Ki67 expression in breast cancer

Objectives: To evaluate Ki67 immunoexpression pattern in Saudi breast cancer (BC) patients and investigate any possible predictive or prognostic value for Ki67.

Methods: This is a retrospective study designed to quantitatively assess the Ki67 proliferative index (PI) in retrieved paraffin blocks of 115 Saudi BC patients diagnosed between January 2005 and March 2015 at the Department of Pathology, King Fahd Hospital, Al Madinah Al Munawarah, Kingdom of Saudi Arabia. The Ki67 PI was correlated with individual and combined immunoprofile data of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu) with their clinicopathological parameters.

Results: Ki67 immunoreactivity was highly expressed (>25% of the tumor cells were positive) in 85 (73.9%) patients. The Ki67 PI was significantly associated with poor prognostic clinicopathological parameters including old age (p<0.02), high tumor grade (p<0.01), lymph node metastasis (p<0.001), and Her-2/neu positivity (p<0.009). However, the association with ER positivity, PR positivity, tumor size, and lymphovascular invasion were not statistically significant. The Ki67 PI was significantly associated with BC molecular subtypes that were Her2/neu positive (luminal B and HER-2) subtypes compared with the Her2/neu negative (luminal A) subtype (p<0.04).

Conclusion: The Ki67 PI is significantly higher in Saudi BC patients comparing with the reported literature. Ki67 PI was highest in the HER-2 and luminal-B molecular subtypes. Along with other prognostic indicators, Ki67 PI may be useful in predicting prognosis and management of Saudi BC patients.