According to the most recent lung cancer statistics from the World Health Organisation/International Agency for Research on Cancer, globally, 2.2 million people had lung cancer in 2020, and 1.8 million passed away from it.
In 2022, the American Cancer Society predicted that there would be 236,740 new cases of lung cancer identified and 130,180 lung cancer-related deaths, making it the second most common cancer (apart from skin cancer) in both men and women in the US.
In Thailand, lung cancer is one of the top five malignancies, being the 2nd most common in men and the 5th most common in women.
What causes lung cancer?
Many factors, which fall into the categories of "modifiable" and "unmodifiable" causes, can result in lung cancer.
Modifiable risk factors can be altered or avoided, lowering the risk of developing lung cancer. Some of them are as follows:
- Smoking tobacco products in any form, such as cigarettes, cigars, pipes, and hookahs, can raise the risk of lung cancer and is the most common cause of lung cancer, responsible for 80% to 90% of lung cancer deaths in both men and women.
- Second-hand smoke inhalation from the combustion of tobacco products can lead to several health issues, including respiratory disorders, heart disease, stroke, and lung cancer in non-smokers. The detrimental effects can occur in as little as five minutes when the arteries become stiffer, with an increased risk of blood clotting after 20–30 minutes and an irregular heartbeat after two hours. Infants and children are impacted more by second-hand smoke and are likely to experience sudden infant death syndrome, frequent ear infections, more severe asthma attacks, pneumonia, and more.
- Radon is a naturally occurring radioactive gas in soil and rocks that can penetrate through building structures. High radon levels in the home can raise the risk of lung cancer, especially in smokers. Since it is odourless, colourless, and tasteless, the US Environmental Protection Agency advises home testing for radon.
- Asbestos is a fibrous silicate mineral widely utilised in construction, insulation, and fireproofing materials before it was known to be a carcinogen. Each asbestos fibre consists of numerous smaller, microscopic fibrils that could be released into the air by rubbing or unsafe removal. Inhaling asbestos fibres increases the risk of lung cancer and mesothelioma.
- Toxic chemicals in the workplace, such as benzene, arsenic, and nickel, can also raise the risk of lung cancer. Industrial workers in metal manufacturing and petrochemicals are at increased risk.
- 5 can trigger lung cancer among chronic smokers. Studies also found a strong correlation between PM2.5 exposure and lung cancer in people without a smoking history. At the European Society for Medical Oncology (ESMO) Congress 2022, researchers at the Francis Crick Institute and University College London presented findings elucidating the cancer-causing mechanism of the pollutant PM2.5 particles. They found higher rates of EGFR-mutant lung cancer in people living in areas with higher levels of PM2.5 pollution. Many healthy individuals may already accumulate cells with a copy of the mutated EGFR gene, commonly found in lung cancer in people who have never smoked, which increases with age. PM2.5 incites an inflammatory response, stimulating and nudging these lung cells to proliferate and potentially form tumours.
Non-modifiable risk factors are genetics, air pollution, and previous radiation therapy for cancer.
Lung cancer types:
Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC) are the two main types of lung cancer.
- Non-Small Cell Lung Cancer (NSCLC) is the most common type, accounting for about 85% of all cases. Non-Small Cell Lung Cancer (NSCLC) is typically slower growing than Small Cell Lung Cancer (SCLC) and consists of several subtypes, including adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
Treatment for Non-Small Cell Lung Cancer (NSCLC) depends on the stage and location of the tumour and the patient's overall health. Surgery is the primary treatment modality for early-stage Non-Small Cell Lung Cancer (NSCLC), where the tumour is localised to the lung and has not spread to other body sites. The surgery may involve removing a portion of the lung (lobectomy) or the entire lung (pneumonectomy). Combination with adjuvant therapy, such as radiation therapy, chemotherapy, targeted therapy, and immunotherapy, may be indicated depending on the pathology and molecular testing of the cancer.
- Small cell lung cancer (SCLC) is a less common but more aggressive type of lung cancer, accounting for about 10–15% of all cases, and is almost always associated with cigarette smoking. Because SCLC often occurs in both lungs, surgery may or may not be the primary treatment, and adjuvant therapies are necessary. It typically responds well to chemotherapy, but since it also spreads rapidly, radiation therapy is a crucial tool to help control the spread of cancer.
Signs and symptoms of lung cancer
Early lung cancer is asymptomatic. However, once cancer progresses, symptoms may include the following:
- Persistent coughs that may produce mucus
- Hemoptysis, characterised by the expectoration of blood or blood-tinged sputum from the lungs or trachea
- Chronic chest pain
- Hoarseness
- Difficulty breathing associated with wheezing and breathlessness
- Tiredness or weakness
Lung cancer screening
- Screening for lung cancer begins with taking a patient's medical history and inquiring about their personal and family medical histories to identify any risk factors that may increase their likelihood of developing the disease. Some of the risk factors that a doctor may ask about include:
- Cigarette smoking is the leading cause of lung cancer, and patients with a smoking history are at increased risk of developing the disease.
- Occupational exposure. Exposure to some substances and chemicals in the workplace, such as asbestos or radon, can increase the risk of lung cancer.
- Family history. A family history of lung cancer may indicate a genetic predisposition to lung cancer.
- Medical history. Certain medical conditions, such as chronic obstructive pulmonary disease (COPD) or previous lung cancer, increase the risk of developing lung cancer.
- Chest X-rays, or low-dose CT (LDCT)is a way to detect lung cancer in its early stages before symptoms appear, when it is more treatable and potentially curable.
- Based on a patient's risk profile, doctors may recommend additional screening with a low-dose lung CT scan to detect lung cancer at an early stage. Early detection of lung cancer is crucial for improving treatment outcomes and increasing the chances of a full recovery.
Benefits of low-dose CT screening for lung cancer
- Low-Dose CT (LDCT) is a non-invasive imaging technique that can detect small suspicious nodules or lung lesions more effectively than a regular chest X-ray. It is fast, accurate, safe, and can detect early-stage cancer in asymptomatic patients.
- The scanner rotates around the patient, taking a cross-sectional slice of images that are subsequently computer-reconstructed into a 3D image of the lungs.
- The radiation dose of a Low-Dose CT (LDCT) is lower than the annual exposure to environmental background radiation.
- The procedure does not require special preparation or food and water restrictions before the examination.
Low-dose CT for lung cancer screening indications
- A history of heavy smoking (more than a 20-pack-year smoking history, which means smoking one pack per day for 20 years or two packs per day for ten years), and
- Currently a smoker or ex-smoker quitting within the last 15 years, and
- Ages 50–80 years old
Lung Cancer Prevention:
- Don't smoke or quit smoking right away if you're a smoker.
- Avoid indoor pollutants that can damage the lung, like second-hand smoke, chemicals, and radon.
- Minimise exposure to outdoor air pollution and occupational risks.
- Prevent colds and respiratory infections.
- Exercise regularly.
- Eat a nutritious diet.
- Get regular lung check-ups.
Primary prevention to lower the risk of getting cancer is most effective through eliminating carcinogens, particularly smoking, and implementing air pollution mitigation measures.
Author: Tasha Princeton, MD. Occupational Physician, Health Screening Centre, MedPark Hospital. Tel. +66 2023 3333.
Series Editor: Katalya Bruton, Healthcare Content Editor and Director, Dataconsult Ltd. Dataconsult’s Thailand Regional Forum at Sasin provides seminars and extensive documentation to update business on future trends in Thailand and the Mekong Region. Contact: info@dataconsult.co.th Tel: 662-233-5606/7.
