ABSTRACT: Annual updates on cancer occurrence and trends in the United States are provided through collaboration between the American Cancer Society (ACS), the Centers for Disease Control and Prevention (CDC), the National Cancer Institute (NCI), and the North American Association of Central Cancer Registries (NAACCR). This year's report highlights the increased cancer risk associated with excess weight (overweight or obesity) and lack of sufficient physical activity (<150 minutes of physical activity per week).Data on cancer incidence were obtained from the CDC, NCI, and NAACCR; data on cancer deaths were obtained from the CDC's National Center for Health Statistics. Annual percent changes in incidence and death rates (age-standardized to the 2000 US population) for all cancers combined and for the leading cancers among men and among women were estimated by joinpoint analysis of long-term trends (incidence for 1992-2008 and mortality for 1975-2008) and short-term trends (1999-2008). Information was obtained from national surveys about the proportion of US children, adolescents, and adults who are overweight, obese, insufficiently physically active, or physically inactive.Death rates from all cancers combined decreased from 1999 to 2008, continuing a decline that began in the early 1990s, among men and among women in most racial and ethnic groups. Death rates decreased from 1999 to 2008 for most cancer sites, including the 4 most common cancers (lung, colorectum, breast, and prostate). The incidence of prostate and colorectal cancers also decreased from 1999 to 2008. Lung cancer incidence declined from 1999 to 2008 among men and from 2004 to 2008 among women. Breast cancer incidence decreased from 1999 to 2004 but was stable from 2004 to 2008. Incidence increased for several cancers, including pancreas, kidney, and adenocarcinoma of the esophagus, which are associated with excess weight.Although improvements are reported in the US cancer burden, excess weight and lack of sufficient physical activity contribute to the increased incidence of many cancers, adversely affect quality of life for cancer survivors, and may worsen prognosis for several cancers. The current report highlights the importance of efforts to promote healthy weight and sufficient physical activity in reducing the cancer burden in the United States.