Survival predictive nomograms for non-surgical lung squamous-cell carcinoma patients with brain metastases: a SEER-based retrospective cohort study with external validation. - Cui, Xing; Jia, Yisen; Qi, Zuo; Li, Mengjia; Liu, Junyu; Shi, Chunxiao; Li, Zhenli (Oncologie (De Gruyter), 2026)