부산대학교 도서관

Ki-67 has been widely performed and become an important biomarker in worldwide clinics, but the standard cut off value of Ki-67 index in breast cancer is still controversy. The objective study was to understand the Ki-67 in breast cancer subtypes and to investigate relative risk of breast cancer subtypes according to Ki-67 cut off value in Korean breast cancer. Immunohistochemical staining (IHC) for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki-67 index was examined from 123 breast cancer patients. Ki-67 index was significantly overexpressed in PR, ER, and HER2 hormone negative groups. Ki-67 index in Triple negative and HER2 subtypes was shown significantly higher than that in Luminal A and Luminal B subtype. Then, we compared the relative risk of each subtype according to 14% and 20% Ki-67 cut off value, which were applied in most clinics. Especially, 20% Ki-67 cut off value in HER2 and Triple negative subtypes was shown 8.41 fold and 2.83 fold higher relative risk than this in Luminal A subtype. Moreover, Ki-67 index in HER2 2+ or 3+ status showed significantly overexpressed than this in HER2 1+ status. At the 20% Ki-67 cut off value, HER2 1+ or 2+ status and 3+ status showed significant difference. Therefore, the 20% Ki-67 cut off value will be useful as a precise prognostic management and helpful for interpreting diverse outcomes of other subtypes in breast cancer patients.