Global research trends on gastrointestinal cancer and mental health (2004–2024): a bibliographic study - Han, Wenjin; Wang, Tianmeng; He, Zhiqiang; Wang, Caihua; Hui, Zhaozhao; Lei, Shuangyan; Hao, Nan; Li, Ning; Wang, Xiaoqin (Frontiers in Medicine, 2025)