West died Saturday night at a hospice in San Dimas, east of Los Angeles, her manager Mara Fox said. She was diagnosed a year ago.
West was only 16 when she started the Runaways in 1975 with Jett, a singer and guitarist.
Along with band members Lita Ford and Cherie Currie, they had such hits as "Cherry Bomb" and "Born to Be Bad."
"We shared the dream of girls playing rock and roll. Sandy was an exuberant and powerful drummer," Jett said in a statement. "I am overcome from the loss of my friend. I always told her we changed the world."
Born in 1959 and raised in Huntington Beach, West was a bona fide California girl, splitting her time between surfing and skiing, Currie said.
After West's grandfather bought her a drum kit, she channeled her athleticism into music.
Following the band's breakup in 1979, West continued to perform as a singer, guitarist and drummer with the Sandy West Band. She also released a solo CD.
"Sandy West loved her fans, her friends and family almost to a fault," Currie said in a statement. "It will never be the same for me again to step on a stage, because Sandy West was the best and I will miss her forever."
West completed her memoirs before she died, and Fox said she hoped to get the book published.
West is survived by her mother, Jeri Williams, stepfather Dick Williams, and six sisters.
A public memorial in Southern California for friends and family is pending, Fox said.