How does smoking cause cancer?

It’s easy to feel overwhelmed by statistics, medical jargon, and grim warnings about smoking. You’ve likely heard that smoking causes cancer, but have you ever quitted to ask how? What’s actually in a cigarette that makes it so dangerous? What are your real risks? And most importantly, is there a way out?

This article offers clear answers to these questions. Allen Carr’s Easyway’s goal isn’t to frighten you. 

Our goal is to help you understand the truth—and empower you to free yourself from the smoking trap for good.

What types of cancer does smoking cause?

Smoking is the single leading cause of preventable death globally. According to the World Health Organisation (WHO), tobacco use is responsible for over 8 million deaths each year, including approximately 1.2 million non-smokers exposed to second-hand smoke.

Of all the diseases associated with smoking, cancer is the most feared—and for good reason. The good news is that the body starts to heal the moment you quit smoking.

Read more about the effects of quitting smoking.

Tobacco smoke contributes to the development of at least 15 different types of cancer. These include:

1. Lung cancer

Lung cancer is the most common and deadliest cancer linked to smoking. Over 70% of all lung cancer cases are caused by smoking.

2. Mouth (oral cavity) cancer

The direct contact between tobacco smoke and the mucous membranes of the mouth significantly increases the risk of cancer of the lips, tongue, cheeks, floor of the mouth, and hard/soft palate.

3. Throat cancer

The direct contact between tobacco smoke and the mucous membranes of the throat significantly increases the risk of cancer in the oropharynx, nasopharynx, and hypopharynx.

4. Laryngeal (voice box) cancer

Smoke directly irritates and damages the larynx, increasing the cancer risk.

5. Oesophageal cancer

The direct contact between tobacco smoke and the mucous membranes of the oesophagus significantly increases the risk of squamous cell carcinoma and adenocarcinoma of the oesophagus.

6. Bladder cancer

Harmful chemicals from smoke are filtered by the kidneys and stored in the bladder, causing direct contact with the bladder lining.

7. Kidney cancer

Smoking leads to systemic exposure to toxins in the smoke causing renal cell carcinoma.

8. Liver cancer

The liver breaks down toxins in cigarette smoke, making it a common site for cancer in smokers.

9. Pancreatic cancer

Smoking increases pancreatic enzyme mutations, one of the most deadly cancers.

10. Stomach cancer

Toxins in cigarette smoke affect digestive enzymes and damage the stomach lining and increases the Helicobacter pylori infection risk.

11. Cervical cancer

Smoking weakens the immune system and reduces the ability of the body to fight off human papillomavirus (HPV), increasing the risk of cervical cancer.

12. Colorectal (bowel) cancer

Smoking increases the risk of developing and dying from colorectal cancer.

13. Acute myeloid leukaemia (AML)

Smoking increases the risk of this blood and bone marrow cancer.

14. Nasal and paranasal sinus cancer

Inhaled tobacco smoke irritates the nasal passages, contributing to cancer risk.

15. Breast cancer (emerging evidence)

Especially in premenopausal women, smoking may increase breast cancer risk, particularly when combined with alcohol.

What ingredients in cigarettes cause cancer?

Cigarette smoke is a cocktail of toxic chemicals, many of which are carcinogenic (cancer-causing). According to the U.S. Centers for Disease Control and Prevention (CDC), tobacco smoke contains over 7,000 chemicals, with at least 70 known carcinogens.

Let’s look at a few key offenders:

1. Tar

Tar is the sticky residue left behind when tobacco is burned. It contains several carcinogens, including benzopyrene, which damages DNA in lung cells.

2. Nicotine

While nicotine itself isn’t directly carcinogenic, it’s the chemical that keeps smokers addicted, ensuring continued exposure to more dangerous substances.

3. Benzene

A well-known industrial chemical, benzene is present in cigarette smoke and associated with leukaemia and other blood cancers.

4. Formaldehyde

This chemical is used to preserve dead bodies. In cigarettes, it’s used to increase shelf life and is a known carcinogen.

