Clearing The Air: Should You Be Concerned About Lung Cancer? (Part 1)
For most people, regular screening for lung cancer is not necessary. Unlike screening for breast and colorectal cancer, it is recommended that only those at risk get screened for lung cancer. Read on to find out why, and to understand the risk factors for lung cancer.
Introduction
Lung cancer is the third most common cancer in Singapore, accounting for just 14% and 7.5% of all cancer cases in men and women, respectively. Nevertheless, it is unfortunately the leading cause of cancer deaths both here and worldwide, being responsible for 26.4% and 15.5% of cancer deaths in men and women, respectively (2014 to 2018 Singapore figures).
Among the three leading cancer types in Singapore, lung cancer has the lowest 5-year survival rate at 29.3%. This may be compared with an 82% 5-year survival rate for breast cancer and a 61% 5-year survival rate for colorectal cancer.
Types of Lung Cancer
There are two major types of lung cancer.
Small Cell Lung Cancer (SCLC), strongly associated with cigarette smoking, is more aggressive and makes up 10–15% of lung cancer cases. It grows and spreads quickly to other parts of the body, including the lymph nodes.
Non-Small Cell Lung Cancer (NSCLC) is less aggressive but more common. It arises from epithelial cells that line the surface of the lung. NSCLC includes three main types:
Squamous cell carcinoma makes up 30% of all NSCLC sub-types. It is often linked to a history of smoking and tends to be found near a main airway in the central part of the lungs. It starts in the flat squamous cells that line the inside of the airways.
Adenocarcinoma is the most common sub-type to be diagnosed in people who have never smoked. It is also more common in women and younger people. It evolves from the mucosal glands that produce mucus, and is more likely to be found before it has spread.
Large cell carcinoma can appear in several types of large cells in any part of the lung, and tends to spread quickly. A sub-type known as large cell neuroendocrine carcinoma is a fast-growing cancer very similar to SCLC.
Risk Factors For Lung Cancer
Smoking cigarettes, pipes, or cigars is the major risk factor for both SCLC and NSCLC. However, 10–20% of lung cancers are found in people who have seldom or never smoked.
Besides smoking, other risk factors include:
Secondhand smoke (exposure to other people’s smoke)
Air pollution
Family history of lung cancer
Asbestos
Radon
You can reduce your risk by staying away from secondhand smoke, diesel exhaust, and various forms of air pollution. Some factors like family history cannot be controlled, in which case you can consult your doctor about preventive measures.
Prevention Of Lung Cancer
Besides regular exercise and a diet high in fruits and vegetables, the best way to minimise the risk of lung cancer is to avoid smoking. There are several approaches:
Primary prevention: If you don’t smoke, don’t start.
Secondary prevention: If you smoke, stop. If you are a non-smoker, avoid secondhand smoke.
Screening: If you are between 55 and 74 years old, have smoked 30 or more pack years (number of packs a day multiplied by years of smoking), and quit less than 15 years ago or are still smoking, consider screening via a low-dose CT scan.
Lung cancer screening is not recommended for non-smokers as the costs of false positives, over-diagnosis, and radiation outweigh the benefits. Screening is recommended only for those who fall into the at-risk group.
Conclusion
If you fall into the at-risk group, do ask your doctor about screening options for lung cancer. For the rest of us, simply take steps to avoid or minimise exposure to smoking, and adopt a healthy diet and lifestyle.
Read Part 2 to find out more about the signs and symptoms of, and treatment for, lung cancer.
