Cancer is one of the leading causes of death worldwide, but research shows that a substantial proportion of cases are preventable. Understanding the modifiable risk factors — and acting on them — is one of the most powerful things a person can do for their long-term health.
Cancer took nearly 10 million lives around the world in 2022 and affects 40 percent of people during their lifetimes. A recent global study found that half of cancer deaths in men and almost 40% in women arise from factors that can be prevented or modified. The choices made every day have a measurable impact on those odds.
This article covers the evidence behind those modifiable factors — including the top three that matter most — along with the current state of cancer screening and what the research says about newer early-detection technologies.
Table of Contents
Avoid Too Much Sun
Sunlight damages skin cells, and cumulative exposure is the primary driver of skin cancer — the most common cancer type in the United States.
Research shows that people who work outdoors have a 60% higher chance of developing skin cancer [1].
Two practical steps offer meaningful protection:
A study published in The Lancet found that using sunscreen with SPF 15 or higher every day can lower the risk of squamous cell skin cancer [2]. Current guidance generally recommends SPF 50 or higher for robust daily protection.
For those looking for a mineral-based option, SPF 50+ mineral sunscreens — which use zinc oxide or titanium dioxide rather than chemical filters — avoid the 12 active ingredients the FDA has flagged for requiring additional safety data. Mineral filters such as bemotrizinol do not get absorbed through the skin to a measurable degree, which many people prefer. One widely available option is CeraVe 100% Mineral Sunscreen SPF 50, available from most pharmacies and online.
Exercise
Regular physical activity strengthens the immune system, lowers insulin levels, reduces chronic inflammation, and produces a range of other changes that lower cancer risk. Exercise acts as a biological shield for cells, keeping them more resilient against the processes that drive malignant transformation.
A study that followed over 750,000 people for 10 years found that those who performed vigorous exercise for 7.5–15 hours per week had a significantly lower risk for 7 out of 15 cancers studied, including colon and breast cancer [3].
Another large study of 1.44 million adults showed a lower risk of 13 types of cancer in people who exercised regularly, including more than a 20% drop in risk for 7 different cancers [4].
For those just starting out, the key is finding movement that feels sustainable:
- Choose an activity that is genuinely enjoyable — walking in nature, dancing, cycling, or pairing a podcast with a jog. Enjoyment is the single biggest predictor of long-term adherence.
- Aim for at least 30 minutes of moderate activity on most days of the week. Even a secondhand exercise bike at home can cover rainy days.
A tip for busy schedules:
"Exercise snacks" — brief bursts of movement spread through the day, such as push-ups, sit-ups, or bodyweight squats during short breaks — accumulate real benefit. Research supports the idea that total daily movement volume matters, not just continuous sessions.
Eat Healthy Foods
Dietary choices are among the most studied modifiable cancer risk factors. Providing the body with adequate nutrition supports cellular repair mechanisms and immune surveillance.
A major review of the evidence found that eating healthy foods overall is associated with a lower risk of certain cancers [5].
What to avoid
Some foods are consistently linked to increased cancer risk.
Processed meats — including hot dogs, sausages, and bacon — are classified as Group 1 carcinogens by the International Agency for Research on Cancer. Multiple studies link regular consumption to a higher risk of colorectal cancer [6].
Ultra-processed foods more broadly are also associated with higher cancer risk. A large study from France found that higher consumption of ultra-processed foods — chips, sodas, instant soups, and ready meals — was linked to increased cancer incidence, particularly breast cancer [7].
What to eat more of
The Mediterranean dietary pattern — emphasising vegetables, legumes, whole grains, fish, nuts, and extra-virgin olive oil — is one of the most evidence-supported eating frameworks. A meta-analysis found that adherence to this diet was associated with a 9% reduction in all-cause mortality and a 6% reduction in cancer mortality [8].
Adequate protein intake also supports muscle mass preservation alongside regular exercise, improving overall metabolic health.
A practical summary:
- Minimise processed meats, sugary drinks, and ultra-processed convenience foods.
- Build meals around fresh vegetables, whole fruits, whole grains, and protein sources such as fish, legumes, and nuts.
- A high-quality multivitamin can help fill nutritional gaps for those whose diet falls short of covering all micronutrient targets — though it is not a substitute for a balanced diet.
