Lung cancer is the uncontrolled development of irregular cells in one or the two lungs. These unusual cells don't complete the elements of typical lung cells and don't form into solid lung tissue.

What is Lung Cancer?

Lung cancer is a condition that causes cells to divide in the lungs uncontrollably. This causes the growth of tumors that reduce a person's ability to breathe. Identifying lung cancer in its earliest stages can be difficult, however, because the symptoms may be similar to those of a respiratory infection, or there may be no symptoms at all.

The Genetic Basis of Lung Cancer

A cancer begins with an error, or mutation, in a cell’s DNA. DNA mutations can be caused by the normal aging process or through environmental factors, such as cigarette smoke, breathing in asbestos fibers, and to exposure to radon gas.

A cancer starts with an error in mutation in a cell's DNA. DNA mutations can be caused by the typical maturing process or through natural elements, for example, tobacco smoke, working in asbestos industries. Scientists have discovered that it takes a progression of mutations to make a lung cancer cell. Before ending up completely cancerous, cells can be precancerous, in that they have a few mutations yet at the same time work ordinarily as lung cells. At the point when a cell with a hereditary mutation separates, . With each new mutation, the lung tissue cell turns out to be more changed and may not be as powerful in completing its capacity as a lung cell. At a later phase of sickness, a few cells may travel far from the first tumor and begin developing in different parts of the body. when cancerous cell spreads to other part of body then it is called metastasis

Epidemiology of Lung cancer in India ( 2012 Report )

Risk factors and Causes for Lung Cancer

A number of factors known to promote/increases risk of lung cancer.

• Tobacco Smoking
• Asbestos
• Family History
• Air pollution
• Lung Infection
• Poor / Low Nutrition Diet

Tobacco Smoking: .Tobacco Smoking: Tobacco use in any shape is hurtful, regardless of whether smoked or smokeless. Cigarette and beedi smoking is the main hazard factor for lung cancer . Smokeless tobacco utilize is related with cancers of the lip, oral cavity, pharynx, stomach related, respiratory and intrathoracic organs . The poisonous synthetic concoctions in tobacco harm the cells in the lungs, making them cells develop anomalous . Cigarette smoking builds a man's possibility of getting lung cancer by 15 to 30 times and these people will probably bite the dust from lung cancer than individuals who don't smoke . Lung cancer hazard increments with the quantity of cigarettes smoked every day and with expanding span of time the individual has been smoking. In India, 87% of guys and 85% of females patients with lung cancer have history of dynamic tobacco smoking and history of aloof tobacco introduction has been found in 3% of patients. Beedi has been observed to be more cancer-causing than tobacco smoke and the relative danger of creating lung cancer is progressively for beedi smokers contrasted with that of cigarette smokers. Hookah smoking has additionally been related with lung cancer

Asbestos: People who work with asbestos (such as in mines, mills, textile plants, places where insulation is used, and shipyards) are several times more likely to die of lung cancer. Lung cancer risk is much greater in workers exposed to asbestos who also smoke. It’s not clear how much low-level or short-term exposure to asbestos might raise lung cancer risk.

Family History of Lung Cancer: .Individuals with a family history of lung cancer in first degree relatives have an expanded danger of lung cancer. There is a danger of creating lung cancer in the other lung, in the event that you have had lung cancer on one side . Cancer survivors who have been given radiation treatment to chest region are likewise at a higher hazard. The hazard might be much higher if there is a positive family history since they share a similar living space, and the introduction to radon

Indoor burning of coal/ angeethi/ chulha: There is adequate confirmation that indoor burning of coal, either to cook or warming, expands the danger of lung cancer. In inadequately ventilated houses, cooking or warming with coal on open flames in conventional stoves results in elevated amounts of indoor air contamination because of an extensive variety of poisons that can cause C.O.P.D and lung cancer

Infections in lung: Having had contamination like chlamydia or ailment like tuberculosis (TB) that can prompt scar tissue development in the lungs may have an expanded hazard for adenocarcinoma of the lung, a sort of lung cancer . Research demonstrates that individuals who have had TB have twofold the danger of lung cancer

Poor / Low Nutrition 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. 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 of Lung Cancer

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

Which Specialist Doctors can Diagnose For Lung Cancer?

• Oncologist
• Palliative Medicine
• Pulmonologist
• Cardiothoracic Surgeon

How Lung Cancer get diagnosed?

early diagnosis is cure for lung cancer

The symptoms of lung cancer usually do not appear until the disease is fairly advanced and in a non-curable stage. The early symptoms of lung cancer (persistent cough, chest pain and shortness of breath) are similar to other lung problems such as an infection or long-term effects of smoking and are not taken notice of. This often delays the diagnosis.

