US pop singer Anastacia underwent seven hours of surgery to remove a cancerous lump in her breast last month, it has emerged.
Anastacia also has Crohn's Disease
The 29-year-old, who was diagnosed with breast cancer six weeks ago, also underwent reconstructive surgery.
Her surgeon said subsequent tests have shown that early detection of the tumour had saved her life.
"Although what Anastacia has is serious, she is very lucky," Dr Alexander Swistel said in a statement issued by the star's publicist.
"Due to the aggressive nature of her cancer, she was a month away from a more immediate life-threatening condition.
"However, her prognosis is good, as are her spirits, which figures into any patient's successful recovery."
Anastacia, who had the surgery on 10 February, will begin a six-week course of radiation therapy in the coming weeks.
In a message to her fans, she said her ordeal had taught her the importance of early detection in fighting breast cancer and she urged other women to have mammograms.
The star, whose hits include I'm Outta Love, also suffers from the bowel condition Crohn's disease and had an operation for this at the age of 13 for the illness.
Hard to market
Anastacia, from Chicago, US, found fame after her strong voice ensured fans took notice of her music.
But it took many years for record companies to notice her talent, with many believing her distinctive sound would be too hard to market.
She was finally signed after Sony bosses saw her on MTV's The Cut.
She has since released two albums, Not That Kind and Freak of Nature.
Her single Boom! was chosen as a World Cup anthem in 2002, which she performed at the closing ceremony in Japan.
The Chicago film soundtrack also features a track from Anastacia, Love is a Crime - a song inspired by the musical.