Leading the list of all cancers, lung cancer is a disease characterized by abnormal growth of malignant cell in the lung(s) that interfere with its structure and function that may progress to life threatening conditions, especially if runs insensibly.

The major cause of lung cancer is smoking. Other contributing factors include second hand smoking, and exposures to carcinogens, such as radon gas, asbestos minerals, arsenic element and air pollution. The tendency may be supported by personal and family history.

Cough is the main symptom of lung cancer, which is mainly persistent and may be accompanied with blood. Other manifestations include respiratory symptoms, fatigue, and weight loss. However, lung cancer often not detected until late stage. The major diagnostic procedures used to prove the disease are imaging tests and biopsies analysis.

As other types of cancer, lung cancer is conventionally treated by one of the trinity: surgery, radiotherapy, and chemotherapy. New, more effective and less harmful treatments are also available, with immunotherapy and targeted therapy as major choices.

Early detection and treatment of lung cancer will increase the chances of having longer and more quality life. However, lung cancer remains the top cancer killer, as it is interrelated with a substantial organ and runs without awareness from the diseased person.

Lung cancer is a disease in which abnormal cells grow out of control in the organs that responsible for breathing; i.e. lungs. It is one of the most common and serious types of cancer. The abnormal cells do not develop into healthy lung tissue, they divide rapidly and form tumors. As tumors become larger, they undermine the lung’s ability to provide the bloodstream with oxygen. Furthermore, the malignant tumor has the ability to spread to other parts of the body causing spread of cancer.

• Non-Small Cell Lung Cancer (NSCLC)

This is the most common type of lung cancer. About 85% of lung cancers are non-small cell lung cancers. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are all subtypes of non-small cell lung cancer.

• Small Cell Lung Cancer (SCLC)

Also called oat cell cancer. About 10%-15% of lung cancers are small cell lung cancers. This type tends to grow more quickly and is more likely to spread to other organs in the body. Occurs almost exclusively in heavy smokers.

• Lung carcinoid tumor (LCT)

Fewer than 5% of lung cancers are lung carcinoid tumors. They are also sometimes called lung neuroendocrine tumors. Most of these tumors grow slowly and rarely spread. All these percentages are in accordance to American cancer society.

Lung cancer emerges from interaction between genetic factors and carcinogens exposure that lead to transformation of the normal cells in the lung into abnormal, rabid dividing cells. The ability for this to happen affect by the following:

• Smoking

Smoking is the principal cause of lung cancer; national health services (NSH) estimates smoking to be responsible for more than 85% of all types of this cancer. According to world health organization, tobacco use sits behind around 20% of global cancer deaths and around 70% of global lung cancer deaths. That may be because smoking involves regularly inhaling a number of different toxic substances. The risk of lung cancer increases with the length of time and number of cigarettes. Other forms of tobacco use, such as cigar smoking and pipe smoking, are also associated with lung cancer.

• Radon

The second leading cause of lung cancer is radon, a naturally occurring radioactive gas that comes from rocks, soil and dirt and can get trapped in houses and buildings. If radon is breathed in with large amount, it can damage the lungs, particularly if the person is smoker. Radon is an invisible, odorless gas that seeps up through the ground and diffuses into the air. It is present in nearly all air, usually at very low levels. However, in areas without adequate ventilation, or where cracks in floors, walls, or foundations, radon can seep and accumulate to levels that substantially increase the risk of lung cancer.

• Asbestos

The most common occupational risk factor for lung cancer is exposure to asbestos. People who work with these silicate minerals (such as in mills, textile plants, places where insulation is used, and shipyards) are several times more likely to die of lung cancer. Exposure to large amounts of asbestos also increase the risk of developing mesothelioma, a cancer that starts in the pleura (the lining surrounding the lungs), as well as larynx and ovary cancer. The civil use of asbestos, like heat insulation, had been restricted, but it may still exist from the old objects. When this material deteriorates, it releases tiny fibers in the air that may be inhaled and settle deeply in the lungs for a long time causing cancer.

