Lung cancer can develop for many different reasons, and not all of them are related to smoking. Understanding the factors that increase risk — alongside those that can be changed or reduced — helps support earlier diagnosis, informed decision-making, and more personalised prevention strategies.
Dr Dionysis Papadatos-Pastos, consultant medical oncologist specialising in thoracic cancers, explains the most important risk factors, how they interact, and what steps individuals can take to reduce their overall risk.
Topics Covered
Topics Covered
Topics Covered
Topics CoveredUnderstanding Lung Cancer Risk Factors
Lung cancer does not have a single cause. Instead, it arises from a combination of genetic susceptibility, environmental exposures, lifestyle influences, and sometimes factors that remain poorly understood. Although smoking remains the strongest known contributor, a significant proportion of cases — particularly in women and in younger patients — occur in individuals who have never smoked.
Recognising these different categories of risk helps clinicians guide patients more effectively and encourages awareness beyond the traditional smoking-only narrative.
Smoking and Tobacco Exposure
Cigarette smoking accounts for the largest proportion of lung cancer cases worldwide. The risk increases with both duration and intensity of smoking, and continues to rise the longer someone smokes. Even low-level or intermittent smoking carries measurable risk.
For former smokers, the risk gradually decreases over time, though it may remain higher than in never-smokers for many years. Exposure to passive smoke at home or in the workplace also increases risk, and may be particularly relevant for people living with smokers even if they do not smoke themselves.
Risk in Non-Smokers
Lung cancer in people who have never smoked is becoming increasingly recognised as a distinct clinical entity. These cancers often arise through molecular alterations such as EGFR, ALK and ROS1 alterations — pathways that are unrelated to tobacco exposure.
Non-smokers may experience delayed diagnosis because symptoms are attributed to benign causes, and because lung cancer is not always considered at early stages. Understanding that lung cancer can occur without any history of smoking is essential for timely assessment.
Environmental and Occupational Exposures
Certain environmental exposures can contribute to lung cancer development, even at lower levels than historically recognized. These include long-term exposure to air pollution, radon gas in poorly ventilated indoor environments, and specific occupational hazards.
While not all exposures carry equal weight, cumulative effects may still be significant — particularly in individuals with underlying genetic susceptibility.
Genetic and Biological Factors
Some individuals have a higher inherent susceptibility to lung cancer due to inherited genetic tendencies or biological characteristics. A family history of lung cancer, particularly in first-degree relatives, may suggest a shared predisposition.
Additionally, certain molecular subtypes occur more commonly in specific demographics — such as EGFR-positive tumours in women and younger non-smokers. These patterns help guide testing, diagnostic pathways, and personalised treatment decisions.
Lifestyle-Related Factors
Although smoking is the dominant lifestyle factor, other behaviours may influence lung cancer risk. Poor air quality in urban environments, chronic inflammation of the airways, and long-term exposure to irritants such as fumes or dust can all contribute to cumulative risk over time.
Regular exercise, balanced nutrition, and avoidance of prolonged indoor pollution can support better respiratory health overall, though they cannot eliminate genetic or environmental risk.
What You Can Change vs What You Cannot
Many individuals believe that lung cancer risk is entirely outside their control — or, conversely, that lifestyle changes alone can prevent the disease. Neither is true.
Non-modifiable risk factors include age, sex, inherited genetic tendencies, and certain molecular alterations. Modifiable factors include smoking, passive smoke exposure, air-quality improvement, and limiting environmental inhalants.
Focusing on what can be changed supports long-term prevention, while understanding what cannot be changed encourages earlier symptom recognition and timely referral.
When to Seek Medical Advice
If you have persistent respiratory symptoms — such as an ongoing cough, breathlessness, chest discomfort, hoarseness, or repeated chest infections — it is appropriate to speak with your GP regardless of smoking history.
People with known risk factors, including a family history of lung cancer or long-term exposure to pollutants, may benefit from earlier assessment if new or unexplained symptoms appear. Early evaluation enables appropriate imaging, investigation, and follow-up where needed.
How Risk Factors Influence Diagnosis and Treatment
Risk factors help clinicians understand the likelihood of different tumour subtypes and guide decisions around imaging, biopsy, and molecular testing. For example, non-smokers are more likely to develop cancers driven by targetable mutations, making molecular profiling essential.
Similarly, individuals with a heavy smoking history may require additional screening for coexisting lung conditions. Understanding risk improves accuracy, personalisation, and timeliness of care.
Support and Follow-Up Care
Dr Papadatos-Pastos and his team provide ongoing support beyond medical treatment.
Patients receive clear communication, psychological care and access to nutrition, physiotherapy and symptom-management services.
Regular follow-up ensures early detection of recurrence and long-term wellbeing.
Book a Consultation
If you or someone close to you has been diagnosed with lung cancer, early consultation with a specialist can make a real difference. Appointments are available at several London clinics.
Faq
Answers to Common Questions
These questions address common concerns about lung cancer risk, including lifestyle, environmental exposure, and factors that can be influenced over time.
Yes. A significant proportion of lung cancer cases — especially in women and younger patients — occur in people who have never smoked. These cancers often arise from specific genetic or molecular changes.
Risk gradually decreases after quitting, and continues to improve over time. However, former smokers still carry a higher risk compared with individuals who never smoked.
Long-term exposure to polluted air, especially in large cities, has been shown to increase lung cancer risk. The effect is cumulative and may be more pronounced in individuals with underlying susceptibility.
Most cases are not directly inherited. However, a family history of lung cancer may indicate shared genetic or environmental tendencies that raise risk.
A persistent cough, breathlessness, chest discomfort, recurrent infections, or coughing up blood should be reviewed — particularly if symptoms last more than three weeks or change over time.
