Lung cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs is a type of cancer that develops in the lungs, which are the primary organs of our respiratory system and allow us to breathe. The lungs are a pair of cone-shaped organs that are located under our ribcage.
The respiratory system is composed of the nose, mouth, tracheathe tube that connects your voicebox (larynx) to the lungs, also known as a windpipe and airways (bronchi and bronchioles) that lead to the lungs, which is where the breathing process primarily occurs. Each lung is made up of lobes, with the right lung being composed of three lobes and the left only having two lobes to accommodate room for the heart. The lungs sit on top of a muscle called the diaphragm, which separates the abdomenstomach, stomach area, belly from the chest. The diaphragm works by contracting/flattening when we inhale, pulling air into the lungs. When we exhale, the diaphragm relaxes and pushes air out of the lungs. The space between the lungs is called the mediastinumthe space between the lungs that holds many important structures, including the heart, trachea and oesophagus, and holds several important structures, including the heart, trachea, oesophagus and lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid. Each lung is covered by a layer of tissuea group of cells that work together to perform a function called the pleuraa thin layer of tissue covering the lungs and the wall of the interior chest cavity.
Lung cancer is more common in males, and is generally diagnosed over the age of 65. However, anyone can develop this disease.
Types of Lung Cancer
There are several types of lung cancer, which are categorised by their cellular appearance under the microscope.
Non-small cell Lung Cancer (NSCLC)
Non-small cell lung cancer (NSCLC) is the most common form of lung cancer. Cancer cellsthe basic structural and functional unit of all living things look larger than regular cells, and may take the form of:
- Adenocarcinomacancer arising from mucus-producing glands in organs, which is commonly found in the outer parts of the lungs.
- Squamous cell carcinomacancer arising from tissues that line organs (cancer arising from squamous cells that line organs), which is commonly found in large airways.
- Large cell undifferentiated carcinoma (cancer that is not an adenocarcinoma or a squamous cell carcinoma), which can begin in several parts of the lungs.
This type of lung cancer tends to be less aggressive than small cell lung cancers, and often have lower metastasiswhen the cancer has spread to other parts of the body, also known as mets rates.
Small cell Lung Cancer (SCLC)
Small cell lung cancer (SCLC), or oat cell carcinoma, is the less common type of lung cancer. Cancer cells often look smaller than NSCLCs, and usually begin in the bronchi. SCLCs are a type of neuroendocrine tumoura tissue mass that forms from groups of unhealthy cells. SCLCs tend to be more aggressive and have higher metastasis rates.
Lung Neuroendocrine Tumours
Lung neuroendocrine tumours (NETS), also known as bronchopulmonary NETS, pulmonary NETs or lung carcinoid tumours, are a group of neuroendocrine tumours that develop in within the lungs. For more information on lung NETs, please refer to the Rare Cancers Australia Lung Neuroendocrine Tumours page.
Paediatric Lung Cancer
In rare cases, lung cancer may be diagnosed in children and adolescents. There are two main types of lung cancers that affect these age groups: pleuropulmonary blastoma and tracheobronchial tumours.
Pleuropulmonary Blastoma
Pleuropulmonary blastoma is the most common type of childhood lung cancer. It often develops in the tissues of the lung and the pleura, but can develop in the organs located in the mediastinum such as the heart, trachea and oesophagus.
Childhood Tracheobronchial tumours
Tracheobronchial tumours are a very rare type of cancer that develop in the lining of the trachea or the bronchi. These types of cancers most commonly occur as a carcinoma, but may also appear as a inflammatory myofibroblastic tumour, rhabdomyosarcoma or a granular cell tumour.
Some information regarding types of lung cancer was obtained from the Childhood Tracheobronical Tumours (PDQ) and Pleuropulmonary Blastoma (PDQ) pages, which were published by the National Cancer Institute.
Treatment
If lung cancer is detected, it will be staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodea small lump or mass of tissue in your body) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localisedaffecting only one area of body cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advancedat a late stage, far along or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Genetic testing
Genetic testing (which is also known as genomic testing, genetic panel testing, biomarker testing and/or molecular testing) is the process of analysing the genetics of your tumour to determine which treatment options have the greatest chance of success. These tests often look for genetic mutations, biomarkers (properties of particular cells), environmental factors, or potentially other unknown factors. Understanding the mutations of cancer cells has changed the way cancer is treated, and has resulted in the development of many different treatment options that may be beneficial in the ongoing development of treatments and outcomes for all cancer research.
