CDCA8 (cell division cycle associated 8), also known as Borealin, is a critical component of the chr1 passenger complex (CPC) essential for mitotic progression 1. During mitosis, CDCA8 regulates sister chr1 segregation, chromosome 1, and spindle assembly while preventing aneuploidy formation 1. Beyond mitosis, CDCA8 functions in meiosis, where it regulates spindle assembly and chromosome 1 during human oocyte meiosis 2. CDCA8 expression is transcriptionally activated by the NF-Y transcription factor in both embryonic stem cells and cancer cells 3. Clinically, CDCA8 is significantly upregulated across multiple cancer types, including hepatocellular carcinoma, lung adenocarcinoma, bladder cancer, melanoma, and endometrial carcinoma 1. Elevated CDCA8 expression correlates with advanced tumor staging, poor overall survival, and reduced chemotherapy responsiveness, establishing it as a pan-cancer prognostic biomarker 4. Mechanistically, CDCA8 promotes tumor progression through multiple pathways: it stabilizes HIF1α under hypoxic conditions in bladder cancer via AKT/GSK3β signaling 5, and influences P53, PI3K/Akt, E2F/Rb, and mTOR pathways across cancers 1. Additionally, CDCA8 expression associates with infiltrating immune cells, particularly CD8+ and CD4+ T cells 4. These findings position CDCA8 as a promising therapeutic target and biomarker for cancer diagnosis, prognosis, and treatment prediction.