Nuclear SOX9 Expression and Short-Term Survival Outcomes in Early-Stage Luminal Breast Cancer: An Immunohistochemical and Retrospective Cohort Analysis.

SOX9 is a transcription factor linked to cellular plasticity and aggressive behavior in breast cancer. We investigated whether nuclear SOX9 expression correlates with short-term (5-year) survival outcomes in luminal breast cancer. In a retrospective cohort of 60 patients with estrogen receptor-positive invasive breast carcinoma, nuclear SOX9 expression was evaluated via immunohistochemical H-scores (0-300). Survival was analyzed continuously, by median-split dichotomy, and using a 1% nuclear-staining threshold via Kaplan-Meier and Cox regression models. Most tumors were luminal B (73.3%), and 45% were node-positive. Nuclear SOX9 was detected in 51.7% of cases (median positive H-score: 30). Over follow-up, 13 disease-free survival (DFS) and 12 overall survival (OS) events occurred. Continuous H-score did not correlate with clinicopathological variables, DFS (p = 0.576), or OS (p = 0.613). A median-split showed higher 5-year DFS for high-expression tumors (89.7% vs. 74.2%, p = 0.048), but this borderline protective trend was unconfirmed by Cox regression (p = 0.063) or the 1% threshold; ROC analysis showed no discrimination (AUC: 0.34-0.36). Standalone nuclear SOX9 expression has no significant impact on short-term (5-year) prognosis in early-stage luminal breast cancer; extended follow-up is warranted to assess potential late recurrence.