Lung Cancer

What is lung cancer?

From: MedlinePlus, National Library of Medicine

Lung cancer is cancer that forms in tissues of the lung, usually in the cells that line the air passages. It is the leading cause of cancer death in both men and women.

There are two main types: small cell lung cancer and non-small cell lung cancer. These two types grow differently and are treated differently. Non-small cell lung cancer is the more common type.

Who is more likely to develop lung cancer?

From: MedlinePlus, National Library of Medicine

Anyone can develop lung cancer, but certain factors raise your risk of getting it:

• Smoking. This is the most important risk factor for lung cancer. Tobacco smoking causes about 9 out of 10 cases of lung cancer in men and about 8 out of 10 cases of lung cancer in women. The more years you smoke and the more cigarettes you smoke each day, the more your risk goes up. Your risk is also greater if you smoke a lot and drink alcohol every day or take beta carotene supplements. If you have quit smoking, your risk will be lower than if you had kept smoking. But you will still have a higher risk than people who never smoked.
• Secondhand smoke, which is the combination of the smoke that comes from a cigarette and the smoke breathed out by a smoker. When you breathe in secondhand smoke, you are exposed to the same cancer-causing agents as smokers, although in smaller amounts.
• A family history of lung cancer.
• Being exposed to asbestos, arsenic, chromium, beryllium, nickel, soot, or tar in the workplace.
• Being exposed to radiation, for example from: Radiation therapy to the breast or chest Radon in the home or workplace Certain imaging tests such as CT scans
• HIV infection. Your risk is higher if you have HIV. However, smoking rates are higher in people who have HIV, so it's not clear whether the increased risk is from the HIV infection or from smoking.
• Air pollution. Studies show that living in areas with higher levels of air pollution increases your risk of lung cancer.

What are the symptoms of lung cancer?

From: MedlinePlus, National Library of Medicine

Lung cancer may not cause any signs or symptoms until the cancer is advanced. Sometimes the cancer is found during a chest x-ray done for another condition.

The symptoms of lung cancer may include:

• Chest pain or discomfort
• A cough that doesn't go away or gets worse over time
• Coughing up blood
• Trouble breathing
• Wheezing
• Hoarseness
• Loss of appetite
• Weight loss for no known reason
• Feeling very tired
• Trouble swallowing
• Swelling in the face and/or veins in the neck

How is lung cancer diagnosed?

From: MedlinePlus, National Library of Medicine

To find out if you have lung cancer, your health care provider:

• Will take your medical history, which includes asking about your symptoms
• Will ask about your family history
• Will do a physical exam
• May order certain imaging tests, such as a chest x-ray or chest CT scan
• May order lab tests, including tests of your blood and sputum
• May do a procedure to take a biopsy of the lung

If you do have lung cancer, your provider will do other tests to find out if it has spread through the lungs, lymph nodes, and the rest of the body. This is called staging. Knowing the type and stage of lung cancer you have helps your provider decide what kind of treatment you need.

If you have small-cell lung cancer, your provider may also do genetic testing to look for certain gene changes (variants) in your cancer cells. The results of the testing may help guide treatment.

What are the treatments for lung cancer?

From: MedlinePlus, National Library of Medicine

For most patients with lung cancer, current treatments do not cure the cancer.

Your treatment will depend on which type of lung cancer you have, how far it has spread, your overall health, and other factors. You may get more than one type of treatment.

The treatments for small cell lung cancer may include:

The treatments for non-small cell lung cancer may include:

• Surgery.
• Chemotherapy.
• Radiation therapy.
• Immunotherapy.
• Laser therapy, which uses a laser beam to kill cancer cells.
• Endoscopic stent placement. An endoscope is a thin, tube-like instrument used to look at tissues inside the body. It may be used to put in a device called a stent. The stent helps to open an airway that has been blocked by abnormal tissue.
• Surgery.
• Radiation therapy.
• Chemotherapy.
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells.
• Immunotherapy.
• Laser therapy.
• Photodynamic therapy (PDT), which uses a medicine and a certain type of laser light to kill cancer cells.
• Cryosurgery, which uses an instrument to freeze and destroy abnormal tissue.
• Electrocautery, a treatment that uses a probe or needle heated by an electric current to destroy abnormal tissue.

