Can Cigarette Smoking Cause Colon Cancer?

It’s clear that cigarette smoking can pose lots of health risks. This bad habit hosts many toxic and harmful chemicals that can be very bad for your overall health. Even second-hand smoke is still dangerous, too. Rectal and colon cancers (both are often referred to as bowel or colorectal cancers) are also pretty common in smokers. Does it mean that smoking play a significant role?

Yap, smoking can trigger and cause colon cancer

If you are looking for the most effective steps to prevent cancer, quitting smoking if you are a smoker should be one of your top lists. Even many experts say that cigarette smoking is by far the greatest preventable cause of many cancers.

Many studies have shown the connection between smoking and the risk of cancer, this link is now very clear. Even it was responsible for about 100 million deaths in the world for one decade (in 20th century). If there is no significant change and this trend continues, there will be about a billion deaths in the next century, according to the World Health Organization (WHO).

Bowel cancers are not the only one of cancer linked to smoking. Many times, it is associated with increased risk of lung cancer since your lungs are the most exposed organ to toxic and other harmful chemicals when you are smoking. Even almost cases of lung cancers (9 out of 10) are triggered by smoking.

In less common cases, it is also a risk factor for other types of cancer. These include cancers of mouth, esophagus, bladder, pancreas, kidney, larynx, liver, stomach, leukemia, cervix, and ovaries. See the picture below (credit to Cancer Research UK)!


*Larger circle means more cases of cancer associated with smoking. For instance, lung cancer has the largest circle.

There is also evidence that it may raise the risk of breast cancer, too. It seems that smoking is associated with the risk of at least 14 types of cancer!

How does cigarette smoking trigger and cause colon cancer?

You may wonder why quitting smoking is not easy. The answer is a powerful substance in tobacco called nicotine. It can make smoking become very addictive! Even the addiction level can be in much the same way as cocaine or heroin.

And the bad news, cigarettes are usually made to give a smoker the fast nicotine hit. Not more than 20 seconds after you inhale cigarette smoke, nicotine has reached your brain!

Again, lungs are the most exposed organ. But this is not the end since it can affect your entire body. Harmful chemicals and toxics in cigarette smoke will enter to the bloodstream and then can travel throughout the body. Therefore, it is linked to lots of health risks such as various lung diseases, cancers mentioned before, heart disease, etc.

image_illustration352How does it lead to colon cancer? In general, there may be two main answers:

  1. Toxic from tobacco can weaken the body immune system in long term. If your immune system is not as strong as usual, your body is relatively easier to become sick. Cancer cells are also easier to grow since the immune system is weak and doesn’t work well to stop them.
  2. Chemicals in tobacco can cause damage to cells of DNA, including essential DNA that help protects the body against cancer. Some of these chemicals include nitrosamines, polonium-210, benzene, and benzo(a)pyrene.

Furthermore, numerous different chemicals in tobacco also pose the risk of other health conditions. Even some can worsen the effect in causing cancer. For instances, nickel and arsenic can interfere with the ability of the body to repair damaged DNA. Another harmful chemical such as chromium can make benzo(a)pyrene stick more easily and strongly to DNA.

Smoking is not only a trigger for colon cancer, but also can inhibit the ability of your body to fight against the cancer.

Smoking and alcohol, both are risk factors of colon cancer

While smoking has its own ways to contribute to cause the disease, it also promotes another bad habit ‘abusing alcohol’. Many times, smokers are also a heavy drinker. And did you know that the habit of drinking too much alcohol also can increase the risk of bowel cancer?

Some studies have shown that alcohol has a role to increase the risk. About 11 percent of colorectal cancers are associated with drinking alcohol, see more in here!

The cancerogenic effect can get worse when both bad habits (smoking and drinking alcohol) are done together at the same time. This is worse than for either one of them by itself!

Together, they may also promote other risk factors such as becoming a sedentary individual (lack of physical activity) and obesity. See also more factors and conditions that can increase the risk of colon cancer in this section!