• Other occupational exposures

a variety of less, but probable carcinogenic chemicals found in some workplaces that can increase lung cancer risk include radioactive ores such as uranium, and Inhaled chemicals or minerals such as arsenic, beryllium, cadmium, silica, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas, wood dust, formaldehyde and chloromethyl ethers. These substances acts as carcinogens that damage the lining of the lung and cause developing of cancer

• Personal or Family History

Being a lung cancer survivor, there is a risk to develop another one, especially if the person is smoker. The risk of lung cancer may be higher if parents, brothers, sisters, or children have had the disease. This could be true because they also smoke, or they live or work in the same place where they are exposed to radon and other substances that can cause lung cancer.

• Previous radiation therapy to the lungs

People who have had radiation therapy to the chest for other cancers are at higher risk for lung cancer, particularly if they smoke. Examples include people treated for Hodgkin lymphoma or women who get radiation after a mastectomy for breast cancer. However, Radiation therapy to the breast after a lumpectomy do not appear to increase the risk of lung cancer.

• Air pollution

Bad air quality in cities - especially near heavily trafficked roads and factories -appears to raise the risk of lung cancer slightly. This risk is far less than the risk caused by smoking, but some researchers estimate that worldwide about 5% of all deaths from lung cancer may be due to outdoor air pollution. Diesel exhausts are of the pollutants with a sufficient evidence for their lung carcinogenicity.

• Certain dietary supplements

 Scientists are studying many different foods and dietary supplements to see whether they change the risk of getting lung cancer. Scientists had found that smokers who take beta-carotene supplements have increased risk of lung cancer.

The pathogenesis of lung cancer is like other cancers, beginning with carcinogen-induced initiation events, followed by a long period of promotion and progression in a multistep process that lead to cellular and molecular genetic changes. The initiation event happens early on, as evidenced by similar genetic mutations between current and former smokers. Continued cancer-causing substances (carcinogens) exposure allows additional mutations to accumulate.

Smoking both initiates and promotes carcinogenesis. It can damage the cells that line the lungs. Cigarette smoke is full of carcinogens that make changes in the lung tissue immediately after inhaled. At first the body may be able to repair this damage, but with each repeated exposure, normal cells that line the lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.

There are usually no signs or symptoms in the early stages of lung cancer, but many people with the condition eventually develop symptoms including:

• A chronic cough that gets worse over time;
• Coughing of blood;
• Persistent chest pain, especially with breathing or coughing;
• Shortness of breath, wheezing, or hoarseness;
• Repeated pneumonia or bronchitis;
• Swelling of the neck and face;
• Loss of appetite or weight loss;
• General weakness.

Lung cancer may not be discovered until symptoms appear. Having these symptoms with a history of lung cancer risk factor will push to ascertain the problem by undergoing several tests that may include:

• Imaging tests

Several imaging procedures are available to detect lung tumors and the degree of caner spread. Also, they may be helpful to determine if treatment is working and to look for possible signs of cancer recurrence after treatment. They include:

• • Chest x-ray. This is often the first test will be done to look for any abnormal areas in the lungs. Most lung tumors show up on X-rays as a white-grey mass. However, chest X-rays can't give a definitive diagnosis.

• • Computed tomography (CT) scan. a CT scanner takes many pictures to make detailed cross-sectional images of the lung. It is more likely to show lung tumors than routine chest x-rays. It can also show the size, shape, and position of any lung tumors and can help find enlarged lymph nodes caused by cancer spread from the lung. It can also detect masses in the other areas.
  • Magnetic resonance imaging (MRI) scan. Like CT scans, MRI scans provide detailed images of soft tissues, but by using radio waves and strong magnets instead of x-rays. MRI scans are most often used to look for possible spread of lung cancer to the brain or spinal cord.
  • Positron emission tomography (PET) scan. For this test, a form of radioactive sugar is injected into the blood. Because cancer cells in the body are growing quickly, they absorb more of the radioactive sugar. This radioactivity can be seen with a special camera. It can be used with CT scan to be more helpful to see if the cancer has spread to nearby lymph nodes or other areas.
  • Ultrasound imaging and endoscopies. Used mainly after lung cancer has been found to know if it has spread to the lymph nodes and nearby organs. Areas that may be checked include mediastinum (the space between the lungs), esophagus, or chest wall.

