Cancer is not always bad luck: 10 preventable risk factors you should know

Cancer is one of the most feared diagnoses. Many people believe that developing cancer is simply a matter of bad luck, ageing or family history. Although these factors can influence risk, there is also encouraging news: a substantial proportion of cancers are linked to causes that we can prevent or modify.

A global analysis published by the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) in February 2026 estimated that approximately 37 per cent of new cancer cases worldwide in 2022 were attributable to preventable causes. In India, the estimated proportion was 37.1 per cent, representing approximately 520,000 cases.

What can we do to reduce our risk?

Quit tobacco (in every form)

Tobacco is one of the most important preventable causes of cancer. Cigarettes and bidis increase the risk of lung cancer, but tobacco-related cancers are not confined to the lungs.

In India, smokeless tobacco products such as gutkha, khaini and chewing tobacco are major concerns. Tobacco use is strongly associated with cancers of the mouth, throat and oesophagus, among others. Areca nut or betel quid containing areca nut, is also carcinogenic, even when tobacco is absent. It can cause oral submucous fibrosis, a potentially precancerous condition. There is no safe form of tobacco. Quitting at any age is beneficial. 

Avoid alcohol

Alcohol is an established cause of several cancers, including those of the mouth, throat, oesophagus, liver, colorectum and breast. The risk generally increases with the amount consumed. For cancer prevention, avoiding alcohol offers the lowest alcohol-related risk. 

Maintain a healthy body weight

Excess body fat is associated with increased risk of several cancers, including postmenopausal breast, colorectal, endometrial, kidney and liver cancers. Maintain a healthy weight, pay attention to waist circumference, and avoid gradual weight gain over the years. Sustainable dietary changes combined with regular physical activity are more useful than crash diets.

Exercise regularly

Physical activity helps maintain a healthy weight and is associated with lower risk of several cancers, particularly colorectal and breast cancers. Aim for at least 150–300 minutes of moderate-intensity aerobic activity each week, or the equivalent vigorous activity, alongside muscle-strengthening exercise on at least two days weekly. Brisk walking, cycling, swimming, dancing and sport all count. If you are currently inactive, begin gradually. Some activity is better than none.

Eat a balanced diet

No single food, juice, spice or supplement has been shown to prevent cancer on its own. Build your diet around vegetables, fruits, pulses, whole grains and other minimally processed foods. Limit processed meat, avoid excessive calorie intake, and reduce frequent consumption of highly processed, energy-dense foods. Be sceptical of products marketed as detoxifying the body or eliminating cancer-causing toxins. Expensive supplements are not substitutes for a balanced diet.

Vaccinate against cancer-causing infections

Some cancers arise because of persistent infections. This creates an important opportunity for prevention. Human papillomavirus (HPV) causes almost all cervical cancers and contributes to several other cancers. HPV vaccination, ideally before exposure to the virus, can substantially reduce the risk of HPV-related disease.

Hepatitis B infection can lead to chronic liver disease and liver cancer. Hepatitis B vaccination is an established preventive measure. Discuss age-appropriate vaccination with your healthcare professional. Vaccination does not eliminate every cancer risk, but it can prevent important causes of cancer.

Reduce avoidable environmental and occupational exposures

Air pollution is associated with lung cancer. Where possible, reduce exposure to tobacco smoke, improve indoor ventilation and support measures that reduce outdoor pollution. Workers may be exposed to carcinogens such as asbestos, silica, benzene and certain industrial chemicals. Appropriate protective equipment, workplace safety standards and exposure controls are essential. Use sun protection to reduce excessive ultraviolet exposure and skin cancer risk. Avoid indoor tanning devices.

Know your family history

Some people inherit genetic variants that increase susceptibility to cancers such as breast, ovarian, colorectal and prostate cancer. A family history of cancer does not mean that you will necessarily develop it. However, multiple affected relatives, unusually young ages at diagnosis, or certain combinations of cancers may warrant genetic counselling.

If you have a strong family history, discuss whether earlier or more intensive screening is appropriate. Do not assume that a normal lifestyle alone removes inherited risk.

Do not confuse screening with prevention

Screening looks for cancer or precancerous changes before symptoms develop. It does not prevent every cancer, but appropriate screening can detect selected cancers early and, in some cases, prevent cancer by identifying and treating precancerous lesions. Cervical screening can identify precancerous changes. Breast cancer screening and colorectal cancer screening are useful for appropriately selected age and risk groups, according to local guidelines and available services.

In India, oral cancer awareness and early evaluation are particularly important, especially for people who use tobacco or areca nut. Do not routinely undergo whole-body scans, indiscriminate tumour-marker tests or multiple investigations without a clear indication. These can lead to false alarms, unnecessary procedures and avoidable anxiety.

Never ignore a persistent warning sign

A new lump, an unexplained ulcer in the mouth, persistent difficulty swallowing, blood in the urine or stool, unexplained weight loss, unusual bleeding, or a persistent change in bowel habits deserves medical assessment. These symptoms are often caused by conditions other than cancer. However, if they persist, recur or worsen, do not repeatedly self-medicate or delay seeking advice. Early diagnosis can improve treatment options and outcomes. 

Cancer prevention is not about following a perfect diet, buying expensive supplements or undergoing every available test. It is about reducing established risks and using effective preventive health care.