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Everyday Health
Smoking Causes 12 Types of Cancers: Here's What You Need to Know
By By Stephanie Watson. Medically Reviewed by Conor Steuer, MD,
18 hours ago
Cigarettes contain more than 7,000 chemicals, at least 69 of which are known to cause cancer. Adobe Stock In 1946, the R.J. Reynolds Tobacco Company released an ad campaign featuring the slogan, " More Doctors Smoke Camels ," with images of doctors lighting up Camel cigarettes. Today, with decades of research behind us, the message couldn't be clearer that tobacco smoke is harmful. Smoking is linked to lung disease , heart disease , stroke , diabetes , and several other serious health conditions, according to the Centers for Disease Control & Prevention (CDC). It also causes 12 different cancers, per the CDC:
Even so, more than 28 million people in the United States smoke cigarettes. Why aren't Americans getting the message?
"There's no one who doesn't know the risks," says Peter Shields, MD , a professor of internal medicine and epidemiology at the Ohio State University in Columbus. But, he says, nicotine is incredibly powerful. Teens start smoking to mimic their parents and peers. Quickly, they become addicted and can't stop.
How Does Smoking Lead to So Many Cancers?
When you light up a cigarette, you ignite more than 7,000 chemicals, at least 69 of which are known to cause cancer. Dr. Shields likens smoking to "putting your head in a fireplace and inhaling as deeply as possible."
"If you're smoking, you're bathing your lungs in these carcinogens [cancer-causing substances]," he says.
Changes in DNA
One way that smoking causes cancer is by altering DNA, the genetic information that directs the function of our cells, says Shields. Normally, cells finish their jobs and die off. Chemicals in cigarette smoke change DNA in ways that prevent cells from dying. "They become immortal, and then they replicate," says Shields.
Free Radical Damage
Smoking also causes inflammation, an important contributor to cancer development. And it depletes antioxidants , which are protective substances that neutralize free radicals (unstable molecules that cause disease, including cancer). "[Antioxidants are] our defense against harmful agents, so it makes the smoker more susceptible to other carcinogens," explains Anthony Alberg, PhD, MPH , an epidemiologist at the University of South Carolina Arnold School of Public Health in Columbia who studies the health effects of tobacco.
How Do Cigarette Toxins Reach So Many Organs?
The lungs are the most vulnerable organ, because tobacco smoke touches them directly. That's why smokers are up to 30 times more likely to get lung cancer or to die from it than people who don't smoke, according to the CDC. The mouth and throat are at risk because chemicals must travel through them to get to the lungs. Carcinogens reach other organs, like the liver and pancreas, via the bloodstream.
Cancer-causing chemicals can also get into the urine. "For bladder cancer, the thinking is that the carcinogens remain in urine and are interacting with the bladder tissue in ways that could ultimately cause [DNA] mutations and lead to cancer," says Dr. Alberg.
Smoking isn't linked to other types of cancer, however, like breast and prostate. The reason for this isn't clear, but it could have to do with how much of the toxins from cigarette smoke reach those organs, Alberg says.
Are Genes Linked to Greater Risk for Smoking-Related Cancers?
Why is it that some people can smoke three packs a day and not get lung cancer, while others smoke far less and do get cancer? The answer likely lies in our genes. Certain genes affect the ability to break down carcinogens and other toxins, says Alberg.
But you can't look to relatives for clues to your smoking-related cancer risk, he says. Just because your parent or sibling smoked for years and didn't get cancer, doesn't mean you'll be as lucky.
Is Social Smoking Safe?
What if you have the occasional cigarette with your cup of coffee or glass of wine? The cancer risk from smoking is dose-dependent, meaning the more cigarettes you smoke and the longer you smoke, the greater your risk of getting cancer.
Social smoking is undoubtedly less harmful than a three-pack-a-day habit. On the other hand, as Albert stresses, "There's no safe level of exposure to tobacco smoke."
How Does Secondhand Smoke Affect Cancer Risk?
Even the smoke from someone else's cigarette increases your risk of cancer, although not as much as a personal smoking habit. About 7,300 out of the 127,000 lung cancer deaths each year are due to secondhand smoke exposure. The ill health effects of secondhand smoke are mostly due to sidestream smoke - the smoke that streams out of a smoldering cigarette sitting in an ashtray, says Shields.
How Safe Is Smokeless Tobacco?
