Even though the exact cause of each case of lung cancer may not be known, many risk factors that make a person susceptible to lung cancer.
However, smoking is considered one of the most prominent factors in people who develop lung cancer; this is why the first thing your doctor confirms before a lung cancer screening is whether you are a smoker.
Lung cancer can be a life-threatening condition, whose treatment is often toxic for the patient and could lead to other complications.
However, when diagnosed in time, lung cancer can be managed with relative ease and has been cured for many patients. Thus, everyone should consider getting regular check-ups with a lung specialist for assessing lung health and catch lung cancer early on.
Here, you will find the most common risks factors that can lead to lung cancer and learn about the different types and stages of lung cancer and their treatment options.
- Types of lung cancer
- Stages of lung cancer
- Symptoms of lung cancer
- How is lung cancer caused?
- What causes lung cancer in non-smokers?
- Lung cancer treatment
- Outlook for patients
Types of lung cancer
The prognosis, lung cancer cure plan, and other important aspects of treating lung cancer are decided based on which type of lung cancer you have. The following are the most common types of lung cancer:
1. Small cell lung cancer (SCLC)
This cancer almost exclusively occurs in people who are heavy smokers and is less prevalent in non-smokers. A high percentage of reported SCLC cases comprise women who have a long history of smoking or are heavy smokers; non-smokers have an extremely rare chance of developing small cell lung cancer. SCLC accounts for about 15% of the total cases of lung cancer.
2. Non-small cell lung cancer (NSCLC)
This type of lung cancer accounts for about 85% of all lung cancer cases; smokers and non-smokers can both get this type of cancer. NSCLC is an umbrella term used for several types of lung cancers, including the following:
This is one of the most common types of lung cancer that accounts for about 40% of all cases. Both smokers and non-smokers can get this type of lung cancer, but women are more likely to get this cancer than men.
b. Squamous cell carcinoma
The second-most common type of lung cancer, squamous cell carcinoma accounts for about 30% of all lung cancer cases. This is highly prevalent in men who have a long history of smoking or are heavy smokers.
c. Large cell carcinoma
This type of lung cancer occurs in about 10% of all lung cancer, which is highly prevalent in male smokers.
Occurring in about 5% of the total lung cancer cases, carcinoid can happen in both men and women in an equal ratio with no link to smoking.
Stages of lung cancer
The stage of this disease plays a vital role in determining the treatment plan and whether the patient can be cured.
- Stage 0
People who are diagnosed at this stage have abnormal cells, which are not yet cancerous, in their airway or the top lining of the lung.
- Stage I
In this stage, lung cancer patients usually have a small lung tumour in their lungs.
- Stage II
This stage usually involves the spread of cancerous cells due to the presence of lung tumours near lymph nodes.
- Stage III
In this stage, the lung tumour is large, and the cancer has spread to other lobes/sections of the lung or lymph nodes.
- Stage IV
In this stage, lung cancer patients have cancer in both their lungs or have fluids surrounding the lungs/heart. Stage IV lung cancer is incurable.
Symptoms of lung cancer
You may not realise you have lung cancer until the disease has passed the early stages as the symptoms don’t usually show up early. Thus, it is important to go for regular check-ups at the specialist for lungs or an oncologist if you are at a high risk of developing lung cancer.
The following are some of the common symptoms associated with lung cancer:
- Persistent cough that doesn’t improve
- Shortness of breath
- Blood in your cough
- Hoarseness, chronic fatigue, and chest pain
- Unexplained weight loss
- Pain in your bones
How is lung cancer caused?
Lung cancer is caused by the abnormal growth and division of cells. Usually, the cells in our body grow and divide on a daily basis, but they have a built-in mechanism to stop the division or prevent them from dying. When a cell undergoes changes (or mutates) or is divided too many times, this built-in mechanism might fail, leading to abnormal growth of cells—cancer. These cancer cells keep on multiplying unchecked and interfering with the normal cells.
Cancer cells might get into the bloodstream through the vessels or spread to other parts of the body through the lymph nodes and spread the damage. Although there is no clear answer as to what causes lung cancer yet, certain risk factors have been identified over time that increase the chances of developing lung cancer.
According to doctors who are specialists for lungs, smoking is the biggest contributor of lung cancer cases in smokers and non-smokers who are exposed to second-hand smoke. Smoking damages the cells lining the lungs, and every time you smoke, the cells and tissue of the lungs change almost immediately; the smoke is full of carcinogens (cancer-causing substances). Your body may be able to repair the initial damage, but overtime, the healthy cells in your lungs are increasingly damaged; this damage may be irreversible. These damaged cells may start acting abnormally and develop into lung cancer.
Smoking is one of the biggest factors of lung cancer, but there are some other factors as well. Smokers who are exposed to other known risk factors, such as asbestos and radon, are at an increased risk of getting lung cancer.
Research has shown that certain changes in the DNA of the lung cells can lead to abnormal cell growth and sometimes even cancer. DNA makes up our genes that control the cell function; some genes control cell growth, division, and death.
