Is Cancer Just "Bad Luck?"

Thursday, Jan 22, 2015

Breast surgeon and breast cancer expert Donna Angotti, MD looks closely at recent research that considers "bad luck" to be a factor in cancer. There's a lot more to it than that, says Dr. Angotti.

An article about cancer;published by the journal Science attracted a lot of media attention in recent weeks. In the article, two researchers from Johns Hopkins write that cancer is often times due to "bad luck," or random changes in an otherwise normal cell's DNA.

The researchers, Cristian Tomasetti, PhD and Bert Vogelstein, MD start with the observation that the risk of cancer is "millions" of time higher in certain tissues of the body than others. For instance, lung cancer and breast cancer are pretty common in the United States, while cancer of the thymus gland (an organ of the immune system) is not.

Let's begin with a basic understanding of cancer. First, a primer on stem cells. These special cells have the potential to develop into many different types of the body's cells during early life and growth. When they divide, each new cell has the potential to either remain a stem cell or "specialize" and become a specific cell such as a muscle cell, a red blood cell, or a brain cell.

Once a stem cell has "specialized" it cannot go back and become any other type of cell. Once we are fully grown, stem cells remain on the job for our entire lives, replacing old worn-out cells and repairing wounds or injured cells or tissues. Usually this occurs in a very orderly fashion, but if something goes awry with the genetic material (DNA) of the cell and the usual repair mechanisms or immune system killer cells don't function properly, cancer results. This results in uncontrolled, uncoordinated cell growth that allows the abnormal cells to invade surrounding tissues and, eventually, break off and spread to other organs of the body (metastasize) where they interfere with normal function and can result in death.

For their research, Drs Tomasetti and Vogelstein decided to compare the total number of times stem cells from certain tissues divide in their lifetime, to a person's lifetime risk of developing cancer in that tissue in the United States. They did not look at two of the most common cancers in the U.S., breast and prostate cancers, because they said they could not find enough data.

Not surprisingly, the more times cells in a type of tissue divided during their lifetime, the greater the incidence of cancer in that tissue. This seems to make sense, because, if there is a risk to a behavior or process, that behavior or process has to happen in order for the consequence to occur. In other words, if someone never drives or rides in an automobile, there is almost no chance they will be involved in an automobile accident.

The authors believe that the data suggest that up to two-thirds of the genetic damage that results in cancer happens because of "bad luck". Random errors in the genetic code occur because the cells are dividing more frequently and, therefore, there is a greater chance of mistakes.

The researchers say only one-third of cancers are caused by genetic or environmental factors. Environmental factors include things like a person's diet, how much they exercise, and if they use tobacco products.

When questioned, the authors try to make it clear, however, that they are not suggesting taking up cigarette smoking without regard to increased lung cancer risk. They also suggest a greater emphasis on screening, or looking for cancers before they cause any symptoms.

But are their arguments strong or true?

Centuries ago, the great philosophers, Plato, Socrates, and Aristotle examined the science and art of logic, or the way the human mind analyzes things. They outlined a series of logical fallacies which are flaws in reasoning. One of those, called "False Cause," is an argument that presumes that a real or perceived relationship between things means that one is the cause of the other.

For example, a college environmental studies class investigates a fish pond and finds that the fish population has greatly decreased. They observe that there is also a decrease in the fishes' food supply and argue that that is a good reason for a decrease in fish. Later, however, they find that a manufacturing plant is discharging a dangerous toxin into the stream that feeds the pond, and that is the real reason there are less fish.

From other studies and observations, it does make sense that the more times cells divide the greater the chance there is for errors. But what role does the environment that the cells are exposed to play? Could poor diet choices and external toxins (like those found in cigarettes) limit our cells' ability to repair themselves or to destroy abnormal cells?

Recent literature shows that people who have a better immune response to their cancers, as shown by the number of immune cells that invade the cancerous tissues, have a better prognosis than people whose immune systems do not respond strongly. This has stimulated a whole new line of exciting research investigations.

The take home message?

We should not let this article change anything. There are clearly well established environmental causes of cancer that should be avoided. Smoking is strongly linked to the majority of lung cancers, and if you want to reduce your risk of lung cancer, don't smoke or stop if you do smoke. When cancer does occur, finding it at an earlier stage increases the likelihood the cancer can be cured, so it follows that screening programs should not be abandoned. Most of all, question what medical information is being presented to you and, if needed, use your relationship with your trusted health care provider to help you make good personal health decisions.

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