Lung cancer starts in the cells of the lung. A cancerous (malignant) tumour is a group of cancer cells that can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. When cancer starts in lung cells, it is called primary lung cancer.
The lung is part of the respiratory system. You use your lungs when you breathe. The lungs are in the chest, one on each side of the heart. The right lung has 3 main parts, called lobes. The left lung is a bit smaller and has 2 lobes. The lungs are cushioned and protected by a thin covering called the pleura.
Cells in the lung sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous (benign) tumours such as hamartoma and papilloma. But in some cases, changes to lung cells can cause cancer.
Lung cancers are divided into non–small cell lung cancer and small cell lung cancer based on the type of cell in which the cancer started.
What are the symptoms of lung cancer?
Symptoms of non-small cell lung cancer and small cell lung cancer are basically the same.
Early symptoms may include:
- lingering or worsening cough
- coughing up phlegm or blood
- chest pain that worsens when you breathe deeply, laugh, or cough
- hoarseness
- shortness of breath
- wheezing
- weakness and fatigue
- loss of appetite and weight loss
You might also have recurrent respiratory infections such as pneumonia or bronchitis.
As cancer spreads, additional symptoms depend on where new tumors form. For example, if in the:
- lymph nodes: lumps, particularly in the neck or collarbone
- bones: bone pain, particularly in the back, ribs, or hips
- brain or spine: headache, dizziness, balance issues, or numbness in arms or legs
- liver: yellowing of skin and eyes (jaundice)
- Tumors at the top of the lungs can affect facial nerves, leading to drooping of one eyelid, small pupil, or lack of perspiration on one side of the face. Together, these symptoms are called Horner syndrome. It can also cause shoulder pain.
Tumors can press on the large vein that transports blood between the head, arms, and heart. This can cause swelling of the face, neck, upper chest, and arms.
Lung cancer sometimes creates a substance similar to hormones, causing a wide variety of symptoms called paraneoplastic syndrome, which include:
- muscle weakness
- nausea
- vomiting
- fluid retention
- high blood pressure
- high blood sugar
- confusion
- seizures
- coma
What causes lung cancer?
Anyone can get lung cancer, but 90 percent of lung cancer cases are the result of smoking. Exposure to radon, a naturally existing radioactive gas, is the second leading cause.
Other substances that can cause lung cancer are:
- arsenic
- cadmium
- chromium
- nickel
- some petroleum products
- uranium
- Inherited genetic mutations may make you more likely to develop lung cancer, especially if you smoke or are exposed to other carcinogens.
Sometimes, there's no obvious cause for lung cancer.
Risk factors for lung cancer
The biggest risk factor for lung cancer is smoking. That includes cigarettes, cigars, and pipes. Tobacco products contain thousands of toxic substances.
Your risk of developing lung cancer is higher if you're exposed to toxic substances such as asbestos or diesel exhaust in the workplace.
Other risk factors include:
- family history of lung cancer
- personal history of lung cancer, especially if you're a smoker
- previous radiation therapy to the chest
Treatment for lung cancer
It's usually a good idea to seek a second opinion before beginning treatment. Your doctor may be able to help make that happen. If you're diagnosed with lung cancer, your care will likely be managed by a team of doctors who may include:
- a surgeon who specializes in the chest and lungs (thoracic surgeon)
- a lung specialist (pulmonologist)
- a medical oncologist
- a radiation oncologist
Discuss all your treatment options before making a decision. Your doctors will coordinate care and keep each other informed.
Treatment for non-small cell lung cancer (NSCLC) varies from person to person. Much depends on specific details of your health.
Stage 1 NSCLC: Surgery to remove a portion of the lung may be all you need. Chemotherapy may also be recommended, especially if you're at high risk of recurrence.
Stage 2 NSCLC: You may need surgery to remove part or all of your lung. Chemotherapy is usually recommended.
Stage 3 NSCLC: You may require a combination of chemotherapy, surgery, and radiation treatment.
Stage 4 NSCLC: is particularly hard to cure. Options include surgery, radiation, chemotherapy, targeted therapy, and immunotherapy.
Options for small cell-lung cancer (NSCLC) also include surgery, chemotherapy, and radiation therapy. In most cases, the cancer will be too advanced for surgery.
Clinical trials provide access to promising new treatments. Ask your doctor if you're eligible for a clinical trial.