Some 70 percent of women with early-stage breast cancer and an intermediate risk of cancer recurrence can safely skip chemotherapy after their tumors have been removed, U.S. researchers said Sunday.

"This is a major finding," said Dr. Larry Norton, a breast cancer expert at Memorial Sloan Kettering Cancer Center in New York, who helped organize the government-funded study more than a decade ago.

"It means that maybe 100,000 women in the United States alone do not require chemotherapy," Norton said.