Assessing the role of colonic and other anatomical sites uptake by [18F]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.