Sad news for the Wainwright family.

Canadian folk singer and songwriter Kate McGarrigle, best known for performing with her sister Anna, has died of cancer. She was 63.

McGarrigle's brother-in-law, Dane Lanken, said the singer died at her Montreal home Monday night surrounded by her sisters, Jane and Anna, and her children, Rufus and Martha Wainwright, also singers.

He said McGarrigle had been battling cancer since the summer of 2006. He said the cancer started in her small intestine and spread to her liver.

Kate and Anna, known as the McGarrigle Sisters, began their careers performing at Montreal coffeehouses in the 1960s with a group called the Mountain City Four. They got their break in the 1970s, when their songs were covered by numerous artists, including Linda Ronstadt, who used "Heart Like a Wheel" as the title song to one of her albums.

In 1975 they made their first record, "Kate and Anna McGarrigle," which brought them critical acclaim and additional famous covers by artists including Emmylou Harris, Judy Collins and Billy Bragg.

Their own well-known releases included "The Work Song," "Cool River" and "Lying Song."

Kate McGarrigle received the Order of Canada in 1994, one of the country's highest honors.

McGarrigle was once married to American singer-songwriter Loudon Wainwright III. Her son, Rufus Wainwright, recently canceled an upcoming tour, citing an illness in the family.

Born in Montreal, the famous singing duo grew up in the Laurentian Mountains village of Saint-Sauveur-des-Monts, Quebec. There, they learned the piano from the village nuns.