U.S. Cancer Deaths Continue Steady Decline
According to the latest data on nationwide death rates from cancer, overall mortality from cancer declined from 1999 to 2008, maintaining a trend seen since the early 1990s. Mortality fell for most cancer types, including the four most common types of cancer in the United States (lung, colorectal, breast, and prostate), although the rate of decline varied by cancer type and across racial and ethnic groups. The complete Annual Report to the Nation on the Status of Cancr, 1975–2008 appeared March 28 in Cancer.
NCI, the American Cancer Society, the Centers for Disease Control and Prevention (CDC), and the North American Association of Central Cancer Registries (NAACCR) collaborated on the report. Cancer incidence data came from NCI’s Surveillance, Epidemiology, and End Results (SEER) database and from the CDC, with analyses of pooled data by NAACCR. Mortality data came from the CDC’s National Center for Health Statistics.
The declines in cancer death rates (mortality) averaged 1.7 percent per year for men and 1.3 percent per year for women from 1999 through 2008.
Among men, the overall rate of new cancer cases (incidence) fell by an average of 0.6 percent annually from 1999 to 2008. Among women, incidence dropped by an average of 0.5 percent annually from 1999 to 2006 but held steady from 2006 to 2008.
Cancer incidence in children ages 0 to 14 rose from 1999 to 2008 (by 0.5 percent a year), continuing a trend seen in previous Annual Reports to the Nation. However, advances in treatment contributed to a steady decline in mortality rates for children with cancer in the last 5 years (an average of 2.8 percent per year).
“Steady progress, as measured by declines in cancer death rates for many cancers, is good because we have an aging, growing population,” said Dr. Brenda K. Edwards, NCI’s senior advisor for surveillance. “While the number of people diagnosed with cancer or who die of the disease may be increasing, the decline in cancer death rates for more than a decade is the best indicator of progress due to prevention, screening, diagnosis, and treatment,” she added.
Not All Good News
There were some notable exceptions to the overall decreases in incidence and mortality. From 1999 to 2008, death rates rose for pancreatic cancer in men and women, for liver cancer and melanoma in men, and for endometrial cancer in women. The cervical cancer death rate, which had been falling for decades, showed no further decrease over the last 5 years.
And, although incidence rates fell overall for men and women from 1999 to 2008, the decline was not distributed evenly across racial and ethnic groups. Cancer incidence rates did not decrease significantly among American Indian/Alaska Native men and women combined or among black, Asian and Pacific Islander, and American Indian/Alaska Native women.
Although incidence rates in black men did decline, this group still had the highest cancer incidence rate of any racial and ethnic group, 15 percent higher than that of white men and nearly double that of Asian and Pacific Islander men.
Major Modifiable Risk Factors
Each Annual Report to the Nation includes a special feature that focuses on a topic of importance to the cancer research community and the public. This year's report featured an analysis on the contribution of excess weight (overweight and obesity) and insufficient physical activity to the nation’s cancer burden.
More than 60 percent of the U.S. adult population is estimated to be overweight or obese, and a similar percentage of adults do not get the recommended amount of physical activity. The rates of insufficient physical activity are even worse for children; for example, up to 90 percent of high school girls do not engage in recommended levels of physical activity.
Excess weight “is a major modifiable risk factor for cancer and other diseases—probably second only to tobacco use in terms of its impact on cancer incidence and mortality,” said Dr. Edwards. “The risk may be modest but it’s so pervasive that we felt this was the time to look at [cancer] incidence in this context.” Physical inactivity not only contributes to excess weight but is itself a risk factor for several cancer types.
The report was not designed to quantitatively link the trends in excess weight and lack of physical activity to the national trends for cancer, explained Dr. Rachel Ballard-Barbash, associate director of the Applied Research Program in NCI’s Division of Cancer Control and Population Sciences. Many other studies have shown convincing links between excess weight and several cancer types, including endometrial, postmenopausal breast, colorectal, kidney, esophageal, and pancreatic cancer.
The point of the special feature, she noted, “is to highlight specific types of cancer that are related to [excess weight and lack of sufficient physical activity], show how these behaviors relate to these cancers in terms of their relative risks, and briefly describe some of the mechanisms by which they relate.” The special feature also highlights national- and state-level prevention strategies in policy and environmental change that are intended to help people achieve recommended changes in their diets and physical activity levels.
As the nation’s weight has risen, so has the incidence of some, although not all, types of cancer related to excess weight and lack of sufficient physical activity. From 1999 to 2008, incidence rates of kidney cancer and of adenocarcinoma of the esophagus each rose about 3 percent per year for men and women, while incidence of pancreatic cancer rose 1.2 percent per year among men and women.
In addition, incidence rates of endometrial cancer rose significantly among black, Asian and Pacific Islander, and Hispanic women. Incidence of postmenopausal breast cancer stabilized from 2005 to 2008, after a period of decline.
“Although all of these cancers are influenced by multiple factors, the high prevalence of excess weight and insufficient physical activity likely contributed to these observed increases and to the lack of decline in breast cancer,” the authors wrote. “Continued progress in reducing cancer incidence and mortality rates will be difficult without success in promoting healthy weight and physical activity, particularly among youth.”
Excess weight and lack of physical activity also influence cancer survivorship, explained Dr. Ballard-Barbash, as both can negatively affect outcomes after a cancer diagnosis, further increasing the need for these risk factors to be addressed on a personal and societal level.