Is Cancer Really Caused By Bad Luck?

Nearly every year, medical researchers announce a new cause of cancer. Smoking tobacco causes lung cancer, so scientists look for a relationship between smoking marijuana and lung cancer. Obesity is associated with a long list of health problems, and epidemiologists find connections between weighing too much and being diagnosed with cancer. Alternative medicine gurus re-read medical studies from the 1920's and (mistakenly) conclude that cancer is a fungus that grows on sugar, so they suggest sugar causes cancer.

The Surprisingly Random Nature Of Cancer

This latest observation from years of research comes from the work of Dr Christian Tomasetti and Dr Bert Vogelstein, cancer researchers at Johns Hopkins University. Like many other researchers, Tomasetti and Vogelstein had long suspected that chance played an important role in the initial development of cancer, but they became the first to find out how much or a role bad luck plays in the disease.

Tomasetti and Vogelstein based their research on a nearly century-old observation that cancer is far more common in some organs than in others. Breast and prostate cancer, for example, are very common, but cancers of the heart or retina, on the other hand, are very rare. They took an especially close look at cancers of the intestine. Cancers of the small intestine are quite rare, striking only about 1 in 500 people at some time during life. Cancers of the large intestine, in contrast, are relatively common, occurring in about in 1 in 25 people are some point in their lifetimes. What could account for the difference?

The More Often Cells Are Created, The More Often Cancer Occurs

One important difference at the cellular level between the small intestine and the large intestine is the activity of stem cells. As you probably know, stem cells are the body's replacement cells, possessing the ability to transform themselves into different kinds of tissues.

Both the large intestine and the small intestine repair themselves with the help of stem cells, but the large intestine's stem cells divide much more often than the small intestine's stem cells, about 73 times a year compared to 24 times a year. Three times as many cell divisions results in three times as many opportunities for DNA to incorrectly copied, or for the ends of chromosomes to be mismatched so that some protein or enzyme isn't properly formed. These mutations may cause cancer, or the may disable the cell's machinery for stopping cancer. 

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In many other tissues, rates of stem cell division go hand in hand with rates of cancer development. Dr. Tomasetti compares the process to taking a long trip in a car. The longer the journey, the greater the risk of an accident. To a certain extent, cancer is just a matter of chance, and the longer someone lives, the greater the risk of eventually developing the disease.

Cancer Isn't Strictly a Matter of Chance

Tomasetti and Vogelstein do not suggest that the occurrence of cancer is strictly a matter of chance. Certain kinds of cancer, such as thyroid cancer, have a clearly identified genetic component. People who have parents, grandparents, or siblings who had thyroid cancer have a much higher risk of developing this particular form of carcinoma.

In other cases, there are clear relationships between lifestyle or environmental exposure and the development of cancer. People who smoke are more likely to develop lung cancer. People who are exposed to certain kinds of chemicals are more likely to develop bladder cancer. Many of the causes of cancer, however, are beyond the ability of individuals to control.

What Are The Implications Of Tomasetti and Vogelstein's Findings?

The implication of Tomasetti and Vogelstein's research for many people who have cancer is that cancer is not their fault. They do not need to feel guilty about having cancer. To a large degree, even in cases of lung and colon cancer, the disease resulted from random forces that caused the DNA damage that led to the disease.

There are also important implications of these findings for future cancer research. If there are no clear environmental or lifestyle factors that cause cancer, then it becomes even more important to have the clinical tools that detect cancer at the earliest possible stage. The focus shifts from preventing cancer to treating it effectively, and early.

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What Can Help You To Avoid Becoming A Cancer Statistic?

Nothing in this research suggests that it is OK to smoke or to carry about massive excesses of body fat. Nothing in this research suggests that asbestos workers will not get mesothelioma or that people exposed to radiation will not develop leukemia. However, the strategy for leading the longest and healthiest life possible shifts from prevention to treatment.

• Certain kinds of cancer have a clear hereditary component. It is still important for your doctor to know your family history in order to be on the lookout for these kinds of cancers.
• The older you get, the more likely you are to develop cancer. The dreaded colonoscopy is essential at age 50, and it is even more that you have had it by age 60 or 70.  The risk of cancer due to errors in stem cell division is cumulative, so that by the time you are 85 or older, you are tremendously more likely to develop cancer than you were, say, at age 30 or 40.
• Aiming for an ideal weight is a useful goal for many reasons, but don't assume you will develop or any other disease just because you have not been able to take off the pounds. Weight control is important to good health, but it is not the only factor in the development of disease. Do your best to achieve a healthy weight, but don't neglect other healthy lifestyle choices in the process.