(CNN) Ellen DeGeneres revisits abuse she experienced as a teenager in an upcoming episode of David Letterman's Netflix show, "My Next Guest Needs No Introduction."

In the interview, which releases Friday, DeGeneres talks about being sexually assaulted by her mother's then-husband when she was a teen.

The abuse started, DeGeneres said, after her mother, Betty, was diagnosed with breast cancer.

"He told me when [my mom] was out of town that he'd felt a lump in her breast and needed to feel my breasts," she recalled in her conversation with Letterman. "Anyway, he convinced me that he needs to feel my breasts and then he tries to do it again another time, and then another time."

DeGeneres first opened up about the abuse by her stepfather, who is deceased, in an 2005 interview with Allure.

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