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An "Unplanned Triumph" in Cancer Prevention
He correctly concludes that our genes provide "a predisposition to disease, not a death sentence".
An "Unplanned Triumph" in Cancer Prevention: Leveling the Genetic Playing Field
by Dr. Gerry Lower | May 13 2007 - 1:32pm |
Dean Ornish at Newsweek has recently discussed the relationships between genes and chronic diseases such as the cancers, coronary heart disease, diabetes and the non-disease problem of obesity (1). He correctly concludes that our genes provide "a predisposition to disease, not a death sentence".
Genes do not play a directly causal role in obesity (2). "The idea that it's all in your genes is nonsense. The human genome changes only one half of one percent every million years. The obesity epidemic is only about 30 years old, so changes in genes do not explain the recent dramatic rise in obesity" (1).
Genes do not play a directly causal role in the human cancers either (3). Causation is due to exposures to mutagens, e.g., viruses, radiations and chemicals, with chemical mutagens playing by far the largest role, a fact that makes most cancers preventable.
Rather, genes establish a predisposition to developing cancer. In other words, given exposure to causal mutagens, one's risk of developing cancer is a function of both relative exposures and relative susceptibility. Relative exposures are determined by external cultural factors and relative susceptibility is determined by internal genetic factors (3).
Some people are just more susceptible to cancer than others. Those individuals most susceptible just have to work harder to avoid those cultural factors adding to risk. In Ornish's words, "You have to make bigger changes in diet and lifestyle than someone who has better genes" (1).
It must be interjected here that the notion that some people have "better genes" than other people is a rather large load of intellectual rot. The genomic diversity that makes some people more susceptible to certain diseases than others is the source of human adaptability. Without that adaptability, we could not possibly have survived our collective evolutionary journey on earth.
There is, however, yet another option that helps level the genetic playing field. No matter how susceptible one might be by virtue of genetic factors, very few people would get cancer in the absence of exposures to causal mutagens.
In other words, prevention by elimination of mutagen exposures is the most direct route to eliminating the human cancers, regardless of human susceptibility. Given the absence of coherent and cohesive approaches to cancer causation and control (i.e., our failure to think within conceptual frameworks embracing causation) (3), one might ask just what is the precedent for believing that the cancers can be prevented?
The most triumphal story of cancer prevention still occasionally gets mentioned in academics (4) but the story has not become part of the public knowledge base. Even here, corporate America would see a story that is best not disseminated lest we get serious about studying cancer causation and thereby threaten an out-of-control marketplace.
The story begins in the 1930s when preventable tobacco-related lung cancer in males was just beginning to be recognized as a national health problem. At that time, the most common cause of cancer death in America was gastric cancer. By the late 1930s, the incidence of gastric cancer began to fall and it fell every year until today it is only the eighth most common cause of cancer death in the U.S. (5).
In the world of experimental carcinogenesis, Hans Druckrey gets the credit for discovering nitrosamines and nitrosamides as a very potent class of chemical carcinogens. This all occurred in Germany in the 1950s when working on rocket fuels where workmen began developing occupation-related cancers.
It was soon established that the nitrosamines required metabolic activation to mutagenic forms and, as a result, they caused cancer in organs with the ability to metabolize nitrosamines, e.g., liver. The nitrosamides were recognized to be direct-acting and they affect the tissues which are exposed.
The story of gastric cancer prevention goes back to 1923 when the Department of Agriculture established guidelines for the use of sodium nitrite and nitrate in preserving meats and fish, a practice emerging just prior to the turn of the century. The maximum level of 200 ppm was established based on the amount of nitrites and nitrates actually required to preserve meats and fish. Sodium nitrite was also discovered to be the active curing agent.
Prior to that ruling, the levels of nitrites and nitrates in home-cured meats and fish ranged from 10,000 to 30,000 ppm. In other words, levels of nitrites and nitrates in cured meats was reduced by up to 99 percent following 1923. Coupled with the emergence of electric refrigeration in the 1930s and the consumption of fresh meats and fish, the stage was set for gastric cancer to begin going away (5).
We know that nitrites in acidic gastric contents react quickly with alkylamides and ureas naturally-occurring in meats and fish to produce alkylnitrosamides and nitrosoureas which are among the most potent direct-acting carcinogens known. Gastric cancer incidence was on the increase prior to 1923. With a latent period of 10 to 15 years, the gastric cancer problem peaked out in the late 1930s and it began to go away by itself, without public acknowledgment or fanfare.
We ignore the most amazing example of cancer prevention known. One does wonder what the incidence of gastric cancer might be if nitrites were completely eliminated from the human diet. It would seem quite likely that the incidence of gastric cancer could be further reduced. By the late 1970s, the FDA moved toward a ban on nitrites (6) and by 1980, the FDA made a "surprising retreat" from doing so (7). Imagine that.
Again, such a story of cancer causation and prevention just seems to hit our capitalistic leadership in medicine the wrong way. Whether medical scientists and practitioners are aware of it or not, they do actively make effort to avoid any viewpoints that might pose a threat medicine's takeover by corporate America. To do otherwise is threaten one's sources of income.
Cancer research has been increasingly off track since the early 1970 when Nixon launched the "war on cancer". In spite of knowing better, we have ended up devoting our efforts almost entirely to diagnosis and palliative (non-curative) therapy where there is money to be made. We have done so in the absence of knowledge of causation. In the absence of this knowledge (causal mutagens and specific mutations), there is very little precedent for the discovery of specific preventive interventions or curative therapeutic interventions.
"I read the news today, oh boy"