Health Care Guide

Health Care: “Lung Cancer : Symptoms , Causes And Cure”

Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung. The lungs are a pair of cone-shaped breathing organs inside the chest. The lungs bring oxygen into the body when breathing in and send carbon dioxide out of the body when breathing out. Each lung has sections called lobes. The left lung has two lobes. The right lung, which is slightly larger, has three. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs. There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer.

How common is lung cancer?
Lung cancer is one of the most lethal of cancers worldwide, causing up to 3 million deaths annually. Only one in ten patients diagnosed with this disease will survive the next five years. Although lung cancer was previously an illness that affected predominately men, the lung cancer rate for women has been increasing in the last few decades, which has been attributed to the rising ratio of female to male smokers.

Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens. The most common means of such exposure is tobacco smoke.

Lung cancer was not common prior to the 1930s but increased dramatically over the following decades as tobacco smoking increased. In many developing countries, the incidence of lung cancer is beginning to fall following public education about the dangers of cigarette smoking and effective smoking cessation programs. Nevertheless, lung cancer remains the most common form of cancer in men worldwide and the fifth most common form of cancer in women.
Lung cancer is responsible for the most cancer deaths in both men and women throughout the world. The American Cancer Society estimates that 173,770 new cases of lung cancer in the U.S. will be diagnosed and 160,440 deaths due to lung cancer will occur in 2004.

Symptoms that suggest lung cancer include:

    * Dyspnea (shortness of breath)

    * Hemoptysis (coughing up blood)

    * chronic cough or change in regular coughing pattern

    * wheezing

    * chest pain or pain in the abdomen

    * Cachexia (weight loss), fatigue and loss of appetite

    * Dysphonia (hoarse voice)

    * clubbing of the fingernails (uncommon)

    * difficulty swallowing

At present there is no effective screening test for lung cancer.

If you are worried that you have lung cancer, your doctor may order a chest X-ray, which allows doctors to look out for shadowy areas on the lungs.

Sometimes a more detailed series of x-rays, called a CT scan, is ordered.

In many cases, this will be followed by a bronchoscopy or mediastinoscopy, which means that a thin flexible telescope is put down the airways of your lungs, after which a biopsy of any suspicious area is performed.

What causes lung cancer                    

Smoking-
The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked over time; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10 pack-year smoking history, those with 30 pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer.

Pipe and cigar smoking can also cause lung cancer, although the risk is not as high as with cigarette smoking. While someone who smokes one pack of cigarettes per day has a risk for the development of lung cancer that is 25 times higher than a nonsmoker, pipe and cigar smokers have a risk of lung cancer that is about five times that of a nonsmoker.

Tobacco smoke contains over 4,000 chemical compounds, many of which have been shown to be cancer-causing, or carcinogenic. The two primary carcinogens in tobacco smoke are chemicals known as nitrosamines and polycyclic aromatic hydrocarbons. The risk of developing lung cancer decreases each year following smoking cessation as normal cells grow and replace damaged cells in the lung. In former smokers, the risk of developing lung cancer begins to approach that of a nonsmoker about 15 years after cessation of smoking. For more, please read the Smoking and Quitting Smoking article.
Passive smoking
Passive smoking, or the inhalation of tobacco smoke from other smokers sharing living or working quarters, is also an established risk factor for the development of lung cancer. Research has shown that non-smokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with other non-smokers. An estimated 3,000 lung cancer deaths occur each year in the U.S. that are attributable to passive smoking.
Asbestos fibers
Asbestos fibers are silicate fibers that can persist for a lifetime in lung tissue following exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, as asbestos was widely used in the past for both thermal and acoustic insulation materials. Today, asbestos use is limited or banned in many countries including the Unites States. Both lung cancer and mesothelioma (a type of cancer of the pleura or of the lining of the abdominal cavity called the peritoneum) are associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing an asbestos-related lung cancer in exposed workers. Asbestos workers who do not smoke have a fivefold greater risk of developing lung cancer than non-smokers, and those asbestos workers who smoke have a risk that is 50 to 90 times greater than non-smokers.

Radon gas
Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. It decays to form products that emit a type of ionizing radiation. Radon gas is a known cause of lung cancer, with an estimated 12% of lung cancer deaths attributable to radon gas, or 15,000 to 22,000 lung cancer-related deaths annually in the U.S. As with asbestos exposure, concomitant smoking greatly increases the risk of lung cancer with radon exposure. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. The U.S. Environmental Protection Agency estimates that one out of every 15 homes in the U.S. contains dangerous levels of radon gas. Radon gas is invisible and odorless, but can be detected with simple test kits.
Air pollution
Air pollution, from vehicles, industry, and power plants, can raise the likelihood of developing lung cancer in exposed individuals. Up to 1% of lung cancer deaths are attributable to breathing polluted air, and experts believe that prolonged exposure to highly polluted air can carry a risk similar to that of passive smoking for the development of lung cancer.
How is lung cancer diagnosed?

Sadly, most lung cancer is diagnosed too late for curative treatment to be possible. In over half of people with lung cancer the disease has already spread (metastasised) at the time of diagnosis.

Early diagnosis is difficult because many of the common symptoms of lung cancer are similar to those of smokers’ lung (chronic obstructive pulmonary disease or COPD).

