Lung cancer - Risk Factors, Symptoms, Prognosis. Types of Lung cancers
Lung cancer is the most commonly diagnosed cancer worldwide.
The vast majority (85%) of cases of lung cancer, are due to long-term tobacco smoking.
But, About 10–15% of cases occur in people who have never smoked.
Lung cancer, a highly invasive, rapidly metastasizing and prevalent cancer, is the top killer cancer in both men and women in the United States of America.
Signs and symptoms.
Respiratory symptoms: coughing, coughing up blood, wheezing, or shortness of breath.
Systemic symptoms: weight loss, weakness, fever, or clubbing of the fingernails
Symptoms due to the cancer mass pressing on adjacent structures: chest pain, bone pain, superior vena cava obstruction, or difficulty swallowing.
Many of the symptoms of lung cancer, (poor appetite, weight loss, fever, fatigue) are not specific.
Symptoms of metastatic disease include weight loss, bone pain, and neurological symptoms (headaches, fainting, convulsions, or limb weakness).
Common sites of spread include the brain, bone, adrenal glands, opposite lung, liver, pericardium, and kidneys.
Risk Factors:
The most common age at diagnosis is 70 years. In most countries the five-year survival rate is around 10 to 20%.
Tabaco smoking is the major risk factor for Lung Cancer.
The risk of lung cancer secondary to passive smoking increases by 20 to 30%.
Other risk Factors include.
Outdoor air pollutants, especially chemicals released from the burning of fossil fuels, increase the risk of lung cancer.
Outdoor air pollution is estimated to cause 1–2% of lung cancers.
Indoor air pollution in relation to the burning of wood, charcoal, dung, or crop residue for cooking and heating.
it is believed to result in 1.5% of lung cancer deaths.
About 8% of lung cancer cases are caused by inherited (genetic) factors.
Other factors include radiation for non-lung cancer treatment, especially non-Hodgkins lymphoma and breast cancer.
Exposure to metals such as chromium, nickel, arsenic, and polycyclic aromatic hydrocarbons is also associated with lung cancer.
Lung diseases like idiopathic pulmonary fibrosis increase the risk of lung cancer independent of smoking.
Asbestos and radon are established risk factors for lung cancer as well.
There are several common type of lung cancer.
Squamous cell lung cancers represent about 25%–30% of cases.
Nearly 40% of lung cancers are adenocarcinomas, which usually come from peripheral lung tissue.
Although most cases of adenocarcinoma are associated with smoking, it is also the most common form of lung cancer among people who never smoked.
Small cell lung cancers derived from the hormonal cells of the lung, are the most dedifferentiated cancers. and comprise 10%–15% of all lung cancers.
Small cell lung cancers are extremely aggressive and disseminating rapidly, with a rapid fatal spread.
Diagnosis:
Chest radiograph (x-ray).
Computed tomography (CT) .
CT imaging is also used to provide more information about the type and extent of disease. Bronchoscopic or CT-guided biopsy is often used to sample the tumor for histopathology.
Prevention:
The major method of prevention is the avoidance of risk factors, including smoking and air pollution.
Vitamin C supplementation might reduce the risk of lung cancer.
Vitamins A, B, and E may increase the risk of lung cancer in those who have a history of smoking.
Some studies suggest that people who eat food with a higher proportion of vegetables and fruit tend to have a lower risk.
Treatment:
Treatment for lung cancer depends on the cancer's specific cell type, how far it has spread, and the person's performance status.
Common treatments include palliative care, surgery, chemotherapy, and radiation therapy.
Most cases are not curable.
Prognosis.
Non-Small Cell Lung Cancer have the best prognosis.
Surgical resection of stage-IA disease, with up to 70% five-year survival.
Small Cell Lung Cancer average five-year survival rate is less than 1%.
Adenocarcinoma is deadly with overall 5-year survival of 12%.
For Stage 1 disease, 5-year survival varies from 70% to 85%.
But if already distant metastases, less than 5% survive five years.
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