Yes, to a large extent. In a large analysis of 185 countries by the International Agency for Research on Cancer (part of the World Health Organization), nearly 4 in 10 new cancers were linked to causes that can be changed; the biggest were tobacco, infections and alcohol [1]. The most important steps are: do not smoke cigarettes, waterpipe (hookah) or opium, keep a healthy weight and stay active, avoid alcohol, get the HPV and hepatitis B vaccines, have H. pylori treated if your doctor advises it, protect your skin from the sun and have the screening tests recommended for your age [6, 7, 8, 9, 10, 11].
Key points
- Nearly 4 in 10 cancers are linked to causes that can be changed; in men, nearly half of all cancers [1].
- Tobacco is the biggest preventable cause, followed by infections (such as HPV, hepatitis B and H. pylori) and alcohol [1].
- Some simple steps have proven effects: the HPV vaccine, the hepatitis B vaccine, treating H. pylori and sunscreen all reduced cancer in studies [7, 8, 9, 10].
- Screening finds some cancers early, and some even before they start, at the precancerous stage [11].
How much cancer can be prevented?
Cancer does not have a single cause. Some risk factors cannot be changed, such as getting older or genes inherited from our parents; inherited genes are the main cause of at most about 1 in 10 cancers [12] (Is cancer hereditary?). But a large share of cancers is linked to causes that are in our own hands:
- Worldwide: in an analysis of 185 countries, nearly 4 in 10 new cancers in 2022 were linked to 30 changeable causes; nearly half of cancers in men and about 3 in 10 in women [1].
- The biggest causes: first tobacco, then infections, then alcohol. Lung, stomach and cervical cancers made up nearly half of all preventable cancers [1].
- Deaths from cancer: a little under half of cancer deaths worldwide were linked to changeable risk factors; the most important were smoking, alcohol and excess weight [2].
9 important steps to lower your cancer risk
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Give up cigarettes, waterpipe (hookah) and opium
Tobacco is the biggest preventable cause of cancer in the world [1]. Waterpipe smoking is not safe either and has been linked to mouth and lung cancer [3] (Does hookah cause cancer?). Opium is also a definite cause of cancer [4] (Does opium cause cancer?). Ask your family doctor for help with quitting (How much does quitting smoking lower cancer risk?).
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Keep a healthy weight
After smoking and alcohol, excess weight is one of the main causes of cancer deaths worldwide [2]. The advice is to keep your weight within the healthy range [6] (Does obesity cause cancer?).
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Avoid alcohol
Alcohol is one of the three main causes of preventable cancer worldwide [1], and for cancer prevention it is best not to drink alcohol at all [6] (Does alcohol cause cancer?).
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More plant foods, less processed meat
Base most meals on whole grains, vegetables, fruit and pulses; limit red meat and eat very little, if any, processed meat (sausages, ham, salami); drink mostly water instead of sugary drinks [6]. See red meat and processed meat and sugar and cancer.
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Get vaccinated: HPV and hepatitis B
In Sweden, girls who had the HPV vaccine before the age of 17 were far less likely to develop cervical cancer [7]. In Taiwan, after all newborns were vaccinated against hepatitis B, liver cancer in children nearly halved [8]. Ask your doctor which vaccines are right for you and your children (HPV vaccine).
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Have H. pylori treated if needed
In close relatives of people with stomach cancer, treating this germ cut the risk of stomach cancer by more than half [9]. See Should I be tested for H. pylori?
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Protect your skin from the sun
In a study in Australia, people who used sunscreen every day for several years developed melanoma (the most dangerous skin cancer) less often over the following ten years [10].
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Have the screening tests recommended for your age
HPV tests and Pap smears find precancerous changes in the cervix so they can be treated before they become cancer; colonoscopy can also remove bowel polyps before they turn into cancer. Mammography and bowel cancer screening tests reduce deaths from these cancers [11]. See the list in cancer screening.
What should I do? One step for today
If you smoke cigarettes, a waterpipe or opium, quitting will make the biggest difference, because tobacco is the biggest preventable cause of cancer [1]. If you do not, check today which screening tests are recommended for your age (cancer screening) and ask your doctor about vaccines at your next visit. To learn the warning signs, read 5 simple steps to find cancer early.
