Potential epigenetic modifications implicated in triple- to quadruple-negative breast cancer transition: a review.

When the androgen hormone receptor becomes inactive in triple-negative breast cancer (TNBC) patients, it results in another subtype of breast cancer called quadruple-negative breast cancer (QNBC). This is because these patients already lack the biological activities of three other important hormone receptors. The functions of these receptors are targeted by some drugs used in the management of breast cancers, so the lack of these receptors in TNBC and QNBC patients is thought to be linked with poor response to treatment. Some epigenetic modifications are involved in a more severe disease that is very difficult to control in TNBC patients and could facilitate its transition to the more aggressive QNBC subtype. Treatment response could be improved by restoring the normal function of the altered genes by reversing the observed epigenetic alterations.