In addition to this, most lung cancer patients will also have COPD because both conditions are mainly caused by smoking. However, only 1 or 2 per cent of COPD patients will go on to develop lung cancer.

The first investigation is a chest X-ray. If a lung tumour is present, it needs to be at least a centimetre in diameter to be detectable by an ordinary X-ray. However, by the time a tumour has reached this size the original cell which became cancerous has divided (or doubled) 36 times. As death usually results after 40 such cell divisions, it is clear that lung cancer is a disease that is usually detected late in its natural course.

Some simple blood tests and further examinations may also be carried out.

Bronchoscopy is direct inspection of the inside of the breathing tubes with a thin fibre-optic instrument using local anaesthetic and is the best test for tumours in the main bronchi (air passages) in the centre of the chest.

Depending on the site of the cancer, a biopsy will be obtained either by a bronchoscopy or a needle biopsy. Needle biopsy is better for cancers near the periphery of the lungs (ie closer to the ribs than the centre of the chest), beyond the reach of the bronchoscope.

Usually, a sample of sputum - the material coughed up from the respiratory tract - will also be examined for cancer cells and this can avoid the need for biopsy.
A CT scan provides more information about how much the tumour may have spread.

There are three main types of lung cancer, based on their appearance when examined under the microscope by a pathologist:

• small cell carcinoma
• squamous cell carcinoma
• adenocarcinoma.

It is important to know which type of cancer a patient has because small cell cancers respond best to chemotherapy (anti-cancer medicines) whereas the other types (often referred to collectively as non-small cell cancer) are better treated with surgery or radiotherapy (X-ray treatment). The pathologist therefore needs a small tissue sample (biopsy) to examine. This will confirm that the diagnosis of suspected cancer is definitely correct and show which type of cell is involved.
Prevention & Treatments
Primary prevention
Prevention is the most cost-effective means of fighting lung cancer on the national and global scales. While in most countries industrial and domestic carcinogens have been identified and banned, tobacco smoking is still widespread. Eliminating tobacco smoking is a primary goal in the fight to prevent lung cancer, and smoking cessation is the most important preventative tool in this process.
Policy interventions to decrease passive smoking (e.g. in restaurants and workplaces) have become more common in various Western countries, with California taking a lead in banning smoking in public establishments in 1998, Ireland playing a similar role in Europe in 2004, followed by Norway in 2005 and Scotland as well as several others in 2006. New Zealand has also recently banned smoking in public places. (See Smoking ban).

Only the Asian state of Bhutan has a complete smoking ban (since 2005). In many countries pressure groups are campaigning for similar bans. Arguments cited against such bans is criminalisation of smoking, increased risk of smuggling and the risk that such a ban cannot be enforced.

Screening and secondary prevention

Because prognosis depends heavily on early detection there have been several attempts at secondary prevention. Regular chest radiography and sputum examination programs were not effective in early detection of this cancer and did not result in a reduction of mortality.

Computed tomography (CT) scanning is now being actively evaluated as a screening tool for lung cancer, and it is showing promising results. The National Cancer Institute (USA) is currently completing a randomized trial comparing CT scans with chest radiographs. Several single-institution trials are ongoing around the world. A large group of investigators (the International Early Lung Cancer Action Project) are currently collating the results of 26,000 screen-detected lung cancers and are showing excellent preliminary survivals with these patients. More work is needed in this area.
Treatment depends on the type of lung cancer and the state or extent of the disease.

Surgery can cure lung cancer, but only one in five patients are suitable for this treatment. If the tumour has not spread outside the chest and does not involve vital structures such as the liver, then surgical removal may be possible, but only if the patient does not also have severe bronchitis, heart disease or other illnesses. These additional complications put too great a strain on the patient for them to be able to stand surgery.

Small cell lung cancer is treated with chemotherapy. This is given either by an oncologist (a specialist in cancer treatment) or sometimes by a physician in chest diseases with special experience in chemotherapy. It is given in courses which means that the patient has to stay in hospital for about 48 hours approximately every three weeks.

Popular misconceptions about chemotherapy are common and there is often concern about its perceived difficulties and usefulness. However, there is no doubt that chemotherapy is effective and that it both prolongs and improves the quality of survival in small cell lung cancer. The number of courses required will depend on how well the individual patient responds.

Chemotherapy does have side effects, particularly nausea, vomiting and hair loss. However there are very good drugs to control these side effects. Hair always grows again about three months after the chemotherapy courses have finished.

There is scope for improving the results of chemotherapy and many research trials are going on. Patients who are asked for their consent to take part in a trial should not be frightened. Hundreds of patients take part in trials to detect any benefit between one treatment regime and another. This research must be done if cancer chemotherapy can continue to improve.
Non-small cell cancer may be treated with radiotherapy, chemotherapy (as part of a research trial), or with supportive care. Radiotherapy is either ‘radical’ or ‘palliative’. Radical is used in selected patients with localised tumours who are inoperable, and involves using high doses of radiation.

Palliative radiotherapy is widely used. It involves using lower doses of radiation - often in just one or two doses. It is very good for relieving symptoms, such as blood in the sputum (haemoptysis), bone pain, and also for helping obstruction to the airway or large veins in the chest.

Posted in Lung Cancer | No Comments »