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Lung Cancer

lung cancer


There are two lungs, one on either side of the chest. Air goes into the lungs via the windpipe (trachea) which divides into a series of branching airways called bronchi. Air goes from the airways into millions of tiny air sacs (alveoli).Oxygen from the air is passed into the bloodstream through the thin walls of the alveoli.

Lung cancer is one of the most common cancers in the world.

Primary lung cancers

Primary lung cancers arise from cells in the lung. There are several types of primary lung cancer. The two most common types are called small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC).

NSCLCs include squamous cell cancers (the most common type of lung cancer), adenocarcinoma and large cell carcinoma.

Secondary lung cancers

Secondary lung cancers (or lung metastases) are tumours which have spread to the lung from another cancer somewhere else in the body. The lung is a common site for metastases from other cancers. This is because all blood flows through the lungs and may contain tumour cells from any other part of the body.

What causes lung cancer?

A cancerous tumour starts from one abnormal cell. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply out of control. Certain risk factors increase the chance of certain cancers forming.

Smoking

Smoking is a major risk factor and is the main cause of lung cancer. Chemicals in tobacco smoke are carcinogens - substances which can damage cells and lead to cancer developing. About 9 in 10 cases of lung cancer are caused by smoking.

Other factors

  • People who are regularly exposed to other people's smoke (passive smokers) have a small increased risk.
  • People who work with certain substances, such as radioactive materials, asbestos, nickel and chromium, have an increased risk, especially if they also smoke.
  • People who live in areas where there is a high level of background radiation from radon have a small increased risk.
  • Air pollution may be a small risk too.
  • A family history of lung cancer in a first-degree relative (mother, father, brother, sister) slightly increases the risk of lung cancer.

What are the symptoms of lung cancer?

  • Many people do not have symptoms in the early stages and lung cancer may be diagnosed when a chest X-ray is performed for a different reason.
  • Persistent cough.
  • Coughing up blood or bloodstained sputum.
  • Chest and/or shoulder pains.
  • Tiredness and loss of energy.
  • Weight loss.
  • Shortness of breath or wheezing.
  • Hoarse voice.
  • A change in shape at the end of your fingers (clubbing).

As the cancer grows in the lung, the symptoms may become worse and may include one or more of the following:

  • The same symptoms as above but more severe.
  • Pneumonia (lung infection).
  • Fluid which may accumulate between the lung and chest wall (pleural effusion).
  • A tumor near to the top of the lung, which can press on nerves going down the arm and cause pain, weakness, and pins and needles in the arm and shoulder.
  • Swelling of the face (face edema) which may develop if a tumor presses on a main vein (superior vena cava) coming towards the heart from the head.
  • Some small cell tumors which can produce large amounts of hormones which can cause symptoms in other parts of your body.
  • If the cancer spreads to other parts of the body, various other symptoms can develop such as bone pain or swelling of the neck or above the collarbone.

How is lung cancer diagnosed?

If a doctor suspects that you may have lung cancer, the common initial test is a chest X-ray.

Confirming the diagnosis

You may be offered a computerized tomography (CT) scan which will help to confirm the diagnosis of lung cancer.

Assessing the extent and spread

This assessment is called staging of the cancer. The aim of staging is to find out:

  • How much the cancer in the lung has grown?
  • Whether the cancer has spread to local lymph nodes or to other areas of the lungs.
  • Whether the cancer has spread to other areas of the body (metastasized).

By finding out the stage of the cancer, it helps doctors to advice on the best treatment options. It also gives a reasonable indication of outlook (prognosis).

Staging tests

If the CT scan shows the cancer is at an early stage and you are fit to be treated you may be asked to have another type of scan called a positron emission tomography-computerised tomography (PET-CT) scan. This shows up areas of active cancer and whether it has spread to the lymph glands in the chest.

Bronchoscopy is the most common procedure to look into the airways and to obtain a biopsy from a tumour in a main airway. A bronchoscope is a thin, flexible, telescope. It is about as thick as a pencil. The bronchoscope is passed through the nose, down the back of the throat, into the windpipe (trachea) and down into the bronchi.

Bronchial wash. A bronchoscope is passed but, instead of taking a biopsy, in some cases it is thought better to flush the area of the tumour with fluid which is then sent off for analysis.

Fine-needle biopsy. This is often done where the cancer is at the edge of the lung, where a doctor inserts a thin needle through the chest wall to obtain a small sample of tissue (this is called a trans-thoracic needle biopsy). CT or ultrasound pictures help to guide the doctor to insert the needle into the suspicious area.

Surgical biopsy.

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). In this test a thin bronchoscope is inserted into the lungs. Images of the area between the two lungs (the mediastinum) are obtained using a special ultrasound probe attached to the bronchoscope. A biopsy can be taken at the same time.

Magnetic resonance imaging (MRI) scan is another type of scan you may be offered. It is often used to detect spread of cancer to the brain or bones.

What are the treatment options for lung cancer?

Treatment options which may be considered include surgery, chemotherapy and radiotherapy. The types of treatment regimes for SCLC and NSCLC can be very different.

Surgery

An operation may be an option if the cancer is in an early stage. Surgery usually involves removing part or all of an affected lung. However, in many cases, the cancer has already spread when it is diagnosed and surgery is not usually then an option.

Surgery is not usually performed for people with SCLC. Also, surgery may not be an option if your general health is poor

Radiotherapy

Radiotherapy is a treatment which uses high-energy beams of radiation which are focused on cancerous tissue. This kills cancer cells, or stops cancer cells from multiplying. Radiotherapy may be given to people with SCLC and NSCLC. It is usually offered when the cancer is restricted to the lung or has only spread to nearby lymph glands. It can sometimes result in remission of the cancer if surgery cannot be performed. Radiotherapy is sometimes given to the head (known as prophylactic cranial radiotherapy) to reduce the risk of the cancer spreading to the brain in people with SCLC.

Chemotherapy

Chemotherapy is a treatment of cancer by using anti-cancer drugs which kill cancer cells, or stop them from multiplying. If you are going to have surgery you will normally be offered this after the operation. Chemotherapy is usually the treatment given to people with SCLC. Chemotherapy is sometimes given after surgery for NSCLC. This is known as adjuvant chemotherapy.

Other treatments

Radiofrequency ablation is a fairly new technique which involves inserting a small probe into the tumour and using a radiofrequency energy to generate heat and kill the surrounding tumour tissue. This is usually done at the same time as having a CT scan which helps to guide the probe. It most commonly used in people with small early-stage lung cancer for whom surgery is not appropriate.

A new treatment called photodynamic therapy (PDT) uses low-powered lasers combined with a light-sensitive drug to destroy cancer cells.

What is the prognosis?

The outlook is best in those who are diagnosed when the cancer is still small, and has not spread. Surgical removal of a tumour in an early stage may then give a good chance of cure. However, most people with lung cancer are diagnosed when the cancer has already spread. In this situation a cure is less likely. However, treatment can often slow down the progression of the cancer.


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