"I am determined to bite the bullet and fight the fight while going through the next six weeks of cutting edge, state-of-the-art treatment," the 59-year-old actress said in a statement. "I should be able to return to my life as it was before."
Her publicist, Mike Pingel, didn't reveal what kind of cancer Fawcett has but said it was recently diagnosed and involves a fast-growing tumor.
The actress, who appeared with her former "Charlie's Angels" co-stars at an Emmy tribute in August to the late TV producer Aaron Spelling, said she has been overwhelmed by the "outpouring of concern, love, prayers and compassion" she has received from people around the world.
"I deeply believe in one's own positive will to overcome even the most daunting challenges," she said.