Lung Cancer

What is lung cancer?

Lung cancer is a type of cancer that arises in the lungs. It may spread to lymph nodes or other organs in the body, such as the brain.

Lung cancers usually are grouped into two main types, non-small cell lung cancer (NSCLC) and small cell lung cancers (SCLC) based on appearance of tumor cells under the microscope.  Non-small cell lung cancer (75-80 % of cases) is more common than small cell lung cancer (15-20%).

Causes

1. Tobacco smoking : Tobacco use in any form is harmful, whether smoked or smokeless. Cigarette and beedi smoking is the number one risk factor for lung cancer. Smokeless tobacco use is associated with cancers of the lip, oral cavity, pharynx, digestive, respiratory and intrathoracic organs. The toxic chemicals in tobacco damage the cells in the lungs, causing them cells to grow abnormally.
   Cigarette smoking increases a person’s chance of getting lung cancer by 15 to 30 times and these persons are more likely to die from lung cancer than people who do not smoke. Lung cancer risk increases with the number of cigarettes smoked each day and with increasing duration of time the person has been smoking. The risk decreases if the person quits smoking.
   Second-hand smoking (SHS): Regular exposure to smoke from other’s cigarettes, can increase a person’s risk of getting lung cancer, even if the person himself/herself does not smoke. This is called ‘second-hand smoke (SHS) or passive or environmental smoking’.
2. Asbestos: Asbestos is classified as a known human carcinogen, and has been directly and scientifically linked to lung cancer and other respiratory conditions. Asbestos is a set of six naturally occurring fibrous mineral widely used in house construction materials, automobiles parts and textiles due to its extremely durable and fire resistant property. Asbestos fibres are microscopic in nature and when inhaled, they get lodged in the soft internal tissue of respiratory system and can irritate the lungs. There is no safe level or no safe type of asbestos. The combination of smoking and occupational exposure to asbestos is very dangerous.
3. Occupational exposure to chemical carcinogens: Workplace exposure to arsenic, chromium, diesel exhaust, silica and nickel can also increase risk of developing lung cancer and the risk is even higher for those who also smoke. Chemicals used in rubber manufacturing, iron and steel founding and painting have also been considered as risk factors but the exact constituents which trigger carcinogenesis are not known.
4. Radon: Exposure to radon has been associated with an increased risk of some types of cancer, including lung cancer. Radon is an invisible, odourless gas released naturally from dirt and rocks by the breakdown of uranium that gets mixed with the air we breathe eventually. The main sources of indoor radon are soil, construction material, tap water, and the natural gas used for cooking. This gas can get accumulated in homes and buildings to unsafe levels. A preventive measure to reduce radon accumulation is to ventilate basements well.
5. Family/Personal History of Lung Cancer: People with a family history of lung cancer in first degree relatives have an increased risk of lung cancer. There is a risk of developing lung cancer in the other lung, if you have had lung cancer on one side. Cancer survivors who have been given radiation therapy to chest area are also at a higher risk. The risk may be even higher if there is a positive family history since they share the same living space, and the exposure to radon.
6. Indoor burning of coal: There is sufficient evidence that indoor combustion of coal, either for cooking or heating, increases the risk of lung cancer. In poorly ventilated houses, cooking or heating with coal on open fires in traditional stoves results in high levels of indoor air pollution due to a wide range of pollutants that damage health.
7. Infections in lung: Having had infections like chlamydia pneumoniae or disease like tuberculosis (TB) that can lead to scar tissue formation in the lungs may have an increased risk for adenocarcinoma of the lung, a type of lung cancer. Research indicates that people who have had TB have double the risk of lung cancer.
8. Diet: Evidence suggests that some dietary factors may be protective for lung cancer and some may increase the risk of lung cancer. Persons with the low intake of foods rich in beta-carotene, such as carrots, have a higher risk for lung cancer.
9. Vitamin A deficiency increases the chance of developing squamous cell carcinoma of lung in smokers. Also, arsenic in drinking water (primarily from private wells) can increase the risk of lung cancer.

Symptoms

Lung cancer typically does not cause any specific signs and symptoms in its initial stages. The patients may just have general symptoms of not feeling well.   In most people with lung cancer, the symptoms arise only when the disease is advanced.  The common symptoms include:

1. Persistent cough that gets worse despite usual treatment.
2. Shortness of breath
3. Coughing up phlegm (sputum) with traces of blood in it
4. Coughing up frank blood
5. Wheezing
6. An ache or pain in the chest or shoulder
7. Unexplained weight  loss
8. Feeling of extreme tiredness
9. Loss of appetite

Less Common Symptoms of Lung Cancer

These symptoms are usually associated with more advanced lung cancer

• Difficulty in swallowing
• Hoarseness in  voice
• Swelling in the neck caused by enlarged lymph nodes.
• Repeated attacks  of pneumonia
• Rise in platelet count (thrombocytosis)
• Pain  under the  ribs on the right side
• Changes in the shape of  fingers and nails, called finger clubbing
• Severe shoulder pain or pain that travels down the arm

Prevention

There is no proven way to completely prevent lung cancer, but there are steps to lower the risk of getting lung cancer. You can help lower your risk of getting lung cancer in the following ways:

• Don't smoke : If you've never smoked, don't start. Begin conversations about the dangers of smoking with your children early so that they know how to react to peer pressure.
• Stop smoking : Stop smoking now. Quitting reduces your risk of lung cancer, even if you've smoked for years. Talk to your doctor about strategies and stop-smoking aids that can help you quit. Options include nicotine replacement products, medications and support groups.
• Avoid second hand smoke : If you live or work with a smoker, urge him or her to quit. At the very least, ask him or her to smoke outside. Avoid areas where people smoke, such as bars and restaurants, and seek out smoke-free options.

• Avoid carcinogens at work : Take precautions to protect yourself from exposure to toxic chemicals at work. Follow your employer's precautions. For instance, if you're given a face mask for protection, always wear it.
• Lower your exposure to radon: If you live in an area where radon is a known problem, get the radon levels in your house checked and take measures to reduce exposure.
• The following help in reducing the risk of cancer in general, not specifically for lung cancer:
• Diet rich in fruits and vegetables
• Regular physical activity

Source : India against Cancer portal