J Cancer 2018; 9(18):3216-3224. doi:10.7150/jca.27291

Research Paper

Distribution and Clinical Utility of the 21-gene Recurrence Score in Pure Mucinous Breast Cancer Patients: a case-control study

Wei Wang1, Xiaosong Chen1✉, Lin Lin2, Xiaochun Fei3, David H. Garfield4, Jin Hong1, Weiqi Gao1, Siji Zhu1, Jiayi Wu1, Ou Huang1, Jianrong He1, Yafen Li1, Li Zhu1, Weiguo Chen1, Kunwei Shen1✉

1. Comprehensive Breast Health Center, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, 197 Ruijin Second Road, Shanghai 200025, P.R. China
2. Department of clinical laboratory, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
3. Pathology Department, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, 197 Ruijin Second Road, Shanghai 200025, P.R. China
4. University of Colorado Comprehensive Cancer Center, Aurora, CO 80045, USA

Abstract

The 21-gene recurrence score (RS) is increasingly being used for patients with early stage, hormone receptor-positive, Her-2-negative breast cancer. However, these results are largely from populations with infiltrating ductal carcinoma (IDC). The clinical value of RS testing in mucinous carcinoma has not been well investigated. Pure mucinous breast cancer (PMBC) and paired pure IDC patients who underwent 21-gene RS were retrospectively reviewed and matched with tumor stage and molecular subtype. Clinic-pathological factors, treatment strategies, and RS distribution were compared between the PMBC and IDC patients. A total of 35 PMBC and 70 IDC patients were included. We found that RS was lower in the PMBC as compared with the IDC group: 21.26 vs. 24.40 (P=0.037). Regarding RS categories, PMBC patients had a relatively lower percentage of high RS patients than the IDC group: 8.57% vs. 22.86% (P = 0.048). Multivariate analysis showed that histologic type was an independent factor predicting RS distribution: IDC patients were associated with a higher RS as compared with PMBC patients (OR: 1.27, 95% CI: 1.03-2.13; P=0.014). Among genes in 21-gene RS testing, HER2, STMY3, STK15, and BAG1 were significantly different between the PMBC and IDC groups (P < 0.05). Two patients (5.71%) in the PMBC group, both with high RS, were recommended to receive adjuvant chemotherapy, much lower than patients with IDC (57.14%, P < 0.001). In multivariate analysis, histologic type of IDC was an independent factor for chemotherapy recommendation (OR = 22.00, 95% CI: 4.89-98.97, P<0.001). With a medium follow-up time of 24 months, one IDC patient had ipsilateral axillary lymph nodes recurrence and one PMBC patient had contralateral breast cancer. In conclusion, PMBC patients, mostly classified with low or intermediate RS category, were associated with lower RS as compared with IDC patients. PMBC and IDC had different genes expression patterns. Patients with high RS in the PMBC group might be recommended to receive adjuvant chemotherapy, which deserves further clinical evaluation.

Keywords: Breast Neoplasm, Mucinous Carcinoma, Infiltrating breast carcinoma Recurrence Score, Chemotherapy

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How to cite this article:
Wang W, Chen X, Lin L, Fei X, Garfield DH, Hong J, Gao W, Zhu S, Wu J, Huang O, He J, Li Y, Zhu L, Chen W, Shen K. Distribution and Clinical Utility of the 21-gene Recurrence Score in Pure Mucinous Breast Cancer Patients: a case-control study. J Cancer 2018; 9(18):3216-3224. doi:10.7150/jca.27291. Available from http://www.jcancer.org/v09p3216.htm