In 2007, there were about 11.7 million Americans with a history of cancer, the Centers for Disease Control and Prevention said. Forty years ago, the number of cancers survivors was about 3 million. That increased to 10 million in 2001 and to 11.4 million in 2006.
Healthy eating, less smoking and other preventive steps may also be playing a role in the increase, health officials said.
"There are some cancers that we can't prevent and they are terrible tragedies," said CDC Director Dr. Tom Frieden. "But there are many that are preventable, or if caught early can result in much longer life."
Demographics are a factor in the survivor increase, too. Cancer is most common in people 65 and older, and the nation's elderly population is growing. The CDC said 7 million -- 60 percent -- of the cancer survivors were 65 or older.
Women diagnosed with breast cancer made up the largest share of cancer survivors, at 22 percent, followed by men with prostate cancer, at 19 percent.
The estimates from the CDC and the National Cancer Institute were based on information from nine U.S. cancer patient registries.
The survivor count includes anyone who had a cancer diagnosis, including people who had been successfully treated as well as those still getting treated or who may be dying from the disease. About 65 percent had survived for at least five years, and 40 percent for 10 years or more.