Thursday, February 09, 2006

Cancer Death Trends as Evidence of Environmental Progress?

The death rate from cancer has been declining over time. Despite population aging, the actual count of cancer deaths has declined! Is this evidence of environmental progress? If "new toxics" were poisoning us would we see such absolute progress in an aging society? This Times article highlights the behavioral changes and improvements in health care that have played key roles in bringing about this progress. I would like to see a simple statistical study that documents time trends in death rates from cancers that might have an environmental component (such as lung cancer) with the timet rend in death rates for cancers known to not have an environmental component.

February 9, 2006
Dip in Cancer Deaths Is Reported, First Decline in U.S. in 70 Years

The number of cancer deaths in the United States has dropped slightly, the first decline in more than 70 years, the American Cancer Society is reporting today.

Much of the decrease is because of a decline in smoking and improved detection and treatment of breast, colorectal and prostate cancers, according to the society.

The decline occurred in 2003, the latest year for which figures are available. There were 556,902 cancer deaths, 369 fewer than in 2002. Deaths fell in men by 778, but rose by 409 in women.

"Even though it's a small number, it's a notable milestone," said Dr. Michael Thun, head of epidemiological research for the society.

Dr. Thun (pronounced tune) said the death rate from cancer had been falling by slightly less than 1 percent a year since 1991, but even so, the actual number of deaths kept rising because the population was growing and aging.

"The decrease from 2002 to 2003 means that the decline in death rates had become sufficiently large that it was bigger than the aging and growth of the population," Dr. Thun said.

"You would predict this is a trend that may have a few bumps but will continue," he said.

Dr. Robert A. Hiatt, deputy director of the Comprehensive Cancer Center at the University of California, San Francisco, said, "From the beginning of the century it's been going up and up and up, and this is the first time we've turned the corner."

Elizabeth Holly, a professor of epidemiology and biostatistics at the University of California, San Francisco, said, "It's quite good we've made some progress in our advance against cancer, but what it really is reflecting, fortunately, is a change in personal smoking habits and early detection and treatment in prostate, colorectal and breast cancer."

Tobacco still accounts for 30 percent of cancer deaths, she said, and death rates from smoking are not decreasing in women as they are in men, because women began to quit smoking later than did men.

Dr. Holly added a note of caution. "We still have some real tragedies and very substantial national failures," she said, noting that the five-year survival rate for pancreatic cancer is less than 4 percent and that African-Americans with prostate cancer have twice the death rate of other groups.

In addition, Dr. Holly said, increases in obesity could lead to increased cancer rates.