Chewing tobacco and snuff remove the combustion part of tobacco use, but they still expose you to cancer-causing chemicals such as tobacco-specific nitrosamines (TSNAs). TSNAs are linked to cancers of the mouth, esophagus, and pancreas, according to the American Cancer Society. These chemicals get absorbed through the lining on the inside of the mouth and can make their way down the esophagus in saliva. The link between smokeless tobacco and pancreatic cancer is less clear, but animal studies suggest that nicotine might damage this organ in ways that ultimately lead to cancer formation. A safer smokeless tobacco alternative from Sweden called snus doesn't seem to increase cancer risk to the same extent because of the way it's manufactured. "It cures the tobacco differently, so the nitrosamines aren't made," says Shields. But snus still carries a potential for increased cancer risk of the esophagus, pancreas, stomach, and rectum.
Reasons to Quit - and How to Kick the Habit
Quitting smoking at any age is good for your health. "The impact is almost immediate," says Shields. The longer you've been off smoking, the more your cancer risk drops.
Within 5 to 10 years after you quit, the additional risk of mouth and throat cancers caused by smoking drops by half, says the CDC. Within 10 to 15 years, the additional risk of lung cancer is also cut in half. And 20 years after quitting, your risk of mouth, throat, and pancreatic cancers drops to nearly that of a nonsmoker's. Your odds of developing heart disease and other conditions linked to smoking also go down. Thinking about quitting smoking is easy. Doing it is another matter entirely. "The major problem with nicotine is that it's so addictive," says Shields. A study in BMJ Open found that it can take 30 attempts or more for smokers to break their cigarette habit.
Anyone who wants to quit smoking can find help from many different resources: quit helplines (1-800-QUIT-NOW), apps such as QuitGuide and quitSTART , counseling, nicotine replacement products, and medications like varenicline (Chantix) and bupropion .
"There are lots of resources out there. Sometimes people just need to understand their cues - why they're smoking," Shields says. "It's much harder for some [people to quit] than others, but everybody can do it."
The Takeaway
Decades of research show that smoking is linked to 12 types of cancer and other serious health conditions. If you smoke, each puff exposes your body to thousands of harmful chemicals, increasing cancer risk significantly. Remember, quitting smoking even now can dramatically cut your cancer risk in the coming years.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy . We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Clarke E et al. Snus: A Compelling Harm Reduction Alternative to Cigarettes. Harm Reduction Journal . November 27, 2019.
A systematic review of cancer risk among users of smokeless tobacco (Swedish snus) exclusively, compared with no use of tobacco. International Journal of Cancer . July 21, 2023.
Chaiton M et al. Estimating the Number of Quit Attempts It Takes to Quit Smoking Successfully in a Longitudinal Cohort of Smokers. BMJ Open . June 9, 2016.
Conor E. Steuer, MD, is medical oncologist specializing in the care of aerodigestive cancers, mesothelioma, and thymic malignancies and an assistant professor in the department of hematology and medical oncology at the Emory University School of Medicine in Atlanta. He joined the clinical staff at Emory's Winship Cancer Institute as a practicing physician in July 2015. He currently serves as chair of the Lung and Aerodigestive Malignancies Working Group and is a member of the Discovery and Developmental Therapeutics Research Program at Winship.
Dr. Steuer received his medical degree from the New York University School of Medicine in 2009. He completed his postdoctoral training as a fellow in the department of hematology and medical oncology at the Emory University School of Medicine, where he was chief fellow in his final year.
He has been active in research including in clinical trial development, database analyses, and investigation of molecular biomarkers. He is interested in investigating the molecular biology and genomics of thoracic and head and neck tumors in order to be able to further the care of these patient populations. Additionally, he has taken an interest in utilizing national databases to perform clinical outcomes research, as well as further investigate rare forms of thoracic cancers.
Steuer's work has been published in many leading journals, such as Cancer , the Journal of Thoracic Oncology , and Lung Cancer , and has been presented at multiple international conferences.
Stephanie Watson is a freelance health writer who has contributed to WebMD, AARP.org, BabyCenter, Forbes Health, Fortune Well, Time , Self , Arthritis Today , Greatist, Healthgrades, and HealthCentral. Previously, she was the executive editor of Harvard Women's Health Watch and Mount Sinai's Focus on Healthy Aging . She has also written more than 30 young adult books on subjects ranging from celebrity biographies to brain injuries in football. See full bio See Our Editorial Policy Meet Our Health Expert Network
Start teaching kids in school why theyshouldn't smoke. Ask their's parents not2 smoke around them. it is good now u can't smoke on the job, park, Bars.A co worker start me off to smoke.l am sorry l start now can't stop but shedid. Glad l not on drugs.
Gary Westberg
30m ago
Just say no to all nicotine products! It’s very easy
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