Why Do People Still Get Cancer Despite Living a Healthy Lifestyle?

Ms. N.T.T., 40, from Hanoi, visited the hospital because of persistent back pain. At first, she thought it was just a common musculoskeletal problem often seen in office workers. By May, however, she began developing a dry cough that did not improve even after using lozenges.

“The cough went on for weeks. I kept blaming it on the air conditioning. I found every excuse to delay seeing a doctor until the sharp back pain forced me to go,” the mother of two recalled.

At the hospital, after undergoing tests and scans, doctors discovered that she had a tumor in her lung as well as multiple lesions on her bones caused by metastasis. The results shocked her husband and close friends. Looking at the MRI images, with each dark spot on the lungs and bones carefully explained by the doctors, the reality of her illness sank in deeply.

What made it even more surprising was that Ms. T. had always lived a healthy lifestyle, exercising regularly and eating a balanced diet. Her friends were stunned: “How could someone so healthy get cancer?”

The family later realized that Ms. T. had been exposed to secondhand smoke for nearly 20 years of her marriage. Although her husband never smoked directly in front of her, the lingering smell of cigarettes filled the air. Upon learning of his wife’s diagnosis, he decided to quit smoking for good.

Image: Full-body MRI scan of a lung cancer patient. Credit: Minh Duc

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Expert Insights

Professor Mai Trong Khoa, senior specialist at the Nuclear Medicine and Oncology Center, Bach Mai Hospital (Hanoi), explained that lung cancer is one of the most common cancers in Vietnam, with an increasing incidence, particularly in developing countries.

He emphasized that anyone exposed to cigarette smoke—whether active or passive—faces a high risk.

While genetic mutations can also cause cancer, this accounts for only a small proportion of cases. This is why even young people who never smoke and maintain healthy lifestyles may still develop the disease.

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Why Lung Cancer Is on the Rise

• Population growth: As the population increases, so does the number of cancer cases.

• Longer life expectancy: Older people are more likely to develop lung cancer.

• Environment and lifestyle: Air pollution, pesticides, alcohol, and tobacco are major risk factors. In particular, tobacco use—including e-cigarettes—is rising across age groups. Cigarette smoke contains thousands of toxic chemicals that foster cancer development. Secondhand smoke is just as harmful as active smoking.

According to Professor Khoa, a worrying trend is the growing rate of smoking among young people, which may drive lung cancer cases even higher in the near future.

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Screening and Treatment

For those at high risk—such as smokers or people exposed to secondhand smoke—low-dose CT scans can help detect small lung lesions early. Advanced techniques like PET, PET/CT, and PET/MRI, combined with molecular biology, allow doctors to identify gene mutations and choose targeted treatments.

Lung cancer is known for its tendency to metastasize early. Current treatment methods include surgery, radiotherapy, chemotherapy, immunotherapy, and targeted therapy, offering patients more hope than ever before.

Globally, lung cancer remains the most common type of cancer. According to Globocan 2022, it accounted for 12.4% of all new cases and 18.7% of cancer deaths worldwide. In Vietnam, lung cancer ranks third in incidence (13.5%)—after liver cancer (13.6%) and breast cancer (13.6%)—and second in mortality (18.8%), just behind liver cancer (19.8%).