Lung cancer is one of the most prevalent causes of death worldwide, specifically in the United States. It has no gender predilection and can occur in both genders equally. It is the abnormal growth of the cells with rapid cell division. The most common cause of lung cancer is smoking cigarettes. Other risk factors also include familial predisposition to lung cancer and environmental factors. Lung cancer majorly consists of two types that are small-cell lung cancer and non-small-cell lung cancer.

What Are the Causes of Lung Cancer?

Lung cancer is mainly caused by cigarette, pipe, or cigar smoking. It depends upon the duration and frequency of smoking. The more a person smokes, the more the chances of developing lung cancer.

Other factors, such as: can cause lung cancer in people who do not smoke.

Genetic changes.
Exposure to Radon.
Exposure to air pollution.
Second-hand smoke.
Exposure to asbestos and arsenic.
Family history of lung cancer.
Exposure to radiation therapy.

Second-hand smoke and Radon exposure are the two main contributors to non-smoking lung cancer. Radon is a naturally occurring radioactive gas typically formed from the breakdown of uranium in rocks and soil. It is an inert, colorless, and odorless gas. It is naturally found in the atmosphere in traces. It leaks through cracks and holes and gets entrapped indoors. Breathing the gas over time increases the risk of lung cancer.

A combination of smoke from the burning end of a cigarette and the smoke exhaled by smokers is known as second-hand smoke. It contains more than 7,000 chemicals, out of which hundreds are toxic, and about 70 of them can cause cancer.

Older age increases the risk factor for developing cancer by many folds. The chances of getting cancer increase when combined with other risk factors. It is even worse than normal smoke.

What Are the Types of Lung Cancer in Non-Smokers?

Adenocarcinoma.
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Squamous cell carcinoma.
Small cell lung cancer.

Adenocarcinoma: It is a type of non-small cell lung cancer. Seen in almost 50-60 % of non-smoker lung cancers.

Squamous Cell Carcinoma is also a non-small cell lung cancer type.

Small Cell Lung Cancer: Rarely affects those with lung cancer who do not smoke.

What Are the Symptoms of Lung Cancer?

The symptoms of lung cancer include

A persistent cough that worsens with time.
Haemoptysis.
Recurrent pulmonary infections such as pneumonia or bronchitis.
Hoarseness of voice.
Continuous chest pain.
Shortness of breath.
Wheezing.
Loss of appetite.
Fatigue.
Bone pain.

How Is Lung Cancer Diagnosed?

Tests that diagnose lung cancer are

Chest X-ray.
Computed tomography (CT) scan.
Sputum cytology.
Thoracocentesis.

If lung cancer is suspected, other tests are done, such as:

Fine Needle Aspiration Biopsy: A fine needle removes tissues or fluid from the lungs. A needle is inserted, and a small incision is made, the required sample is removed with the needle and sent to a laboratory for further testing. It is done with the help of an endoscopic ultrasound which guides the needle biopsy to the exact location from which the tissues or fluid needs to be removed.

Bronchoscopy: It is a fine, thin tube-like instrument with a camera inserted into the trachea and the larger airways to view abnormal areas inside.

Thoracoscopy: It is a procedure to view the organs of the chest. An incision is made between two ribs, and a thin, tube-like instrument fitted with a camera is inserted into the chest.

Lymph Node Biopsy: It is a procedure that involves the removal of a part of the lymph node for further investigation if suspected cancer cells are present.

What Are the Factors Affecting the Treatment?

The treatment of lung cancer depends upon various factors:

Stage of cancer, whether the cancer cells are limited to the lungs or it has spread to involve other organs.
Patient's lung function.
Individual's overall health.
Familial history of cancer.

What Are the Different Treatment Modalities?

The different treatment modalities are:

Surgery.
Radiotherapy.
Chemotherapy.
Radiofrequency ablation.
Immunotherapy.
Laser therapy.
Targeted drug therapy.

Surgery:

It is done by removing questionable lymph nodes. Sometimes it may be used to remove some tissues from the lungs to know the type of lung cancer. It is never used alone and is always combined with radiotherapy or chemotherapy to ensure that no cancer cells are left in the body.

Radiotherapy:

Radiotherapy or radiation therapy uses high-energy X-rays to kill cancer cells. External radiation therapy uses a machine from outside to send radiation to a particular area of the body where cancer cells are seen. It may also be used as a palliative therapy to treat the symptoms.

Chemotherapy:

The therapy involves drugs to cease the growth of cancer-causing cells, either by killing the cells or limiting their ability to divide. The drugs can be administered orally or parenterally. If the drug is given directly to an organ, cerebrospinal fluid, or body cavity, the drug mainly affects those targeted areas and thereby avoids systemic effects. It is known as regional chemotherapy.

Radiofrequency Ablation:

It is also known as radiofrequency neurotomy, in which heat is applied to the areas of the nerve, which destroys the pain-causing nerves and thereby prevents them from sending signals to the central nervous system.

Immunotherapy:

It uses the body's immune system to fight cancer-causing cells. It is a type of biological therapy. Usually, PD1 is a protein found on the T-cell surface, and PDL1 is a protein present in cancer cells. Whenever PD1 and PDL1 interact, it prevents the T-cell from killing the cancer cells. Therefore, a PD1 and PDL1 inhibitor is required in order to avoid their interaction with each other and thereby ensure T-cells kill these cells.

Laser Therapy:

It is a cancer treatment that uses a narrow beam of laser light to a targeted area of action.

How Can Lung Cancer Be Prevented?

It can be prevented by:

Quit smoking.
Avoid exposure to harmful chemicals.
Avoid staying close to a person while they smoke.
Lower exposure to Radon. A radon test can be done at home if one suspects high levels of Radon.

Conclusion:

The main goal of lung cancer, or any cancer, is to cure the cancer patient and prolong their life. Therefore, a proper diagnosis, early intervention, and treatment is the key to cancer treatment. Further, awareness programs, educating patients, families, and communities about cancer risk, and taking precautionary steps to avoid cancer can help achieve the goal.

Frequently Asked Questions

1. Is Lung Cancer Seen on X-Ray?

On X-rays, most lung tumors appear as a white-grey mass. Chest X-rays, on the other hand, cannot provide a definitive diagnosis because they frequently fail to distinguish between cancer, lung abscess, and other conditions.

2. Does Lung Cancer Occur in Non-Smokers?

Other than smoking cigarettes, pipes, or cigars, other risk factors can cause lung cancer. Exposure to other people's smoke, air pollution, radon, and a family history of asbestos and lung cancer are all examples.

3. Where Does Non-Small Cell Cancer Spread?

Non-small cell lung cancer, like many other cancers, can spread to other parts of the body. NSCLC typically spreads to the bones, brain, liver, skin, lymph nodes, or adrenal glands. This is referred to as metastatic non-small cell lung cancer.

4. Where Does Lung Cancer Metastasize?

In general, lung cancer cells prefer the brain, bones, and adrenal glands, and small-cell neuroendocrine carcinomas and adenocarcinomas metastasize into the brain, whereas squamous cell carcinomas prefer the bones.

5. When Does Lung Cancer Spread to Lymph Nodes?

Before spreading to other body parts, lung cancer frequently spreads to the lymph nodes. Therefore, which lymph node groups are involved and where they are in relation to the primary (original) tumor are important factors in determining the cancer stage and treatment.

6. Can Lung Cancer Recur?

3 in 10 people with stage 1 lung cancer will recur within five years, while 7 in 10 people with stage 4 lung cancer will relapse. This rarer and more aggressive form of lung cancer has a poor prognosis.