From the MicroVitamin range
For those looking to cover nutritional gaps, MicroVitamin provides 26 evidence-based micronutrients — including methylated B vitamins, glycinate minerals, and clinical-dose carotenoids — formulated at doses drawn from human randomised controlled trials.
Avoid Drinking Alcohol
Alcohol is a well-established carcinogen. It alters hormone levels, irritates cell linings, and appears to facilitate the penetration of other carcinogens across tissue barriers.
A large study in Korea found a clear dose-response relationship: people who drank more alcohol had a higher cancer risk, while those who drank less had a lower risk [9]. Alcohol is particularly strongly linked to cancers of the mouth, throat, liver, and breast [10].
How much alcohol is safe?
Even modest amounts carry risk. Research from the American Institute for Cancer Research found that drinking as little as one alcoholic drink per day raises the risk of several common cancers [11]. Their position: for cancer prevention, it is best not to drink alcohol at all.
Maintain a Healthy Weight
Excess body fat is estimated to be responsible for around 40 percent of all cancers in the United States [12]. It is one of the most consequential — and most underappreciated — modifiable cancer risk factors.
Why does weight matter?
Adipose tissue is metabolically active. Excess fat drives chronic low-grade inflammation, disrupts hormone signalling (particularly oestrogen and insulin), and promotes cell proliferation — all processes that contribute to cancer development.
A study in the UK found that excess weight is linked to 41% of uterine cancers and more than 10% of gallbladder, kidney, liver, and colon cancers [13].
A study of over 1.7 million people demonstrated that a high BMI in young adulthood increases cancer risk later in life. Importantly, the research also shows that losing significant weight reverses some of that risk — a study found that people who underwent gastric bypass surgery had a 60% lower risk of dying from cancer [14].
What to do
Regular exercise and a healthy diet are the foundation. Maintaining a healthy weight is not a separate goal — it is a downstream outcome of addressing exercise and nutrition. For those who have tried lifestyle changes and continue to carry significant excess weight, speaking with a doctor about evidence-based medical options (including newer GLP-1 medications) is a reasonable step. Using appropriate medical tools when needed is a sign of good health management, not failure.
Don't Smoke
Tobacco smoking is the single largest preventable cause of cancer worldwide. It substantially increases the risk of lung cancer and at least 15 other cancer types, and was responsible for 21% of all cancer deaths globally in 2011 [15].
Reducing exposure matters, even incrementally
It is always best not to start. But for people who currently smoke, reduction has meaningful benefit: a study found that cutting from 20 to 15 cigarettes per day lowered lung cancer risk by 20% [16].
The benefits of quitting are rapid
Within two weeks of quitting, most people notice measurable improvements in energy, breathing capacity, and general wellbeing [17].
Evidence-based strategies for quitting:
- Identify and write down personal motivations for quitting.
- Modify routines to reduce exposure to smoking triggers.
- Use the four Ds:
- Delay: Wait at least five minutes before lighting up — the urge often passes.
- Deep breathing: Slow, deliberate breaths can reduce craving intensity.
- Drink water: Keeps the mouth occupied and supports general health during withdrawal.
- Do something else: Physical activity or a task that requires focus interrupts the craving cycle.
Pharmacological support (varenicline, nicotine replacement therapy, bupropion) and structured cessation programmes substantially improve quit rates. Healthcare providers can advise on the most appropriate option.
Get Vaccinated Against Viruses
Approximately 13 percent of all new cancers worldwide are caused by infectious agents — bacteria, viruses, and parasites [18]. This is a substantial and largely preventable fraction.
HPV and cervical cancer
Human papillomavirus (HPV) is the primary cause of cervical cancer. A landmark study from Scotland found that women who had been fully vaccinated against HPV during the national programme had no cases of cervical cancer — a finding that underscores just how powerful vaccination can be as a cancer prevention tool [19].
The hepatitis B vaccine also substantially reduces the lifetime risk of hepatocellular (liver) cancer, as chronic hepatitis B infection is a major driver of that disease.
What to do
Ensuring that recommended vaccinations are up to date — including HPV (available to both males and females) and hepatitis B — is a straightforward, evidence-supported step for reducing infection-related cancer risk.
Catching Cancer Early with Screenings
Even with all preventive steps in place, cancer can still develop. Early detection is the next most powerful tool: cancers found before they have spread are dramatically more treatable.
