Lung Cancer in Non-Smokers Is on the Rise: Understanding the Causes
by AZ Demon - June 07, 2025Martha, a lifelong non-smoker, was diagnosed with Stage IIIA lung cancer after an X-ray showed a shadow in her lung. Her case reflects a growing trend: 10% to 20% of people with lung cancer have no history of smoking. This kind of cancer behaves differently from the type caused by smoking
Lung Cancer in Non-Smokers Is Rising
Martha, who never smoked, found out she had lung cancer. At first, her doctors thought her cough came from another health problem. But after more tests, they found a tumour. Cases like Martha’s are becoming more common. Today, around 10% to 20% of people with lung cancer have never smoked. This type of cancer is different from the kind caused by smoking.
This cancer often starts deep in the lungs and does not show signs early. People usually find out they have it at Stage 3 or 4, when it has already spread. It is more common in women, especially in women from Asia. One reason is a mutation in a gene called EGFR, which helps the cancer grow faster.
If these people did not smoke, what caused their cancer? Experts say pollution may be to blame. Breathing in second-hand smoke, fumes from cooking, or smoke from wood fires can be risky. But the biggest danger now is outdoor air pollution. Tiny dust-like particles, called PM2.5, come from cars and factories. These may not damage DNA like smoking does. Instead, they may “wake up” cells in the lungs that already have harmful gene changes.
The good news is that scientists have made new medicines. These drugs, called EGFR inhibitors, block the bad gene. Martha is taking one of these drugs. It has side effects like tiredness and sore muscles, but it is helping her live longer.
Experts hope this new information changes how people think about lung cancer. It is not just a smoker’s disease anymore. Cleaning the air and cutting down on pollution are important steps to keep more people safe.
Lung Cancer in Non-Smokers Is on the Rise: Understanding the Causes
Martha, a lifelong non-smoker, was diagnosed with Stage IIIA lung cancer after an X-ray showed a shadow in her lung. Her case reflects a growing trend: 10% to 20% of people with lung cancer have no history of smoking. This kind of cancer behaves differently from the type caused by smoking.
Non-smoker lung cancer often appears as adenocarcinoma, which starts in cells that make mucus deep in the lungs. These tumors can grow without warning and are often found at later stages (Stage 3 or 4), when they may have already spread. This cancer happens more often in women, especially those from East Asia. It is often linked to specific mutations, like changes in the EGFR gene that help cancer cells grow. Scientists are still studying why these mutations are more common in some groups.
The environment is now a main focus for researchers. Besides second-hand smoke, breathing in cooking fumes and smoke from burning fuel indoors are known dangers. These may partly explain higher cases in women in some lower-income areas. The most serious cause now is outdoor air pollution, which is the second leading global cause of lung cancer after smoking. Tiny particles in the air (PM2.5) from cars, factories, and wildfires are a major issue. These particles don’t change DNA like tobacco, but they can “wake up” cells with hidden mutations and help tumors grow.
The good news is that doctors now understand more about this cancer’s biology. Special medicines called EGFR inhibitors block the bad protein and slow cancer. Though patients may build resistance over time, newer drugs are helping people live much longer. Some live for more than 10 years. Martha has taken one of these drugs for three years and is managing well, though she feels fatigue as a side effect.
This new knowledge is changing how we think about lung cancer. It’s no longer just a “smoker’s disease.” At the same time, cutting air pollution is becoming an important way to prevent cancer. The World Health Organization has lowered safe air levels, but most people still breathe dirty air. This makes clean air a key health and climate goal.
The Silent Epidemic: Unraveling the Rising Incidence of Lung Cancer in Non-Smokers
Martha, a non-smoker, represents a troubling trend: the rising number of lung cancer cases in people who have never smoked. At first, she thought her ongoing cough was from another health issue. But tests showed she had Stage IIIA lung adenocarcinoma. She is part of a group that makes up 10% to 20% of lung cancer cases and shows different traits compared to cancers caused by smoking.
Doctors now know that lung cancer in non-smokers follows a unique path. It usually appears as adenocarcinoma, beginning in mucus-making cells deep inside the lungs. Unlike cancers in smokers, these tumors grow quietly and are often found late, at Stage 3 or 4, when the cancer has already metastasized. This type is more common in women, especially those from East Asia, and often involves gene changes called mutations, especially in the EGFR gene. Scientists are still studying why this gene is more often affected in these groups.
Since smoking isn’t the cause, experts are now looking closely at the environment. Second-hand smoke, cooking fumes, and indoor burning of wood or coal are known risks, especially in lower-income countries. But outdoor air pollution is now seen as a major cause. Tiny particles in the air, known as PM2.5, come from cars, factories, and wildfires. These particles don’t usually damage DNA directly but may "wake up" cells that already have hidden mutations, causing cancer to grow.
Thankfully, new treatments are helping. Medicines called EGFR inhibitors, used for about 20 years, can block the faulty protein and often shrink tumors. While the cancer can become resistant over time, newer versions of these drugs are giving people more years of life. Some now live 10 years after being diagnosed—much better than in the past. Martha has been using this kind of treatment for three years and is doing well, though she does feel tired and has skin problems as side effects.
Experts hope that better knowledge will change how people see lung cancer. It's not just a “smoker’s disease” anymore. Health leaders around the world are also working to clean up the air. Even though the World Health Organization has made its PM2.5 limits stricter, nearly everyone still breathes air that's too polluted. Fixing this is now a top priority for public health and cancer prevention.
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I. Basic
Mutation – a change in a gene that can cause disease
Pollution – harmful substances in the air, water, or ground
Inhibitors – drugs that stop something harmful from working
II. Intermediate
Tumors – abnormal growths of cells that may become cancer
Mutations – changes in genes that can lead to disease
Fatigue – feeling very tired and lacking energy
III. Advanced
Adenocarcinoma – a type of cancer that begins in cells that make mucus or other fluids
Metastasized – spread of cancer from one part of the body to another
Mutations – changes in a gene that can lead to diseases like cancer