What is Lung Cancer?
What is Lung Cancer?
The lungs are an essential part of the respiratory system. The respiratory system consists of a pair of lungs that also have different parts. The right lung has three lobes, and the left lung has two. A thin layer called the pleura protects the lungs. Cells in the lungs do tend to change and can grow or stop behaving normally. Some of these cells can grow into benign, non-cancerous tumors or malignant tumors.
These cells can destroy the nearby tissue and can also spread to other parts of the body, causing lung cancer. Lung cancers can be primary and secondary, depending on the location that it starts. Primary tumors in the lungs start locally, and secondary ones start in another part of the body and spread to the lungs.
It is also further divided into non-small cell lung cancer and small cell lung cancer, depending on the appearance of the cancer cells under the microscope.
What are the different types of Lung Cancer?
The type of lung cancer that a person has can help doctors understand the cell that cancer started in. Lung cancer is of two common types, small cell lung cancer, and non-small cell lung cancer. Lung cancer can also be of the primary and secondary type depending on the origin of cancer.
Small cell lung cancer
This type of cancer has been characterized by small cells that multiply very quickly and form large tumors that spread throughout the body. This kind of cancer is common among smokers. Also called oat-cell cancer; it constitutes about 10-15% of all lung cancer.
Non-small cell lung cancer
Non-small cell lung cancer constitutes about 80% of the lung cancer cases, and it further comprises four different types depending on the cell of origin.
Adenocarcinoma
Adenocarcinoma forms the mucus-producing glands and is the most common in women and non-smokers.
Bronchioalveolar carcinoma
This type of cancer forms near the air sacs of the lungs.
Squamous cell carcinoma
Squamous cell carcinoma forms in the lining of the bronchial tubes, commonly seen in smokers.
Large cell carcinoma
Large cell carcinomas form near the outer edges or surface of the lungs. This type of cancer is rare.
Other types of lung cancer
Pancoast tumors
Pancoast tumors are the kind that affects the top part of the lungs.
Mesothelioma
Mesothelioma is the kind of cancer that affects the covering (the pleura) of the lungs.
What are the signs and symptoms of Lung Cancer?
The most common early signs and symptoms of lung cancer are listed below:
What are the causes of Lung Cancer?
A risk factor is something that increases the chances of developing the disease. The chance of developing lung cancer increases with age. Smoking tobacco is known to be the most critical risk factor in the case of lung cancer.
What are the common risk factors that can lead to lung cancer?
Smoking
Smoking cigarettes are known to be the leading cause of developing lung cancer as the smoke from cigarettes contains chemicals known as carcinogens. Carcinogens are chemicals that cause changes in the cells in the lungs, which results in cancer.
The risk of developing lung cancer has many other factors involved. Namely, the age at which a person started smoking, the number of cigarettes smoked in a day and for how long the person has continued smoking.
Passive smoking
The inhaling of secondhand smoke or passive smoking is one of the leading risk factors among non-smokers. The breathing in secondhand smoke is as harmful as smoking a cigarette as it contains the same amount of chemicals when inhaled.
Radon
Radon is a colorless, odorless gas that comes from the breakdown of uranium in the soil and rocks. Radon is a leading cause of cancer in non-smokers. Furthermore, lung cancer risk increases with exposure to gas.
Occupational exposure to certain chemicals
People exposed to particular carcinogens at work are at higher risk of developing lung cancer. An example of these carcinogens would be arsenic and inorganic arsenic compounds, silica dust, chromium, cadmium, and mustard gas.
Asbestos
The asbestos fiber is a silicate that can last a lifetime in the lungs. Research has linked the risk of developing lung cancer to exposure to asbestos.
Air Pollution
Constant exposure to polluted air is a cause of lung cancer. Polluted air is as harmful as cigarette smoke, and some lung cancer deaths occur on account of the smoke.
Prior history of lung cancer
People who have had lung cancer before are at higher risk of developing it again in comparison to the general population who have not had a history of lung cancer before.
What are the stages of Lung Cancer?
Stages of Small cell lung cancer (SCLC)
Small cell lung cancer is mainly caused by tobacco smoking. For small cell lung cancer, the staging process is done differently and it is classified as either limited stage or extensive-stage disease.
Limited stage SCLC
At this stage, the cancer is found in one lung and sometimes in the lymph nodes too.
Extensive stage SCLC
At this stage, cancer has spread to the other lung and to the fluid in the lungs as well. Cancer might have spread to other parts of the body too.
Stages of non small cell lung cancer (NSCLC)
Non-small cell lung cancer uses the TNM system of staging. Tumor (T): The size of the original tumor is described. Lymph nodes (N): This factor indicates if the cancer has spread to the lymph nodes. Metastasis (M): This factor refers to whether the cancer has spread to other parts of the body.