The actual diagnosis is made by looking at lung cells with a microscope. The cells can be taken from lung secretions, fluid removed from the area around the lung, or from a suspicious area using a needle or surgery. From these:

• • Sputum cytology. A sample of mucus that coughed up from the lungs is examined under a microscope to see if it has cancer cells. This test is more likely to help find cancers that start in the major airways of the lung, such as squamous cell lung cancers. It may not be as helpful for finding other types of non-small cell lung cancer.
  • Thoracentesis. Up taking sample of plural fluid that drains in the space between the lung and the chest wall to show if there is malignant cells inside or if cancer has spread to the pleura. It may be repeated to remove buildup of plural fluid that happens with some cases of lung cancer.
  • Bronchoscopic biopsy. If imaging tests show suspected cancer in the chest, a thin tube called a bronchoscope is used to examine the lungs and take a sample of cells from inside (biopsy). The bronchoscope is passed through the mouth or nose, down to throat and into the airways of the lungs. The up taken cells will be analyzed to confirm the disease. Transbronchial needle aspiration is an example.
  • Percutaneous needle biopsy. Involves removing a sample from a suspected tumor throw a needle inserted through the skin. The doctor will use a CT scanner to guide a needle to the site of a suspected tumor. A local anesthetic is used to numb the surrounding area. A common example is transthoracic needle biopsy.

Based on these test results, the doctor can determine disease stage, which may reflect the degree of cancer progression that will determine the best treatment.

• Stages of Non-Small Cell Lung Cancer:
  • Occult stage: Cancer cells are found in sputum, but no tumor is found in the lung by imaging tests or bronchoscopy, or the tumor is too small to be checked.
  • Stage 0: also called in situ disease, meaning the cancer is tiny in size and has not spread into deeper lung tissues or outside the lungs.
  • Stage I: Cancer may be present in the underlying lung tissues, but the lymph nodes remain unaffected. Tumor width is less than 3-5 cm.
  • Stage II: The cancer is in the lung and nearby lymph nodes. The disease also is classified in this stage if tumor width is larger than 5 cm even without lymph nodes involvement. Also, if present in the main bronchus.
  • Stage III: The cancer is continuing to spread from the lungs to the lymph nodes or to nearby structures and organs, such as ipsilateral mediastinal nodes.
  • Stage IV: The most advanced stage of lung cancer, when the cancer has spread to both lungs, plural fluid, or to another part of the body. This process is called metastasis.
• Stages of Small Cell Lung Cancer
  • Limited stage: Cancer is found on one side of the chest, involving just one part of the lung and nearby lymph nodes.
  • Extensive stage: In this condition, cancer has spread to other regions of the chest or other parts of the body.

After diagnosing lung cancer, determining the type and stage of the disease, Treatment will be carried out by a team of specialists who will work together to provide the best possible treatment.

1. Non-small cell cancer treatment

• Surgery

Surgery to remove the tumor(s) may be an option for early stage non-small cell lung cancer. If surgery can be done, it provides the best chance to cure this type of cancer. Nearby lymph nodes may also be removed to look for possible spread of the cancer.

Types of lung surgery

• • Pneumonectomy: This surgery removes an entire lung. This might be needed if the tumor is close to the center of the chest, or the cancer is spread through the whole lung. Patient can breathe normally with only one lung if it healthy.
  • Lobectomy: The lungs are made up lobes (3 on the right and 2 on the left). In this surgery, the entire diseased lobe is removed. This is often the preferred type of operation for NSCLC if it can be done.
  • Segmentectomy: In these surgeries, only part of a lobe is removed. This approach might be used, for example, if a person doesn’t have enough lung function to withstand removing the whole lobe.
  • Sleeve resection: This operation may be used to treat some cancers in large airways in the lungs instead of a pneumonectomy to preserve more lung function. The surgeon will bypass the tumor area and rejoin the subsequent parts.

Lung cancer surgeries carry some risks. Possible complications during and soon after surgery can include reactions to anesthesia, excess bleeding, blood clots in the legs or lungs, wound infections, and pneumonia. While it is rare, some people may not survive the surgery. Recovering from lung cancer surgery typically takes weeks to months.

