Ki-67 Expression in Breast Cancer, Its Correlation with ER, PR and Other Prognostic Factors in Nineveh Province

Objectives: The aggressiveness of malignant tumors of breast can be correlated with the proliferation of neoplastic cells, and this detected by immunohistochemical study of proliferative index (Ki-67). American Society of Clinical Oncology (ASCO) does not recommend the use of Ki-67 routinely to predict the outcome of breast cancers, therefore the aim of current study is to detect the expression of Ki-67 in patients with primary breast cancer in Nineveh Province/North of Iraq and to correlate it with estrogen and progesterone receptors in addition to other prognostic factors. Methods: In this retrospective-case series study eighty cases of histologically proven primary breast carcinomas were included. The cases were collected from hospitals and private laboratories in Nineveh Province / North of Iraq and studied Immunohistochemicaly for Ki-67, estrogen receptor (ER) and progesterone receptor (PR) were done on tissue sections embedded in paraffin wax. An area with the maximum proliferation was chosen to evaluate Ki-67 and the cases with ≥20% positive nuclei were considered as high Ki-67 expression while those with <20% positive nuclei were considered as low Ki-67 expression.(10-14). The findings of Ki-67 were correlated with the age of the patients, histological type, grade of the tumors and with the estrogen and progesterone receptors. Results: The Ki-67 immunoreactivity was highly expressed in (45%) of the cases. Estrogen and progesterone receptors observed in (77.5%) and (67.5%) of the cases respectively. The Ki-67 was significantly associated with grade of tumor, estrogen receptor and progesterone receptor (P= 0.0057, 0.037 and 0.006 respectively). While the association with patientsˈage and histological types were not statistically significant. Conclusion: Ki-67 expression shows a significant direct correlation with grade of tumors and a significant inverse correlation has been shown with a well-known predictive factors, (estrogen and progesterone receptors).