Stage 1 Non small cell Lung cancer (NSCLC)
68-92% 5-year survivalEarly stage cancer confined to the lung
Stage 2 Non small cell Lung cancer (NSCLC)
53-60% 5-year survivalCancer has spread to nearby lymph nodes or is larger
Stage 3 Non small cell Lung cancer (NSCLC)
13-36% 5-year survivalCancer has spread to lymph nodes in chest but not distant organs
Stage 4 Non small cell Lung cancer (NSCLC)
0-10% 5-year survivalCancer has spread to distant organs
How do I know if I have Lung Cancer?
Screening refers to a type of test that is performed to detect the cancer at the earliest, in the absence of clear symptoms. In the case of lung cancer, there are different systems used for screening and they are listed below.
Low-dose computed tomography (LDCT)
In the case of lung cancer, low dose computed tomography is conducted on individuals who have a higher risk of developing lung cancer but show no signs and symptoms. LDCT is the most common method used as the images produced are of good quality and the abnormalities that can be detected are up to 90%.
Chest X-ray
A chest x-ray is particularly used in emergency diagnosis and treatment as it is a fast method. This method of screening is most commonly used to evaluate symptoms like shortness of breath, chest pain and persistent cough.
Sputum cytology
Sputum cytology is a kind of diagnostic test that is conducted wherein a sample of the mucus that contains blood is taken and view under a microscope to check for the presence of abnormal cells.
What is lung cancer diagnosis?
The diagnostic tests used for lung cancer can vary from patient to patient. There are also numerous other factors that doctors look into while diagnosing a patient such as medical history, symptoms, and findings from previously conducted physical examinations.
Common diagnostic methods for lung cancer:
- Computed tomography (CT): X-ray machines project a cross-sectional view of the lungs on a computer
- Positron emission tomography (PET) scan: Helps understand if cancer has spread to other parts of the body
- Bronchoscopy: A tube passes through the nose or mouth and into the lungs to check for tumors
- Mediastinoscopy: Surgical tools are inserted behind the breastbone to take tissue samples
- Fine needle biopsy (FNAC): A fine needle scrapes off cells from the affected area
- Biopsy: The standard gold test for cancer diagnosis
How is Lung Cancer treated?
Lung cancer treatment depends on its pathological type. Lung cancers are broadly divided into two types, Non small cell lung cancer (NSCLC) and small cell lung cancer. The chosen sequence and type of modality often depends on the type of cancer that the patient has and how far the cancer has spread.
What are the treatment options for non-small cell lung cancer?
Surgery
Surgical options for lung cancer are usually done in stage 1 and stage 2, this procedure of treatment is mainly done to remove the tumor. The extent of surgery may be from segmentectomy (small lung part) to Pneumonectomy (whole single side lung).
Chemotherapy
When patients are given adjuvant chemotherapy, which is chemotherapy that has been given after the surgical removal of the tumor, the cancer has very little chances of coming back. For stage 4 chemotherapy or targeted therapy is considered to be the main treatment.
Neoadjuvant treatment
Neoadjuvant treatment is treatment where chemotherapy is given before surgery or radiation. This kind of treatment may help with shrinking the tumor into a smaller size which makes it easier to remove it surgically.
Targeted treatment
Targeted treatment is the kind of treatment that is designed specifically to attack only the cancer cells by attaching or blocking targets (specific proteins) that appear on the surface of the cancer cells.
Immunotherapy
Immunotherapy has become the newest method of treatment for lung cancer. Immunotherapy is a well tolerated treatment and causes minimal sides effects because of its mechanism of action.
What are the treatment options for small cell lung cancer?
Chemotherapy and radiation
For people with small cell lung cancer, regardless of what stage the cancer is at, chemotherapy is an important treatment. For people with limited stage small cell lung cancer, they are given chemotherapy in combination with radiation.
Preventive radiation therapy
Preventive radiation therapy is mainly used in patients whose lung cancer has responded well to chemotherapy and preventive radiation therapy is prescribed to stop cancer from spreading to the brain.
Surgery
A very small percentage of people with limited stage small cell lung cancer benefit from surgery only if there are no lymph node tumors. After the surgery, they are given adjuvant chemotherapy.
Advanced And Targeted Treatment Options For Lung Cancer
Targeted therapy specifically targets cancer cells. It is very different from chemotherapy. Targeted treatment works by target specific genes or proteins to stop the lung cancer cells from growing or multiplying.
Types of targeted treatments for lung cancer
Monoclonal Antibodies
Drugs known as monoclonal antibodies are drugs that target the outside of a cancer cell or the area around the cancer cells. They are known as anti-angiogenesis inhibitors.
Small molecule drugs
Small molecule drugs block the process that helps cancer cells grow and multiply. These drugs are usually oral pills.