How Does Tobacco Lead to Cancer? (Post #21)

Welcome back to the Spiramen Founder's Blog! For those readers that are new, my name is Ria, and I am the founder of Spiramen Foundation.

At Spiramen, we work on reducing death rates related to throat and oral cancer by promoting early screenings. One way we do this is by conducting free screenings for the underpriveleged community. We also spread awareness about prevention for oral and throat cancers and I post these weekly blog posts.

With that, let's get into this week's topic.

We've all heard that tobacco usage, whether chewing or smoking, can cause cancer. But have you ever questioned why? Today, we'll be learning all about how tobacco affects the body, and how that may lead to cancer cell formation.

Before we dive in, let's recap what cancer cells are: cells that have uncontrolled growth due to DNA mutations. In a sentence, we can say that tobacco leads to cancer, or is carcinogenic, because of its ability to cause mutations. However, the full process is more complex.

Tobacco is classified as carcinogenic because it contains chemicals called carcinogens. These chemicals increase the chance of developing cancer because they damage DNA. When DNA gets damaged, cells usually try to repair the DNA. If it is not repaired correctly, the cell doesn't follow the instructions it is supposed to. As people expose themselves to more carcinogens, the likelihood of incorrect repair increases, leading to mutations. Since tobacco contains many such carcinogens, it is likely to cause cancer.

Carcinogens form in tobacco during its curing, processing, and storage. Smokeless tobacco contains at least 28-30 carcinogens, including tobacco-specific nitrosamines, polynuclear aromatic hydrocarbons, and radioactive elements like polonium-210.

As we know, these chemicals damage the DNA. We can think of DNA as an instruction manual for a cell. DNA tells a cell how to function, including when to multiply, how to repair itself, and when to die. When DNA is damaged, the cell doesn't follow the instructions it is supposed to. So, it multiples, divides, and grows incorrectly, forming tumors.

Cancer cells also avoid apoptosis or self-distruction. When cells are usually badly damaged, they self-destroy. However, cancer cells completely pass by this instruction, likely due to an additional mutation in the apoptosis-related gene.

The cells' specific actions depend on which gene in the DNA was mutated. Not every mutation in DNA leads to cancer. The mutations that usually do cause cancer are in genes responsible for controlling cell growth and survival. The most commonly mutated gene in cancer patients is the TP53 gene. This gene acts as a "tumor suppressor" in healthy cells, ensuring that the cell doesn't divide too often.

Over time, a cell accumulates many mutations, and a group of abnormal cells forms. This is a tumor.

But tobacco doesn't only cause mutations, it also leads to a condition called chronic inflammation. Tobacco repeatedly irritates and injures tissue lining. The body then send blood cells to the injured area, leading to inflammation.

In common situations, inflammation is usually helpful. It helps fight infection and repairs the damaged tissue. However, tobacco chewers or smokers usually experience hronic inflammation, where inflammation continues for a long time. This is because these people are repeatedly exposed to tobacco for months, or even years. The body is therefore in a state of inflammation for just as long. This repeated inflammation leads to the production of reactive oxygen species.

So what are reactive oxygen species? Well, they are highly reactive molecules that can damage cellular components like DNA. They also change the chemical environment around cells to promote abnormal cell growth.

So, tobacco causes cancer in 2 ways:

• through direct damage to DNA

• through chronic inflammation, which leads to additional damage to DNA

With all of this damage happening over years, an incorrect repair is not unlikely.

In India, oral cancer constitites 31% of global cases. South-Central Asia has also been recorded to have the highest number of oral cancer cases caused by tobacco. As members of this community, it is out responsibility to educate others about the risks of tobacco and do our best to reduce oral cancer mortalities.

Thanks for reading this week's post! See you next week!

Information Citations:

“Smokeless Tobacco and Cancer.” National Cancer Institute, Cancer.gov, 25 Oct. 2010, https://www.cancer.gov/about-cancer/causes-prevention/risk/tobacco/smokeless-fact-sheet.

“How Does Cancer Start? Genes and Cancer.” Www.Cancer.Org, https://www.cancer.org/cancer/understanding-cancer/genes-and-cancer.html. Accessed 3 Aug. 2026.

Image Citations:

StoryMD. Tobacco Use Causes Cancer. https://storymd.com/journal/wdoq42gu4j-cancer-and-the-environment/page/xbn753saz8vp-tobacco-and-cancer-risk. Accessed 4 Aug. 2026.