Correlation of securin and Ki67 in invasive breast carcinoma.

Aims: To identify the role of securin (PTTG) as a prognostic marker in invasive breast carcinoma and its possible relation to ki67 and to evaluate the use of ImmunoRatio® as a tool for calculating ki67 and securin labelling indices.

Methods: Securin and ki67 immunohistochemical staining were performed on tissue microarray sections representative of 118 patients diagnosed with invasive breast carcinoma from 2005 to 2011. Assessment of immunohistochemical staining was carried out using both visual counting and ImmunoRatio®. The 118 cases were categorized into 2 groups according to their clinical outcome; the first group (G1) (n=77) comprised patients who were disease-free while the second group (G2) (n=41) included patients who developed either recurrence and/or metastasis at the end of 24 months follow-up duration.

Results: Both securin and ki67 labelling indices (LIs) obtained by visual counting were significantly higher in G2, while only securin LIs acquired by ImmunoRatio® were significantly higher in G2. Securin assessment by visual counting was the most accurate (AUC=0.775) in identifying patients who will likely suffer from recurrence and/or distant metastasis. Pearson correlation showed r=0.638, p<0.001 for Ki67 and r=0.671, p<0.001 for securin. Linear regression analysis showed a significant correlation between ki67 and securin, B=1.75, p<0.001.

Conclusion: The present results suggest that securin may add to the prognostic value of ki67 in highlighting intra-tumoural heterogeneity in invasive breast carcinoma patients with poor clinical outcome. In addition, the study showed that since securin has a visual counting cutoff with more than 1%, making it easier to use as a breast cancer biomarker in conjunction with ki67 to predict the outcome of the cases more accurately than using only ki67. However, a multivariate analysis on a larger cohort of patients is mandatory to test its potential prognostic value.