Screening for Lung Cancer

Screening means use of tests to detect a disease in patients who do not have symptoms of the disease. For lung cancer, three tests have been studied for use as screening tests:

1. Chest X-ray: It is an X-ray of the organs and bones inside the chest.

2. Sputum cytology: This is a procedure where a sample of sputum (mucus coughed up from lungs) is viewed under a microscope by a pathologist to look for cancer cells.

3. Low-dose spiral/ helical CT scan: This involves a CT scan with low-dose radiation to make a series of detailed pictures of the organs inside the body.

Of these three tests, chest X-ray and sputum cytology have been found to have a low sensitivity for detection of lung cancer. Only low-dose spiral/ helical CT scan has been recommended to be used in high-risk patients for lung cancer screening.[39]

There are no recommended guidelines for lung cancer screening in India.

As per the guidelines of The American Cancer Society, if you meet all the following criteria, you should go for lung cancer screening

1. Your age is between 55 and 74 years
2. You have a 30-pack-year smoking history (calculated as number of packs of cigarettes multiplied by the number of years you have been smoking)
3. You are either still smoking or have quit in the last 15 years
4. You are in fairly good health (you should not have symptoms of lung cancer or serious medical problems or metal implants or prior history of lung cancer treated)

Low Dose Computed Tomography (Low Dose CT or LDCT) is better than plain X-ray of the chest at finding small abnormalities in the lungs. LDCT uses a much lower dose of radiation than a normal chest CT. Screening is to be done every year till the age of 74 years or till symptoms appear.

Though screening can detect lung cancer better than X-ray chest, one must remember that not all lung cancers are found by LDCT screening and not all lesions detected by LDCT are cancer.

Diagnosis of Lung Cancer

If you have one or more symptoms indicative of lung cancer, you should visit your doctor, who will examine you and ask for relevant tests.

Medical history and physical exam: If your doctor suspects you might have lung cancer, he will ask you about the presence of risk factors like smoking, your occupation, etc. He will also examine you for signs of lung cancer and other health problems.
Depending upon the findings, the doctor might advise certain tests.

Imaging Tests:

• Chest X-ray: This is usually the first test your doctor will get done to look for a mass in the lungs. If something suspicious is seen in the X-ray, further tests will be ordered.

• Computed tomography (CT) scan: A CT (or CAT) scan is more likely to show lung masses than X-ray. CT scans can also provide information about the size, shape and position of lung tumors and help find spread of the cancer to lymph nodes or other organs.

CT-guided needle biopsy: If a suspicious mass is seen in the lung during CT scan, your doctor may perform a guided biopsy to take some tissue for diagnosis.

• Magnetic resonance imaging (MRI) scan: MRI scans are most often used to look for spread of lung cancer to brain and spinal cord to help in staging of the cancer. Unlike CT scans, MRI uses radio waves and strong magnets and there is no exposure to radiation.

• Positron emission tomography (PET) scan: A PET scan can be used to see if the cancer has spread to lymph nodes or other areas. This determines whether surgery can be done or not. PET scan is also useful if your doctor thinks that your lung cancer has spread but does not know where.

Laboratory Tests:

Imaging can help in detecting a mass in the lung, but the actual diagnosis of lung cancer can be made by looking at the cells under a microscope. The cells can be taken from lung secretions (sputum), in fluid removed from area around the lung (pleural fluid) or from a suspicious area using a needle or surgery (biopsy).

• Sputum Cytology: A sample of sputum (mucus that is coughed up from lungs) is viewed under a microscope to look for cancer cells. For this, the best method is to submit early morning sputum samples obtained after a deep cough for 3 days in a row.

• Needle biopsy: This involves the insertion of a hollow needle into the mass to get a small sample for testing. It can be done by fine needle aspiration biopsy (FNAB), where a very fine needle with syringe is used to withdraw or aspirate cells and fragments from the mass; or core biopsy, in which a larger needle is used to remove small cylinders or cores of tissue.[45]

If the suspected tumor is in the outer portion of lung, either kind of needle may be inserted through the chest wall skin (trans-thoracic needle biopsy). This procedure is performed under local anesthesia and radiologist’s guidance.

