Information about Asbestos and Lung Cancer

Lung cancer is a malignant lung tumor. Most frequently, it is bronchogenic carcinoma (about 90%). Lung cancer is the most lethal malignant tumour worldwide, causing up to 3 million deaths annually. Read the information on this site to learn about the link between asbestos and lung cancer.

The leading risk factor for lung cancer is smoking.

Treatment and prognosis depend upon the type of lung cancer and the stage (degree of spread)lung cancer. Possible treatment options for lung cancer include surgery, chemotherapy) and/or radiotherapy.

Some signs of lung cancer

• dyspnea (shortness of breath)
• hemoptysis (coughing up blood)
• chronic cough
• wheezing
• chest pain
• cachexia (weight loss), fatigue and loss of appetite
• dysphonia (hoarse voice)
• clubbing of the fingernails

If the cancer grows into the lumen it may obstruct the airway, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, making the patient vulnerable to pneumonia.

Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed out.

Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease. In lung cancer, this can be Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia and SIADH. Tumors in the top of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to altered sweating patterns and eye muscle problems (a combination known as Horner's syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.

In a large number of patients, the cancer has already spread beyond the original site by the time they seek medical care.

Diagnosis

Performing a chest X-ray is the first action taken if a patient describes symptoms that indicate lung cancer. Th X-ray may reveal a mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (infection) and pleural effusion. If there are no X-ray findings but the suspicion is high (e.g. a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. In any case, bronchoscopy or CT-guided biopsy is often necessary to identify the tumor type.

If investigations have confirmed lung cancer, scan results and often positron emission tomography (PET) are used to find out whether the disease is localised and amenable to surgery or whether it has spread so much that it cannot be cured surgically. Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is healthy enough for surgery. If spirometry reveals a very poor respiratory reserve, as may occur in chronic smokers, surgery may not be advisable.

Types

There are two types of lung cancer categorized by the size and appearance of the malignant cells seen under a microscope: small-cell (roughly 20%) and non-small cell (80%) lung cancer. This classification has significant implications for clinical management and prognosis of the disease.

The non-small cell lung cancers (NSCLC) are grouped together because their prognosis and management is roughly identical. The subtypes are:

• Epidermoid carcinoma (or Squamous cell carcinoma) also starts in the larger breathing tubes but grows slower meaning that the size of these tumors varies when on diagnosis.
• Adenocarcinoma (or for slower growing forms alveolar cell cancer) is a form which starts near the gas-exchanging surface of the lung. It is less closely associated with smoking.
• Large cell carcinoma is a fast-growing form that grows near the surface of the lung.

Small cell carcinoma (SCLC, also known as "oat cell carcinoma") is the less common form of lung cancer. It usually starts in the larger breathing tubes and becomes large quite quickly. The oncogene most commonly involved is L-myc. The "oat" cell contains dense neurosecretory granules which give this an endocrine/paraneoplastic syndrome association. It is more sensitive to chemotherapy, but carries a worse prognosis and is often metastatic at presentation.

The main representatives in this group are carcinoid. Rarer lung cancers include cylindroma and mucoepidermoid carcinoma.

Causes

Exposure to carcinogens, such as those present in tobacco smoke, immediately causes cumulative changes to the tissue lining the bronchi of the lungs (the bronchial mucous membrane) and more tissue gets damaged until a tumour develops.

There are four main causes of lung cancer:

• Carcinogens such as those in cigarette smoke
• Radiation exposure
• Genetic susceptibility
• Viral infection

Asbestos can cause many types of lung diseases. It raises the likelihood of developing lung cancer. There is a cumulative effect of tobacco smoking and asbestos in causing lung cancer.

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