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Honma N, Horii R, Ito Y, Saji S, Younes M, Iwase T, Akiyama F. Differences in clinical importance of Bcl-2 in breast cancer according to hormone receptors status or adjuvant endocrine therapy. BMC Cancer 2015; 15:698. [PMID: 26472348 PMCID: PMC4607008 DOI: 10.1186/s12885-015-1686-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 10/06/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bcl-2 plays an anti-apoptotic role, resulting in poor clinical outcome or resistance to therapy in most tumor types expressing Bcl-2. In breast cancer, however, Bcl-2 expression has been reported to be a favorable prognostic factor. The positive correlation of Bcl-2 with estrogen receptor (ER)/progesterone receptor (PR) status, and endocrine therapy frequently given for hormone receptor-positive tumors, may obscure the independent pathobiological role of Bcl-2. We constructed a large systematic study to determine whether Bcl-2 has an independent role in breast cancer. METHODS Bcl-2 expression was immunohistochemically evaluated and compared with other clinicopathological factors, including clinical outcome, in 1081 breast cancer cases with long follow-up, separately analyzing 634 cases without any adjuvant therapy and 447 cases with tamoxifen monotherapy. The χ (2)-test for independence using a contingency table, the Kaplan-Meier method with the log-rank test, and a Cox proportional hazards model were used for the comparison of clinicopathological factors, assessment of clinical outcome, and multivariate analyses, respectively. RESULTS In both patient groups, Bcl-2 expression strongly correlated with positive ER/PR status, low grade, negative human epidermal growth factor receptor 2 (HER2) status, and small tumor size, as previously reported. Bcl-2 expression did not independently predict clinical outcome in patients with ER-positive and/or PR-positive tumors or in those who received tamoxifen treatment; however, it was an independent unfavorable prognostic factor in patients with ER-negative/PR-negative or triple-negative (ER-negative/PR-negative/HER2-negative) tumors who received no adjuvant therapy. The latter was even more evident in postmenopausal women: those with hormone receptor-negative or triple-negative tumors lacking Bcl-2 expression showed a favorable outcome. CONCLUSION Bcl-2 expression is an independent poor prognostic factor in patients with hormone receptor-negative or triple-negative breast cancers, especially in the absence of adjuvant therapy, suggesting that the anti-apoptotic effect of Bcl-2 is clearly exhibited under such conditions. The prognostic value of Bcl-2 was more evident in postmenopausal women. The present findings also highlight Bcl-2 as a potential therapeutic target in breast cancers lacking conventional therapeutic targets such as triple-negative tumors. The favorable prognosis previously associated with Bcl-2-positive breast cancer probably reflects the indirect effect of frequently coexpressed hormone receptors and adjuvant endocrine therapy.
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Affiliation(s)
- Naoko Honma
- Department of Pathology, School of Medicine, Toho University, 5-21-16 Omori-Nishi, Ota-ku, Tokyo, 143-8540, Japan. .,Department of Pathology, Cancer Institute, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
| | - Rie Horii
- Department of Pathology, Cancer Institute, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
| | - Yoshinori Ito
- Breast Medical Oncology, Breast Oncology Center, Cancer Institute Hospital, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
| | - Shigehira Saji
- Department of Medical Oncology, Fukushima Medical University, School of Medicine, 1 Hikarigaoka, Fukushima City, Fukushima, 960-1295, Japan.
| | - Mamoun Younes
- Department of Pathology and Laboratory Medicine, University of Texas Medical School, 6431 Fannin, MSB 2.270, Houston, TX, 77030, USA.
| | - Takuji Iwase
- Breast Oncology Center, Cancer Institute Hospital, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
| | - Futoshi Akiyama
- Department of Pathology, Cancer Institute, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
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