As a result of advances in early detection and treatment, cancer has become a curable disease for some and a chronic illness for others; persons living with a history of cancer are now described as cancer survivors rather than cancer victims. From 1971 to 2001, the number of cancer survivors in the United States increased from 3.0 million to 9.8 million. To update those data, published in 2004, the National Cancer Institute (NCI) and CDC analyzed cancer incidence and follow-up information from nine Surveillance, Epidemiology, and End Results (SEER) programs to estimate the number of persons in the United States ever diagnosed with cancer who were alive on January 1, 2007. This report summarizes the results of that analysis, which indicated that the number of cancer survivors increased from 9.8 million in 2001 to 11.7 million in 2007. Breast, prostate, and colorectal cancers were the most common types of cancer among survivors, accounting for 51% of diagnoses. As of January 1, 2007, an estimated 64.8% of cancer survivors had lived≥5 years after their diagnosis of cancer, and 59.5% of survivors were aged≥65 years. Because many cancer survivors live long after diagnosis and the U.S. population is aging, the number of persons living with a history of cancer is expected to continue to increase. Public health and health-care professionals should understand the potential long-term needs of cancer survivors, engage in health promotion (e.g., urging cancer screening and smoking cessation), and ensure coordination of follow-up care for this growing population.