What should you know about lung cancer caused by smoking?

Tobacco smoke contains substances that can injure the DNA inside lung cells. Repeated exposure may allow abnormal cells to grow and divide in an uncontrolled way. Risk is influenced by how long and how much a person smoked, as well as exposure to other inhaled irritants. Lung cancer can also occur in people who never smoked, so smoking history is one part of the clinical picture rather than a diagnostic test.

Doctors classify the cancer by its cell type, extent and molecular features. These details help determine whether surgery, radiotherapy, chemotherapy, targeted treatment or another approach is suitable. A biopsy and scans may be used to confirm the diagnosis and understand its spread. You can read more about [Lung Cancer](/conditions/lung-cancer/) and [Genomic Tumour Profiling](/treatments/diagnostics-and-staging/genomic-tumour-profiling/).

Arrange an assessment for persistent or changing respiratory symptoms, particularly a cough, chest discomfort, breathlessness, unexplained weight loss or a hoarse voice. A [Hoarse Voice](/symptoms/hoarse-voice/) page explains that symptom separately. If lung cancer has been diagnosed, bring your medication list and smoking history, including current use and previous attempts to stop.

Stopping smoking can make breathing easier and may help the body tolerate treatment, whatever the stage of care. Ask for structured support rather than trying to manage withdrawal alone. Your team may discuss an operation such as [Lung Lobectomy](/treatments/surgical-oncology/lung-lobectomy/), [Chemotherapy](/treatments/systemic-therapy/chemotherapy/), [Radiotherapy](/treatments/radiation-oncology/radiotherapy/) or symptom-focused [Palliative Care](/treatments/supportive-and-palliative-care/palliative-care/).

Seek urgent medical help for severe or rapidly worsening breathlessness, coughing up more than a small streak of blood, new confusion, fainting, or chest pain that is severe or persistent. New weakness, trouble speaking or a seizure also needs urgent assessment because lung cancer can sometimes spread to the brain; see [Brain Metastases](/conditions/brain-metastases/) for background.

Ask which tests confirm the diagnosis, what cell type and stage are present, whether molecular testing is appropriate, and how stopping smoking could support your treatment. Clarify the aim of each proposed treatment, likely effects on daily activities, and who to contact if symptoms change.