Lung cancer is cancer that develops in the lungs as a result of abnormal multiplication of cells that eventually form a tumor. This type of cancer, if diagnosed in a timely manner, can be treated and cured.
The lungs main function is to process gas exchange between the air we breathe and the blood. It allows oxygen to enter the blood stream and remove carbon dioxide from the blood.
The anatomy of the lung is composed of smaller units called lobes. These lobes have lung fissures (double-fold of serous membrane that is directly attached to the outer surface of each lung) that separate the lobes from each other. The left lung has inferior and superior lobes, while the right lung has inferior, middle and superior lobes. The lungs also have airways that enter the lungs called bronchi, and smaller airways branching from bronchi called the bronchioles that end in tiny sacs known as alveoli where gas exchanges.
When the cells in the lungs do more than the required cell division, they grow quickly, without disintegrating therefore forming a tumor. Usually, the cells are supposed to die after a certain period of time in their life cycle, which prevents the multiplication of too many cells. But in the case of cancer they tend to grow and multiply continuously.
Types of Lung Cancer
Lung cancer starts in the lungs and is classified by cells that fall in two different categories. These are:
Non-small Cell Lung Cancer (NSCLC)
NSCLC is the most common type of lung cancer and accounts for about 85% of all lung cancers. It comes in various types named according to the tumor found in the type of cell. These include:
Adenocarcinomas: These are found in the outer areas of the lungs and is commonly associated with smoking but can also be found in non-smokers. Adenocarcinoma starts to build up in the tiny air sacs called alveoli.
Squamous carcinomas: Also known as epidermoid carcinomas, these are cancer cells which begin to form in squamous cells found at the center of the chest area in the main airway called bronchus.
Large cell (undifferentiated) carcinomas: These cells appear and grow in any part of the lung. They spread quickly which tends to make treatment difficult.
Sarcomatoid and adenosquamous carcinoma are other subtypes of non-small cell lung cancer but are considered rare.
Small Cell Lung Cancer (SCLC)
Also known as oat cell cancer, small cell lung cancer has a tendency to increase and spread quite fast than the non-small cancer cells. The cells are usually discovered after a definitive diagnosis, but the good thing is that it responds well to radiation and chemotherapy. Unfortunately, their rate of reoccurrence is high.
There are other types of lung tumors such as lung carcinoid tumors, lymphomas, cystic carcinomas and benign tumors. Other types of cancers may start from other parts of the body organs then spread to the lungs, however, these are not considered lung cancers.
Symptoms of Lung Cancer
In its earliest stages, lung cancer may not present any symptoms. Overall, the symptoms will depend on where and how fast the cancer spreads. These symptoms include:
- Persistent dry cough that doesn’t get better
- Shortness of breath
- Unexplained weight loss
- Chest pain
- Shortness of breath
- Coughing up blood
- Shoulder pain that flows down to the outer nerves
- Infections such as pneumonia and bronchitis
- Voice hoarseness
- Bone pain
- There are non-specified symptoms such as fatigue, depression and weight loss.
Causes and Risk Factors of Lung Cancer
Lung cancer is one of the most common types of cancer and one which has a high mortality rate. There are various factors that can cause the disease, including:
Smoking and Passive Smoking
Cigarette smoking is the greatest cause lung cancer. This is because the tobacco has toxic chemicals called polycyclic aromatic hydrocarbons (PAHs), Nicotine, Carbon monoxide and nitrosamines. Tobacco has radioactive materials in the leaves used to make cigarettes and cigars which are given off in the smoke when it’s burned. This smoke is what the smokers inhale into their lungs causing a high risk of cancer and lung disease.
Passive smoking on the other hand is where a non-smoker inhales the tobacco smoke from an environment where smokers are smoking. The exposure of non-smokers living with a smoker increases the risk of lung cancer.
Exposure to Minerals and Gas
Cancer can also rise from pleura and is called mesothelioma cancer (inhaled asbestos fibers from naturally occurring minerals, which can lead to malignant tumors that form in the lining of the lungs or heart.
