Negative impact of the microvascular area to tumor area ratio on the response to EGFR-TKI in NSCLC with EGFR mutation

The aim of this study was to investigate whether a tumor microenvironment, abundant in microvessels, affects epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) efficacy in patients with non-small cell lung cancer (NSCLC) and EGFR mutations. We retrospectively studied the data of 40 post-operative patients with recurrent NSCLC and EGFR mutations who received EGFR-TKIs as a first-line treatment at Kumamoto University Hospital between January 2010 and February 2021. Tumor sections were retrieved from the tissue registry and analyzed for CD34-positive microvessels using immunohistochemical techniques. The microvascular area ratio (MVR), which is the CD34-positive microvascular area compared to the total tumor area, was measured using StrataQuest. The predictive value of MVR on treatment outcome, assessed via progression-free survival (PFS), was evaluated using a multivariate Cox proportional hazard model. The median PFS in the high MVR group (≥0.058) was significantly shorter than that in the low MVR group (<0.058; 296 d [95% confidence interval [CI]: 217–374 d] vs. 918 d [95% CI: 279–1556 d], P =0.002). Multivariate analysis revealed that high MVR was an independent negative predictor of PFS (hazard ratio, 3.21 [95% CI: 1.18–8.76], P =0.022). High MVR may critically affect EGFR-TKI resistance in patients with NSCLC and EGFR mutations.