title: Clinical and histopathological factors associated with Ki-67 expression in breast cancer patients.
abstract: The aim of the present study was to identify the optimal Ki-67 cut-off value in breast cancer (BC) patients, and investigate the association of Ki-67 expression levels with other prognostic factors. Firstly, a retrospective search was performed to identify patients with stage I-III BC (n=462). A range of Ki-67 index values were then assigned to five groups (<10, 10-14, 15-19, 20-24 and ≥25%). The correlation between the Ki-67 index and other prognostic factors [age, tumor type, histological and nuclear grade, tumor size, multifocality, anin situcomponent, lymphovascular invasion (LVI), estrogen and progesterone receptor (ER/PR) expression, human epidermal growth factor receptor (HER-2) status, axillary involvement and tumor stage] were investigated in each group. The median Ki-67 value was revealed to be 20% (range, 1-95%). A young age (≤40 years old), tumor type, size and grade, LVI, ER/PR negativity and HER-2 positivity were revealed to be associated with the Ki-67 level. Furthermore, Ki-67 was demonstrated to be negatively correlated with ER/PR expression (P<0.001), but positively correlated with tumor size (P<0.001). The multivariate analysis revealed that a Ki-67 value of ≥15% was associated with the largest number of poor prognostic factors (P=0.036). In addition, a Ki-67 value of ≥15% was identified to be statistically significant in association with certain luminal subtypes. The rate of disease-free survival was higher in patients with luminal A subtype BC (P=0.036). Following the correlation analysis for the Ki-67 index and the other prognostic factors, a Ki-67 value of ≥15% was revealed to be the optimal cut-off level for BC patients.
authors: Department of Radiation Oncology, Gayrettepe Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Gul
authors: G
authors: Alco
authors: Department of BiostatisticsSurgery, Istanbul Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Atilla
authors: A
authors: Bozdogan
authors: Department of Breast Surgery, Istanbul Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Derya
authors: D
authors: Selamoglu
authors: Department of Medical Oncology, Istanbul Bilim University, Gayrettepe, Istanbul 34349, Turkey.
authors: Kezban Nur
authors: KN
authors: Pilanci
authors: Department of Pathology, Istanbul Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Sitki
authors: S
authors: Tuzlali
authors: Department of Medical Oncology, Istanbul Bilim University, Gayrettepe, Istanbul 34349, Turkey.
authors: Cetin
authors: C
authors: Ordu
authors: Department of Radiation Oncology, Istanbul Bilim University, Gayrettepe, Istanbul 34349, Turkey.
authors: Sefik
authors: S
authors: Igdem
authors: Department of Radiation Oncology, Gayrettepe Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Sait
authors: S
authors: Okkan
authors: Department of Radiation Oncology, Gayrettepe Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey.
authors: Maktav
authors: M
authors: Dincer
authors: Department of Medical Oncology, Istanbul Bilim University, Gayrettepe, Istanbul 34349, Turkey.
authors: Gokhan
authors: G
authors: Demir
authors: Department of Breast Surgery, Istanbul Florence Nightingale Hospital, Gayrettepe, Istanbul 34349, Turkey ; Department of General Surgery, Istanbul Medical Faculty, Istanbul University, Capa, Istanbul 34390, Turkey.
authors: Vahit
authors: V
authors: Ozmen
keywords: Ki-67; age; breast cancer; cut-off value; molecular subtypes; prognostic factors