Lung Cancer: Causes, Symptoms and Screening

Lung cancer is one of the most common types of cancer, with more than 43,000 people in the UK being diagnosed every year. Early diagnosis is key to improving survival rates, yet many people are not aware of the symptoms or the importance of screening if you are at higher risk.

In this guide, we’ll explain what lung cancer is, the risk factors and symptoms to look out for, and how screening with a low-dose CT scan can help detect the disease at an earlier, more treatable stage.

What is lung cancer?

The lungs are two sponge-like organs in the chest that form part of your respiratory system. They draw in oxygen when you breathe and remove carbon dioxide from your blood when you exhale.

Lung cancer begins when abnormal cells in the lung grow uncontrollably. These cells can form tumours, interfere with normal lung function, and in some cases spread (metastasise) to other parts of the body.

Types of lung cancer

There are two main types of lung cancer:

• Non-small cell lung cancer (NSCLC) is the most common type, making up about 85–88% of all lung cancers. Subtypes include adenocarcinoma and squamous cell carcinoma.
• Small-cell lung cancer (SCLC) is a faster-growing, more aggressive type, usually linked to smoking. It accounts for about 12% of cases.

Adenocarcinoma is a non-small cell lung cancer that is more commonly found in women and non-smokers, and it’s the most common type of lung cancer for people under 45. The incidence of adenocarcinoma of the lung is on the increase in the UK, and it is now one of the most common types of lung cancer.

Adenocarcinoma accounts for approximately 50% of all non-small cell lung cancers. It begins in the outer sections of the lung (although it can occur as central lesions), which can make it difficult to detect in the early stages of the disease. It develops from lung cells that produce mucus, and, unlike many other types of lung cancer, it is more likely to remain in one area, giving better opportunities for treatment.

Lung cancer symptoms

In most cases, people with early stages of lung cancer will have no signs or symptoms.

Symptoms may develop as the disease progresses over time. Any symptoms that are present will vary depending on how advanced the cancer is and its position.

The main symptoms of lung cancer to look out for include:

• Loss of appetite
• Unexplained fatigue and weakness
• Unintentional weight loss
• A persistent cough or a change in a long-standing cough
• Persistent breathlessness or shortness of breath
• Headaches
• Coughing up blood (phlegm with blood in it)
• Aches or pains when breathing or coughing
• Persistent chest infections that don’t respond to medical treatment

The following symptoms are less common and are usually associated with the more advanced stages of lung cancer:

• Difficulty swallowing (dysphagia)
• A hoarse voice
• Finger clubbing – changes to the shape of the fingers and fingernails
• Swelling of the face and neck, which may be due to obstruction of the venous drainage
• Persistent pain in the chest and/or shoulder
• Pain and swelling in the joints
• Bone pain

Many of these signs and symptoms can also be caused by other medical conditions, so are not always indicators of cancer. Nevertheless, if you have any of these symptoms, it’s important to always see a doctor. Lung cancer is much easier to treat when detected early.

Lung cancer causes and risk factors

Anything that can increase your chance of getting a disease, such as lung cancer, is called a risk factor.

The single and most significant cause of lung cancer is smoking, which is linked to around 72% of cases.  

Even occasional or light smoking increases the risk of lung cancer, and your risk goes up the longer and more you smoke. Exposure to second-hand smoke, even if you don't smoke yourself, can also increase your risk of lung cancer.

In addition to smoking, key risk factors that can increase your chance of developing lung cancer include:

·      Family History

A family history of lung cancer in a first-degree relative (parent/sibling/child) is associated with a two-fold increased risk, independent of smoking. Lung cancer is more common in White people than in Black or Asian people.

·      Exposure to radon gas

Radon gas is a naturally occurring radioactive gas that comes from the breakdown of tiny amounts of uranium in rock, soil and water. As radon gas is produced, it goes into the air and enters your lungs as you breathe, increasing your risk of developing lung cancer.

Unsafe levels of radon gas can build up in homes and other buildings, and certain areas of the UK, such as the southwest of England, have been identified as having higher-than-average levels.

