The prognostic value of detection methylation level panel of gene in DNA circulating after and before treatment in patients with breast cancer.

Abstract

67 Background: Objective of this study was to determine the concordance of promoter methylation of 14-3-3σ and ESR1 in circulating DNA of breast cancer patients with response and their association with clinicopathological parameters and disease prognosis. Methods: Plasmawas sampled prospectively from 110 patients diagnosed of breast cancer. A PCR quantitative technique was used to analyze the utility of circulating DNA with CpG island hypermethylation of ESR1, 14-3-3σ, Rar-B and APC genes promoter regions as breast cancer biomarkers. Results: The cutoff points for the genes methylated promoters were established from the ROC curves, selecting values that gave the maximal likelihood ratio. Presence of methylated ESR1 in serum of breast cancer patients was associated with ER-negative phenotype (p=0.0179); and presence of methylated 14-3-3σ was associated with T3-4 stage (p<0.05) and nodal positive status (p<0.05). Mean serum values of methylated genes before treatment was for ESR1:0.009µg/ml, 14-3-3σ:0.047µg/ml, Rar B:0.0001µg/ml and APC:0.012µg/ml. Mean serum values of methylated genes after treatment was for ESR1:0.003 µg/ml, 14-3-3σ:0.038µg/ml, Rar-B:0 µg/ml and APC:0.001µg/ml. In the light of the discriminatory power of ESR1 and 14-3-3σ and the finding that serum levels of methylated gene promoters changed after breast cancer treatment, post-treatment modifications in these two promoters were analyzed. We observed lower methylated ERS1,14-3-3-σ and APC values after surgery, respect pretreatment levels, but without an overall statistically significant difference.With a median follow-up of 8 years, we found that patients with a significant decrease of sera methylated levels of these genes after surgery had better time to progression an overall survival respect patients without this observation. Conclusions: These findings cast some doubts on the utility for early cancer diagnosis of highly sensitive techniques to identify hypermethylation of specific gene promoters in DNA extracted from serum. Although numerous issues remain to be resolved, the quantitative measurement of circulating methylated DNA is a promising tool for cancer prognostic assessment.