The lung cancer is a neoplasm that develops inrespiratory system, starting from the cells that make up the bronchi, bronchioles or alveoli. Therefore, there is not just one type of lung cancer, but different types of disease depending on the lung tissue involved. In addition, the lung can represent the site of distant secondary lesions (metastases) originating from other types of cancer (for example that of the breast). The risk of lung cancer is increased in the presence of factors such as pollution and cigarette smoking. Let's see together the causes, symptoms and possible treatments of lung cancer.
Generalities on the respiratory system
L' respiratory system is the seat of the breathing, one of the fundamental functions of the human organism, which allows the oxygenation of the blood and therefore the survival of all the vascularized tissues of the body. It is carried out through the collaboration of multiple structures, which allow the three phases of breathing: the ventilation (entry and exit of air, through the airways), the diffusion (diffusion of gases from air to blood and vice versa) and the perfusion (blood circulation within the pulmonary vessels).
These structures are essentially the rib cage, the muscles respirators, the lungs and the airways, and are composed of numerous different types of tissue, from the bone tissue of the musculoskeletal system to the thin epithelium of the alveolo-capillary membrane; in addition there are also cells responsible for endocrine functions, such as those that produce the enzyme ACE (angiotensin - converting enzyme).
Lung cancer: introduction and epidemiology
The malignant tumor to the lung it is an extremely important pathology for the number of people it affects, for its link with environmental conditions and other risk factors and above all because it is affected by a high mortality rate in both men and women.
From the Italian epidemiological point of view, lung cancer is the second type of tumor more frequent in men and third in women but rises to first place, in both sexes, as a cause of death from cancer, reaching almost 30% of total deaths from cancer. This poor survival of the tumor al lung it is due to the almost absence of initial symptoms and therefore to a diagnosis that is made only when final or late symptoms are present due to the advancement of the tumor and the possible presence of metastases.
Over the past 30 years, thanks to diagnostic and therapeutic advances, there has been one decrease of the mortality for lung cancer in both males and females, along with a decreased incidence in males and stationary in females (due to widespread cigarette smoking).
With diction "Pulmonary neoplasm" we mean, in reality, a heterogeneous group of several tumor types, united by the growth inside the lung parenchyma; what differentiates them is essentially the type of cells from which the tumor mass originates, and this difference also gives rise to a different presentation of signs and symptoms and a different therapy and prognosis.
We can therefore distinguish two large types of tumors:
- Tumor to small cells, or microcytoma (SCLC, small cell lung cancer), which originates from the neuroendocrine cells deriving from neural crest. They account for approximately 20% of cases.
- Tumor of the non-small cell lung (NSCLC, not small cell lung cancer), which derives from the epithelium, includes the 80% of lung cancer cases and is further divided into three subtypes:
- lung adenocarcinoma
- squamous carcinoma
- carcinoma to large cells.
Causes and risk factors
What are the causes of lung cancer? As with almost any type of cancer, there are no unique and defined causes of cancer, as the process that triggers the uncontrolled growth of cells can derive from a set of numerous different alterations (acquired or genetically determined) in the affected cells; for this reason it is more correct to speak of risk factors that can increase the incidence of cancer.
THE main risk factors I am undoubtedly the smoke of cigarette (active or passive) and the pollution atmospheric, which each year are considered responsible for hundreds of thousands of deaths around the world. The risk with cigarette smoking increased in correlation with the number of cigarettes smoked and the number of years they smoked, especially in people who have familiarity for lung cancer (first-degree relatives who got cancer).
Additional risk factors are the chemotherapy and exposure to radiation (radiation therapy) to treat another cancer; even the constant inhalation of particular substances for many years (radon, asbestos and others) is correlated with an increased risk of lung cancer.
Symptoms and signs
What are the symptoms of lung cancer? The first symptoms (early symptoms) can be different depending on whether the lung cancer is a lung microcytoma or a non-small cell carcinoma. Unfortunately, especially in non-small cell tumors, the extent of the manifestations is absent or scarce (because the lungs do not have nerve endings that cause pain) and often the subject does not go to the doctor, leading to a diagnostic delay that allows the tumor to grow.
Symptoms can be divided into local growth symptoms, distant metastatic symptoms, chronic disease symptoms, and paraneoplastic syndromes.
