Cancer develops in our cells, the body’s basic unit of life. To understand lung cancer, it is helpful to know how normal cells become cancerous.
The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as needed to keep the body healthy and functioning properly. Sometimes, however, the process goes astray — cells keep dividing when new cells are not needed. The mass of extra cells forms a growth or tumor. These abnormal cells primarily originate when the lungs are exposed to cancer causing substances (carcinogens), such as those found in cigarette smoke, asbestos and silica dust. Tumors can be benign or malignant.
Benign lung tumors are not lung cancer. They often can be removed and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body. Most important, benign tumors are rarely a threat to life.
Malignant lung tumors are lung cancer. Cells in malignant tumors are abnormal and divide without control or order. These cancer cells can invade and destroy the tissue around them. Cancer cells can also break away from a malignant tumor and enter the bloodstream or lymphatic system (the tissues and organs that produce, store, and carry white blood cells that fight infection and other diseases). This process, called metastasis, is how cancer spreads from the original (primary) tumor to form new (secondary) tumors in other parts of the body.
Types of Lung Cancer
There are two major types of lung cancers, non-small cell lung cancer and small cell lung cancer, depending on how the cells look under a microscope. Each type of lung cancer grows and spreads in different ways and is treated differently.
Lung cancer refers to malignant tumors that originate in the lung itself. A cancer of lung lining or pleura is called mesothelioma and is a different type of cancer.
Small cell lung cancer
About 20 out of every 100 lung cancers diagnosed are small cell lung cancer Which is so called because the cancer cells are small cells that are mostly filled with the nucleus (the control centre of cells). Small cell cancer can also be called ‘oat cell’ cancer. This type of cancer is usually always caused by smoking. It is not common for someone who has never smoked to develop it. Small cell lung cancer often spreads quite early so doctors often suggest treatment with chemotherapy rather than surgery.
Non-small cell lung cancer
There are three types of non-small cell lung cancer. These are grouped together because they behave in a similar way and respond to treatment differently to small cell lung cancer. The three types are:
• Squamous cell carcinoma
• Large cell carcinoma
Secondary cancer is cancer that has spread from somewhere else in the body. There are quite a few different cancers that can spread to the lungs, including breast cancer and bowel cancer.
It is important to know what you are dealing with so that you can find the right information. The choice of cancer treatment depends on where the cancer started. When cancer spreads to the lung from the breast, the cells are breast cancer cells, not lung cancer cells. So they respond to breast cancer treatments. And cancer that has spread from the bowel should respond to bowel cancer treatments.
• A cough that doesn’t go away and gets worse over time
• Constant chest pain
• Coughing up blood
• Shortness of breath, wheezing, or hoarseness
• Repeated problems with pneumonia or bronchitis
• Swelling of the neck and face
• Loss of appetite or weight loss
These lung cancer symptoms may be caused by lung cancer or by other conditions. It is important to check with a doctor.
To help find the cause of lung cancer symptoms, the doctor evaluates a person’s medical history, smoking history, exposure to environmental and occupational substances such as asbestos, and family history of cancer. The doctor also performs a physical exam and may order a chest x-ray and other tests. If lung cancer is suspected, sputum cytology (the microscopic examination of cells obtained from a deep-cough sample of mucus in the lungs) is a simple test that may be useful in detecting lung cancer. To confirm the presence of lung cancer, the doctor must examine tissue from the lung. The removal of a small sample of tissue for examination under a microscope by a pathologist can show whether a person has lung cancer. A number of procedures may be used to obtain this tissue:
• Bronchoscopy. The doctor puts a bronchoscope (a thin, lighted tube) into the mouth or nose and down through the windpipe to look into the breathing passages. Through this tube, the doctor can collect cells or small samples of tissue.
• Needle aspiration. A needle is inserted through the chest into the lung cancer tumor to remove a sample of tissue.
• Thoracentesis. Using a needle, the doctor removes a sample of the fluid that surrounds the lungs to check for cancer cells.
• Thoracoscopy. Surgery to open the chest is sometimes needed to diagnose lung cancer. This procedure is a major operation performed in a hospital.
Lung cancer treatment depends on a number of factors, including the type of lung cancer (non-small or small cell lung cancer), the size, location, and extent of the tumor, and the general health of the lung cancer patient. Many different treatments and combinations of treatments may be used to control lung cancer, and/or to improve quality of life by reducing symptoms.
• Surgery is an operation to remove the cancer. The type of lung cancer surgery a doctor performs depends on the location of the tumor in the lung. An operation to remove only a small part of the lung is called a segmental or wedge resection. When the surgeon removes an entire lobe of the lung, the procedure is called a lobectomy. Pneumonectomy is the removal of an entire lung. Some tumors are inoperable (cannot be removed by surgery) because of the size or location, and some patients cannot have surgery for other medical reasons.
• Chemotherapy is the use of anticancer drugs to kill cancer cells throughout the body. Even after cancer has been removed from the lung, cancer cells may still be present in nearby tissue or elsewhere in the body. Chemotherapy may be used to control cancer growth or to relieve symptoms. Most anticancer drugs are given by injection directly into a vein (IV) or by means of a catheter, a thin tube that is placed into a large vein and remains there as long as it is needed. Some anticancer drugs are given in the form of a pill.
• Radiation Therapy, also called radiotherapy, involves the use of high-energy rays to kill cancer cells. Radiation therapy is directed to a limited area and affects the cancer cells only in that area. Radiation therapy may be used before surgery to shrink a tumor, or after surgery to destroy any cancer cells that remain in the treated area. Doctors also use radiation therapy, often combined with chemotherapy, as primary treatment instead of surgery. Radiation therapy may also be used to relieve symptoms such as shortness of breath. Radiation for the treatment of lung cancer most often comes from a machine (external radiation). The radiation can also come from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation).
• Photodynamic therapy (PDT), a type of laser therapy, involves the use of a special chemical that is injected into the bloodstream and absorbed by cells all over the body. The chemical rapidly leaves normal cells but remains in cancer cells for a longer time. A laser light aimed at the cancer activates the chemical, which then kills the cancer cells that have absorbed it. Photodynamic therapy may be used to reduce symptoms of lung cancer — for example, to control bleeding or to relieve breathing problems due to blocked airways when the cancer cannot be removed through surgery. Photodynamic therapy may also be used to treat very small tumors in patients for whom the usual treatments for lung cancer are not appropriate.