DNA methylation is associated with breast cancer recurrence or metastasis.

Objective: We aimed to explore the prognostic value of DNA methylation in breast cancer.

Methods: Breast cancer patients with and without recurrence or metastasis and matched non-breast cancer patients were screened retrospectively from 2014 to 2016. Bisulfite conversion and fluorescence quantitative methylation-specific polymerase chain reaction were used to detect the methylation status and distribution levels in patient breast tissues.

Results: DNA methylation was more frequent in breast cancer tissues than in non-breast cancer tissues, but was not significantly correlated with any relevant breast cancer patient clinicopathological characteristic. methylation rates were higher in patients with recurrence or metastasis. methylation, tumor size, lymph node status, and progesterone receptor (PR) expression could influence prognosis. methylation was significantly associated with worse disease-free survival in breast cancer patients, with receiver operating characteristic curve analysis indicating that it had good prognostic ability, with an area under the curve (AUC) value of 0.719. The AUC values increased when methylation was combined with tumor size, lymph node status, and PR to predict prognosis.

Conclusions: DNA methylation was an independent predictors of breast cancer prognostic risk. This could possibly help improve comprehensive prognosis prediction methods when combined with other risk factors.