Can lung cancer be prevented?

From: MedlinePlus, National Library of Medicine

Avoiding the risk factors may help prevent lung cancer. For example, you can:

• Quit smoking. And if you don't smoke, don't start.
• Lower your exposure to hazardous substances at work.
• Lower your exposure to radon. Radon tests can show whether your home has high levels of radon. You can buy a test kit yourself or hire a professional to do the test.

Genetic causes described in the linked summary

From: MedlinePlus Genetics

Cancers occur when genetic mutations build up in critical genes, specifically those that control cell growth and division (proliferation) or the repair of damaged DNA. These changes allow cells to grow and divide uncontrollably to form a tumor. In nearly all cases of lung cancer, these genetic changes are acquired during a person's lifetime and are present only in certain cells in the lung. These changes, which are called somatic mutations, are not inherited. Somatic mutations in many different genes have been found in lung cancer cells. In rare cases, the genetic change is inherited and is present in all the body's cells (germline mutations).

Somatic mutations in the TP53, EGFR, and KRAS genes are common in lung cancers. The TP53 gene provides instructions for making a protein, called p53, that is located in the nucleus of cells throughout the body, where it attaches (binds) directly to DNA. The protein regulates cell growth and division by monitoring DNA damage. When DNA becomes damaged, p53 helps determine whether the DNA will be repaired or the cell will self-destruct (undergo apoptosis). The EGFR and KRAS genes each provide instructions for making a protein that is embedded within the cell membrane. When these proteins are turned on (activated) by binding to other molecules, signaling pathways are triggered within cells that promote cell proliferation.

TP53 gene mutations result in the production of an altered p53 protein that cannot bind to DNA. The altered protein cannot regulate cell proliferation effectively and allows DNA damage to accumulate in cells. Such cells may continue to divide in an uncontrolled way, leading to tumor growth. Mutations in the EGFR or KRAS gene lead to the production of a protein that is constantly turned on (constitutively activated). As a result, cells constantly receive signals to proliferate, leading to tumor formation. When these genetic changes occur in cells in the lungs, lung cancer develops.

Mutations in many other genes have been found to recur in lung cancer cases. Most of these genes are involved in the regulation of gene activity (expression), cell proliferation, the process by which cells mature to carry out specific functions (differentiation), and apoptosis.

Researchers have identified many lifestyle and environmental factors that expose individuals to cancer-causing compounds (carcinogens) and increase the rate at which somatic mutations occur, contributing to a person's risk of developing lung cancer. The greatest risk factor is long-term tobacco smoking, which increases a person's risk of developing lung cancer 25-fold. Other risk factors include exposure to air pollution, radon, asbestos, certain metals and chemicals, or secondhand smoke; long-term use of hormone therapy for menopause; and a history of lung disease such as tuberculosis, emphysema, or chronic bronchitis. A history of lung cancer in closely related family members is also an important risk factor; however, because relatives with lung cancer are frequently smokers, it is unclear whether the increased risk is the result of genetic factors or exposure to secondhand smoke.

Inheritance described in the linked summary

From: MedlinePlus Genetics

Most cases of lung cancer are not related to inherited genetic changes. These cancers are associated with somatic mutations that occur only in certain cells in the lung.

When lung cancer is related to inherited genetic changes, the cancer risk follows an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to increase a person's chance of developing the disease. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit mutations in these genes will develop lung cancer.

Which doctor should you see?

The suggested department for discussing Lung Cancer is Oncology, with a oncologist and relevant organ specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics; Relevant organ specialist / Surgical Oncology as indicated.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Has the exact tumour type been confirmed, and is staging relevant?
• What is the goal of each proposed treatment option?
• How will side effects, daily function and supportive care be addressed?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.