Patient selection
cancer, micropapillary bladder cancer, Tumor
CANCER, DISEASES, TUMOR
We searched the SEER database including 17 cancer registries and covering 26.5% of the US population. The inclusion site code was C67.0-C67.9, and the histological code was 8131/2, 8131/3, according to the International Classification of Tumor Diseases, Third Edition (ICD-O-3). The exclusion criteria were (1) incomplete survival data; (2) patients in SEER database diagnosed before 2004 since their TNM stage information was not recorded; (3) lymph node examined and positive lymph node were unknown; (4) surgical approach, radiotherapy or chemotherapy was unknown. Patients with micropapillary bladder cancer in Qilu hospital of Shandong University were considered to be included in the external validation set. The exclusion criteria were similar to those of the SEER database. After selection, 627 patients were enrolled from the SEER database and 41 patients from the tertiary center.