Published online Jan 24, 2026. doi: 10.5306/wjco.v17.i1.113612
Revised: October 16, 2025
Accepted: December 10, 2025
Published online: January 24, 2026
Processing time: 144 Days and 4.5 Hours
We have previously reported that the cancer/testis antigen Kita-Kyushu lung cancer antigen-1 (KK-LC-1) is frequently expressed in gastric cancer (GC), with a particularly high positivity rate observed in patients with multiple GCs. Thus, we conducted a preliminary study to further investigate the relationship between KK-LC-1 expression and multiple GCs. Specifically, we aimed to explore the potential clinical utility of KK-LC-1 as a biomarker for identifying patients at risk of developing multiple gastric cancers, with a focus on its expression in the initial tumor lesions.
To investigate the association between KK-LC-1 expression and the development of multiple GCs in a preliminary cohort.
Among 124 patients (177 lesions) treated for GC at Toho University Medical Center Ohashi Hospital between September 2020 and November 2023, 109 (single cancer: 82; multiple cancers: 27) with available initial tumor specimens were enrolled. KK-LC-1 expression was assessed using immunohistochemistry, and clinicopathological correlations were analyzed using Fisher’s exact test. Tumor locations were classified anatomically and analyses were performed, focusing on the initial cancer sites.
In tumors located in the upper stomach, KK-LC-1 expression did not correlate with clinicopathological features. However, in the middle and lower stomach, KK-LC-1 expression was significantly associated with older age, differentiated histological types, and multiple cancers. Notably, all patients with multiple GCs had KK-LC-1-positive tumors (100%) in their initial lesions. The KK-LC-1 positivity rate in the initial tumors of multiple cancers in the middle and lower region was significantly higher than that in solitary cancers. Conversely, the absence of KK-LC-1 expression in a solitary tumor located in the middle and lower region may suggest a reduced risk for the subsequent development of multiple primary cancers.
KK-LC-1 expression in the initial gastric tumors, particularly in the middle and lower stomach regions, may serve as a predictive biomarker for the future development of multiple GCs.
Core Tip: We have previously reported that the cancer/testis antigen Kita-Kyushu lung cancer antigen-1 (KK-LC-1) is frequently expressed in gastric cancer (GC), with high expression observed in multiple GCs. Therefore, as a preliminary study, we investigated the relationship between KK-LC-1 expression and multiple GCs, focusing on its potential clinical utility. In the middle and lower stomach regions, KK-LC-1 expression was significantly associated with older age, differentiated histological type, and the presence of multiple cancers, with all cases in the multiple cancer group exhibiting KK-LC-1 positivity (100%). KK-LC-1 expression in primary gastric tumors suggests a higher risk of subsequent development of multiple GCs.
