Effectiveness and safety of immune checkpoint inhibitor monotherapy in advanced upper tract urothelial carcinoma: A multicenter, retrospective, real‐world study oleh Ruopeng Su, Zeyu Chen, Daoping Hong, Shuai Jiang, Yichu Yuan, Xingyun Cai, Hailong Hu, Changde Fu, Zhiyang Huang, Zhenyu Wang, Bing Zheng, Jian Huang, Zaoyu Wang, Yige Bao, Ming Cai, Jianming Guo, Minfeng Chen, Qiang Wei, Jiwei Huang, Wei Xue