Environmental Cancer Orthodoxy

There’s little time to post today, but I wanted to draw attention to this article by Gina Kolata in the New York Times discussing environmental carcinogens, which includes this bit of orthodoxy:

Rates of cancer have been steadily dropping for 50 years, if tobacco-related cancers are taken out of the equation, said Prof. Richard Peto, an epidemiologist and a biostatistician at Oxford University.

What appear as increases in cancers of the breast and prostate, Dr. Peto added, are in fact artifacts of increased screening. When healthy people are screened, the tests find not only cancers that would be deadly if untreated, but also a certain percentage of tumors that would never cause problems if let alone.

His analysis of cancer statistics leads Dr. Peto to this firm conclusion: "Pollution is not a major determinant of U.S. cancer rates."

Not everyone would agree. I’ve had a chance to skim the report from the Lowell Center for Sustainable Production titled Environmental and Occupational Causes of Cancer: A Review of Recent Scientific Literature (mentioned previously here), which does a reanalysis of cancer trend data published by the federal government, SEER, for example, and at best showing a lot of flat time trends – not steady drops in rates.

The Lowell report (co-published by the Collaborative on Health and the Environment – another interesting find) makes a reasonable point:

Cancer evolves from a complicated combination of multiple exposures. Attempting to assign certain exposures (i.e. diet, smoking, environment, etc.) certain roles in causing cancer that will total 100% is inappropriate given that no one exposure singlehandedly produces cancer and many causes of cancer are still unknown. Comprehensive cancer prevention programs need to reduce exposures from all avoidable sources. Cancer prevention programs focused on tobacco use, diet, and other individual behaviors disregard the lessons of science.

More on this later. The gym beckons.