Smoking and lung cancer are almost always considered together, and there is a lot of truth to that. In fact, tobacco’s increased risk of developing lung cancer is one of the most basic known harmful health effects.

How does smoking cause cancer?

Cigarette smoke is loaded with chemicals that act as poisons to the body. Upon inhalation, these poisonous chemicals enter the bloodstream, from where they lead to various diseases, including cancer. The lung, of course, remains the most easily affected organ. Tobacco smoke carries more than 7,000 chemicals, of which 250 are known to be poisonous. 69 chemicals out of those 250 have carcinogenic properties. Let’s take a look at the different ways smoking leads to lung cancer:

• DNA damage – Chemicals in cigarette smoke, such as nitrosamines, benzene, benzo(a)pyrene, nickel and arsenic, and polonium-210, are known to have carcinogenic properties. These chemicals damage the DNA of genes that help protect against cancer by either binding to the DNA or by interfering with cellular processes that help repair damaged DNA.
• Weakening of the body’s defense system. – There are several ways in which the chemicals in smoke reduce the body’s defense mechanism. For example, formaldehyde destroys the lining of the hair in the airways, which otherwise prevents foreign substances from reaching the lower respiratory tract. Smoke also suppresses the action of cells that prevent abnormal cell proliferation (or cancer). The cadmium in smoke inhibits the action of detoxifying proteins in the body.
• long term exposure – Smokers are exposed to high levels of toxins over the years. Although cancer takes years to develop, the high levels of toxic substances in a smoker’s body make it difficult to cope with their damaging effects. Damage to lung cells and their DNA accumulates over the years to turn those cells into a cancerous state.
• Addictive nature of nicotine. – Nicotine, the main component present in tobacco plants, is really addictive. When inhaled, it enters the lungs, transfers to the bloodstream, and reaches the brain within seconds. The nicotine in cigarettes and other products creates an addiction much like drugs like cocaine. This makes it difficult for many regular smokers to quit even if they want to. Habitual use over time increases the risk of cancer.

So does quitting help, even for a long-term smoker?

The good news is that yes! Quitting smoking is the first step in reducing the risk of cancer. It may not be easy and may require outside help, but the health benefits far outweigh the harmful effects:

• Carbon monoxide levels in the blood return to normal within 12 hours of quitting.
• Lung function and circulation begin to show improvements within 12 weeks of quitting.
• Remaining smoke-free for 10 years reduces the risk of lung cancer to half the risk of a smoker, in addition to reducing the risk of other types of cancer.
• Life expectancy increases regardless of the age at which a person quits smoking; however, the benefit is greater if one quits earlier.

What about a person who already has a positive diagnosis of lung cancer? Will it help you to quit smoking now? The answer is yes, quitting during treatment helps the body respond to therapy and recover faster, while reducing the risk of other infections and respiratory failure. Cancer patients who quit smoking also reduce the risk of cancer coming back or a second cancer at a later time. Better late than never!