Lung cancer is a tumor characterized by the breakdown of the lung's natural defense mechanisms, caused by carcinogenic stimuli over the years, leading to the disorganized growth of malignant cells.
It can attack from the trachea to the periphery of the lung. Considered one of the main causes of death among neoplasms in Brazil, with 18 thousand new cases in 2012, being the main cause of death from cancer among men and second cause among women.
The subtype of lung cancer is determined by analyzing a sample of the lesion analyzed under a microscope by a pathologist.
The main subtypes are:
Large cell undifferentiated lung carcinoma: called undifferentiated non-small cell lung cancer. It grows and spreads more slowly than small cell lung cancer but more quickly than other types of lung cancer. It can be found anywhere in the lung, which can make it more difficult to treat. Responsible for 10% to 15% of lung cancers.
Adenocarcinoma: is the most frequent currently. Responsible for approximately 40% of lung cancers. Most common type of lung cancer among non-smokers. It starts in the cells that produce mucus and other substances and tends to progress more slowly than other types of lung cancer.
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Squamous cell carcinoma: accounts for about a quarter of lung cancer cases. It begins in the cells lining the inner airways of the lungs, and is usually found in the center of the lung next to the bronchi.
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Small cell lung carcinoma: known as small cell lung cancer. It is the cancer that spreads most quickly through the lungs. It can be divided into small cell carcinoma and combined small cell carcinoma. Data indicate that 15% of all lung cancer cases are small cell, being more common in men than women. It is the most aggressive form of lung cancer, generally starting in the bronchi and with a high potential to metastasize to other parts of the body, such as the brain, liver and bone. Almost all cases of small cell lung cancer are due to smoking.
Lung cancer can be metastatic (appear as a metastasis of another cancer, such as bladder or breast cancer).
Causes
The most common cause of lung cancer is smoking for a long period of time. Other risk factors are: Inhalation of chemical agents, such as asbestos, radon, asbestos and arsenic; Inhalation of dust and air pollution; Secondhand smoke and some diseases, such as: tuberculosis and chronic obstructive pulmonary disease (COPD). A diet poor in fruits and vegetables also ends up being a risk factor. Genetic factors and family history are also part of the risk factors.
Symptoms
The initial symptoms of lung cancer are easily confused with common diseases, the most common of which are: Cough; Shortness of breathe; Wheezing in the lung; Presence of blood in the sputum; Chest pain; Rapid loss of weight and appetite may also occur in patients with lung cancer. It may also happen that the patient does not feel anything at all in the initial phase, which is considered to be a greater danger.
Diagnosis
Diagnosis in its initial phase is difficult, precisely due to the absence of symptoms. Thus, it is almost always diagnosed at an advanced stage or allocated elsewhere.
In early diagnosis, periodic imaging exams help detect the disease at a time when treatment with curative intent may still be possible.
A simple chest x-ray assists in the initial assessment. In the x-ray examination, an abnormality will lead to the need to perform a computed tomography of the chest. This exam will provide detailed information about the lungs, especially in smoker patients. If these tests reveal changes that are suspicious of cancer, a biopsy is necessary (removal of a small fragment of the suspicious area for analysis), which may confirm the presence of lung cancer.
Many tests can be used to diagnose lung cancer. The main ones are: computed tomography, bone scintigraphy and positron emission tomography (PET-CT). The latter is equipment that combines the diagnostic resources of Nuclear Medicine (PET) and Radiology (CT). All of them can help with early diagnosis, assess the extent of the disease, the effectiveness of treatment, as well as in planning radiotherapy. In some cases, procedures can even be avoided.
Also: Bronchoscopy, Bone scintigraphy, Computed tomography of the chest, Chest radiography, Cytological studies of pleural fluid or saliva, Needle lung biopsy and Surgical lung biopsy.
Treatment
The treatment with the greatest chance of control and cure is surgery. There are few candidates for a complete resection, around 10% to 20% of cases only. Among these, a small percentage clearly benefit from surgery. Radiotherapy with curative intent, whether or not associated with chemotherapy, has been reserved for patients who cannot be operated on due to technical issues, such as the location of the tumor, or clinical issues, such as the patient's health.
Non-small cell undifferentiated carcinoma can be treated with surgery, while small cell carcinoma responds better to chemotherapy and radiotherapy. In cases where the disease is metastatic, chemotherapy can be performed to increase the average survival rate compared to supportive treatment, as well as quality of life.
Prevention against lung cancer involves avoiding risk factors and increasing protective factors. Among them: avoid smoking and secondhand smoke.
