Lung Cancer in Nonsmokers

Why nonsmokers get lung cancer

Lung cancer in never-smokers (people who smoked fewer than 100 cigarettes in their lifetime) is often a different disease from smoking-related lung cancer. Tumors usually have fewer mutations overall but more often carry a single "driver" mutation that fuels growth.

Risk factors

• Radon: a natural radioactive gas from soil that can build up in homes. It is the leading cause of lung cancer among never-smokers in the US, according to the EPA.
• Secondhand smoke: living or working with smokers increases risk by about 20% to 30%.
• Air pollution: fine particle pollution (PM2.5) is linked to lung cancer and may trigger tumor growth in cells already carrying EGFR mutations.
• Occupational exposures: asbestos, diesel exhaust, silica, arsenic, chromium, nickel.
• Household fumes: high-temperature cooking with oil in poorly ventilated kitchens, and burning coal or wood indoors.
• Family history and genetics: a parent or sibling with lung cancer increases risk.
• Previous radiation to the chest.
• Lung scarring from conditions such as pulmonary fibrosis or tuberculosis.
• Hormonal factors are being studied as a possible reason for higher rates in women.

Types

Small cell lung cancer is rare in never-smokers.

Symptoms

Early lung cancer often causes no symptoms. When present:

• a persistent cough or a change in a chronic cough
• coughing up blood (hemoptysis)
• shortness of breath
• chest, shoulder or back pain
• hoarseness
• repeated chest infections
• tiredness, loss of appetite and weight loss
• in advanced disease: bone pain, headaches, neurological symptoms, swelling of the face

Because never-smokers and their doctors may not suspect lung cancer, diagnosis can be delayed. Persistent symptoms deserve a chest x-ray or CT scan.

Screening

Current US screening with yearly low-dose CT is recommended only for people aged 50 to 80 with a significant smoking history. There is no routine screening for never-smokers. Research is ongoing into screening never-smokers with strong family histories or other risk factors, as is done in some Asian countries.

Diagnosis

1. Chest x-ray and CT scan.
2. Biopsy: by bronchoscopy, CT-guided needle or surgery.
3. Biomarker (molecular) testing: essential for all adenocarcinomas, testing for EGFR, ALK, ROS1, BRAF, KRAS, MET, RET, NTRK, HER2 and PD-L1. Blood-based liquid biopsies can supplement tissue testing.
4. Staging: PET-CT and brain MRI.

Treatment

Early-stage disease

• surgery to remove the tumor, often with lymph nodes
• stereotactic radiotherapy for people who cannot have surgery
• adjuvant targeted therapy: for EGFR-mutated cancer, osimertinib after surgery reduces recurrence
• chemotherapy or immunotherapy before or after surgery in some cases

Advanced disease

• Targeted therapy pills: for tumors with driver mutations, such as osimertinib for EGFR, alectinib or lorlatinib for ALK, and others. These often control cancer for years with fewer side effects than chemotherapy.
• Immunotherapy and chemotherapy: for tumors without targetable mutations.
• Radiotherapy for symptom control.
• Drainage of fluid around the lungs (malignant pleural effusion).

Prevention

• Test your home for radon with an inexpensive kit; fix levels at or above 4 pCi/L (148 Bq/m³), as recommended by the EPA.
• Avoid secondhand smoke at home and work.
• Use ventilation when cooking, and avoid burning solid fuels indoors.
• Follow workplace safety rules for asbestos, silica and diesel exhaust.
• Limit exposure to outdoor air pollution on high-pollution days where practical.

Outlook

Survival depends on stage and tumor genetics. People whose tumors have targetable mutations often live much longer than in the past, with many living years with advanced disease on targeted therapy. Early detection allows potentially curative surgery.

Frequently asked questions

Why do nonsmokers get lung cancer?

Major causes include radon gas in homes, secondhand smoke, air pollution, workplace exposures such as asbestos, indoor cooking or heating fumes, and inherited susceptibility. Many cases are driven by specific gene mutations, such as EGFR, that develop without smoking.

What are the first signs of lung cancer in nonsmokers?

Early lung cancer often causes no symptoms. The first signs may be a persistent cough, breathlessness, chest pain, coughing up blood, hoarseness or unexplained weight loss. Symptoms lasting more than 3 weeks should be checked by a doctor.

Is lung cancer in nonsmokers different?

Often, yes. It is usually adenocarcinoma, more common in women and people of Asian descent, and more likely to have targetable mutations such as EGFR or ALK. These cancers often respond well to targeted pill treatments.

Should nonsmokers be screened for lung cancer?

Routine screening is currently recommended only for people with a significant smoking history. Never-smokers with symptoms should get tested. Research is exploring screening for never-smokers with strong family histories or other major risk factors.

How can I lower my risk of lung cancer if I don't smoke?

Test your home for radon and fix high levels, avoid secondhand smoke, ventilate your kitchen, avoid burning solid fuels indoors, follow workplace safety rules for asbestos and other hazards, and limit exposure to heavy air pollution.