Cancer and Lifestyle: How Daily Habits Increase Cancer Risks

Cancer is no longer a disease that strikes only the elderly or the unlucky. A large share of cases today are tied to the way we live, eat, work, and unwind. India is feeling this shift sharply. The country recorded roughly 14 lakh new cancer cases in recent years, and an ICMR analysis suggests that 1 in 9 people may develop cancer in their lifetime. The encouraging part is that many of these cases trace back to habits we can change. Understanding how cancer begins, what raises the risk, and which warning signs deserve attention puts a surprising amount of control back in your hands.

What is cancer and how does it spread? 🔗

Your body is made of trillions of cells that grow, divide, and die in an orderly cycle. Cancer begins when this control breaks down. A cell picks up damage in its DNA, ignores the usual signals to stop dividing, and refuses to die when it should. The result is a mass of abnormal cells that keeps multiplying. This is why cancer is best described as uncontrolled cell growth.

There is no single disease called “cancer.” There are more than a hundred types, usually named after the organ or cell where they start. Carcinomas arise in the skin or in tissues lining internal organs and are the most common group. Sarcomas form in bone, muscle, and connective tissue. Leukaemias develop in blood-forming tissue, while lymphomas begin in the immune system. In India, the cancers that cause the most illness and death include breast, lung, oesophagus, oral, cervical, stomach, and colon cancers. Oral, lung, and oesophageal cancers are especially common in men, while breast and cervical cancers dominate among women.

How metastasis works 🔗

The feature that makes cancer dangerous is its ability to spread. This process is called metastasis. Cancer cells break away from the original, or primary, tumour and travel to distant parts of the body through the bloodstream or the lymphatic system. They settle in a new location and start forming fresh tumours there.

An important detail: metastatic cancer keeps the identity of the original cancer. If breast cancer spreads to the liver, the new growth is still made of breast cancer cells and is treated as breast cancer, not liver cancer. Doctors confirm this by examining the cells under a microscope, where the spread cells resemble the primary tumour rather than the tissue around them. The most common destinations for cancer spread are the bone, liver, and lung, along with nearby lymph nodes. Cancer that has spread to a distant organ is usually called stage 4 cancer, which is why early detection matters so much.

Lifestyle risk factors linked to cancer 🔗

Here is the part that should grab your attention. A recent analysis published in The Lancet found that at least 42% of cancer deaths worldwide were linked to preventable risk factors such as smoking, poor diet, and high blood sugar. The World Health Organization estimates that more than a third of cancers could be prevented by addressing a handful of key risks. In India specifically, the picture is even starker, with some reviews suggesting that 70% to 90% of cancers are related to lifestyle and could be reduced through healthier choices.

Tobacco 🔗

Tobacco is the single largest preventable cause of cancer. It is responsible for almost 40% of cancer cases in India and dramatically raises the risk of lung, oral, and throat cancers. The danger is not limited to cigarettes. Bidis, gutka, khaini, and other forms of chewed tobacco are deeply tied to the high rates of mouth and oesophageal cancer seen across the country. A long-running study in Kerala found that bidi smoking was significantly associated with gastric cancer risk. There is no safe level of tobacco use.

Alcohol 🔗

Alcohol is a recognised carcinogen, and the risk rises with the amount consumed. It is the leading attributable factor for cancers of the pharynx in Indian data and is strongly linked to cancers of the mouth, throat, oesophagus, liver, and breast. What surprises many people is that even light to moderate drinking adds risk; in one WHO regional assessment, a notable share of alcohol-linked cancers occurred among light drinkers. There is no threshold below which alcohol becomes completely safe for cancer.

Diet and obesity 🔗

What you eat shapes your long-term risk. In 2015, the WHO’s International Agency for Research on Cancer classified processed meat as “carcinogenic to humans” and red meat as “probably carcinogenic,” based on links to colorectal cancer. Processed meat means anything preserved by salting, curing, smoking, or fermentation. It is worth keeping perspective here: this classification reflects the strength of the evidence, not the size of the risk, so processed meat and tobacco are not equally dangerous even though both sit in the same category.

Closely tied to diet is body weight. Being overweight or obese is linked to cancers of the oesophagus, colon and rectum, breast, endometrium, and kidney. This is a growing concern in India, where obesity rates climbed from around 9% in 2016 to about 20% in 2023. Diets rich in fruits and vegetables, by contrast, have a protective effect against many cancers.

Physical inactivity 🔗

A sedentary lifestyle independently raises cancer risk, partly through its effect on weight and hormones. Globally, more than 40% of cancer cases are attributable to preventable causes including poor diet, physical inactivity, and obesity. Regular movement helps regulate insulin and inflammation, both of which influence how cells grow.

Infections, pollution, and stress 🔗

Not every lifestyle-linked risk involves food or tobacco. Persistent infection with certain types of human papillomavirus (HPV) is responsible for nearly all cervical cancers, and the hepatitis B and C viruses cause liver cancer. The bacterium Helicobacter pylori raises stomach cancer risk. Air pollution, both indoor and outdoor, is a major and rising factor in India, contributing heavily to lung cancer. While chronic stress is harder to measure as a direct cause, it often pushes people toward smoking, drinking, poor eating, and disturbed sleep, all of which carry their own risks.

