Ki-67 Expression is a Significant Prognostic Factor Only When Progesterone Receptor Expression is Low in Estrogen Receptor-Positive and HER2-Negative Early Breast Cancer

Young-Joon Kang; Han-Byoel Lee; Yun Gyoung Kim; JaiHong Han; Yumi Kim; Tae-Kyung Yoo; Eun-Shin Lee; Hyeong-Gon Moon; Dong-Young Noh; Wonshik Han

doi:10.1155/2019/7386734

Ki-67 Expression is a Significant Prognostic Factor Only When Progesterone Receptor Expression is Low in Estrogen Receptor-Positive and HER2-Negative Early Breast Cancer

J Oncol. 2019 Dec 28:2019:7386734. doi: 10.1155/2019/7386734. eCollection 2019.

Authors

Young-Joon Kang¹, Han-Byoel Lee^{2

3}, Yun Gyoung Kim⁴, JaiHong Han⁵, Yumi Kim^{2

3}, Tae-Kyung Yoo⁶, Eun-Shin Lee^{2

3}, Hyeong-Gon Moon^{2

3}, Dong-Young Noh^{2

3}, Wonshik Han^{2

3}

Affiliations

¹ Department of Surgery, Incheon St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Incheon, Republic of Korea.
² Department of Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea.
³ Department of Surgery and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
⁴ Department of Surgery, Bundang Jesaeng General Hospital, Seongnam, Republic of Korea.
⁵ Department of Surgery, National Cancer Center, Goyang, Republic of Korea.
⁶ Department of Surgery, Seoul St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Seoul, Republic of Korea.

Abstract

Objective: While the value of Ki-67 has been recognized in breast cancer, controversy also exists. The goal of this study is to show the prognostic value of Ki-67 according to progesterone receptor (PgR) expression in patients who have estrogen receptor- (ER-) positive, human epidermal growth factor receptor 2- (HER2-) negative early breast cancer.

Methods: The records of nonmetastatic invasive breast cancer patients who underwent surgery at a single institution between 2009 and 2012 were reviewed. Primary end point was recurrence-free survival (RFS), and secondary end point was overall survival (OS). Ki-67 and PgR were assessed with immunohistochemistry for the tumor after surgery.

Results: A total of 1848 patients were enrolled in this study. 223 (12%) patients had high (≥10%) Ki-67, and 1625 (88%) had low Ki-67 expression. Significantly worse RFS and OS were observed in the high vs. low Ki-67 expression only when the PgR was low (<20%) (p < 0.001 and 0.005, respectively, for RFS and OS). There was no significant difference in RFS and OS according to Ki-67 when the PgR was high (p=0.120 and 0.076). RFS of four groups according to high/low Ki-67 and PgR expression was compared. The low PgR and high Ki-67 expression group showed worst outcome among them (p < 0.001). In a multivariate analysis, high Ki-67 was an independent prognostic factor when the PgR was low (HR 3.05; 95% CI 1.50-6.19; p=0.002).

Conclusions: Ki-67 had a value as a prognostic factor only under low PgR expression level in early breast cancer. PgR should be considered in evaluating the prognosis of breast cancer patients using Ki-67.