[Evaluation of Serum KL-6 Levels in Metastatic Gastric Cancer Patients without Interstitial Lung Disease].

Serum KL-6 is elevated in patients with various diseases such as interstitial lung disease(ILD), lung cancer, or breast cancer. However, whether serum KL-6 levels would be increased in patients with gastric cancer remains unclear. In this study, we aimed to reveal the frequency and characteristics of patients with gastric cancer exhibiting high serum KL-6 levels and no ILD. Therefore, we retrospectively reviewed the medical records of patients with gastric cancer and serum KL-6 levels measured prior to nivolumab-containing therapies. No patients had ILD at pretreatment. The median serum KL-6 level at pretreatment was 314 U/mL. Serum KL-6 levels increased above 500 U/mL in 16 of 56 patients at pretreatment. Serum KL-6 levels were higher in smokers and ex-smokers than in never-smokers as well as in patients with multiple metastases than in those with a single metastatic lesion. Moreover, we conducted a representative case presentation. Due to the increasing immune checkpoint inhibitor use in gastric cancer management, awareness concerning potentially increased serum KL-6 levels in patients with gastric cancer without ILD would be useful for physicians due to the more frequent opportunities to measure serum KL-6 levels for early detection and differential diagnosis of ILD.