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How Many Cigarettes Cause Cancer? Find Out Here

Medically reviewed by John Paul Abrina, MD · Oncology · Davao Doctors Hospital

Written by Lorraine Bunag, R.N. · Updated Jul 27, 2022

How Many Cigarettes Cause Cancer? Find Out Here

Experts don’t get tired of reminding us that smoking causes numerous diseases, like stroke, heart diseases, and cancer. According to the US National Institute of Cancer, smoking leads to cancers of the mouth, larynx, esophagus, lung, kidney, bladder, pancreas liver, stomach, cervix, colon, and rectum. But how exactly does smoking result in the “big C”? And another thing: how many cigarettes cause cancer? Find out here. 

How Does Smoking Cause Cancer? 

The US Center for Disease Control explains that smoking causes cancer in two ways: through triggering changes in the DNA and compromising the immune system. 

Our DNA contains the “instruction manual” on how our cells would operate, including their growth and death. A change or damage in the DNA can cause cells to behave abnormally and grow uncontrollably, resulting in tumors. 

Numerous reports say a stick of cigarette contains thousands of compounds and at least 60 have been identified as carcinogens, substances that promote carcinogenesis (formation of cancer). 

The harmful chemicals in cigarettes also damage the parts of DNA that supposedly protect it against cancer. Furthermore, other chemicals make it more difficult for the cells to repair these damages. 

Finally, smoking weakens the immune system, making it harder to destroy cancer cells. 

How many cigarettes cause cancer?

Now that we have a better understanding of how smoking causes cancer, let’s try to answer a common question among smokers: how many cigarettes cause cancer? 

Many people accept that heavy smoking increases the risk of cancer, but those who only smoke occasionally, or only go through a stick or two daily, feel as though they are in the clear. 

However, the phrase “everything in moderation” doesn’t apply to smoking. 

Authorities state that there is no safe level of smoking. They reiterate that even a stick a day over your lifetime can lead to smoking-related cancers.    

In Other Words, Light and Social Smokers Are Not Safe

We don’t have a standard definition of “light smoking,” but some reports say it’s when you smoke less than a pack, less than 15 sticks, or less than 10 sticks daily. Others say it’s when you light 1 to 39 cigs a week. 

There’s also no standard definition for social or intermittent smoking, but many agree it’s when you don’t smoke daily. 

And while it’s easy to believe that light and social smoking is “better” than heavy smoking (at least 25 cigs per day), experts say they still pose many dangers, including: 

  • Stomach, pancreatic, esophageal, and lung cancers
  • Respiratory tract infections
  • Cardiovascular diseases due to damaged blood vessels and clogged arteries
  • Cataracts
  • One Study Revealed The Risks

    There might be no exact answer to the question, how many cigarettes cause cancer, but a group of researchers compared the risks between heavy and light or social smokers. 

    Results showed that:

    • The risk of dying from lung cancer is 23 times more in men and 13 times more in women who smoke greater than 20 cigs a day compared to non-smokers. 
    • While lower, the risk for light and occasional smokers is still substantial. Men and women who smoke 1 to 4 sticks daily are 3x more and 5x more likely to develop lung cancer compared to non-smokers. 
    • Light and social smokers are also almost 5 times more at risk of having esophageal cancer, 2.4 times more likely to develop stomach cancer, and almost twice as vulnerable against pancreatic cancer. 

    Key Takeaways

    How many cigarettes cause cancer? While light and social smoking are not as severe as heavy smoking, experts agree that there’s no safe level of smoking, as even a cigarette a day over a lifetime can negatively impact your life. 

    You can learn more about the benefits of quitting smoking here. Also, if you’re having difficulty quitting, you can check out the 5As Approach to Smoking Cessation


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Medically reviewed by

    John Paul Abrina, MD

    Oncology · Davao Doctors Hospital

    Written by Lorraine Bunag, R.N. · Updated Jul 27, 2022

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