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    Cancer prevention: the evidence on smoking, alcohol, HPV and more

    A 2026 Nature Medicine analysis estimated that 37.8% of new cancers worldwide in 2022 were attributable to modifiable risk factors, led by smoking, infections and alcohol; WHO cites about 38% as preventable.[1] The strongest levers are avoiding tobacco, limiting alcohol, HPV and hepatitis B vaccination, a healthy weight and sun protection, though the evidence behind each differs.[2]

    Editor reviewedStrict sourcingUpdated ExplainerHealth and medicine, Life sciences

    Many cancers are linked to exposures people can change. WHO estimates that nearly a quarter of cancer deaths are due to tobacco, alcohol, high body mass index, low fruit and vegetable intake and physical inactivity.[3] A large 2026 analysis put the share of new cases attributable to modifiable risks at 37.8%.[1] This page sets out the main measures and how strong the evidence is for each.

    This page is not medical advice. Talk to a clinician about your own risks, vaccinations and screening.

    How strong is the evidence?

    Prevention evidence comes in different kinds. Randomised trials, such as the Nambour sunscreen trial, directly test whether an intervention works.[4] Population studies, such as the 2026 Nature Medicine analysis, estimate how much cancer is linked to an exposure. They cannot by themselves prove that changing it removes all the excess risk.[1] Classifications such as IARC’s Group 1 for alcohol say how sure scientists are that something causes cancer, not how large the risk is.[5]

    MeasureMain evidenceWhat it shows
    Avoiding tobaccoDecades of epidemiology, summarised by NCITobacco causes at least a dozen cancer types; no safe level[6]
    Limiting alcoholIARC Group 1 classification; observational studiesRisk rises with amount drunk; even light drinking raises some risks[5]
    Healthy weightObservational studies, summarised by NCIObesity linked to at least 13 cancer types[7]
    HPV vaccineRandomised trials (infection, precancer) plus real-world data (cancer)Highly effective against infection; greatly reduces cancer incidence[8]
    Hepatitis B vaccineWHO assessmentNearly 100% protection against the virus, a major cause of liver cancer[9]
    Sun protectionOne randomised trial for melanoma (Nambour); UV biologyDaily sunscreen halved new melanomas, borderline significance[4]

    Tobacco and alcohol

    Smoking is the biggest single contributor to preventable cancer worldwide.[1] The NCI says it causes cancers of the lung, mouth, throat, oesophagus, bladder, kidney, pancreas, bowel, cervix and more, and that no level of tobacco use is safe.[6] Stopping helps at any age: people who quit gain substantial life expectancy compared with those who keep smoking.[10]

    Alcohol also causes cancer. The more someone drinks, the higher the risk, and even light drinking raises the risk of some cancers.[5] The NHS advises drinking no more than 14 units a week.[11]

    In the 2026 Nature Medicine estimate, smoking accounted for 15.1% of new cancers worldwide and alcohol for 3.2%.[1] IARC classified alcohol as a Group 1 carcinogen in 1987.[5] The NCI notes that a recent US Surgeon General’s Advisory called for reconsidering the alcohol limits in the Dietary Guidelines because of cancer risk at or below those limits.[12] In the US, falling smoking rates are one of the main reasons the American Cancer Society credits with averting an estimated 4.8 million cancer deaths since 1991.[13]

    Vaccines against cancer-causing infections

    Infections caused 10.2% of new cancers worldwide in the 2026 estimate.[1] Vaccines exist against two of the main cancer-causing viruses.

    • HPV. About a dozen HPV types can cause cancers of the cervix, anus, throat (oropharynx), penis, vulva and vagina. Types 16 and 18 cause about 70% of cervical cancers.[14] The NCI says HPV vaccines are highly effective in trials, protect best when given before first exposure, and greatly reduce cancer incidence in real-world data.[8] Vaccinated people should still follow cervical screening recommendations.[15]
    • Hepatitis B. WHO says hepatitis B caused about 1.1 million deaths in 2024, mostly from cirrhosis and liver cancer. A vaccine gives nearly 100% protection against the virus.[9]

    These are preventive vaccines against viruses. Therapeutic cancer vaccines, which train the immune system against an existing tumour, are covered in the site’s cancer immunotherapy crash course.

