The President's Cancer Panel published their annual report yesterday. The report (pdf), entitled "Reducing Environmental Cancer Risk, What We Can Do Now", has spurred on an ongoing debate within the cancer sciences community about the proportion of cancer caused by environmental hazard.
In a letter to the President, the Panel presents a succinct thesis of what they consider to be the problem:
Environmental exposures that increase the national cancer burden do not represent a new front in the ongoing war on cancer. However, the grievous harm from this group of carcinogens has not been addressed adequately by the National Cancer Program. The American people—even before they are born—are bombarded continually with myriad combinations of these dangerous exposures. The Panel urges you most strongly to use the power of your office to remove the carcinogens and other toxins from our food, water, and air that needlessly increase health care costs, cripple our Nation’s productivity, and devastate American lives.
In their coverage of the report, MSNBC notes, however, that as many as two-thirds of cancer cases are caused by lifestyle choices like smoking, poor diet and lack of exercise.
The American Cancer Society has a similar perspective. According to the New York Times article on the disagreement:
The cancer society estimates that about 6 percent of all cancers in the United States — 34,000 cases a year — are related to environmental causes (4 percent from occupational exposures, 2 percent from the community or other settings).
In an online statement, Dr. Michael Thun, an epidemiologist from the cancer society, had this to say:
Unfortunately, the perspective of the report is unbalanced by its implication that pollution is the major cause of cancer, and by its dismissal of cancer prevention efforts aimed at the major known causes of cancer (tobacco, obesity, alcohol, infections, hormones, sunlight) as “focussed narrowly.”
The report is most provocative when it restates hypotheses as if they were established facts. For example, its conclusion that “the true burden of environmentally (i.e. pollution) induced cancer has been grossly underestimated” does not represent scientific consensus. Rather, it reflects one side of a scientific debate that has continued for almost 30 years.
There is no doubt that environmental pollution is critically important to the health of humans and the planet. However, it would be unfortunate if the effect of this report were to trivialize the importance of other modifiable risk factors that, at present, offer the greatest opportunity in preventing cancer.
The New York Times followed up with both Dr. Thun and the chairman of the President's Council Dr. LaSalle D. Leffall Jr. Here are their responses (lengthy excerpt):
Suggesting that the risk is much higher, when there is no proof, may divert attention from things that are much bigger causes of cancer, like smoking, Dr. Thun said in an interview.
“If we could get rid of tobacco, we could get rid of 30 percent of cancer deaths,” he said, adding that poor nutrition, obesity and lack of exercise are also greater contributors to cancer risk than pollution.
But Dr. Thun said the cancer society shared the panel’s concerns about people’s exposure to so many chemicals, the lack of information about chemicals, the vulnerability of children and the radiation risks from medical imaging tests.
The chairman of the president’s panel, Dr. LaSalle D. Leffall Jr. of Howard University, said the panel stood by the report.
“This is an evenhanded approach, and an evenhanded report,” Dr. Leffall said. “We didn’t make statements that should not be made.”
He acknowledged that it was impossible to specify just how many cancers were environmentally caused, because not enough research had been done, but he said he was confident that when the research was done, it would confirm the panel’s assertion that the problem had been grossly underestimated.
This is an interesting debate that warrants further discussion.
What do you think? Share you views by replying in the thread.