Pyrosequencing quantified methylation level of BRCA1 promoter as prognostic factor for survival in breast cancer patient

// Feng-Feng Cai 1, * , Su Chen 2, * , Ming-Hong Wang 3, * , Xiao-Yan Lin 1 , Lian Zhang 1 , Jia-Xin Zhang 4 , Lian-Xin Wang 5 , Jun Yang 5 , Jin-Hua Ding 6 , Xin Pan 7 , Zhi-Ming Shao 8 , Ewelina Biskup 9 1 Department of Breast Surgery, Yangpu Hospital, Tongji University School of Medicine, Shanghai, PR China 2 Department of Molecular and Cellular Biology, School of Forensic Sciences, Xi’an Jiao Tong University Health Science Center, Xi’an, Shaanxi, PR China 3 Department of General Practice, Yangpu Hospital, Tongji University School of Medicine, Shanghai, PR China 4 Department of Breast Surgery, Fudan University Shanghai Cancer Center, Shanghai, PR China 5 Department of General Surgery, Qidong Hospital, Jiangsu, PR China 6 Department of Thyroid and Breast Surgery, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo, Zhejiang, PR China 7 Central Laboratory, Yangpu Hospital, Tongji University School of Medicine, Shanghai, PR China 8 Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, PR China 9 Department of Oncology, University Hospital of Basel, Basel, Switzerland * These authors have contributed equally to this work Correspondence to: Feng-Feng Cai, e-mail: caifengfeng@medmail.com.cn Zhi-Ming Shao, e-mail: zhimingshao@yahoo.com Xin Pan, e-mail: xinpanpx@163.com Keywords: breast cancer, BRCA1, methylation, pyrosequencing, prognosis Received: February 21, 2016     Accepted: March 16, 2016     Published: March 25, 2016 ABSTRACT BRCA1 promoter methylation is an essential epigenetic transcriptional silencing mechanism, related to breast cancer (BC) occurrence and progression. We quantified the methylation level of BRCA1 promoter and evaluated its significance as prognostic and predictive factor. BRCA1 promoter methylation level was quantified by pyrosequencing in surgical cancerous and adjacent normal specimens from 154 BC patients. A follow up of 98 months was conducted to assess the correlation between BRCA1-methylation level vs. overall survival (OS) and disease free survival (DFS). The mean methylation level in BC tissues was significantly higher (mean 32.6%; median 31.9%) than in adjacent normal samples (mean 16.2%; median 13.0%) ( P < 0.0001). Tumor stage (R = 0.6165, P < 0.0001) and size (R = 0.7328, P < 0.0001) were significantly correlated with the methylation level. Patients with unmethylated BRCA1 had a better OS and DFS compared to the methylated group (each P < 0.0001). BRCA1 promoter methylation level has a statistically significance on survival in BC patients (HazR = 1.465, P = 0.000) and is an independent prognostic factor for OS in BC patients (HazR = 2.042, P = 0.000). Patients with ductal type, HER2 negative, lymph node negative stage 1+2 tumors had a better OS and DFS. Classification of grades and molecular subtypes did not show any prognostic significance. Pyrosequencing is a precise and efficient method to quantify BRCA1 promoter methylation level, with a high potential for future clinical implication, as it identifies subgroups of patients with poorer prognosis.