RT Journal Article
SR Electronic
T1 Menstrual cycle could affect Ki67 expression in estrogen receptor-positive breast cancer patients
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 825
OP 829
DO 10.1136/jclinpath-2015-203085
VO 68
IS 10
A1 Horimoto, Yoshiya
A1 Arakawa, Atsushi
A1 Tanabe, Masahiko
A1 Kuroda, Keiji
A1 Matsuoka, Joe
A1 Igari, Fumie
A1 Himuro, Takanori
A1 Yoshida, Yuko
A1 Tokuda, Emi
A1 Shimizu, Hideo
A1 Hino, Okio
A1 Saito, Mitsue
YR 2015
UL http://jcp.bmj.com/content/68/10/825.abstract
AB Background Ki67 is a potent prognostic marker for determining systemic treatment of patients with hormone receptor-positive breast cancer. However, evaluation of Ki67 expression can be difficult, due mostly to its heterogeneity. The Ki67 expression level, which indicates that a cell is undergoing division (cell cycle), rises when proliferation activity increases. Thus, Ki67 expression might be affected by hormonal stimuli. We hypothesised that Ki67 expression level might change during the menstrual cycle. We examined pairs of biopsy and surgical specimens from individual patients to evaluate this hypothesis.Methods First, the effects of estradiol on Ki67 expression in breast cancer cell lines were examined employing immunocytochemistry and Western blotting. Next, differences in Ki67 expression between biopsy and surgical specimens from 131 patients with estrogen receptor-positive tumours were retrospectively examined.Results In vitro experiments showed Ki67 expression in estrogen receptor-positive cancer cells to be dependent on estradiol stimulation. Ki67 expression was higher in biopsy samples collected in the luteal phase than in those from other phases. When biopsy and surgical samples were obtained at different times during the menstrual cycle in the same individual, there were differences in Ki67 expression between these samples. Those collected in the luteal phase showed higher Ki67 expression than samples obtained during other phases (p<0.01).Conclusions Ki67 expression varied in the same patients according to menstrual cycle phase. Our results suggest that Ki67 expression in estrogen receptor-positive breast cancer should be carefully assessed bearing in mind the patient's menstrual cycle, since the interpretation of expression could affect treatment decisions.