Cancer death rates for men, women and children steadily decreased from 2004 to 2008, according to a new report from four major national cancer tracking groups. The declines in death and new cases of cancer reflect progress against the disease in terms of prevention, diagnosis and treatment, but experts say rising obesity may present a new challenge in the fight against cancer.
From 1999 to 2008, cancer death rates declined by an average of 1.7 percent per year for men, 1.3 percent per year for women and 1.5 percent annually for children, according to the report from the U.S. Centers for Disease Control and Prevention, the American Cancer Society, the National Cancer Institute and the North American Association of Central Cancer Registries. The report was published online today in the journal Cancer.
The declining death rates applied to all types of cancer, including the four most common: lung, colorectal, breast and prostate cancers.
The numbers of new cases of many cancers have also been on the decline. Cancer of all types among men dropped by 0.6 percent each year from 2004 to 2008, the report said. Among women, the rate of new cases declined by 0.5 percent each year from 1998 to 2006, then leveled off until 2008.
New cases of many specific cancers went down, including prostate, colorectal, lung and breast cancers. But certain kinds of cancer actually increased, such as those of the pancreas, kidney, thyroid, liver and melanoma.
The news of declining deaths from cancer is not completely new. The rate of cancer deaths has been on a steady downward trend since the 1990s. Experts say the declines in both deaths and new cases of cancer are the result of a general better scientific understanding of how to diagnose, treat and prevent cancer.
"The declines we've been seeing now, this reflects a lot of what we knew and applied and advances in the delivery of care that has been going on for a while," said Brenda Edwards, a senior advisor for surveillance at the National Cancer Institute.
The arsenal of weapons to fight cancer has grown in recent years, helping doctors detect and treat cancer at earlier stages, and making it easier to beat. Equally important, say doctors, is the progress made in preventing cancer, particularly lowering the number of people who smoke.
"We know much more in terms of cancer prevention, particularly with regard to smoking," said Ahmedin Jemal, vice president for surveillance research at the American Cancer Society. "Quitting smoking substantially reduces the risk of developing cancers related to smoking. But there are still many people who smoke."
The CDC reports that in 2010, 43.5 million Americans were current smokers, a number that has remained fairly steady since 2005.
The new report focused on the number of Americans who are overweight or obese, a factor that could undo some of the recent advances. The report noted that certain kinds of cancer that have been increasing, such as pancreatic and kidney cancers and adenocarcinoma of the esophagus, are associated with excess body weight.
Some studies have estimated that as much as 40 percent of certain kinds of cancer, such as endometrial cancer or esophageal adenocarcinoma, can be attributed to obesity.
Dr. Rachel Ballard-Barbash, associate director of the Applied Research Program at NCI, said the report doesn't specifically tie rises in these cancers with the growing numbers of overweight and obese Americans, but that it's possible the two are connected. She said efforts targeting U.S. obesity rates could have a major impact on cancer rates in the coming decades.
"We could have some sense of optimism from looking at what has happened to lung cancer rates. As population smoking declined, that led to marked reductions in lung cancer incidence and mortality," she said. "For people who do not smoke, what one does on a daily basis in terms of diet and physical activity is something you can control the most in terms of your cancer risk."