Lung cancer is one of the most common causes of global cancer incidence and mortality, accounting for 2,094,000 cases in 2018 and 1,761,000 deaths in 2018.1 Despite its prevalence, many people still have questions regarding lung cancer. This article aims to answer some of the most frequently asked questions about lung cancer.
Cancer is defined as uncontrolled cell growth that can lead to death through the disruption of organs. Cancer is a genetic disease, arising from DNA damage which can lead to mutations that result in changes in the DNA sequence. These mutations alter the cell's ability to grow, multiply, and die at the appropriate time. Often, cancerous mutations occur in oncogenes, genes that accelerate cancer growth/division, which are activated in a gain-of-function manner. Tumour suppressor genes act as a brake on cancer growth, which acts in a loss-of-function manner. This causes damaged cells to divide uncontrollably, forming solid masses (tumours) that disrupt organ function.
The lungs are crucial for gas exchange, allowing oxygen into the body and expelling carbon dioxide. Lung cancer can begin in the windpipe, lung tissue, or bronchus. Lung cancers that start in the lung are known as primary tumours, while cancer that spreads to the lung from other body parts are secondary cancers.
The main types are non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). About 80% to 85% of cancers are NSCLC,2 which includes subtypes such as adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. SCLC accounts for roughly 10% to 15% of lung cancers.3 SCLC is more aggressive, spreads more quickly than NSLC, and is often diagnosed late, with 70% of patients already in stage IV at the time of diagnosis.4
Most frequently, the symptoms described within the literature are persistent cough, coughing up blood, chest pain, shortness of breath, swelling of lymph nodes, weight loss, fatigue, fever, and aching pain.5
Less common symptoms include changes in the appearance of your fingers (more curved on the end of the finger becoming larger), difficulty swallowing, wheezing, and a hoarse voice. Lung cancer may present all these symptoms, and some people may not experience symptoms early on. It’s recommended to seek medical assistance if you have any of the main symptoms of lung cancer or any of the less common symptoms.
The biggest risk factor for lung cancer is tobacco smoke, which contains 69 carcinogens (agents capable of causing cancer). Tobacco smoke is responsible for approximately 90% of lung cancer risk in people assigned male at birth (AMAB) and 70 to 80% in people assigned female at birth (AFAB).6 Other risk factors include second-hand smoke, asbestos, age, radon gas, and other carcinogens. Genetic factors also play a role; several studies show that having a family history of lung cancer increases an individual’s risk of developing the disease.7
The median age of lung cancer diagnosis in the USA is 71 years old (8), which is relevant to most other parts of the world. Ageing is one of the important risk factors for cancer overall.
Lung cancer is often diagnosed through imaging tools such as X-rays, CT, and PET scans. A chest X-ray is usually conducted first to detect a solid mass (tumour), which will appear as white-grey matter. To further confirm the presence of cancer, a CT scan, which uses X-rays to generate three-dimensional images of the inside of your body, may be conducted. A PET scan may also be used.
If the imaging tools show cancer in the central part of your chest, a bronchoscopy may be conducted to see inside the airways and remove a small sample of cells (biopsy) for examination.
Early detection of lung cancer significantly improves the chances of successful treatment and survival. Low-dose CT (LDCT) scans are recommended for high-risk individuals, such as long-term smokers and those with a family history of lung cancer. Regular screening can help detect lung cancer at an earlier stage, making it more treatable and potentially allowing for surgery to remove the tumour (this is known to be the most successful way to ‘cure’ cancer). Furthermore, studies show lung cancer screening reduces the risk of dying of lung cancer.
The common system to divide cancer into stages is the TNM system, which is an internationally accepted system used to characterise the stage of the disease. TNM is an acronym for T being the size and location of the main tumour, N is the number of lymph nodes that have cancer, and M refers to whether the cancer has metastasised.
NSCLC goes from stage 0-IV. In stage 0, the tumour is small and only in the top of the lining of the lung or bronchus, stage I cancer is still in the lung tissue but hasn’t spread to the lymph nodes, in stage II the tumour has grown, and starts to spread to the nearby lymph nodes (IIA and IIB), stage III cancer has spread to the lymph nodes in the chest area, and lastly stage IV is the most advanced stage and cancer has spread (metastasized) to distant parts of the body. Cancer metastasis is responsible for approximately 90% of cancer deaths.9
SCLC has 2 stages. There is a limited stage, in which the cancer cells can be seen in one lung and the nearby lymph nodes. Secondly, there is an extensive stage, in which the cancer has spread out the lung usually to the chest area or other parts of the body.
Treatment varies based on the type of cancer (NSCLC or SCLC), the stage at which the cancer is, and your general health. Patients are assessed individually for what might work best for them as opposed to using a ‘one size fits all’ approach. Common treatments include:
Supportive care is also important for people suffering from lung cancer. It aims to address the physical, practical, emotional, and spiritual challenges of cancer. Supportive care increases the quality of life for people with lung cancer and their families.
Most cases of cancer, let alone lung cancer, can be prevented! However, for lung cancer, the reduction is significantly reduced by avoiding smoking or quitting smoking. It’s believed up to 20% of all cancers worldwide could be prevented by eliminating tobacco smoking.10 Also, population studies show a 50% decrease in lung cancer risk after quitting smoking for 5-6 years.11 However, it is important to note that you are still at risk of developing lung cancer even if you don’t smoke. Avoid second-hand smoke, radon, and carcinogens at work such as exposure to elements like asbestos, silica, and heavy metals, eat a healthy balanced diet with fruit and vegetables, and exercise regularly.
This article aimed to address some of the frequently asked questions about lung cancer, providing support and reliable information for those affected by the disease. Understanding lung cancer can help make better decisions, with early detection, treatment advances, and ongoing research offering hope for better outcomes.
