Last Updated 8:46 a.m. ET
OSLO, Norway - Grete Waitz, the Norwegian runner who won nine New York City Marathons and the silver medal at the 1984 Los Angeles Olympics, died Tuesday after a six-year battle with cancer. She was 57.
Helle Aanesen, the manager of the Active Against Cancer Foundation in Norway, said Waitz died early Tuesday at the Ulleval University Hospital in Oslo.
A former Oslo schoolteacher, Waitz won her first New York City Marathon in 1978, setting a world best in 2 hours, 32 minutes, 30 seconds in her first attempt at running the distance. She went on to win eight more times, with her last victory coming in 1988.
She won the London Marathon twice, in 1983 and '86, the Stockholm Marathon in 1988 and earned five titles at the world cross-country championships from 1978-81 and 1983.
Waitz also won the gold medal in the marathon at the 1983 world championships in Helsinki, Finland. A year later, she took second behind Joan Benoit in the first women's Olympic marathon.
Waitz competed at the 1972 and 1976 Olympics in the 1,500 meters, but missed the 1980 Moscow Games because of the American-led boycott.
"Grete is in my eyes one of the greatest Norwegian athletes of all time," Norwegian Athletics Federation president Svein Arne Hansen said. "Not only through her performances in the sport, but also as a role model for women in sports."
In a Twitter posting, marathon world record-holder Paula Radcliffe remembered Waitz as "an amazing champion and more amazing person."
Retired cyclist Lance Armstrong, who overcame testicular cancer to win the Tour de France seven times, called Waitz "a good friend and an incredible athlete" on his Twitter feed.
Aanesen said a private funeral ceremony is planned for next week, according to Waitz's wishes.
Waitz is survived by her husband Jack Waitz and her two brothers, Jan and Arild.
Waitz had never run a marathon when she started the New York City race in October 1978. Her husband had talked her into trying, but after about 30 kilometers (18 miles) she regretted it.
"I was hurting. I was mad. I was angry. I told Jack: 'Never again," Waitz recalled in 2008.
She broke the world record three more times: In New York in 1979 and '80 and in London in '83.
Waitz started undergoing cancer treatment in 2005 but rarely discussed her condition in public.
"That's not my personality," she said in November 2005. "I've always been a private person. ... I'll do that when I cross the finish line and win this race."
At the time she was optimistic she could conquer the disease.
"I'm crossing my fingers," she said. "I will beat it."
Like Waitz, Aanesen declined to specify which type of cancer she had.
"She didn't wish to put too much focus on herself and her disease, but hoped she could contribute in some way to help others," said Aanesen, who got to know Waitz through her work with the foundation.
"She was a fantastic and immensely successful sports practitioner and also a role model and pioneer in women's sports," Aanesen said. "She showed that women too can run longer distances than 1,000 meters."
Born in Oslo as Grete Andersen on Oct. 1, 1953, she trained and raced in her youth at Oslo's Bislett stadium, which raised a bronze statue in her honor in 1984.
Waitz received numerous other awards and honors for her achievements on and off the track.
In 2008 Norway's king bestowed upon her the prestigious Order of St. Olav for being a role model for female athletes. Last year she received the International Olympic Committee's Women and Sport Award for Europe.
To this day, Waitz holds the Norwegian records in the 1,500 and 3,000 meters.