5. Polonium-210

A radioactive element found in tobacco leaves due to certain fertilisers. Yes – radioactive. This substance emits radiation that damages DNA.

6. Arsenic

Commonly used in rat poison, arsenic is also found in cigarette smoke and is linked to skin, lung, and bladder cancers.

How do chemicals in tobacco smoke lead to cancer?

Understanding how smoking causes cancer isn’t about memorising complex biochemistry; it’s about seeing the truth clearly, so you can free yourself from the illusion that smoking helps you cope or brings you pleasure.
Here’s how it works:

1. DNA damage

Many chemicals in cigarette smoke directly damage the DNA in cells. DNA mutations are the first step in the development of cancer. The body normally repairs such damage, but with frequent exposure, repair mechanisms are overwhelmed or sabotaged.

2. Inflammation

Tobacco smoke causes chronic inflammation in tissues throughout the body. Inflammation leads to cell damage and increases the chances of cancerous changes.

3. Immune system suppression

Smoking weakens the immune system, making it harder to eliminate cancerous cells before they grow uncontrollably.

4. Free radical production

Free radicals are unstable molecules that damage cells and DNA. Cigarette smoke contains and generates these radicals in massive quantities.

5. Angiogenesis and tumour growth

Some chemicals in cigarettes promote the growth of new blood vessels (angiogenesis), which tumours use to grow and spread.
To visualise this, consider a single cigarette as a match to a dry forest. One may not cause an inferno, but the damage accumulates over time until disaster is inevitable.

What’s My Cancer Risk from Smoking?

Every cigarette increases your risk. However, individual cancer risk depends on factors like:

• How long you’ve smoked
• How many cigarettes per day
• Your age, genetics, and lifestyle
• Environmental exposure

Let’s break it down:

Lung Cancer Risk

• Smokers are 15 to 30 times more likely to get lung cancer than non-smokers.
• Even “light” smokers (fewer than 10 per day) have a significantly elevated risk.

2. Passive Smoking

• Second-hand smoke causes over 1.2 million deaths annually.
• Non-smokers living with smokers are at increased risk of lung and breast cancers.

3. Quitting Matters

The good news is that once you quit smoking, your risk starts to drop:

Years after quitting:             Risk of cancer decreases by:
1 year                                      50% drop in heart disease risk
5 years                                    Risk of mouth, throat, oesophagal cancer halved
10 years                                  Lung cancer death risk is halved
15 years                                  Risk of most smoking-related cancers approaches non-smoker level

Do you know what happens to the body when you quit smoking?

Learn How Allen Carr’s Easyway Program can help you quit smoking for good

You already know smoking is harmful. But fear alone doesn’t make it easy to quit. That’s why scare tactics don’t work. What does work is understanding how the smoking trap works—and how to escape it.

At Allen Carr’s Easyway, we don’t rely on nicotine patches, gums, or willpower. We dismantle the illusion that smoking relieves stress or offers any real pleasure. You will be able to quit smoking, socialise and enjoy life with smokers the minute you complete the course.

Once you see the truth, there’s no sacrifice. No cravings. Just freedom

Why Easyway works

• No willpower required
• No withdrawal pain
• Immediate results for most
• Scientifically proven (Two independent randomised controlled trials, approved by NICE in UK, Belgium & German Governments and The World Health Organisation)

Choose the Right Program for You

• Live Seminars – Real-time live interaction with a trained facilitator either at a center or online.
• Video Programs – Go at your own pace with pre-recorded expert guidance.

We’ve helped over 50 million people across the globe. You can be next.

“It’s not about quitting smoking—it’s about being free.” – Allen Carr

Take your first step toward a smoke-free life today and learn more about our programs.

Choose your program

Final Thoughts

Smoking doesn’t cause cancer randomly; it does so through specific, well-understood biological mechanisms. But that doesn’t mean you will get cancer. It means that once you quit, your body begins to heal, your risks drop, and your life opens up in ways you may have forgotten were possible.

Don’t feel scared into quitting – feel empowered. That’s what we offer.

Take your first step toward a smoke-free life today and learn more about our programs.