Definition of lung cancer
The human respiratory tract is composed of the nasal cavities, the trachea and the two lungs. Its role is to provide oxygen and expel carbon dioxide, via the mechanisms of inhalation and exhalation. Air is breathed in through the mouth, arrives in the trachea and is transported to the bronchi and then the bronchioles. The oxygen then circulates into the alveoli. It is through the pulmonary alveoli that the oxygen is taken into the blood system, from where it is distributed to the various cells and organs. The exhalation mechanism corresponds to the same journey, but in the opposite direction. That is, from the alveoli to the trachea, then the nasal cavities and the mouth. It is carbon dioxide (CO2) that takes this path.
The lungs can be affected by different forms of tumour:
- Benign tumours. These can form and focalise in a single area. They will only have a very low impact on the person’s health, and their symptoms can sometimes even be absent.
- Malignant tumours. These are harmful and put the patient’s health at risk. They develop in particular in the cells of the bronchi, or in the pulmonary alveoli.
There are two types of tumour responsible for lung cancer (malignant tumours):
- Primary tumours, whose original site of development is the lungs.
The cancer can then spread to other organs, forming metastases.
- Secondary tumours: their site of origin is an organ that is not the lungs. The cancer has thus spread from its site of origin to the lungs. The migration of the cancer can occur through the blood or lymphatic tissue.
Certain elements encourage the development of lung cancer:
- Smoking remains the primary cause at the origin of lung cancer.
- Certain causes vary from one individual to another. A genetic predisposition and age are thus factors that have an effect on lung cancer.
- Exposure to certain toxic substances, particularly at work, can play a part in triggering lung cancer. Asbestos, nickel, chromium or ionising radiation thus play a role in triggering lung cancer.
All these causes (smoking, toxic substances and pollutants) have an even greater incidence on triggering a future case of lung cancer if the duration of the patient’s exposure, and the quantity, is longer.
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A modified general state of health and breathing problems are two common symptoms of lung cancer.
They come in the following forms:
- Loss of appetite and weight loss.
- Severe and persistent fatigue.
- Chronic cough, or aggravation of a pre-existing cough.
- Intense pain (in bouts or continuously).
- Lung infections: bronchitis, pneumonia.
- Coughing up blood (bloody sputum).
Less common symptoms can also raise the alarm for the development of lung cancer. Alterations to the tone of voice and losing one’s voice for longer than normal are symptoms that can indicate lung cancer. Wheezing, trouble swallowing, breathing difficulties and a drooping or weak eyelid are also symptoms of lung cancer. Compression of the trachea (wheezing), pressure on the oesophagus (trouble swallowing), and the presence of fluid in the pleural cavity (breathing difficulties) are the problems behind the manifestation of the symptoms of lung cancer.
Today, lung cancer can be treated in 3 possible ways: thoracic surgery, chest radiation therapy, and medical treatments (chemotherapy and targeted biotherapies).
A single type of treatment for lung cancer can be prescribed, as well as a combination of two treatments. It will all depend on how advanced the lung cancer is, its localisation and the general state of health of the patient.
Surgery and radiation therapy are thus recommended for local action on lung cancer. These modes of treatment focus on the cancer site (tumour) alone, as well as its direct environment. The medical name for this type of treatment is “loco-regional treatments”.
On the contrary, so-called “systemic” treatments, which include chemotherapy and targeted biotherapies, act on the cancer cells throughout the body.
Thoracic surgery is a treatment that consists in removing the cancerous pulmonary tumour surgically. Depending on the type of cancer and how advanced it is, a lung lobe or the whole lung may be removed. Radiation therapy consists in subjecting the cancer cells to ultraviolet rays, which destroy them.
Chemotherapy is drugs that can be taken either in the form of a perfusion, or orally. Their action is to destroy the cancer cells by targeting their cell division process.
Targeted biotherapy is a drug-based treatment for lung cancer with an action that differs from that of chemotherapy. The drugs prescribed do not attack the cell division mechanism, but rather the development process, which is specific to cancer cells.
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