The most common genetic mutations associated with lung cancer include:
- EGFR (epidermal growth factor receptor).
- ALK (anaplastica term used to describe abnormal cancer cells that grow uncontrollably in the body and have little or no resemblence to regular cells lymphomacancers of the lymphatic system kinase).
- ROS1 (reactive oxygen species 1).
- KRAS (Kirsten rat sarcomacancer arising from bones and/or soft tissue viral oncogene homolog).
Each of these genes play an important role in regulating/initiating cell growth and division, and so a mutation in these genes may drive abnormal cell growth.
The presence of a genetic mutation may indicate how your tumour will react to certain treatments, and many can be treated by targeted therapies. However, genetic mutations may not always be present in patients with lung cancer. In these instances, your doctor may recommend other treatment options, such as chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells, immunotherapya treatment that uses a person's immune system to fight cancer, or a combination of both.
Treatment options
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for lung cancers may include:
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
- Pneumonectomycomplete removal of affected lung.
- Lobectomya surgical procedure where a lobe of an organ (e.g. the lung) is removed.
- Segmentectomy (lung)removal of a portion of a lobe of the lung or wedge resectiona surgical procedure where a small, triangular portion of tissue or organ is removed.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Chemotherapy.
- Immunotherapy.
- Home oxygen therapya treatment that increases the amount of oxygen in the blood to assist people with breathing difficulties.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Treatment for SCLC does not often include surgery. Due to its aggressive nature, the tumour has often metastasised to other parts of the body, commonly the lymph nodes, before it is diagnosed. In rare cases, where the cancer has been caught early and has not metastasised, surgery may be used to treat SCLC.
Risk factors
The riskthe possibility that something bad will happen factors for developing any type of lung cancer include:
- Tobacco/cigarette smoking.
- Second-hand or passive smoke.
- Exposure to asbestos.
- Exposure to hazardous workplace substances, such as:
- Radon (radioactive gas).
- Arsenic.
- Cadmium.
- Steel.
- Nickel.
- Diesel.
- Silica.
- Exposure to air pollution.
- Having a family history of lung cancer.
- Having a personal history of any type of cancer.
- Increasing age.
- A history of chronica long-lasting disease that changes slowly over time lung diseases, including chronic obstructive pulmonary disease and pulmonary fibrosis.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
Early-stage lung cancers may appear asymptomatic, or with a vague set of symptoms. As the tumour progresses, some of the following symptoms may appear:
- Persistent cough (lasting more than a few weeks).
- Coughing or spitting up bloodthe red bodily fluid that transports oxygen and other nutrients around the body.
- Dyspneadifficulty breathing, shortness of breath.
- Changes in a cough you have experienced for a long time.
- Persistent chest infections.
- Chest and/or shoulder pain.
- Hoarse voice.
- Fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
- Unexplained weight loss.
- Loss of appetite.
- Wheezing.
- Difficulties swallowing.
- Abdominal and/or joint pain.
- Enlarged fingertips (finger clubbing).
Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.
Diagnosis
If your doctor suspects you have lung cancer, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Imagingtests that create detailed images of areas inside the body tests, potentially including:
- Chest x-raya type of medical imaging that uses x-ray beams to create detailed images of the body .
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- PET (positron emission tomography) scana type of medical imaging that uses radioactive tracers to create detailed images of the body.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Pulmonary function testa test that examines how well your lungs are working.
- Sputum cytologyan examination of sputum (or mucus) from your lungs to see if any cancer cells are present.
- Thoracentesisa procedure that drains the fluid from your lungs using a needle.
- Exploratory surgeryan exploratory surgical procedure used for conditions that cannot be confirmed by scans and tests alone, potentially including:
- Bronchoscopyan examination of the trachea and lungs with a small, flexible instrument known as a bronchoscope.
- Mediastinoscopyexamination of the mediastinum (area between the lungs) with a small, flexible instrument called a mediastinoscope .
- Thoracoscopyexamination of the inside of the chest cavity with a small, flexible instrument known as a thorascope.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
