Letter to the editor: Smoking causes lung cancer

Steffan Puwal, Contributor

As a teacher, I find working with students at Oakland University personally fulfilling.  Your optimism at the start of your career is encouraging.  Sadly, I’m seeing more and more students who smoke cigarettes.  As a scientist, it is distressing to know that some of those students will die as a result of this habit.  There are very few things more life-shortening than the use of tobacco products, and I implore you to please seek medical help and try to stop smoking.

Cigarettes cause cancers

Cancer is a term used for over a hundred different diseases, with the common factor being an uncontrolled growth in the number of cells.  Substances that cause cancer are known as carcinogens.

Researchers have identified two things that are clearly and incontrovertibly carcinogenic: ionizing radiation and cigarettes.  Cigarettes cause so many types of cancer, and in so many different ways, that discussing them all would fill volumes of textbooks.  One third of all cancers in the United States can be attributed to smoking, in particular lung cancers.

Lung cancer: Epidemiology

Lung cancers used to be rare in the United States.  Then, during the Second World War, GIs developed the habit of smoking.  The decades that followed saw a dramatic increase in the number of lung cancer cases.

In 1951, epidemiologists Richard Doll and Austin Bradford Hill surveyed tens of thousands of doctors in Britain, identifying their lifestyles and habits.  In the first decade of the study, enough of the participants died to allow researchers to establish that smoking had contributed to a 50% increase in mortality.  By 1991, the study concluded that those who had stopped smoking before the age of 35 had life expectancies similar to the nonsmokers.

Study after study has shown an epidemiological link between smoking and lung cancer.  Evarts Graham was so alarmed by the results of his own study that he immediately quit smoking.  But the damage had already been done and he would die of lung cancer in 1957.

Lung cancer: Experimental biology

Evarts Graham and his colleagues understood that smoking causes cancer, but what specifically about cigarettes was causing the cancer?  A 1953 study by Graham and his colleagues would provide some insight.  Cigarette smoke contains a tar.  When they painted the backs of mice with this tar, 44% of them developed skin cancer.  In 1969, the Surgeon General finally issued a warning about the health effects from smoking.

These studies should have conclusively made the case that smoking increases the risk of death, in particular from cancers like lung cancer.  Merchants of doubt, unfortunately, continued to argue that there simply wasn’t enough evidence, or that each study was poorly designed.  Graham’s study, for example, was attacked on the premise that people do not distill cigarette smoke and paint it on their skin, completely overlooking the fact that a carcinogenic substance had been identified in cigarette smoke.

Lung cancer: Molecular biology

By the early 1990s, molecular biologists like Gerard Pfeifer and Mikhail Dennisenko would confirm in great detail how cigarette smoke can cause cancer.

There are a number of carcinogenic compounds in the tar from cigarette smoke.  One of them is called benzo(a)pyrene (BaP).  When this substance gets into a cell, the cell tries to get rid of it.  In the process BaP is transformed into benzo(a)pyrene diol epoxide (BPDE), which has an unfortunate tendency to stick to DNA.

DNA’s combination of letters codes for the proteins and biological products our cells need to function.  With just 4 letters, Adenine, Cytosine, Thymine, and Guanine, the cell can make proteins like p53.  This particular protein stops a cell from reproducing until mistakes can be fixed.  It is, therefore, a very important tumor suppressing protein.

BPDE sticks to DNA at three specific codons in the gene for p53, and once there it swaps Guanine and Thymine.  This mutation, a spelling error in the DNA code, is fatal to the function of the protein.  And to the patient.  In 1996, a study of 500 lung cancer patients found these specific mutations were present in the vast majority of smokers, and were rarely present in nonsmokers.

This is just one example of how the many compounds from cigarettes can cause cancer.

Secondhand smoke

Lung cancers aren’t just confined to the smoker.  Secondhand smoke is known to cause cancer as well.  Waiters, for example, who never smoked themselves nonetheless can develop lung cancer.  The risks associated with smoking are shared by your family and friends.  The life you save by quitting smoking may not just be your own.

What can you do?

Cancer can seem very far off, something that affects others.  And so, it’s easy to downplay the risks and continue doing something you know can cause cancer.  Then, one day cancer will seem very close.  Somewhere between one-third and half of all Americans will be diagnosed with a cancer at some point in their life.  You or someone you love will be diagnosed with cancer.  That much is certain.  And more than half a million Americans will die each year from causes related to smoking.

Quit smoking

You need help trying to quit.  Tobacco products contain nicotine, which is an addictive substance.  It’s not simply a matter of willpower.  Please reach out to a health professional, such as the Graham Health Center on campus.  If that doesn’t work, reach out to another health professional.  And another.  The important thing is to keep trying until you find something that works.

Encourage others to quit

If you know someone who smokes, reach out to them.  Research has shown that shaming someone for their addictive habit does not help them to quit.  Remind those you care about that you’re there for them and you want to help.

Join the American Lung Association’s LUNG FORCE Walk

While smoking is the leading cause of lung cancer, it is not the only cause of lung cancer.  Lung cancer can still affect you or someone you care about.  The American Lung Association is seeking to improve treatment and support the kind of research that will one day lead to a cure.  You can join their annual LUNG FORCE Walk to help raise funds.  This year’s walk will be held on October 2 at the Detroit Zoo.  I hope to see you there.