Risk Factors

• Cigarette smoking is the number one risk factor of lung cancer. The risk of having lung cancer increases with the number of cigarettes smoked each day and the duration of smoking.
• Second hand smoke (passive smoke) is a major risk factor of lung cancer among non-smokers. Passive smoking can increase the risk of developing lung cancer by about 30%. No amount of exposure to second-hand smoke is safe.
• Age. Lung cancer is more common in people above the age of 40.
• Exposure to cancer-causing chemicals increases the risk of lung cancer, e.g. asbestos, coal gas, chromates, nickel, arsenic, vinyl chloride, mustard gas and radon.
• Air Pollution. Those who live in more polluted cities have a higher risk of lung cancer than those who live in less polluted cities. The World Health Organisation estimates that there are about 4 million excess deaths per year worldwide due to air pollution. One of the largest reasons is due to lung cancer.
• Personal or family history: the risk of lung cancer may be higher if your parents, brothers or sisters, or children have had lung cancer. A lung cancer survivor, especially those who have smoked, may develop another form of lung cancer. 

The most effective method to reduce the risk of getting lung cancer is to avoid smoking totally. 

Screening

1. Low-Dose CT Scan

When lung cancer is diagnosed in the early stages, patients have a much higher chance of survival, in comparison to when lung cancer has spread. Low-dose CT scans may be used for the screening of lung cancer in individuals at higher risk. These individuals include those between 50 to 80 years old who smoked at least one pack of cigarettes daily for 20 years and who are currently still smoking or have quit within the recent 15 years. However, this method is not perfect, and one needs to be prepared for false positive results, which are CT scan findings that are eventually proven to not be cancer upon further testing.

2. Liquid Biopsy

A liquid biopsy detects cancer cells by picking up the presence of cancer DNA in the blood. Cancer cells, if present in the body, will have a certain cell-turnover. Even as they multiply rapidly, some cancer cells will die and break down (apoptosis). The DNA of these apoptotic cells will leach into the blood. If cancer DNA is detected in the blood, it is fairly possible that a cancer is hiding somewhere in the body. Since multiple cancers can be detected using the same technique, only one test is needed to screen for different cancers. As cancers of different origins have somewhat different DNA signatures, we can figure out where it is hiding and direct further medical investigations in that direction.

*Do note that the liquid biopsy has not been approved by the Food and Drug Administration in the United States and are not part of international screening guidelines yet.

Signs & Symptoms

Often, there are no symptoms of lung cancer during its early stages. However, common symptoms of lung cancer may include:

• General weakness, tiredness, and unexplained weight loss
• A change in the voice
• Persistent coughs that worsen over time
• Blood in sputum (Haemoptysis)
• Shortness of breath, wheezing, or hoarseness
• Recurring chest infection and fever
• Constant chest pain
• Loss of appetite
• Symptoms resulting from the metastases of lung cancer, such as a swollen liver, paleness, swelling of lymph nodes

Diagnosis

Diagnosis is made using one or more of these tests:

• Analysis of patient history and a physical examination
• Chest X-ray
• Sputum cytology: In some cases, examination of the sputum under the microscope may reveal cancer cells. Cancer cells may be coughed up from the lungs or airways
• Bronchoscopy: A fibre-optic tube is passed through the nose or mouth into the trachea to the airways or bronchi. Suspicious-looking growths can be biopsied (a small piece of tissue are taken for examination under the microscope) to confirm cancer
• Imaging studies: CT (computerised tomography), MRI (magnetic resonance imaging) and PET (positron emission tomography) scans are performed to determine the extent of the cancer
• Transthoracic needle biopsy: Under CT scan guidance, a needle is inserted into the chest to biopsy suspicious lumps in the lungs
• Mediastinoscopy or video-assisted thoracoscopic surgery are invasive procedures that require general anaesthesia and hospitalisation; they are necessary if earlier tests do not provide conclusive results

Treatment

Surgery, radiation, and chemotherapy are the 3 main methods of treatment. The type of treatment depends on the size, extent of the disease, the type of lung cancer, and the general health of the patient.

Non-Small Cell Lung Cancer (NSCLC)

Surgery, radiotherapy, chemotherapy and targeted therapies may be used to treat NSCLC. As this tends to grow and spread slowly, surgery may offer a chance of a cure if discovered early. Depending on the staging of NSCLC, the treatments are:

Small Cell Lung Cancer (SCLC)

As SCLC is aggressive and tends to spread early to other organs, it is usually treated with chemotherapy. If the cancer is still localised in the lymph nodes of one lung, radiotherapy can be combined with chemotherapy to effectively treat the cancer and remove the cancer cells. Advanced forms of SCLC may be treated with a combination of chemotherapy and immunotherapy. Surgery is usually not recommended for SCLC.

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