The methylation features of plasma tumor suppressor gene promoters in patients with primary Epithelial Ovarian Cancer (EOC) were analyzed in the present study. The methylation status of tumor suppressor genes BRCA1 and RASSF1A in primary EOC tissues and plasma was detected by Methylation-Specific polymerase chain reaction (MSP) to analyze the correlation of methylation and clinical as well as pathological parameters of EOC. The methylation proportion of tumor suppressor gene BRCA1 and RASSF1A was 17.1 and 42.9% in EOC tissues, respectively. There was positive correlation between BRCA1 methylation and histological stage, RASSF1A and clinical stage or histological stage. Meanwhile, the methylation proportion of BRCA1 and RASSF1A was 8.7 and 30.8% in the plasma of EOC patients, respectively. But, the methylation proportion of plasma BRCA1 and RASSF1A was 33.3 and 53.3% in EOC patients with abnormal BRCA1 and RASSF1A methylation in EOC tissues. The methylation ofBRCA1 and RASSF1A promoters may participate in the occurrence and development of primary EOC. The methylation proportion of plasma BRCA1 and RASSF1A is coincident with that in tumor tissues, and thus plasma DNA can effectively reflect the features of primary EOC.

Key words: Ovarian neoplasms, plasma DNA, tumor suppressor gene, methylation, promoter.