Mariah Carey's estranged sister, Alison Carey Scott, has been diagnosed with cancer. Scott, a 50-year-old former drug addict who's been arrested twice for prostitution and is also HIV positive, told the National Enquirer that she is suffering from liver cancer.

A reporter from the tabloid magazine spoke with Scott outside of a hotel in Riverhead, N.Y., where she confirmed the news. She stated she was ill, "not with AIDS... liver cancer."

The "Emotions" creator, who has been in the studio recording her 14th album with Jermaine Dupri and Bryan-Michael Cox, reportedly is clueless about her sibling's condition. Recently, Mariah Carey has dealt with her husband Nick Cannon's own battles with a rare form of autoimmune disease lupus. News of Alison Carey Scott's liver cancer diagnosis is sure to come as a blow to the singer.

"Mariah's been to hell and back with Nick's health problems... Now Alison's tragedy will be a double whammy for her," a source told the National Enquirer.

Though Mariah Carey and her sister have had a rocky relationship since the performer stepped into the spotlight, she's supported Alison Carey Scott while undergoing treatment for her drug addiction, even paying for her visit to rehab.

See Photos of Mariah Carey in the Studio


Watch Mariah Carey's "Emotions" Video