Lung cancer

Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is the invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. Lung cancer, the most common cause of cancer-related death in men and also the most common in women, is responsible for 1.3 million deaths worldwide annually. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.

The main types of lung cancer are small cell lung carcinoma and non-small cell lung carcinoma. This distinction is important, because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation. The most common cause of lung cancer is long-term exposure to tobacco smoke. The occurrence of lung cancer in nonsmokers, who account for as many as 15% of cases , is often attributed to a combination of genetic factors, radon gas, asbestos, and air pollution, including secondhand smoke.

Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed via bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. With treatment, the five-year survival rate is 14%.

Source : wikipedia.org

General

• What is mesothelioma?
• What is cancer?
• References

Causes and diagnosis

• Causes
• Symptoms

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Symptoms of mesothelioma

Mesothelioma often starts as a lot of tiny lumps (nodules) in the pleura, which may not show up on scans or x-rays until they are quite large. The main symptoms of pleural mesothelioma are breathlessness and chest pain. Some people find that their voice becomes hoarse and they have a cough that does not go away.

Peritoneal mesothelioma often causes swelling and pain in the abdomen.

General symptoms

Both types of mesothelioma can cause other general symptoms, such as loss of appetite, sweating (especially at night), weight loss and tiredness. As many of these symptoms can also be caused by other illnesses, your doctor will need to do a series of tests before a diagnosis can be made.

Causes of mesothelioma

Asbestos is the most common cause of mesothelioma. Up to nine out of ten cases of mesothelioma are caused by exposure to asbestos. Asbestos is a natural mineral, mined from rock found in many countries. It is made up of tiny fibres that are as strong as steel but can be woven like cotton and are highly resistant to heat and chemicals.

During the 1960s the first definite link between mesothelioma and asbestos was made. In the past asbestos was imported to the UK in large quantities. It was used in construction, ship-building and in household appliances. Asbestos was very widely used in insulation materials, such as amosite insulation board, and building materials, including asbestos cement.

When asbestos is disturbed or damaged, it releases tiny fibres that can be breathed into the lungs. Asbestos fibres are very fine and, when breathed in, they can make their way into the smallest airways of the lung, so they cannot be breathed or coughed out. Once the fibres are in the lungs, the body's defence mechanism tries to break them down and remove them, which leads to inflammation in the lung tissue.

The asbestos fibres can also penetrate through the lung tissue to settle in the pleura (the membrane around the lung). Over many years they can cause mesothelioma or other lung diseases to develop.

Asbestos fibres can also be swallowed, and some of the fibres can stick in the digestive system. They can then move into the membrane that lines the abdomen (the peritoneum), where they cause inflammation.

The people most likely to have been exposed to asbestos include:

• construction workers
• plumbers
• electricians
• boilermakers
• shipbuilders
• demolition workers
• people who worked in other places where asbestos was present and
• people who lived near to asbestos factories.

Family members of people who worked with asbestos and brought the dust home on their clothes have also sometimes developed mesothelioma.

There are three types of asbestos: blue, brown and white. Blue and brown asbestos are the types most commonly linked with mesothelioma. They are now very rarely used and cannot be imported into the UK. Originally, white asbestos was thought not to be dangerous but recent studies have now shown that it is also harmful.

In the 1980s, imports of blue and brown asbestos into the UK were stopped, and in 1999 the importation and use of all asbestos was banned. However, as mesothelioma develops so slowly, it is estimated that by 2015 approximately 3000 people will be diagnosed with mesothelioma each year. The number of people who develop mesothelioma will then start to reduce each year.

Mesothelioma does not usually develop until many years after exposure to asbestos. It can take any time from 10 to 60 years, although the average is about 30 to 40 years after exposure to asbestos.

Occasionally, mesothelioma develops in people who have never been exposed to asbestos. The other causes of the disease are not fully understood, but in rare cases the development of mesothelioma has been linked to exposure to radiation.

Research has not found any evidence that smoking increases a person's risk of developing mesothelioma. It is also thought that exposure to other building materials such as fibreglass does not increase the risk.

Mesothelioma is not contagious and cannot be passed on to other people. It is not caused by inherited faulty genes and so family members do not have an increased risk of developing it, unless they have been in contact with asbestos.

What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells.

Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumour.

Tumours can be either benign or malignant. Cancer is the name given to a malignant tumour. Doctors can tell if a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.

A malignant tumour consists of cancer cells that have the ability to spread beyond the original area. If the tumour is left untreated, it may spread into and destroy surrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system - the body's natural defence against infection and disease. It is a complex system made up of organs, such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes (or glands) throughout the body are connected by a network of tiny lymphatic ducts.

When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or metastasis.

It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

What is mesothelioma?

Mesothelioma is a cancer of the mesothelium. The mesothelium is a thin membrane that lines the chest and abdomen and surrounds the organs in these areas. The lining around the lungs is called the pleura and in the abdomen it is known as the peritoneum.

About 2000 people in the UK are diagnosed with mesothelioma each year.

Mesothelioma of the lining of the lungs, known as pleural mesothelioma, is much more common than mesothelioma in the peritoneum. For every one person with peritoneal mesothelioma, there will be about 12 people who have pleural mesothelioma.

Pleural mesothelioma

The pleura has two layers: the inner (visceral) layer, which is next to the lung; and the outer (parietal) layer, which lines the chest wall. The two layers of the pleura are usually in contact and slide over each other as we breathe. The membranes produce fluid, which allows them to slide over each other easily.

When mesothelioma develops in the pleura (pleural mesothelioma), the delicate membranes thicken and may press inwards on the lung. Fluid may also collect between the two layers of the pleura: this is known as a pleural effusion.

Structure of the lungs and pleura

Peritoneal mesothelioma

The lining of the abdomen is known as the peritoneum. It also has two layers: the inner (visceral) layer, which is next to the abdominal organs, and the outer (parietal) layer, which lines the abdominal wall.

If the mesothelioma is in the peritoneum it is called peritoneal mesothelioma and causes thickening of the membranes surrounding the abdominal organs and a collection of fluid in the abdomen. The collection of fluid is called ascites and causes swelling of the abdomen.

Side view of the abdomen. The peritoneum is shown as the thick line surrounding the abdominal organs.

The Different Types of Cancer

The Different Types of Cancer Include:

Carcinomas: The most common type of cancer, these tumors arise from the cells that cover external and internal body surfaces. The most frequent cancers of this type in the United States are lung, breast, colon, and prostate cancer.

Sarcomas: Cancers that arise from cells found in the supporting tissues of the body, such as bone, cartilage, fat, connective tissue, and muscle.

Lymphomas: Cancers that arise in the lymph nodes and tissues of the body's immune system.

Leukemias: Cancers of the immature blood cells that grow in the bone marrow and tend to accumulate in large numbers in the bloodstream.

The place where a cancer starts is called the primary site. From there, it can spread (metastasize) to other parts of the body. Regardless of where a cancer may spread, it is always named for the place it began. For instance, breast cancer that spreads to the liver is still called breast cancer, not liver cancer.

Different types of cancer can behave very differently. For example, lung cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. That is why people with cancer need treatment that is aimed at their particular kind of cancer.

Not all tumors are malignant (cancerous). Benign, or noncancerous, tumors do not spread to other parts of the body and, with very rare exceptions, are not life-threatening.

During the second half of the 20th century, scientists uncovered many of the intricacies of cancer and developed the technology to pinpoint the exact site of the damage to a specific gene, which has had a tremendous impact on the types of therapies now available.