prolong benefit from tyrosine kinase inhibitors (TKIs). A comparison of PET/CT vs. CT for the detection of OPD at first extra central nervous system (eCNS) progression was performed to determine which modality was more sensitive for OPD detection.Materials and methods: Patients with metastatic EGFR-MT, ALK + or ROS-1+ NSCLC on a relevant TKI from 2010 to 2016 were identified. Scan methodology at first eCNS progression (index scan) was noted and progression was categorized as OPD (≤ 4 lesions) or non-OPD (> 4 lesions).Results: Of the 67 analyzable patients (EGFR-MT = 37, ALK+ = 28, ROS1+ = 2), OPD was detected in 81.3% (26/32) by PET/CT vs. 68.6% (24/35) by CT (p = 0.363). Of these, 17/26(65.4%) in PET/CT and 5/24(20.8%) in CT group had LAT (p = 0.004). Among patients receiving an alternate modality scan within 6 weeks of the index scan that showed first eCNS progression, 91.7% (11/12) had CT prior to index PET/CT, 75% (6/8) had post-index PET/CT showing further progression, whereas 0% (0/5) had post-index CT showing further progression. Time to progression (TTP), Post-progression TKI benefit (TTP2) and overall survival (OS) were longer in the PET/CT-detected group (p = 0.001, p = 0.032, and p = 0.01, respectively). In both PET/CT (N = 26) and CT-detected (N = 24) OPD subgroups, TTP2 and OS were longer in those that received LAT (65.4% [17/26] and 20.8% [5/24]) versus those that did not, although the difference was not statistically significant.Conclusion: PET/CT demonstrated a non-significant trend to detect more eCNS OPD and a significantly higher rate of OPD suitable for LAT than CT. Peri-progression alternate modality scans were also consistent with PET/CT being more sensitive. A prospective randomized study is required to assess the long-term impact of PET/CT vs CT in oncogene-addicted NSCLC patients on TKI therapy.