Lung cancer refers to abnormal division of cells and uncontrolled growth of lung tissue. It is the most common cancer in both men and female in the United States, according to the American Cancer Society. Cancer in the lungs sometimes results from spread of cancer cells from other tissues, for example the breasts. Certain lung cancers, produce substances which cause effects throughout the body. Squamous cell carcinoma of the lungs, produces PTHrP, or a protein that resembles parathyroid hormone, which causes the release of calcium from bone.
Types of Lung Cancer
There are two categories of primary lung cancers: small cell lung carcinoma, or SCLC, and non-small cell lung carcinoma or NSCLC. Small cell lung carcinoma is also known as oat cell carcinoma; it is the most aggressive kind of lung cancer that is most commonly associated with smoking. Small cell lung carcinoma is almost never found in non-smokers. Squamous cell lung carcinoma, is a non-small cell lung carcinoma that is commonly associated with elevation in blood calcium.
Risk Factors
The most common risk factor for lung cancer in the United States is cigarette smoking. A non-smoker, secondhand smoking, or inhalation of smoke from a smoker, also increases risk for cancer. Secondhand smoking is common with relatives of smokers. Exposure to asbestos leads to mesothelioma, or cancer of the lung pleura, which often spreads to the lung itself. Other risk factors include insufficient consumption of fruits and vegetables, previous history of COPD and genetics.
Symptoms of Lung Cancer
The presence of a cancerous lesion in the lungs occupies space and therefore interfere with the exchange of gases in the lung; shortness of breath is a common symptom of certain lung cancer. Hemoptysis, or coughing up blood, is caused by necrosis or death of cells in the interior of the cancer and sometimes by the invasion of blood vessels in the lung by cancer. Cancer increases the requirement of energy in the body and therefore is associated with weight loss. Other symptoms include chronic cough, difficulty swallowing, chest pain, fatigue and hoarseness of the voice.
Calcium Regulation
Calcium is regulated by the parathyroid and thyroid glands. The parathyroid gland produces parathyroid hormone which acts on bone causing the release of calcium to the blood. the thyroid gland produces calcitonin which reduces the level of calcium the blood. These two hormones help to maintain calcium at a level that is best for the body. Squamous cell carcinoma of the lung, distorts this balance of calcium by releasing a protein that resembles parathyroid hormone, thereby fooling the bones to release more calcium to the blood.
Diagnosis
An X-ray of the chest is useful when lung cancer is suspected; it can reveal obvious masses, fluid collections between the lung and chest wall, pneumonia and lung collapse. An X-ray only confirms the presence of an abnormality in the lung but doesn't tell you the type of cancer present. A CT scan offers more precise information than the x-ray and can be used as a guide for a needle biopsy. Bronchoscopy, or viewing of the bronchi, is helpful in viewing and sampling cancer within the bronchi.
