Lung Cancer: Types, Symptoms, Diagnosis, Treatment
The body is made up of millions of cells of different types sizes and functions. These are divided forming tissues and organs. When cells age or suffer some damage, they die and are replaced by new ones.
In some cases, this process may go out of control. The cells contain genetic material, which determines how each of them grows, divides and relates to the others. When this genetic material is damaged, growth and cell division gets out of control. Thus, cells do not die when they should die and new cells are created that the body does not need. These cells form what is known as a tumor, which escapes the control mechanisms of the immune system.
When the cells of this tumor have the ability to spread invading other nearby tissues, it is a malignant tumor or cancer. If the mutated cells originate in the lung, we talk about lung cancer.
Lung cancer is the second most common cancer in men and women behind prostate cancer and breast cancer respectively. Lung cancer is the leading cause of death from cancer worldwide. Every year, more people die from lung cancer than from cancers of the colon, breast, and prostate combined.
Types of lung cancer
Lung cancer is classified based on the type of cell that causes the tumor. In order to determine this nature, it is necessary to carry out a histological diagnosis, which consists of the study of a portion of tissue under a microscope.
There are mainly two different types of lung cancer:
• Small cell lung carcinoma:
Represents approximately 10-15% of lung tumors that are diagnosed and is closely related to smoking. It is usually very aggressive and spreads rapidly to other parts of the body. It tends to present a better response to chemotherapy than other types of lung cancer.
• Non-small cell lung carcinoma:
It represents approximately 85 percent of diagnosed lung tumors. It is subdivided into three types:
»Squamous Cell Carcinoma:
Represents 30% of lung cancers. They are centrally located and their growth is relatively slow causing necrosis (irreversible tissue death) and cavitation (pathological formation of cavities in tissues or organs).
Adenocarcinoma It represents upwards of 50% of cases of lung cancer and is the most common. This tumor is located in the periphery of the pulmonary tissue and can affect the pleura and the chest wall.
Large cell carcinoma:
Represents 10% of lung tumors. It has characteristics other than squamous cell carcinoma and adenocarcinoma.
Since the lung is a large organ, symptoms usually do not appear in the early stages of a tumor. Generally, when the first signs appear, the disease is already advanced. In addition, on many occasions, the symptoms caused by lung tumors are very nonspecific and are associated with other diseases.
The symptoms and signs of lung cancer are derived from local tumor growth, obstruction or invasion of adjacent structures, the involvement of regional nodes, hematogenous extrathoracic dissemination and the effects caused by biological substances produced by the tumor (paraneoplastic syndrome).
Symptoms Related to the Primary Tumor
Chronic cough is the most frequent symptom produced by lung cancer. Hemoptysis (spitting of blood) usually appears when the bronchial mucosa ulcerates. Dyspnea (respiratory distress) is also a frequent symptom, usually associated with an increase in expectoration and cough, although it can also be due to lung collapse or bronchial inflammation.
50% of patients manifest pain intermittent thoracic, but when the tumor affects the pleura the pain becomes intense and constant.
Symptoms and Signs Associated with Compression or Invasion of Intrathoracic Structures
Pleural invasion, in addition to pain, can cause dyspnea due to pleural effusion. The involvement of the chest wall usually causes intense and fixed pain, which can be increased with palpation.
The tumor of the pulmonary vertex, also called Pancoast tumor, can infiltrate the nerve roots of the brachial plexus causing shoulder pain, change in skin temperature and muscle atrophy.
Paralysis of the recurrent laryngeal nerve, either by compression or by tumor invasion, causes dysphonia, coughing and difficulty in expectoration, with the subsequent increased risk of bronchoaspiration.
The affectation of sympathetic chain causes the Horner syndrome (enophthalmos, eyelid drooping, miosis and absence of sweating in the middle of the face).
The tumor can obstruct the superior vena cava, causing the so-called superior cava syndrome (swelling of the face and neck, dilatation of the jugular vein, headache, dizziness, drowsiness and blurred vision).
Symptoms and Signs Associated with Extrathoracic Metastatic
Approximately one third of patients manifest symptoms secondary to metastasis at the time of diagnosis. Although lung cancer can metastasize to any organ, the most frequent seating sites are the bone skeleton, the liver, the adrenal glands and the brain.
