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What is Lung Cancer?

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Lung cancer is a highly prevalent disease in our environment, caused mainly by smoking. The term cancer encompasses a wide range of diseases characterised by the development of abnormal cells, which divide and grow uncontrollably. This can happen in any part of the body. When cancer starts in the lung, it is called lung cancer. Most of these tumours originate from uncontrolled growth of cells that line the bronchi and alveoli.

Following therapeutic advances in recent years, the approach to this disease has changed a lot and survival results have improved. Among the advances contributing the most to this improvement are prevention, early detection programmes and the incorporation of new treatments, such as targeted therapies and immunotherapy.

Lung anatomy

The lungs are located in the chest cavity and are responsible for maintaining the oxygenation of the blood via breathing. Air reaches the lungs through the trachea and bronchi.

The lungs are composed of thousands of tiny sacs, called alveoli, which supply oxygen and remove carbon dioxide from the blood (gas exchange). Oxygen is absorbed during inhalation and carbon dioxide is removed during expiration.

Also, the lungs are surrounded by a thin double membrane called the pleura. One membrane covers the chest cavity and the other the lung. There is a small volume of liquid between these two membranes. The two membranes are attached to each other but can also be displaced.

This property means the lungs remain attached to the chest wall while being able to expand and contract in synchronisation with each breath. The two pleural membranes are joined together in the same way that two sheets of glass can be separated by a thin layer of water; they can move over each other but it requires a lot of force to separate them.

How many people does it affect?

Together with breast cancer, lung cancer was the most frequently diagnosed tumour in the world in 2020 and was responsible for the largest number of cancer deaths. In its 2023 report, the Spanish Society of Medical Oncology (SEOM) stated that lung cancer in Spain is the third most common tumour for both men and women, with a mean age of diagnosis of 65 years.

Lung cancer is responsible for the highest number of deaths from cancer, both in Spain and worldwide. The number of new lung cancer cases diagnosed in Spain during 2023 is estimated at 31,282; and this incidence is expected to increase over the next 20 years. This increase is expected mainly in women, due to the increase in smoking in this population since the 1970s.

Types of lung cancer

Lung cancer is divided into two major types, depending on the shape of the cells causing the disease. Classification of the tumour type is an essential step before selecting treatment.

1. Small cell lung cancer (or microcytic cancer). This represents 15–20% of all lung cancers. It is characterised by its aggressive nature, rapid growth and tendency to spread extensively, including to the brain.

2. Non-small cell lung cancer. This is the most common type of lung cancer (80%).

It is further categorised into three subtypes:

Adenocarcinoma. This is currently the most common subtype of lung cancer. It tends to affect the more peripheral areas of the lung. Adenocarcinoma is characteristic of smokers; although an increased incidence is currently seen in non-smokers.
Squamous cell (epidermoid) carcinoma. After adenocarcinoma, this is the next most common subtype of lung cancer, although its incidence has decreased in developed countries. It tends to grow in a central location and occurs exclusively in smokers.
Large cell carcinoma. This is a less common subtype characterised by the large size of the cells involved. It tends to be more aggressive than other types.

Lung Cancer explained in first person

Lung cancer can be cured with surgical treatment in its earliest stages and it can be transformed into a chronic disease with new drugs that directly attack tumor cells.

You must trust in medical science. Research has changed a lot and it is constantly changing cancer treatment. There are effective treatments. It is not the end of the world because you are diagnosed with cancer, not by a long way.