Lung cancer is characterized by presence of malignant tumor cells which are destroying the healthy lung tissue. There are several types of lung cancer but the most common is bronchogenic carcinoma which accounts for about 90% of all lung cancers. A recent research indicated that inhaling carcinogen substances poses the biggest risk for lung cancer development and the most common mean of exposure to such substances is tobacco smoking. The risk of developing lung cancer increases sharply the more you smoke and the longer you smoke. Incidence
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 mostly affected men, the lung cancer rate for women has been increasing in the last few decades, which has been attributed to the rising number of female smokers. Lung cancer is the number one cause of cancer deaths in both men and women in the United States. More than 154,000 Americans died from lung cancer in 2002. Still, more than 90% of lung cancers are preventable.
Signs and symptoms of lung cancer
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
Possible causes of lung cancer
There are four major causes of lung cancer (and cancer in general):
* Carcinogens such as those in cigarette smoke
* Radiation exposure
* Genetic susceptibility
* Viral infection
Cigarette smoking
Lung cancer is directly related to smoking.
It is proven that there are over 40 carcinogens in the cigarette smoke including radioisotopes from the radon decay sequence, nitrosamine, and benzopyrene. Additionally, nicotine appears to depress the immune response to malignant growths in exposed tissue.
Unfortunately, the risk of getting cancer is not removed immediately after you stop smoking. In fact up to 40% of newly diagnosed lung cancer occurs in former smokers. In the United States, smoking is estimated to account for 87% of lung cancer cases.
Exposure to asbestos and certain chemicals
* Asbestos has been known to increase the risk of getting lung cancer.
* Uranium, chromium and nickel can all cause lung cancer too.
Exposure to radon gas
Radon gas is a naturally occurring radioactive gas that can seep out of the soil into buildings. It is thought that radon gas in very high concentrations may cause lung cancer.
Air pollution
Air pollution may cause lung cancer, although this has only been proven in people exposed to large amounts of diesel exhaust fumes for many years through their work. This type of long term occupational exposure may increase lung cancer risk by up to 47%.
Genetic susceptibility
Experts are still looking into the impact of family history on lung cancer. There is some evidence that there is at least one lung cancer gene because family history of lung cancer does have an impact on the risk. Families of smokers will all be exposed to cigarette smoke and so have an increased risk of lung cancer whether they carry the gene or not.
Passive smoking
Passive smoking refers to inhalation of the smoke coming from someone else%26rsquo;s cigarette. It has recently been identified as a much more possible cause of lung cancer in non-smokers than previously believed. Several researches have been conducted on this subject and they all came to the same conclusion- passive smoking causes lung cancer in non-smokers.
The study found that there was an estimated 16% increased risk of lung cancer among the non-smoking spouses of smokers. It is estimated that workplace exposure increases the risk for 17%.
Histological types of lung cancer
There are two major types of lung cancer:
* Non-small cell lung cancer %26ndash; This type of cancer is much more common. It usually spreads to different parts of the body more slowly than small cell lung cancer.
o squamous cell carcinoma
o adenocarcinoma,
o large cell carcinoma
* Small cell lung cancer- small cell lung cancer also called oat cell cancer, accounts for about 20% of all lung cancers.
Diagnosis of lung cancer
Unfortunately, lung cancer is usually diagnosed too late for treatment to be possible. In over half of people with lung cancer the disease has already spread at the time of the diagnosis.
Early diagnosis is difficult because many of the common symptoms of lung cancer are similar to those of chronic obstructive pulmonary disease.
* X-ray examination
The first investigation of lung cancer should be a chest X-ray. However, this method can't detect all tumors because it needs to be at least a centimeter in diameter to be detectable by an ordinary X-ray.
* Blood tests
Some simple blood tests and further examinations may also be carried out.
* Bronchoscopy
This is a very good diagnostic tool and it represents a direct inspection of the inside of the breathing tubes with a thin instrument called bronchoscope. It is all done using local anaesthetic and is the best method for the diagnosis of tumors in the bronchi in the centre of the chest.
* Biopsy
Depending on the site of the cancer, a biopsy will be obtained either by a bronchoscopy or a needle biopsy.
* Sample of sputum
A sample of sputum, the material coughed up from the respiratory tract, will also be examined for cancer cells.
* CT-scan
A CT scan provides more information about how much the tumor may have spread.
Metastatic lung cancer
The lung is a common place for metastasis from tumors in other parts of the body. These cancers, however, are identified by the site of origin, i.e., a breast cancer metastasis to the lung is still known as breast cancer. The adrenal glands, liver, brain, and bone are the most common sites of metastasis from primary lung cancer itself.
Treatment of lung cancer
Treatment of lung cancer can depend on the size, location and extent of the tumor, and general health of the patient. There are many treatments, which may be used alone or in combination. These include:
SURGERY
Surgery may cure lung cancer but it is used in limited stages of the disease. The type of surgery depends on where the tumor is located in the lung.
RADIATION THERAPY
Radiation therapy is a form of high energy X-ray that kills cancer cells. It is used:
* In combination with chemotherapy and sometimes with surgery.
* To offer relief from pain or blockage of the airways.
CHEMOTHERAPY
Chemotherapy is the use of drugs that are effective against cancer cells. Chemotherapy may be injected directly into a vein or given through a catheter, which is a thin tube that is placed into a large vein and kept there until it is no longer needed.
Chemotherapy may be used:
* In conjunction with surgery.
* In more advanced stages of the disease to relieve symptoms.
* In all stages of small cell cancer.
How come some smokers don%26rsquo;t develop lung cancer?
The fact is that not all smokers develop cancer but it is still not known why. Different people react differently to the 4,000 chemicals contained in cigarette smoke depending on their genetic and biological make-up. However, the fact is that the risk of developing lung cancer increases sharply the more you smoke and the longer you smoke. According to some researches, 1 in 11 men and 1 in 17 women will develop lung cancer in their lifetime.
Tobacco and other types of cancers
* Cancers of the mouth and throat
Several researches have tried to prove that smoking cigarettes is a risk factor for all cancers associated with the larynx, oral cavity and esophagus. It is proven that over 90% of patients with oral cancer use tobacco by either smoking or chewing it. The risk for these cancers increases with the number of cigarettes smoked and those who smoke pipes or cigars experience a risk similar to that of cigarette smokers.
* Bladder cancer
Tobacco smoking is the principal risk factor for bladder cancer in both men and women. It is estimated that current smokers are 2-5 time more likely to develop bladder cancer than non-smokers.
* Breast cancer
Some studies have proven that there is a link between smoking and breast cancer. Most epidemiological studies have found no association between active smoking and breast cancer but a new study found that among women who have smoked for 40 years or longer the risk of breast cancer was 60% higher that that of women who have never smoked.
* Cervical cancer
Cancer of the cervix has been found to be associated with cigarette smoking in many case-control studies. Smoking is the second most significant environmental factor after human papilloma virus.
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