• Radiation therapy

Radiation therapy uses high-energy rays or particles to kill cancer cells. This therapy may be used through different baths of treatment course. That may include before, during, or after other therapies (chemotherapy and surgery).

Types of radiation therapy

• • External beam radiation therapy (EBRT). The most often used type of radiation therapy to treat NSCLC or its spread to other organs. Here, the radiation is focused from outside the body on the cancer after carful adjustment of radiation beam direction and dose. Treatment are given 5 days a week for 5 to 7 weeks, but this can vary.
  • Internal radiation therapy (Brachytherapy). For this type of treatment, the doctor places a small source of radioactive material directly into the cancer or into the airway next to the cancer. This is usually done through a bronchoscope, but it may also be done during surgery. The radiation travels only a short distance from the source, limiting the effects on surrounding healthy tissues. The radiation source is usually removed after a short time. Less often, small radioactive “seeds” are left in place permanently.
  • Radiofrequency ablation (RFA): an option for some people with small lung tumors that are near the outer edge of the lungs, especially if they can’t tolerate surgery. RFA uses high-energy radio waves to heat the tumor. A thin, needle-like probe is put through the skin and moved in guided by CT scans to reach the tumor. Then, an electric current is passed through the probe, which heats the tumor and destroys the cancer cells.

Both doctor and patient should take into account that radiation therapy to the chest may damage the lungs and cause a cough, and shortness of breath. If esophagus exposed to radiation, this could cause a sore throat and trouble swallowing. Also, partial collapse of a lung may happen with RFA. All of these will improve after completion of treatment.

• Chemotherapy

Cytotoxic drugs may be helpful in treating lung cancer. They are used as a main treatment (sometimes along with radiation therapy) for more advanced cancers or for some people who can’t tolerate surgery. However, chemotherapy often is not recommended for patients in poor health.

Chemotherapy treatments are usually given in cycles. A cycle involves taking the chemotherapy medication for several days, then having a break for a few weeks to let the body recover from the effects of the treatment. The number of cycles of chemotherapy needed will depend on the type and the grade of the lung cancer. Most people require four to six courses of treatment over three to six months. Chemotherapy for lung cancer involves taking a combination of different medications. Types may be used:

• Cisplatin;
• Carboplatin;
• Paclitaxel;
• Docetaxel;
• Gemcitabine;
• Vinorelbine;
• Etoposide.

This therapy has a lot of unwanted effects. Of some that occur during treatment are fatigue, nausea, vomiting, and hair loss. It can also weaken immune system, making the patient more vulnerable to infections. Red blood cells and platelets may also decrease, making the treated person anemic and under risk of bleeding.

• Targeted therapy

Newer drugs that have developed to specifically fight cancer cells by interfering with specific molecules that are involved in the growth, progression, and spread of cancer. This therapy is more specific than chemotherapy with lesser side effects. Bevacizumab and Ramucirumab are the main two forms used to treat non- small lung cancer. This therapy still carrying a risk for infection.

• Immunotherapy

Also called biological therapy, this treatment utilizes the immune system to fight cancer. It generally results in fewer short-term side effects than chemotherapy does. It is based on the concept that immune cells or antibodies that can recognize and kill cancer cells can be produced in the laboratory and then given to treat cancer. This therapy may be used alone, or in combination with other cancer treatment. Nivolumab and pembrolizumab are common types of it.

2. Small-cell lung cancer

Small-cell lung cancer is usually treated with chemotherapy, either on its own or in combination with radiotherapy. This can help to prolong life and relieve symptoms. Surgery isn't usually used to treat this type of lung cancer. This is because the cancer has often already spread to other areas of the body by the time it's diagnosed. However, if the cancer is found very early, surgery may be used. In these cases, chemotherapy or radiotherapy may be given after surgery to help reduce the risk of the cancer returning.

Lung cancer affects the organ(s) responsible for breathing. Tumors inside the lung or airway can cause breathing or heart problems, such as:

• Pleural effusion (buildup of fluid between the outer lining of the lungs and the chest wall);
• Coughing up large amounts of bloody sputum;
• Collapse of the lung (pneumothorax);
• Blockage of the airway (bronchial obstruction);
• Recurrent infections, such as pneumonia;
• Pericardial effusion (buildup of fluid in the space between the heart and the sac around it).