A natural radioactive gas called radon is also known to cause cancer of the lungs. This gas is a natural decay of uranium that is emitted by ionizing radiation. Radon gas is odorless and invisible and can penetrate through the soil and can enter drains, pipes or any other openings. A test kit can be used to detect its presence.
While smokers are at risk of developing lung cancer, there are people who are genetically predisposed to the disease. This means that the individual caries the lung cancer gene which increase the risk of him/her developing it.
Diagnosis of Lung Cancer
Early diagnosis of lung cancer can lead to a successful treatment and cure. If you notice or detect any of the lung cancer symptoms mentioned above, then it is recommended to seek medical help for a diagnosis.
Lung cancer is diagnosed through:
- A physical exam for signs or symptoms such as difficulty in breathing or blocked airway.
- An ultrasound scan
- Genetic tests based on family history of cancer genes
- Imaging test: Screenings such as CT Scan (low-dose helical CT imaging /spiral CT scan), X-ray, MRI and PET (Position Emission Tomography) are done to give a detailed view of the affected area(s). This is mostly performed in smokers and can detect lung cancer in its early stages
- Sputum cytology: This is a simple procedure done under microscope to test the phlegm/saliva to allow visualization of tumor cells
- Bone scans: This is done on computer screen to determine if the lung cancer has spread to the bones
- Bronchoscopy: A biopsy examination of visualization of the airways via a thin fiberoptic probe is inserted in the mouth or nose
- Thoracentesis: The cancer may cause the lining tissues in the lung to form fluid at the pleural effusion (space between chest wall and lungs). The biopsy is done with a thin needle to get fluid for examination
- Needle biopsy: The fine needle aspiration (FNA) is inserted through the chest wall into the lung. The cells are sucked into the syringe and are tested for the presence of cancer cells
Lung Cancer Treatment
Lung cancer treatment is usually dependent on:
- The aggressiveness of the cancer
- Type of the cancer
- Stage of the cancer
- Size and location of the tumor
- Age and overall health of the patient
- History of lung cancer in the family
- Gene mutation test results
Treatment options for lung cancer include:
During the procedure, the tumor is surgically removed if it is in stage one or two where the non-small cell lung cancer has not outgrown the lung. Surgery is mostly performed with the NSCLC and not SCLC as they are always scattered. The removal is successful when the cancer is slow growing, and one can survive 5 years after diagnosis.
The radiation therapy uses high-energy X-rays to eliminate the cancer cells that are multiplying. This procedure treats both the non-small and small cells. Radiation is done externally using a machine that is directed towards the cancer cells or can be done internally where radioactive substances that are in a sealed container are located in the area where there is a tumor. Radiation shrinks the tumor which has spread to the trachea or lymph nodes, which cannot be removed by surgery.
Chemotherapy involves the use of anti-cancer drugs to destroy any remaining fast-growing cancer cells in the lungs. This is done to treat both small and non-small cancer cells, but it also destroys the normal cells. Chemotherapy is done either as an intravenous infusion, given drugs or both treatments, and is done in cycles.
EGFR target therapies is one of the drug therapies that target cancer cells by slowing down and stopping cell division without damaging the healthy cells. These drugs include Erlotinib (Tarceva), Gefitinib (Iressa) and Afatinib (Gilotrif). They focus on destroying the epidermal growth factor receptor whose function is to assist the cell division.
At King’s College Hospital Dubai, we focus on offering an exemplary service. From initial consultation through to final diagnosis, treatment and beyond. Our multidisciplinary team of expert doctors and nurses, and technologists led by Dr Hassan Ghazal – an American triple board-certified Consultant Medical Oncologist and a Consultant Clinical Hematologist with more than 3 decades of clinical experience, are here to offer tailored management and treatment of your condition, and to answer any questions that you may have throughout your time with us. Whatever you need us for, we’re only a phone-call away.
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