The role of genetics 🔗

Some cancers run in families because of inherited gene changes, such as the BRCA mutations linked to breast and ovarian cancer. But inherited cancers are a minority. Genes load the gun; lifestyle and environment often pull the trigger. Even people with a family history can lower their odds substantially by avoiding tobacco, limiting alcohol, eating well, and staying active.

Recognising cancer warning signs 🔗

Cancer is far more treatable when caught early, yet late diagnosis remains a major reason for high death rates in India. Knowing the warning signs helps you act in time. None of these symptoms automatically means cancer; most have harmless explanations. The rule is simple: if a symptom is unexplained and persists, get it checked.

Signs that deserve medical attention include unexplained weight loss that is not linked to diet or exercise, and persistent, unexplained tiredness or pain. Other common warning signs are a new lump or thickening anywhere in the body, a sore or ulcer that does not heal, a chronic cough or hoarseness, difficulty swallowing, and unusual bleeding such as blood in the urine, stool, or between menstrual periods. A change in a mole’s size, shape, or colour, and any lasting change in bowel or bladder habits, are also worth investigating.

When cancer has already spread, the symptoms often depend on where it has travelled. According to the National Cancer Institute, common signs of metastatic cancer include bone pain or fractures when cancer reaches the bone, headaches or seizures when it reaches the brain, shortness of breath when it reaches the lung, and jaundice or abdominal swelling when it reaches the liver. Because these overlap with everyday illnesses, persistent symptoms should never be brushed aside.

Prevention and early detection 🔗

The most hopeful fact about cancer is how much of it is avoidable. One Indian modelling study estimated that around 80% of projected future cancer cases are believed to be preventable by tackling modifiable risk factors. Prevention works on two fronts: reducing your risk, and catching disease early when treatment is most effective.

Lifestyle changes that lower risk 🔗

The strongest steps are also the most familiar. Avoid tobacco in every form. Limit or skip alcohol. Eat a diet rich in fruits, vegetables, and whole grains while cutting back on processed and red meat. Stay physically active and maintain a healthy weight. Protect your skin from excess sun. Vaccination is also a genuine prevention tool: the HPV vaccine can prevent nearly all cervical cancers, and the hepatitis B vaccine reduces liver cancer risk. The WHO notes that cancer-causing infections are responsible for up to a quarter of cancer cases in low- and middle-income countries, making vaccination especially valuable.

Why routine screening matters 🔗

Screening looks for cancer before symptoms appear, when it is easiest to treat. India runs population-based screening through the National Programme for Prevention and Control of Non-Communicable Diseases (NP-NCD), which targets everyone aged 30 and above for three common cancers: oral, breast, and cervical. The approach uses simple, low-cost methods such as clinical breast examination, visual inspection with acetic acid for cervical cancer, and oral visual inspection.

These services are delivered through frontline health workers like ASHAs and ANMs, with suspected cases referred to higher facilities, and screening has been expanded to more than 400 districts and integrated into Ayushman Arogya Mandirs. In early 2025, the Health Ministry even launched an intensified drive aiming for 100% screening of everyone aged 30 and above. The takeaway for individuals is straightforward: if you are over 30, ask about these free screenings, and do not wait for symptoms to appear before getting checked.

Prevention is not about fear. It is about recognising that everyday choices, repeated over years, shape your risk far more than chance does. Quitting tobacco, eating better, moving more, and turning up for a screening are small acts with outsized payoffs.

What do you think? Which of these lifestyle risk factors do you think is the hardest for people around you to change, and why? And if free cancer screenings were available in your area, what would make you more likely to actually go for one?

References

1. https://time.com/6965528/india-cancer-capital-world-study/
2. https://www.ocacademy.in/blogs/cancer-risk-india-icmr-study-awareness/
3. https://madhyamamonline.com/amp/lifestyle/health/india-sees-sharp-increase-in-cancer-deaths-4-in-10-cases-linked-to-lifestyle-risks-1450660
4. https://www.cancer.gov/types/metastatic-cancer
5. https://www.who.int/europe/news-room/fact-sheets/item/cancer-prevention
6. https://www.clinicalcasereportsint.com/open-access/risk-factors-associated-with-lifestyle-cancers-in-india-a-systematic-9191.pdf
7. https://who.int/activities/preventing-cancer
8. https://www.who.int/news-room/questions-and-answers/item/cancer-carcinogenicity-of-the-consumption-of-red-meat-and-processed-meat
9. https://www.cancer.org/cancer/risk-prevention/understanding-cancer-risk/known-and-probable-human-carcinogens.html
10. https://cancerprogressreport.aacr.org/progress/cpr22-contents/cpr22-preventing-cancer-identifying-risk-factors/
11. https://en.wikipedia.org/wiki/Signs_and_symptoms_of_cancer
12. https://link.springer.com/article/10.1186/s12885-024-13035-6
13. https://ncd.mohfw.gov.in/ncdlandingassets/aboutus.html
14. https://dghs.gov.in/content/1363_3_NationalProgrammePreventionControl.aspx
15. https://www.mohfw.gov.in/?q=en/pressrelease-216