Lung cancer has the poorest prognosis. It is the leading cause of death among men and women in India. Most of the lung cancers are diagnosed at an advanced stage, making it difficult to save patients’ lives.
Among the risk factors, cigarette smoking is the leading cause of lung cancer. However, lung cancer is reported in non-smokers also. Lung cancer can primarily be detected by x-ray screening.
- Smoking: Smoking continues to be the leading risk factor for lung cancer. Out of 10 diagnosed patients with lung cancer, around 8 have a history of smoking. Even those people who have smoked cigarettes for at least 10 years and stopped within last 15 years carry a very high risk of developing lung cancer.
- Radon gas: Radon is the product of radioactive decay of uranium, which is found in the earth’s crust.
- Asbestos: Many industries including mining, steel, and iron have a high risk of asbestos exposure, which make their workers more vulnerable to lung cancer. The risk significantly increases, if the person is a smoker.
- Environment factors: Environment and eco-surroundings play a significant role in the development of lung cancer. Air pollution increases the risk of lung cancer by 20%. Household pollution like kerosene, gas exposure and charcoal burn increase the risk of developing lung cancer. Women exposed to household pollution have twice the increased risk of developing lung cancer.
- Hereditary factors: Evidences suggest that risk of developing lung cancer increases by 20% if someone in the family has a history of lung cancer. Close relatives of lung cancer survivors should be screened for early symptoms.
- Chronic cough for more than a month
- Coughing up blood (haemoptysis)
- Shortness of breath
- Chest pain
- Difficulty in swallowing
- Progressive weight loss
- Loss of appetite
- Joint problems
- Swelling of the arms and face
Hence regular screening, at least for high-risk population and continuous awareness and education among the public, will help in easing the burden and thereby improve clinical outcomes.
Types of lung cancer
- Non-small-cell-lung-carcinoma (NSCLC): Non small lung cancer is one of the most prevalent forms of lung cancer, which accounts for 80% of overall lung cancer. Non-small cell lung cancer can be divided into squamous and non-squamous lung cancer.
- Non squamous lung cancer: This accounts for 70% of NSCLC, while squamous carcinoma accounts for 30% of overall NSCLC. Primary risk factors for NSCLC are smoking, however squamous non-small cell lung cancer has been seen in non-smokers also, especially women.
- Small-cell-lung-carcinoma: It accounts for 15-30% of overall lung cancer incidence. Primary risk factors for this type of cancer are industrial and radiation exposure.
Stages of lung cancer
A stage I lung cancer is a small tumour that has not spread to any lymph nodes, making it possible for a surgeon to completely remove it. Stage I is divided into 2 sub-stages based on the size of the tumour:
- Stage I tumours are less than 3 centimetres (cm) wide.
- Stage IB tumours are more than 3 cm but less than 5 cm wide.
Stage II lung cancer is divided into 2 sub-stages:
A stage II cancer describes a tumour larger than 5 cm but less than 7 cm wide that has not spread to the nearby lymph nodes. Or, a stage II-A cancer can be a small tumour less than 5 cm wide that has spread to the nearby lymph nodes.
Stage IIB lung cancer describes a tumour larger than 5 cm but less than 7 cm wide that has spread to the lymph nodes. Or, a stage II-B cancer can be a tumour more than 7 cm wide that may or may not have grown into nearby structures in the lung but has not spread to the lymph nodes.
Stage III lung cancers are classified as either stage III-A or III-B. For many stage III-A cancers and nearly all stage III-B cancers, the tumour is difficult, and sometimes impossible, to remove. For example, the lung cancer may have spread to the lymph nodes located in the centre of the chest, which is outside the lung. Or, the tumour may have grown into nearby structures in the lung. In either situation, it is less likely that the surgeon can completely remove the cancer because removal of the cancer must be performed bit by bit.
Stage IV means the lung cancer has spread to more than 1 area in the other lung, the fluid surrounding the lung or the heart, or distant parts of the body through the bloodstream. Once cancer cells get into the blood, the cancer can spread anywhere in the body. But, NSCLC is more likely to spread to the brain, bones, liver, and adrenal glands. Stage IV NSCLC is divided into 2 sub-stages:
- Stage IV-A cancer has spread within the chest.
- Stage IV-B has spread outside of the chest.