The fundamental symptom of bone metastases is pain. Liver metastases usually cause symptoms such as weight loss, asthenia, jaundice, abdominal pain, among others.
Adrenal metastases are usually asymptomatic; Exceptionally, they can cause adrenal insufficiency. Brain metastases can produce headaches, vomiting, convulsions, personality changes and focal neurological alterations (ataxia, paraesthesia, paralysis of the extremities, etc).
The paraneoplastic syndrome, occurring in approximately 10% of patients with lung cancer, may represent the first manifestation of the disease or the first sign of recurrence after treatment. The paraneoplastic syndrome forms a heterogeneous group of symptoms unrelated to the physical effects of the primary tumor or metastases.
The symptoms produced are secondary to the production of biologically active substances by the tumor itself or as an organic response to it.
The syndromes can be systemic (weight loss, asthenia, fever, etc.), endocrine (hypercalcemia, syndrome of inadequate hormone secretion antidiuretic, Cushing's syndrome, etc.), neurological (Subacute cerebellar degeneration, mononeuropathy, Eaton-Lambert syndrome, encephalomyelitis, etc.), skeletal (hypertrophic osteoarthropathy), hematological (hypercoagulability, leukemoid reaction, etc.), renal (nephrotic syndrome, glomerulonephritis), Cutaneous (acanthosis nigricans, dermatomyositis, etc.) and metabolic (lactic acidosis, hypouricemia, etc.). It is important not to confuse these syndromes with metastatic disease, since can lead to adopting palliative treatment inadequate. Generally, paraneoplastic syndromes disappear with effective treatment of lung cancer.
Causes and risk factors
Smoking is the fundamental cause of lung cancer, whether in cigarettes, pipes or cigars. Between 80% and 90% of lung cancer occurs in smokers or former smokers, although there is also a risk in passive smokers. The abandonment of smoking is very important in these patients since it directly affects survival as well as the effectiveness and tolerance of the treatments.
There are factors that increase the risk of developing this type of tumor, such as advanced age and male sex. This last parameter probably related to the highest consumption of tobacco in this group. However, in the last few years, the incidence of lung cancer in women has increased, this can be attributed to the increase in smoking among women. There are other causes that can influence the development of lung cancer:
• Exposure to certain substances such as asbestos or radon.
• Environmental pollution in urban areas.
• Family history of lung cancer
The tests used to diagnose lung cancer have two purposes. First, they help the oncologist determine the exact type of tumor you have. On the other hand, they allow determining in what phase it is. An accurate diagnosis allows determining which will be the most appropriate treatment.
The following are the most commonly used techniques to diagnose lung cancer:
Imaging tests are used to determine the size, shape, and location of the tumor. They are also used to determine if there is a distant metastasis in some other organ or lymph node of the body
• Computed axial tomography
• Positron emission tomography
• Magnetic resonance
Procedures for Staging and Obtaining Samples:
Staging procedures are the diagnostic methods that allow the specialist to see directly the lung and nearby areas and, in addition, obtain samples of lymph nodes or other tissues to be able to analyze them later (biopsy and/or cytology).
• Biopsy with endobronchial ultrasound
Analysis of Tissue Samples:
Tissue samples obtained through the procedures described above are analyzed by a pathologist to determine if cancer cells exist. We must remember that the definitive diagnosis of cancer is provided by the histological study of the tissue obtained by biopsy or cytology.
The treatment of lung cancer depends on several factors:
• The stage in which the disease is found.
• The type of tumor (Small cell lung carcinoma, Non-small cell lung carcinoma, Squamous cell carcinoma, Non-squamous carcinoma)
• The individual characteristics of each patient, such as their age, other pathologies (especially associated with smoking, heart disease, respiratory problems), nutritional status, etc.
For the treatment of lung cancer, there are four therapeutic measures: surgery, radiotherapy, chemotherapy and targeted therapy (against a molecular target of the tumor). Surgery and radiotherapy are considered local therapies, while chemotherapy and targeted therapy are considered systemic since drugs are distributed throughout the body through the bloodstream. Generally, the treatment of lung cancer requires the combination of several of these therapeutic measures.
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