Lung cancer occurs when abnormal cells grow uncontrollably within lung tissue, forming tumors that impair normal lung function. It is one of the most frequently diagnosed cancers globally and a leading cause of cancer-related mortality.

The disease is broadly classified into:

• Non-small cell lung cancer (NSCLC):Accounts for most cases and includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma
• Small cell lung cancer (SCLC): A faster-growing and more aggressive form that often spreads early
  
  

The exact type helps guide treatment choices and planning. At OncoClinic, we combine advanced imaging, pathology, and personalized care planning to help you move forward with clarity and confidence.

Signs and symptoms

• Ongoing or changing cough
• Blood in sputum
• Chest discomfort or pain
• Breathlessness
• Voice changes or hoarseness
• Unintended weight loss or reduced appetite
• Persistent fatigue
• Repeated lung infections
• Bone pain or headaches in advanced disease
• Fluid build-up around the lungs
• Wheezing
• Repeated or slow-to-clear lung infections, such as pneumonia
• Shoulder pain
• Swelling of the face or neck

In later stages, other symptoms can include chest pain, difficulty breathing, fluid build-up around the lungs, and shoulder pain.

Risk factors

• Age: The risk of lung cancer increases with age
• Genetic predisposition or family history: A family history of lung cancer increases risk
• Tobacco smoking (active smoking): Smoking is the leading cause of lung cancer. People who smoke have about 15 to 30 times higher risk of developing lung cancer compared to those who never smoked. The risk increases with the number of cigarettes smoked per day and the number of years of smoking
• Second-hand smoke (passive smoking): Regular exposure to tobacco smoke from others also increases lung cancer risk, even in people who have never smoked
• Environmental toxins: Long-term exposure to environmental or workplace toxins increases the risk
• Asbestos, radon, and industrial chemicals: Contact with substances such as asbestos, radon, or industrial chemicals increases the risk
• Chronic lung conditions: Chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis increase the risk

Screening

Lung cancer screening can detect cancer early, before symptoms appear, when treatment is more likely to be effective, using a low-dose CT scan (LDCT) of the chest.

If you think you may be at high risk, talk to a healthcare provider to see if lung cancer screening is right for you.

Screening recommendation

Lung cancer screening is recommended only for individuals at high risk and is not advised for the general population. It is usually performed once a year and is typically recommended for people who:

• Are between 50 and 80 years old
• Currently smoke or quit smoking within the past 15 years
• Have a long history of smoking (usually 20 pack-years or more, such as 1 pack a day for 20 years)

Screening is not recommended for people who:

• Have never smoked
• Quit smoking more than 15 years ago
• Are unable or unwilling to undergo treatment if cancer is found

Diagnosis

Lung cancer is often diagnosed after symptoms appear or when an abnormality is found on imaging tests such as a chest X-ray or CT scan. If lung cancer is suspected, further tests are done to confirm the diagnosis. These usually include a biopsy, where a small sample of tissue is taken from the lung or nearby lymph nodes and examined under a microscope.

The biopsy allows doctors to determine the histology, which means identifying the type of lung cancer (for example, non-small cell or small cell lung cancer). This step is essential because different types of lung cancer are treated differently.

In addition, molecular testing is performed on the tumor sample to look for specific genetic changes that can guide treatment. This may include next-generation sequencing (NGS), an advanced test that analyzes multiple genes simultaneously. Molecular testing helps doctors decide whether targeted therapies or immunotherapy may be effective and is a key step in choosing the best treatment plan.

Other tests, such as bronchoscopy, may also be used to help obtain tissue or better evaluate the disease.

Staging

Once lung cancer is confirmed, doctors determine the stage, which describes how far the cancer has spread. 

Staging helps guide treatment decisions and usually involves several imaging and diagnostic tests, including:

• CT scans: Used to look at the lungs, lymph nodes, and other organs in the chest and abdomen
• PET/CT scan: Helps show whether cancer has spread to lymph nodes or distant parts of the body by highlighting areas of active disease
• MRI: Often used to check if cancer has spread to the brain or spinal cord
• EBUS (endobronchial ultrasound): Used in selected cases, usually when imaging does not show clear signs of advanced disease, to better assess whether lymph nodes in the center of the chest are involved

Based on the results of these tests, lung cancer is staged from Stage I to Stage IV, ranging from cancer limited to the lung to cancer that has spread to distant organs. Staging, together with histology and molecular testing, is essential for planning the most appropriate treatment.

Treatment and procedures

At OncoClinic, lung cancer care is delivered through an integrated, patient-focused approach. Treatment plans are tailored based on cancer type, stage, and overall health, and may include:

• Surgery: Surgery is an important treatment option for many patients with early-stage lung cancer. When appropriate, it aims to remove the tumor and affected lung tissue and offers the best chance for a cure in selected cases.
• Chemotherapy: Drug-based treatment used to destroy cancer cells or control disease progression. It may be given alone or combined with other treatments.
• Radiation therapy: High-energy radiation used to target and destroy cancer cells. It may be used as the main treatment, after surgery, or in combination with chemotherapy or immunotherapy.
• Targeted therapy: Precision treatments designed to act on specific genetic or molecular features of the tumor, based on molecular testing results.
• Immunotherapy: Therapies that enhance the body’s immune response to recognize and attack cancer cells.
• Combined treatment strategies: Coordinated use of two or more treatments—such as chemotherapy, radiation therapy, immunotherapy, or targeted therapy—to achieve the best possible outcomes.
• Palliative and supportive care: Focused on symptom control, comfort, and quality of life at all stages of the disease, alongside cancer-directed treatment.

References

Lung cancer overview
American Cancer Society, 2026

Signs and symptoms of lung cancer
American Cancer Society, 2025

Lung cancer risk factors
American Cancer Society, 2026

Lung cancer screening guidelines
American Cancer Society, 2026

Lung cancer – patient version
National Cancer Institute (NCI), 2026

Non-small cell lung cancer treatment (PDQ®) – patient version
National Cancer Institute (NCI), 2026

Small cell lung cancer treatment (PDQ®) – patient version
National Cancer Institute (NCI), 2026

NCCN clinical practice guidelines in oncology: non-small cell lung cancer and small cell lung cancer
National Comprehensive Cancer Network (NCCN), 2026

The IASLC lung cancer staging project: TNM classification of lung cancer (8th edition)
Goldstraw P et al. – Journal of Thoracic Oncology, 2016

NCCN guidelines insights: non-small cell lung cancer
Ettinger DS et al. – Journal of the National Comprehensive Cancer Network, 2023

Updated molecular testing guideline for the selection of lung cancer patients for targeted therapies
Lindeman NI et al. – Journal of Thoracic Oncology, 2018

Therapy for stage IV non–small-cell lung cancer
Hanna NH et al. – Journal of Clinical Oncology, 2020

Reduced lung-cancer mortality with low-dose computed tomographic screening
Aberle DR et al. – New England Journal of Medicine, 2011

Lung and bronchus cancer statistics
Surveillance, Epidemiology, and End Results (SEER) Program, 2026