As lung cancer grows, it may spread by the blood, lymph, or direct invasion to other parts of the body, commonly to the mediastinal lymph nodes, liver, bones, adrenal glands, and brain. This process is called metastasis and considered the advanced stage of the disease, where it can be difficult to treat and cause multiple, complicated health problems.

Most lung cancers could be prevented, because they are related to smoking (or secondhand smoke), or less often to exposure to radon or other environmental factors. However, some lung cancers occur in people without any known risk factors for the disease. It is not yet clear if these cancers can be prevented. From lung cancer preventive measures:

• Getting away from smoking

The most important thing can be done to lower the lung cancer risk is to quit smoking and avoid secondhand smoke. The risk will also decrease even if the person has smoked for years. Asking the doctor about strategies and stop-smoking aids that can help quit may help the smoker. If the person has never smoked, he shouldn’t start. If he lives or work with a smoker, he has to urge him to quit, or, at least, ask him to smoke outside. Areas where people smoke should be avoided. Instead, looking for smoke-free options.

• Testing home for “radon”

Radon levels inside the house should be checked, especially if the person lives in an area where radon is known to be a problem. Sealing cracks and other openings in the foundation is a basic part of most approaches to radon reduction. Frequent natural ventilation also prevents accumulation of this gas to dangerous levels. For information on radon testing, people can contact the local department of public health.

• Avoiding carcinogens at work

Workers have to take safety precautions to protect themselves from occupational exposure to toxic chemicals. Assessing the risks and Wearing face mask wherever needed for protection is strongly recommended.

• Eating healthy foods

Choosing a well-balanced diet with a variety of fruits and vegetables and whole grains may decrease the risk of lung cancer. The antioxidants and fibers in these foods reduce the carcinogenesis caused by free radicals. Cruciferous vegetables, such as Broccoli and cabbage, are will-known to play that preventive role.

• Screening test

Several organizations recommend people with an increased risk of lung cancer consider annual scan to look for lung cancer. Those include adults aged 55-80 years who are smoker, or used to smoke (30 years or more), or have quit within the last 15 years. A low-dose computerized tomography (LDCT) scan is the only recommended screening test for lung cancer.

Lung cancer often is discovered in later stages, when it is less treatable. New advances hold great promise for screening, early detection and individualized therapies, but need financial support, as the new immunotherapy for advanced, non-small cell lung cancer. The long-term outcome for lung cancer depends on how much the cancer has grown and spread. Statistics for survival rates of lung cancer are very general. Thus, they can’t tell the patient what will happen in his individual case, or exactly how long he well live with lung cancer.

The outlook for a certain type and stage of cancer are often given as 5-year survival rates, which represent the percentage of people who live at least 5 years after being diagnosed with cancer. However, many of people with cancer live much longer than 5 years after diagnosis, but it can give a general predictor. For instance, the five-year survival rate for lung cancer in the United States is 54 percent for cases detected in the first stage, while the number drops to 4% if the disease has not discovered until stage IV!

Lung cancer is the most common cancer worldwide, forming 13% of the total number of new cases diagnosed in 2012. The world health organization estimated 1.8 million cancer cases around the world in that year, of these 1.24 million cases were in men and 583.000 in women. This may be referred to the publicity of the chief cause of lung cancer (smoking) more among men.

According to the International Agency for Research on Cancer (IARC), the highest incidence of lung cancer in 2012 was in Northern America and Europe; while the lowest was in Africa and, Latin America and Caribbean. About 58 per cent of lung cancer cases occurred in less developed countries. Hungary had the highest rate of lung cancer, followed by Serbia and North Korea.

Lung cancer is the leading cause of cancer deaths worldwide, with more than 1.6 million deaths every year; causing more deaths than breast, colon and prostate cancers together. It is one of the most preventable malignancies affecting modern life. Lung cancer mainly affects older people, with the average age at the time of diagnoses is 70. It's rare in people younger than 45.