·      Exposure to certain chemicals

Exposure to carcinogenic (cancer-causing) chemicals and materials such as asbestos, silica and diesel engine exhaust fumes can increase the risk of lung cancer. People who are often exposed to high levels of these substances include workers in industries such as construction, glassmaking, bricklaying, mechanics and transportation.

·      Air pollution

Outdoor air pollution is responsible for causing around 1 out of 10 lung cancer cases in the UK. Your personal risk depends on the levels of air pollution you’re regularly exposed to.

·      Previous radiation therapy

Your risk of developing lung cancer may be increased if you've had radiotherapy to your chest for another type of cancer in the past.

·      Previous lung disease

Having lung diseases, including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), in the past can increase your risk of developing lung cancer compared to those who have not had a previous lung condition.

Reducing your risk of lung cancer

While not all cases of lung cancer can be prevented, you can reduce your risk by:

• Not smoking or stopping smoking (this is the single most effective step you can take)
• Avoiding second-hand smoke
• Reducing exposure to harmful chemicals and pollutants
• Maintaining a healthy lifestyle with a balanced diet and regular exercise

Why should I get tested for lung cancer?

As with all cancers, survival rates for lung cancer depend on the stage at which the disease is detected, as well as other general factors such as your general health and sex.

Regular screening is key to early detection of lung cancer, which is vital to successful treatment and increased survival rates.

How is lung cancer diagnosed?

If lung cancer is suspected, your doctor may arrange tests such as a chest X-ray, CT scan, PET scan or biopsy. Identifying lung cancer early makes treatment more effective and greatly improves survival.

Currently, there is no national screening programme for lung cancer in the UK. However, targeted lung health checks and low-dose CT (LDCT) scans are available for people at higher risk.

Lung cancer screening

A low-dose CT scan is the most effective way to detect lung cancer at an early stage, even before symptoms appear. It uses a lower level of radiation than a standard CT scan and can spot minor abnormalities in the lungs.

Screening is particularly recommended for:

• People aged 50 and over
• Current or former smokers
• Those with other risk factors, such as a strong family history of lung cancer

If you fall into one of these groups, regular screening could significantly increase the chance of detecting lung cancer early when treatment is more successful.

Lung cancer stages

The stage of cancer indicates how big it is and if it has spread to other areas of the body. By identifying the stage, you have helped your doctor devise the most suitable and effective treatment plan for you. The stage also gives some idea of your prognosis.

• Stage 1 – In the first stage, lung cancer is usually small and is contained in the lungs (hasn’t spread to other areas of the body).
• Stage 2 – In stage 2 lung cancer, a tumour is usually larger than in stage 1. In most cases, the cancer hasn’t spread to the surrounding tissue, but stage 2 can mean that cancer cells have spread into lymph nodes close to the tumour.
• Stage 3 – At stage 3, the cancer is larger, there are cancer cells in the lymph nodes nearby, and it may have started to spread into surrounding tissues.
• Stage 4 – If you have stage 4 lung cancer, this means that your cancer has spread from your lungs into other areas of your body. This stage is also called secondary lung cancer or metastatic lung cancer.

The stage of your cancer will be determined during testing, most often through scans including CT, MRI, PET and bone scans.

Lung cancer treatment

The treatment you’ll need depends on the type and stage of lung cancer you have as well as your general health. Before you start treatment, a specialist team will meet to discuss the best treatment plan for you.

Treatments for lung cancer may include surgery, radiotherapy, chemotherapy, targeted drug therapy, immunotherapy or a combination of these.

Before you start treatment, your doctor will take you through what each option entails and explain any side effects. Together, you’ll also discuss anything you should consider when making treatment decisions.

How can I get tested for lung cancer?

Check4Cancer’s Lung Cancer Screening Test is available to people over 50 years old who have no symptoms, but a history of heavy smoking.

You don't need a referral from your GP - contact us and you will be provided with access to a low-dose CT scan at one of a network of clinics located around the UK, so you can attend whichever clinic is most convenient to you.

The low-dose CT scan is quick, painless and is performed by experienced radiographers. The scans are then analysed, and you will be provided with your detailed report within 3 - 4 weeks. 

Should there be any concerns, we will ensure you know what to do next and will provide you with the necessary support.  

Remember - an abnormal result does not necessarily mean you have lung cancer. But it's always better to know.