Local growth symptoms
The tumor mass can expand within the lung and cause persistent dry cough, dyspnoea, chest pain (if the pleura is affected), blood from the mouth (hemoptysis) e pleural effusion; these symptoms can also be caused by other types of cancer, for example a sarcoma that arises from the rib cage. Furthermore, if the mass of the lung cancer exceeds the pulmonary margin and involves adjacent structures, it can provoke hoarseness (for paralysis of the recurrent laryngeal nerve which allows control of the vocal cords), superior vena cava syndrome (which occurs with cape edema, headache), pericardial effusion. Rarely, symptoms emerge that characterize specific syndromes such as Pancoast syndrome and the Claude-Bernard-Horner syndrome: miosis (narrowing of the pupils), hypohidrosis (absence of sweating), ptosis (lowering of the eyelid) e enophthalmos (eyeball hollowed inwards).
All these symptoms, especially the last ones, are very late as they are present only when the tumor mass is very large.
Distant metastatic symptoms
In most cases, lung cancer metastases are due to the microcytoma, which also causes them very early. Metastases spread through the blood and lymph, and can affect the brain (headache, alterations of the consciousness, motor deficits is psychics, difficulties in word), the bones (with bone pain), The liver (jaundice, liver failure) and less frequently the adrenal gland.
Chronic disease symptoms
As in any other tumor, lung cancer can also be present asthenia (fatigue and tiredness), lack of appetite is lost of weight.
This subgroup of syndromes derives from the activity of the tumor itself, both linked to its mass and to its production of substances. Also in this case it is the microcytoma that most frequently gives paraneoplastic syndromes; the most frequent are the syndrome of Trousseau (state of hypercoagulability; present in about 10-15% of cases), hypercalcemia, production of ADH resulting in inappropriate ADH secretion syndrome (SIADH) and the resulting ACTH production syndrome of Cushing.
There diagnosis of lung cancer it can be based on clinical suspicion (when risk factors or symptoms are present) or be incidental. In the latter case, it is possible that a spot may be found on the lung on x-ray examination when a chest X-ray is taken for a reason unrelated to the lungs themselves, such as trauma.
In general, when investigating the possibility of lung cancer, it is first necessary to perform a chest X-ray (the so-called "Slab ai lungs ") to look for a lung injury. However, the finding of this does not allow a definitive diagnosis (it could be another pathology such as pneumonia, pleural effusions ...): the confirmation takes place with the execution of a Pulmonary CT (CT of the chest), and, if possible with histological examination obtained with a lung biopsy. It is also necessary to perform a staging to understand if the disease is confined only to the respiratory tract or if it has also spread to other parts of the body.
L' histological examination it consists in the study of a sample of tumor tissue obtained by biopsy (the modality of which depends on the site of the tumor) and then in the determination of the type of tumor and its histological and cytological malignancy.
There staging is the determination of the size of the lung cancer itself and the presence of any metastases to lymph nodes or other tissues; this investigation is carried out through total body CT and / or with PET-CT and bone scan as appropriate. With this method it is possible to study with high definition all the lung parenchyma, the possible involvement of lymph nodes in the pulmonary hilum and the presence of metastases in other organs.
How is lung cancer treated? First of all, the first and most important step in avoiding lung cancer is prevention: smokers must immediately stop smoking. Unfortunately, once the cancer has developed, it is irreversible and smoking cessation alone is insufficient (albeit beneficial).
The treatment of lung cancers essentially depends on the patient's condition, the type of cancer and the stage at which it has arrived. For small cell tumors, due to the high frequency with which they metastasize, it is not possible to surgery, as well as in the case of NSCLC which have already metastasized.
Based on the TNM system (tumor size, affected lymph nodes and metastases), four stages are distinguished, in turn divided into A and B: in stages 1, 2 and up to stage 3A, the tumor could still be operated on and is therefore a treatable lung cancer; in stage 3B more often non-surgical treatments are used and in the fourth stage only the chemotherapy or radiotherapy (inoperable lung cancer).
There chemotherapy it consists in the administration of certain drugs that reduce or block the growth of cells, thus preventing the tumor from growing; Chemotherapy has been shown to improve survival, especially in cases where surgery is not possible. There radiotherapy instead it consists in the irradiation of the tumor mass, with the same purpose of reducing the number of tumor cells and therefore the mass, above all improving the quality of life.
Prognosis and life expectancy
Again, the survival of lung cancer depends on the characteristics of the tumor itself. If this is diagnosed very early the expectation of life lung cancer is extremely favorable and the patient can very frequently undergo a cure, while it is very low for tumors diagnosed at stages 3 and 4, which can only be treated with a doctor; Unfortunately, the latter scenario is the one that occurs most frequently, and that is why effective screening methods (currently absent) are needed.Tags: Oncology Pneumology Lungs