Background Pituitary-derived tumor-transforming growth protein (PTTG) (securin) plays a critical role in the cell cycle and its overexpression is associated with chromosomal instability and poor clinical outcome in multiple malignancies including breast cancer.

Patients and methods Securin and Ki-67 immunohistochemical staining were performed on tissue microarray sections representative of 145 patients diagnosed with invasive breast carcinoma from 2005 to 2011. Semiquantitative methods as well as ImmunoRatio (an open source plugin within ImageJ software for offline image analysis) were used for immunostaining assessment.

Results Only 118 cases had representative tissue cores out of 145 cases. The 118 cases were categorized into two groups according to their clinical outcome; the first group (G1) (n=77) comprised patients who were disease free, whereas the second group (G2) (n=41) included patients with recurrence and/or metastasis at the end of 24 months of follow-up duration. Lymphovascular invasion, perinodal fat infiltration, nodal status, estrogen receptor status, human epidermal growth factor receptor-2 status, and molecular subtypes showed risk association with clinical outcome (P=0.005, 0.004, 0.001, 0.044, 0.025, 0.005) using χ²-test. Both securin and Ki-67 scores obtained by semiquantitative method were significantly higher in the second group (P=0.006). Cutoff points for the tested markers were identified using receiver operating characteristic curves.

Conclusion These results suggest that securin may have value superior to Ki-67 in identifying invasive breast carcinoma patients with poor clinical outcome.