    Weight, activity and sun

    The NCI says obesity is linked to at least 13 types of cancer.[7] WHO recommends a healthy weight and diet and regular physical activity.[2] The NHS suggests at least 150 minutes of moderate activity a week.[11] Most of this evidence is observational, so it shows association more reliably than it shows the size of the benefit from changing habits.

    UV radiation from the sun, sunlamps and tanning beds damages skin in ways that can lead to skin cancer. The NCI advises protection including sunscreen of at least SPF 15.[16] The Nambour trial in Australia randomised 1,621 adults to daily or discretionary sunscreen. Over follow-up to 2006, the daily group had 11 new melanomas against 22 in the comparison group. The result was just short of conventional statistical significance (P = .051), and the authors concluded that melanoma may be preventable by regular sunscreen use.[4]

    Prevention and screening together

    Prevention lowers the chance of cancer starting. Screening finds some cancers and pre-cancers early. The NHS advises doing both: attend screening when invited and accept HPV or hepatitis B vaccination if offered.[11] See who should be screened and when and warning signs to get checked.

    Next in the crash course

    Health & medicine

    US Preventive Services Task Force (USPSTF)

    The USPSTF sets the US cancer screening recommendations that shape free coverage. How it grades evidence, what it recommends, and its 2026 overhaul.

    Developing in Health

    Questions readers ask

    What percentage of cancers are preventable?

    WHO says about 38% of cancers can currently be prevented. A 2026 Nature Medicine study estimated 37.8% of new cases in 2022 were attributable to 30 modifiable risk factors.[1]

    What is the biggest preventable cause of cancer?

    Smoking. In the 2026 Nature Medicine analysis it accounted for 15.1% of cancer cases worldwide, ahead of infections (10.2%) and alcohol (3.2%).[1]

    Is any amount of alcohol safe for cancer risk?

    The NCI says risk rises with the amount drunk and even light drinkers can be at increased risk of some cancers. IARC classifies alcohol as a Group 1 carcinogen.[5]

    Does the HPV vaccine prevent cancer?

    The NCI says trials show HPV vaccines are highly effective at preventing infection and real-world data show the vaccine greatly reduces cancer incidence. Protection is greatest before first exposure to the virus.[8]

    If I've had the HPV vaccine, do I still need cervical screening?

    Yes. The NCI says vaccinated people should follow the same screening recommendations, because the vaccine does not cover every cancer-causing HPV type.[15]

    Does sunscreen prevent melanoma?

    In the Nambour randomised trial, adults assigned to daily sunscreen had 11 new melanomas versus 22 in the comparison group, a result just short of conventional statistical significance. The authors concluded melanoma may be preventable by regular sunscreen use.[4]

    Sources

    · 16 claims from 6 publishers

    Each numbered claim is a statement we checked against the sources listed with it. Tap a number in the text to see its sources in place.

    1. [1]

      A 2026 Nature Medicine analysis estimated that 37.8% of new cancer cases worldwide in 2022 (7.1 million of 18.7 million) were attributable to 30 modifiable risk factors, led by smoking, infections and alcohol; WHO cites it as about 38% of cancers being preventable. confirmedas of 2026-10-11

    2. [2]

      WHO lists ways to reduce cancer risk including not using tobacco, a healthy body weight and diet, regular physical activity, avoiding or reducing alcohol, HPV and hepatitis B vaccination for recommended groups, and avoiding UV radiation. confirmedas of 2026-10-11

    3. [3]

      WHO estimates nearly a quarter of cancer deaths are due to tobacco, alcohol, high body mass index, low fruit and vegetable intake and lack of physical activity. confirmedas of 2026-10-11

    4. [4]

      In the Nambour randomised trial of 1,621 Australian adults, the daily-sunscreen group had 11 new melanomas versus 22 in the discretionary group over follow-up to 2006 (hazard ratio 0.50, P = .051); the authors concluded melanoma may be preventable by regular sunscreen use. confirmedas of 2026-10-11