An FNA biopsy may also be done to look for cancer spread into the lymph nodes in the chest by trans-tracheal or trans-bronchial FNA (performed during bonchoscopy or endobronchial ultrasound) or EUS-FNA (performed during endoscopic esophageal ultrasound).[46]

A possible complication of the biopsy procedure is air leak from the lung into the space between lung and chest wall (pneumothorax ). When large, it may lead to collapse of a part of the lung and trouble in breathing. This is usually self limiting and gets better without any treatment.

• Bronchoscopy: For this test, a flexible fiber-optic tube (bronchoscope) is passed through the mouth or the nose and down into the windpipe and further. The doctor can look inside the tube and see for tumor or blockage in the major airways or bronchi. Small instruments can also be passed down the bronchoscope to take biopsies. Cells can also be sampled with a small brush (bronchial brushings) or by rinsing the airway with sterile saline (bronchial washings).[47, 48]

• Thoracocentesis: This procedure is performed if there is a buildup of fluid around the lungs (pleural effusion), which can cause difficulty in breathing. A hollow needle is inserted between the ribs to drain the fluid and check for tumor cells in the fluid (effusion cytology).[49]

If there is difficulty in breathing, removal of fluid can help the patient breathe better.

How Lung Cancer is Treated?

The treatment of lung cancer depends on the

• type of lung cancer (whether its small cell type or non small cell type),
• size of the tumor,
• whether the cancer is local or metastatic and
• general condition of the patient

Treatment Modalities [53] :

Surgery, chemotherapy, radiotherapy and targeted therapy may be used alone or in combination depending on the above mentioned factors.

Surgery

Surgery is mostly used to treat non small cell lung cancer [54] and rarely for small cell lung cancer when the disease is in very early stage. The surgeon might remove a small section of lung (wedge resection), a larger portion of lung (segmental resection), entire lobe of one lung (lobectomy) or an entire lung (pneumonectomy).

Chemotherapy

A combination of chemotherapy drugs are usually given in sessions over a period of weeks or months, with breaks in between. It can either be used before (to shrink cancers) or after surgery (to kill any cancer cells that may remain). In some cases, chemotherapy can be used as palliation to relieve pain and other symptoms of advanced cancer.

Some of the chemotherapy drugs used in the treatment of lung cancer are:

• Paclitaxel
• Carboplatin
• Cisplatin
• Docetaxel
• Etoposide
• Gemcitabine
• Pemetrexed

Radiation therapy

Radiation therapy can be directed at lung cancer from outside the body (external beam radiation ) or it can be administered through needles, seeds or catheters placed inside the body near the cancerous area (brachytherapy).

Radiation therapy can be either used after surgery to kill any cancer cells that may remain or can be used as the palliative therapy to relieve pain and other symptoms in advanced stage lung cancer.

Targeted drug therapy (for non small cell lung cancer)

Targeted therapies are drugs that target specific molecular targets in the tumor cells. They specifically kill cancer cells only, block their growth, prevent cancer from spreading and can stop tumors from growing by blocking signals inside the cancer cells.

Chemotherapy drugs differ from targeted therapies as they act on all rapidly dividing normal and cancerous cells.The side effects from targeted therapy are minimal since they do not have any toxic effects on normal cells.

Some of the available targeted therapy options for treating lung cancer include:

1. Inhibitors of Epidermal growth factor receptor (EGFR)
• Erlotinib
• Gefitinib

2. Monoclonal antibody against EGFR
• Cetuximab

3. Inhibitors of vascular endothelial growth factor (VEGF)
• Bevacizumab

4. Inhibitor of EML4-ALK
• Crizotinib

Link

http://cancerindia.org.in/lung-cancer

Protection and Prevention from Lung Cancer

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:

1. Not Smoking: The best way to prevent lung cancer is to not smoke. People who have never smoked have the lowest risk of lung cancer. Talk to your children about harmful effects of smoking so that they know how to face peer pressure and do not start smoking.

2. Quitting Smoking: However long you have been smoking, it is always worthwhile to quit smoking. If you stop smoking before you attain 50 years of age, you can reduce your risk of getting lung cancer by half in the next 10-15 years. Your doctor can help you in strategies and stop-smoking aids that can help you quit effectively.

3. Avoid second hand smoke: If you live or work with someone who smokes, urge him/ her to quit. If not, request them to smoke outside. Avoid smoking zones in public places like restaurants and bars.

5. Lower exposure to workplace risk factors: Follow your employers’ precautions to protect yourself from toxic chemicals at work.

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

New ways to prevent lung cancer are being studied in clinical trials and may become available in near future.

5 year Survival Rates of the Lung Cancer