Open AccessImmunohistochemical K i67 labeling index has similar proliferation predictive power to various gene signatures in breast cancer
Author(s) -
Niikura Naoki,
Iwamoto Takayuki,
Masuda Shinobu,
Kumaki Nobue,
Xiaoyan Tang,
Shirane Masatoshi,
Mori Kazushige,
Tsuda Banri,
Okamura Takuho,
Saito Yuki,
Suzuki Yasuhiro,
Tokuda Yutaka
Publication year - 2012
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/j.1349-7006.2012.02319.x
Subject(s) - immunohistochemistry , breast cancer , medicine , cancer , oncology , proliferation index , estrogen receptor , mitotic index , biology , pathology , genetics , mitosis
The objective of this study was to examine the association between the immunohistochemical K i67 labeling index ( IHC K i67), K i67 mRNA expression level, and first‐generation gene signatures in a cohort of breast cancer patients. We assessed associations between IHC K i67 and first‐generation gene signatures in a panel of 39 tumor samples, using an oligonucleotide microarray. Gene expression analyses included K i67 alone ( MK i67), 21‐gene signature, mitosis kinome score signature, and genomic grade index. Correlation coefficients were calculated by S pearman's rank correlation test. In all cases, IHC K i67, MK i67, and three genetic markers were highly correlated (ρ, 0.71–0.97). Estrogen receptor ( ER )‐positive cases showed strong correlations between IHC K i67 and other signatures (ρ, 0.79–0.83). The ER ‐negative cases showed slightly lower correlations (ρ, 0.58–0.73). In ER ‐positive cases, the low IHC K i67 group showed significantly longer relapse‐free survival than the high IHC K i67 group ( P = 0.007). This difference was confirmed by multivariate analysis. Our data indicate that IHC K i67 shows similar predictive power for proliferation in ER ‐positive cancers as genomic markers. Further study of IHC K i67 is needed to define prognostic factors and predictive factors for chemotherapy using central laboratory assessment. ( Cancer Sci , doi: 10.1111/j.1349‐7006.2012.02319.x, 2012)