Frequently asked questions
If someone in my family had cancer, is prevention still worth it?
Yes. Inherited genes are the main cause of at most about 1 in 10 cancers [12]. Even with a family history, avoiding risk factors and having screening on time lower the risk. Talk to your doctor about when to start screening (Is cancer hereditary?).
Is a waterpipe (hookah) less harmful than cigarettes?
No. In a review of studies, waterpipe smoking was linked to mouth cancer (several times the risk) and lung cancer (about twice the risk) [3]. See Does hookah cause cancer?
Do vitamins and supplements prevent cancer?
The World Cancer Research Fund advises against taking high-dose supplements to prevent cancer and recommends meeting your body's needs through food [6].
If I do all of this, will I never get cancer?
At what age should I start screening?
It depends on the type of cancer, your sex and your family history. See the cancer screening tool and the pages on when to start mammograms and when to have a screening colonoscopy.
Do mobile phones, hair dye or sugar cause cancer?
We answer these questions with the evidence on separate pages: Do mobile phones cause cancer?, Does hair dye cause cancer? and Does sugar make cancer grow?
Notes for doctors (for physicians)
For physicians
Global estimate for 2022 (IARC, Nature Medicine 2026). GLOBOCAN data for 36 cancers in 185 countries and 30 modifiable factors (tobacco, alcohol, high BMI, insufficient physical activity, smokeless tobacco and areca nut, suboptimal breastfeeding, air pollution, ultraviolet radiation, 9 infectious agents and 13 occupational exposures), using prevalence data from around 2012 to reflect exposure–cancer latency. 7.1 million of 18.7 million new cancers (37.8%) were attributable: 29.7% in women and 45.4% in men (24.6% to 38.2% in women and 28.1% to 57.2% in men across regions). Smoking accounted for 15.1%, infections 10.2% and alcohol 3.2%; lung, stomach and cervical cancers made up nearly half of preventable cancers [1].
GBD 2019 (Lancet 2022). The risk factors analysed accounted for 4.45 million cancer deaths (44.4%) and 42.0% of DALYs; 50.6% of cancer deaths in men and 36.3% in women. Leading factors: smoking, alcohol and high BMI; the largest increase from 2010 to 2019 was in metabolic risks (34.7% rise in attributable deaths) [2].
Intervention evidence. Quadrivalent HPV vaccine (Swedish national registers, 1.7 million girls and women): fully adjusted IRR for invasive cervical cancer 0.37 (0.21 to 0.57); 0.12 (0.00 to 0.34) when vaccinated before age 17 [7]. Universal hepatitis B vaccination in Taiwan: annual HCC incidence in children aged 6 to 14 fell from 0.70 (1981 to 1986) to 0.36 per 100,000 (1990 to 1994) [8]. H. pylori eradication in first-degree relatives (RCT): gastric cancer 1.2% vs 2.7%, HR 0.45 (0.21 to 0.94) [9]. Daily sunscreen (Nambour RCT, 1,621 people): melanoma HR 0.50 (0.24 to 1.02), invasive melanoma 0.27 (0.08 to 0.97) [10]. Waterpipe (meta-analysis of 50 observational studies): OR for oral cancer 4.17 (2.53 to 6.89) and lung cancer 2.12 (1.32 to 3.42) [3]. High vs low physical activity (1.44 million people): lower risk of 13 cancers, including oesophageal adenocarcinoma HR 0.58, liver 0.73 and lung 0.74 [5].
Interpretation. The population attributable fraction (PAF) assumes causality and complete removal of exposure, and is not a prediction for an individual; even so, smoking, infections and alcohol lead in both estimates. Ask about waterpipe and opium use separately when taking the history [3, 4].
Scientific evidence
Scientific evidence
5 itemsHPV Vaccination and the Risk of Invasive Cervical Cancer
Universal Hepatitis B Vaccination in Taiwan and the Incidence of Hepatocellular Carcinoma in Children
Family History of Gastric Cancer and Helicobacter pylori Treatment
Reduced Melanoma After Regular Sunscreen Use: Randomized Trial Follow-Up
Carcinogenicity of opium consumption
Related cancer types
Related questions
References
12 referencesShow all references, 5 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
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- 4Carcinogenicity of opium consumption
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This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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