    5. [5]

      IARC classified alcohol as a Group 1 carcinogen in 1987; NCI says risk rises with the amount drunk and even light drinkers can be at increased risk of some cancers. confirmedas of 2026-10-11

    6. [6]

      NCI says tobacco use is a leading cause of cancer and cancer death, causing cancers of the lung, larynx, mouth, oesophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum and cervix, and that there is no safe level of tobacco use. confirmedas of 2026-10-11

      • Tobacco · National Cancer Institute · Paragraph 1 (retrieved 2026-10-11)
      • Tobacco · National Cancer Institute · Paragraph 2 (retrieved 2026-10-11)
      • Tobacco · National Cancer Institute · Paragraph 3 (retrieved 2026-10-11)
    7. [7]

      NCI says obesity is linked to at least 13 types of cancer. confirmedas of 2026-10-11

    8. [8]

      NCI says HPV vaccines are highly effective at preventing HPV infection in trials, protection is greatest before first exposure, and real-world data show the vaccine greatly reduces cancer incidence. confirmedas of 2026-10-11

    9. [9]

      WHO says hepatitis B caused an estimated 1.1 million deaths in 2024, mostly from cirrhosis and liver cancer, and can be prevented by a vaccine offering nearly 100% protection. confirmedas of 2026-10-11

    10. [10]

      NCI says people who quit smoking at any age gain substantial life expectancy compared with those who continue. confirmedas of 2026-10-11

      • Tobacco · National Cancer Institute · Paragraph 3 (retrieved 2026-10-11)
    11. [11]

      NHS advice on reducing cancer risk includes attending screening when invited, HPV or hepatitis B vaccination if offered, drinking no more than 14 units of alcohol a week, keeping a healthy weight, quitting smoking, sun protection, and 150 minutes of moderate activity a week. confirmedas of 2026-10-11

    12. [12]

      NCI notes that a US Surgeon General's Advisory called for reconsidering alcohol limits in the Dietary Guidelines to account for cancer risk at or below those limits. confirmedas of 2026-10-11

    13. [13]

      The American Cancer Society projects about 2,114,850 new cancer cases and 626,140 cancer deaths in the US in 2026, and estimates that falling mortality since 1991 averted 4.8 million deaths, largely through smoking reductions, earlier detection and better treatment. confirmedas of 2026-10-11

      • Cancer statistics, 2026 · CA: A Cancer Journal for Clinicians (American Cancer Society) · 2026-01-01 · Abstract (retrieved 2026-10-11)
      • Cancer statistics, 2026 · CA: A Cancer Journal for Clinicians (American Cancer Society) · 2026-01-01 · Abstract (retrieved 2026-10-11)
    14. [14]

      About a dozen HPV types can cause cancers of the cervix, anus, oropharynx, penis, vulva and vagina; types 16 and 18 cause about 70% of cervical cancers. confirmedas of 2026-10-11

    15. [15]

      NCI says people vaccinated against HPV are advised to follow the same cervical screening recommendations as unvaccinated people, because the vaccine does not cover all cancer-causing types. confirmedas of 2026-10-11

    16. [16]

      NCI says UV radiation from the sun, sunlamps and tanning beds damages skin in ways that can lead to skin cancer, and advises sun protection including sunscreen of at least SPF 15. confirmedas of 2026-10-11

      • Sunlight · National Cancer Institute · Sunlight (retrieved 2026-10-11)
      • Sunlight · National Cancer Institute · Sunlight (retrieved 2026-10-11)
    Revision history (1)
    1. Page created.

    Created Oct 11, 2026. Last reviewed by an editor on Oct 11, 2026. Next scheduled review: Apr 11, 2027.

    Cite this page

    "Cancer prevention: the evidence on smoking, alcohol, HPV and more." ContentLora, updated Oct 11, 2026. https://contentlora.com/explain/cancer-prevention-explained

    Spotted an error? Suggest a correction or emailcorrections@contentlora.com.

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