Lung cancer causes more cancer deaths than breast, prostate, and colorectal cancers combined — approximately 1.8 million deaths globally each year. Its notoriously poor overall prognosis (five-year survival approximately 20%) reflects the fact that most cases are diagnosed at advanced stages when curative treatment is no longer possible. This makes early detection through screening critically important, and awareness of risk factors and symptoms essential for timely diagnosis.
Risk Factors
Cigarette smoking causes approximately 85% of lung cancers. The risk is dose-dependent: a two-pack-per-day smoker for 40 years has roughly 70 times the lung cancer risk of a non-smoker. Quitting dramatically reduces — though never eliminates — accumulated risk; after 10 smoke-free years, risk drops to approximately half that of continuing smokers. Beyond tobacco, significant risk factors include: radon gas exposure — the second leading cause of lung cancer, particularly in poorly ventilated homes in certain geological regions; asbestos, arsenic, chromium, and nickel exposure in occupational settings; air pollution, including both outdoor particulate matter and indoor cooking smoke; and familial history of lung cancer (suggesting shared genetic susceptibility independent of smoking).
Symptoms
Lung cancer frequently produces no symptoms until locally advanced or metastatic — another reason screening of high-risk individuals is critical. When symptoms occur: a persistent cough that worsens or changes character; haemoptysis (coughing up blood or blood-streaked mucus); shortness of breath or wheezing; chest pain with deep breathing or coughing; hoarseness; unexplained weight loss and appetite loss; fatigue; and recurrent respiratory infections. Paraneoplastic syndromes — distant effects mediated by tumour-secreted hormones or immune responses — may produce neurological, endocrine, or musculoskeletal symptoms without direct tumour involvement.
Screening with Low-Dose CT
Annual low-dose CT (LDCT) screening is recommended for high-risk adults aged 50–80 who have a 20 pack-year smoking history and currently smoke or quit within the past 15 years. The NLST trial demonstrated that LDCT screening reduces lung cancer mortality by 20% compared to chest X-ray in this population. The Nelson trial showed a 24% mortality reduction in men and 33% in women. LDCT has a high false-positive rate (up to 25%), necessitating organised follow-up protocols such as Lung-RADS to minimise unnecessary invasive procedures while not missing early cancers.
Frequently Asked Questions
Can non-smokers get lung cancer?
Yes. Approximately 15–20% of lung cancers occur in never-smokers. Radon exposure, secondhand smoke, asbestos, air pollution, and genetic factors all contribute. Lung cancer in never-smokers tends to be adenocarcinoma, more commonly harbours targetable driver mutations (EGFR, ALK, ROS1), and is increasingly prevalent in women in East Asian populations.
What are targeted therapies for lung cancer?
Approximately 60–70% of lung adenocarcinomas harbour a targetable driver mutation or alteration. EGFR mutations respond to osimertinib; ALK rearrangements to alectinib or brigatinib; ROS1, RET, MET, BRAF, NTRK, and KRAS G12C mutations each have approved targeted agents. Molecular profiling of all advanced non-small cell lung cancers is now standard of care before initiating systemic therapy.
Sources
- WHO. Lung cancer fact sheet. 2023.
- USPSTF. Lung Cancer Screening Recommendation. 2021.
- American Cancer Society. Lung Cancer Facts & Figures 2023.