A recent cell culture study generated widespread media attention and propagated the notion that cancer is mostly a random event. That is a very egregious distortion. I am delighted and honored, as the Ronald B. Herberman Speaker at National Cancer Prevention Day, sponsored by Lesscancer.org, to have an opportunity on February 4 to help set the record straight. Here's a bit of a sneak preview.
First, regarding that recent study, the researchers studied the rate of potentially cancer-causing genetic mutations in different tissues. They then extrapolated potential cancer occurrences, based on a computer model derived from the number and frequency of cell divisions, and the frequency of mutation. The research showed that many ominous mutations happen spontaneously, meaning they are not passed down from one generation to the next; and such mutations happen more often in tissues that divide often.
The study did not examine actual cases of cancer in actual people. The work was in isolated tissues, and only about mutations; not about clinically relevant cancers in actual bodies. If you are now wondering why all the media hoopla- well, that makes two of us.
Gene mutation does not equal cancer.
Cancer is a decades-long process, not a sudden "sneak attack." The predictable course of its development provides many opportunities for prevention. There are three key stages in the development of cancer: initiation, promotion, and expression.
Initiation refers to genetic mutation that has the potential to result in unregulated cell growth. The recent study indicates that such mutations are more likely to occur spontaneously than be handed to us from our parents, making them "random." But otherwise, they are not really random. We know that carcinogens, including toxic exposures such as radiation and chemicals, increase the frequency of such mutations. Healthy living can reduce that frequency.
When mutations do occur, whether despite our best efforts or for want of them, most are not carcinogenic. For a mutation to be carcinogenic, it must occur near, and affect, a growth-regulating gene called an oncogene. Situated normally next to other genes, oncogenes provide signals to cells about when to divide, and when to stop. Removed from their normal position by a mutation, oncogenes can signal the non-stop cell divisions that characterize cancer.
But even a carcinogenic mutation is not cancer. Promotion, the second stage of cancer development, or carcinogenesis, refers to development of a whole colony of abnormal cells. Any exposure, condition, or circumstance that favors the growth of this colony of abnormal cells may be considered a cancer promoter. Promoters are often quite distinct from initiators, although some exposures, such as tobacco, play both roles.
Among the most important cancer initiators are cigarette smoke, food that is charred or smoked, environmental contaminants and chemicals such as radon and dioxin, and obesity. We need help from relevant authorities to deal with environmental hazards, but others are substantially under our control. Not smoking is a powerful intervention in the prevention of cancer initiation. So, too, is healthy living in general, and the resultant avoidance of obesity, and the often associated inflammation that can fan cancer's early flames.
Our immune system is constantly on the prowl for abnormal cells, and generally does a good job of destroying them. Optimal immune function is supported by weight control, stress control, adequate sleep, moderate physical activity, and a balanced, prudent diet. In other words, the same basic lifestyle elements associated with the prevention of chronic diseases in general are a powerful defense against cancer, too.
Tobacco, sunburns and charred food increase the mutation rate, and the immune system's work. Avoidance of these can help avoid overwhelming the system. Another useful strategy is a generous intake of antioxidants, from such sources as fruits, vegetables and tea. Oxidation damages DNA, increasing the risk of initiation; antioxidants can defend against this.
Obesity is a crucial cancer promoter, more than doubling the risk of many leading cancers, including both prostate and breast. For cancers of the head and neck, and breast, alcohol is a promoter. Weight control, and the avoidance of excessive alcohol intake and tobacco, can prevent cancer promotion, even if initiation has occurred.
The final stage in cancer development is expression. Even a colony of abnormal cells may cause no clinical harm. It's when the cancer becomes evident in some way, generally by causing symptoms, that it has been fully expressed. For most cancers, this is one, two, or even three decades after initiation.
The best approach to the prevention of cancer expression, early detection, requires help from your health care provider. Taking advantage of screening tests for cancers such as breast and colon can catch them before they would otherwise be noticed, and much improve treatment options and the likelihood of cure. Largely due to advances in early detection, and treatment, cancer mortality in the U.S. has been declining impressively for years.
Still, avoiding cancer altogether is better than detecting it early and treating it effectively. We have considerable opportunity to do just that.
The evidence is entirely overwhelmingly that how we live influences the likelihood of cancer overall, and that of many specific cancers. Studies show that the very same people, with the very same genes, are subject to higher rates of cancer, along with other chronic diseases, when they leave a healthy, native lifestyle behind, and adopt a more dubious one.
Studies show that some populations around the world get much less cancer, as well as other chronic diseases, not because of genetic advantage, but because of lifestyle advantage, mediated by culture. And perhaps most relevant for those of us not yet living in a Blue Zone, intervention studies show -- over and over and over -- that a constellation of healthful lifestyle practices translates into less cancer along with other chronic diseases, just as it translates into more years in life, more life in years.
Of course, we do not have complete control over our medical destinies. Some people do everything right, and develop cancer nonetheless. There is a truly random element, and no guarantee of a good outcome based on good practice. There is, however, a massive shift of odds in our favor.
A seaworthy craft in the hands of an able captain is far more likely to make a safe passing, no matter what the sea holds in store. Similarly, a body well tended by healthful lifestyle practices is very likely to avoid cancer, no matter the rate of random mutation in any given tissue.
On National Cancer Prevention Day, we can acknowledge the random challenges of wind and wave, but celebrate the mastery of ship and sail, securely in our hands.
This blog post is part of a series produced by The Huffington Post and LessCancer.org in recognition of World Cancer Day and National Cancer Prevention Day (both Feb. 4), and in conjunction with Less Cancer's program on Cancer Prevention in Washington, D.C. on 2/4/14. To see all the other posts in the series, click here. For more information about Lesscancer.org click here.