Diagnostic values of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in second primary cancers with a gastric primary cancer.

Abstract Purpose Currently, the early diagnosis of second primary cancers (SPCs) after gastric cancer (GC) remains a thorny problem. Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been demonstrated to participate in the development of GC. Thus, we investigated diagnostic values of NLR and PLR in SPCs after GC. Materials and methods 78 patients with SPCs after GC, 99 patients with single GC and 107 healthy controls were retrospectively analyzed between 2011 and 2021. We detected their hematological parameters, plotted receiver operating characteristic curves of NLR, PLR, carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) alone or in combination for SPCs, and compared area under the curve (AUC). Results SPC patients had higher levels of NLR, PLR, CEA and CA19-9 than other groups, and all indicators increased synchronically with GC progression. Compared with single GC patients, SPC patients had higher NLR levels in each TNM stage and higher PLR levels in stage II-IV. Moreover, NLR and PLR levels in stage I of SPC patients were significantly higher than those in stage IV of single GC patients. The diagnostic efficiency of NLR (AUC = 0.845) and PLR (AUC = 0.796) was significantly higher than that of CEA (AUC = 0.672) and CA19-9 (AUC = 0.655) in SPCs. Pairwise combination had superior diagnostic performance for SPCs, with the largest being NLR combined with PLR (AUC = 0.881). Conclusions Clinically, existing diagnostic methods can be combined with NLR and PLR in early diagnosing SPCs after GC.