Assessing the role of colonic and other anatomical sites uptake by [18 F]FDG-PET/CT and immune-inflammatory peripheral blood indexes in patients with advanced non-small cell lung cancer treated with first-line immune checkpoint inhibitors

Abstract

Background: Inflammation in non-small cell lung cancer (NSCLC) may impair the response to immune checkpoint inhibitors (ICIs) and can be indicated by peripheral blood inflammatory indexes. 2-deoxy-2-[¹⁸ F]fluoro-D-glucose positron emission tomography/computed tomography ([¹⁸ F] FDG-PET/CT) may be used as a marker of inflammation by measuring glucose metabolism in different colonic sites.

Methods: This retrospective analysis aimed to investigate the correlation between [¹⁸ F] FDGPET/CT SUV_ratio in six gastrointestinal districts, the spleen, the pharynx and the larynx alongside the most avid tumor lesion with peripheral blood inflammatory indexes, including the neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammatory index (SII, i.e., NLR times platelets) and lactate dehydrogenase (LDH), in patients with [¹⁸ F] FDG-PET/CT staged IV NSCLC who received first-line immune checkpoint inhibitors (ICIs). The role of SUV_ratios and peripheral blood inflammatory indexes in predicting overall survival (OS) and progression-free survival (PFS) was then explored.

Results: A total of 43 patients were treated with first-line ICI alone (58%) or in combination with chemotherapy (42%). A significant correlation was only found between the rectosigmoid SUV_ratio and NLR (p = 0.0465). NLR >5.5 and LDH > 333.5 were associated with a worse OS (p = 0.033 and p = 0.009, respectively). The SII was associated with a worse PFS in patients treated with ICI alone (p = 0.033). None of the SUV_ratios were significantly associated with OS or PFS, although a high left colon SUV_ratio showed a trend toward a worse PFS.

Conclusion: There was no significant correlation between [¹⁸ F]FDG PET/CT uptake in different anatomical sites, and in the tumor, and systemic immune-inflammatory indexes. The prognostic role of high left colon SUV_ratio deserves further investigation.

Keywords: NLR; gut microbiome; immune checkpoint inhibitor; immunotherapy; lung cancer.

FIGURE 1

Example of transverse colon manual contouring on transaxial positron emission tomography/computed tomography (PET/CT) fused images., ,

FIGURE 2

Kaplan–Meier from univariable Cox regression model on OS (1, 2, 3) and on PFS (4, 5, 6) according to receiver operating characteristic (ROC) curve‐based cutoff. CI‐L, confidence interval‐lower; CI‐U, confidence interval‐upper; No., number; NLR, neutrophil‐to‐lymphocyte ratio; OS, overall survival; PFS, progression‐free survival; SII, systemic immune‐inflammatory index.