Why early detection matters
When cancer is localised, treatment options are broader and survival rates are substantially higher than for advanced-stage disease.
Established screening programmes
Evidence-based screening tests currently exist for breast, cervical, colorectal, and prostate cancers. These programmes have saved many lives by detecting disease before symptoms appear.
The American Cancer Society publishes regularly updated screening guidelines by cancer type: https://www.cancer.org/cancer/screening/american-cancer-society-guidelines-for-the-early-detection-of-cancer.html
The current gap
A significant limitation is that about 70% of cancer deaths arise from cancers for which no validated population-level screening test yet exists [21]. This means that lifestyle and vaccination prevention remain especially important for those cancer types.
Emerging multi-cancer early detection tests
New technologies are being developed that could change this picture substantially. Multi-cancer early detection (MCED) tests use a simple blood draw to look for circulating tumour DNA or protein biomarkers — molecular signals shed by cancer cells into the bloodstream. The concept is analogous to finding a fingerprint at a scene: these tests look for characteristic cancer signatures across many cancer types simultaneously.
One well-known example is the Galleri test [22], which has been studied in several clinical populations.
Important caveats on MCED tests
These technologies are still being validated in large prospective trials. The American Cancer Society currently does not recommend MCED tests for people without symptoms or elevated personal risk [23]. False positives are possible, leading to further investigations that may be invasive and anxiety-inducing without producing clinical benefit.
Full-body MRI screening
The same caution applies to direct-to-consumer full-body MRI scans. The American College of Radiology states that there is insufficient evidence to recommend routine full-body MRI screening for asymptomatic individuals [24]. These scans frequently detect incidental findings — abnormalities that are not cancer but require follow-up testing to rule it out — creating a cascade of procedures that carry their own costs and risks.
A clear example from the evidence
A large study examined whether combining ultrasound and blood tests could reduce ovarian cancer mortality. Over 16 years of follow-up, the screening programme did not reduce cancer deaths or help people live longer [25]. This illustrates why screening tests must be validated rigorously before widespread adoption.
Wrapping Up
Cancer is a serious and common disease, but the evidence is clear that lifestyle choices have a substantial impact on individual risk. Addressing the major modifiable factors — sun exposure, exercise, diet, alcohol, weight, smoking, and vaccination — can reduce that risk meaningfully.
Early detection remains a powerful complementary strategy
Using established, evidence-based screening tests appropriate for age and risk profile — and following them up when results require it — gives the best chance of catching any cancer that does develop at a stage when it is most treatable. Newer tests like MCED blood draws show genuine promise but are not yet recommended for general population screening.
Cancer is not the only risk to manage
Many of the same lifestyle factors that drive cancer risk also contribute to cardiovascular disease, type 2 diabetes, and cognitive decline. The same healthy habits protect against multiple conditions simultaneously, making them among the highest-value investments in long-term health.
References
- WHO Report on Sun Exposure and Skin Cancer
- The Lancet Study on Sunscreen Use
- Study on Exercise and Cancer Risk
- Study on Physical Activity and Cancer Risk
- Nutrition Reviews on Diet and Cancer Risk
- Meta-Analysis on Red and Processed Meat and Colorectal Cancer
- Study on Ultra-Processed Foods and Cancer Risk
- Meta-Analysis on Mediterranean Diet and Health
- Study on Alcohol Consumption and Cancer Risk
- The Lancet Study on Alcohol and Cancer
- American Institute for Cancer Research on Alcohol Consumption
- PubMed Study on Obesity and Cancer in the U.S.
- UK Study on BMI and Specific Cancers
- NEJM Study on Gastric Bypass Surgery and Cancer Risk
- Avoidable Cancer Deaths Globally
- Study on Smoking Reduction and Lung Cancer Risk
- Government Report on Benefits of Quitting Smoking
- Overview of Cancer Prevention
- Study on HPV Vaccination and Cervical Cancer in Scotland
- American Cancer Society Guidelines for Cancer Screening
- American Cancer Society on Multi-Cancer Early Detection Tests
- Galleri Test Performance
- American Cancer Society on Multi-Cancer Early Detection Tests
- American College of Radiology on Total Body MRI Screening
- NCBI Study on Ovarian Cancer Screening