Oncogenes are responsible for cell growth and division in addition to keeping the cells alive. On the other hand, tumour suppressor genes control cell division or terminate the cells at the right time. If the oncogenes are turned on or tumour suppressor genes are turned off, it can cause cancer; but changes in many genes are usually required to cause lung cancer.
1. Inherited gene mutation
People who have a family history of lung cancer might inherit certain DNA mutations from their parents, which increases the risk of developing certain cancers. Although inheriting these mutations alone is not enough to cause lung cancer, these genes coupled with other environmental factors can lead to lung cancer.
People who have inherited DNA changes in chromosome 6 are highly prone to getting lung cancer, even if they smoke a little or not at all. Those who have inherited faulty DNA repair mechanisms are more likely to show changes in their DNA.
2. Acquired gene mutation
People are more likely to exhibit acquired gene mutations than inherited gene mutations. These mutations are often the result of exposure to environmental risk factors, such as carcinogenic compounds found in tobacco smoke, but may also occur by chance.
Changes in the RB1 tumour suppressor gene are considered important contributors for developing SCLC, and those in p16 tumour suppressor gene and K-RAS oncogene are deemed as crucial factors for developing NSCLC. These are only a few known gene mutations, and others are yet to be found as all lung cancers do not share the same mutation.
What causes lung cancer in non-smokers?
People who don’t smoke can also get lung cancer; this includes people who never smoke and those who have quit smoking for a long time. Some of the factors associated with lung cancer include exposure to radon, second-hand smoke, asbestos, diesel exhaust, and air pollution. Although people who don’t smoke rarely get small cell lung cancer, it is possible. A small portion of lung cancer cases is also seen in people with no known risk factors for lung cancer.
Lung cancer in non-smokers is quite different from that in smokers in terms of the shape and behaviour of the cells. Certain types of lung cancer have specific gene mutations that can be studied for devising a suitable lung cancer care plan.
Lung cancer treatment
Lung cancer can be treated at any stage. However, if it is diagnosed in early stages, the treatment can likely cure the patient. By contrast, people who are diagnosed with end-stage lung cancer usually receive treatment to prolong their life span and manage other symptoms.
Researchers are taking efforts to develop advanced lung cancer treatment options to limit the damage to the patient’s body by treatment. Some of the most prevalent treatment options are listed here:
- Lung cancer surgery
Removing the lung tumour and surrounding tissue is a crucial step in treating lung cancer as the cancer cells can spread damage to other areas of the body.
- Radiation therapy
Doctors have found that radiation therapy works well in removing the left-over cancer cells from the body, which could not be removed with surgery.
Chemotherapy for lung cancer is usually administered intravenously to patients to remove the remaining cancer cells after surgery, but it is toxic for the patient. Chemotherapy is also one of the most popular treatment options among lung cancer patients.
- Targeted drug therapy
This treatment targets lung cancer cells with certain gene mutations. Not everyone is suitable for this treatment, and a doctor will likely biopsy a lung tumour to consider it for the patient.
Lung cancer cells usually have protein markers that interfere with the function of the immune system, rendering it useless. Immunotherapy blocks these protein markers enabling the immune system to function properly.
Outlook for patients
People with early-stage lung cancer have a high survival rate and usually lead a relatively healthy life after being cured. However, people who diagnosed with advanced lung cancer face a difficult time managing their symptoms and might require therapy sessions to cope with their illness.
Lung cancer cannot be prevented as there is no exact known cause for the disease. However, you can reduce your risks of developing lung cancer by doing the following:
- Go for annual lung cancer screening if you have a high risk of getting the disease
- Quit smoking and avoid all kinds of smoke (including passive or second-hand smoke)
- Participate in regular physical activity and eat healthy and balanced meals
In addition to the mainstream treatment, lung cancer patients also receive palliative care to help them manage the symptoms of the diseases and side-effects of the treatment.
What is the main cause of lung cancer?
One of the most prominent causes of lung cancer according to lung specialists is smoking. People who are heavy smokers or have a long history of smoking are at a high risk of developing lung cancer; quitting smoking can lower your risk of lung cancer.
What are the causes of lung cancer besides smoking?
The following factors are known risk factors that can cause lung cancer in non-smokers:
a. Radon exposure
b. Asbestos exposure
c. Radiation exposure in the chest area due to previous cancer treatment
d. Gene mutations
e. Air pollution
People who do not fall under any category of risk factor may still develop cancerous lung tumours.
What causes lung cancer in India?
Some cities in India rank extremely high on the air pollution radar, such as Delhi and Kishangarh, where the air impure that it leads to lung ailments. Additionally, the culture of India and traditional ways prompt people to indulge in smoking tobacco, to celebrate festivals by lighting large bonfires and bursting crackers, and to burn down plantation remains after cultivation. All of these activities increase the air pollution, thereby affecting lung health, and raise the risk of developing lung cancer in India.