Background: Studies looking at immunohistochemical (IHC) staining of Notch receptors in breast cancer and correlation with known prognostic factors are sparse.

Methods: IHC staining for nuclear, cytoplasmic, and membrane Notch-1 (N1), Notch-4 (N4), and Jagged-1 (JAG1) was performed and correlated with known prognostic factors.

Results: Of 48 breast cancers, 36 (67%) were invasive, mean age was 50 years (range 43-86 years), 37 (77%) were estrogen receptor (ERα) positive, and 13 (27%) node positive. There was significantly more marked N1 membranous staining in ERα-positive tumors (P < .05). On univariate analysis, cytoplasmic N1 was significantly correlated with node status and tumor grade (P < .05); both cytoplasmic and membranous N4 significantly correlated with Ki67 (P < .05); and membranous JAG1 significantly correlated with Ki67 (P < .05). On multivariate analysis, only cytoplasmic N1 significantly correlated with node status.

Conclusion: IHC of Notch markers is feasible and correlates with known prognostic factors consistent with a biological role of Notch signaling in breast cancer progression.