What is Lung Cancer and the Treatment Options?
First, some background on the way the body is built. Organs, like the heart, liver, and lung, are made up of tissues, such as blood vessels and muscle. Tissues, in turn, are made up of cells. Cells are the basic building blocks of tissue.
Cancer results from the abnormal proliferation, or repeated divisions, of cells. The rapidly dividing cells of a cancer grow in number, developing into a tumor, or mass. A lung cancer develops when a group of cells in the lung begins dividing rapidly, and creates an enlarging mass within the lung. The size of the mass may double as quickly as every 30 days, or as slowly as every 400 days, depending upon the type of cells that are dividing, and on other factors. Different types of lung cancer originate from different types of cells. These different types of cells are identified by examining the cells under a microscope, and performing special tests on the cells.
If not treated early, most lung cancers have a tendency to eventually spread to other areas of the body. Cancers can spread through the lymphatic system to the regional lymph nodes (tiny filters in the lymphatics), or through the blood, usually to bones or to the brain. The location of distant spread is called a metastasis. The degree of spread of the cancer is known as the “stage” of the lung cancer. The stages of lung cancer are discussed below.
What are the Risk factors for Lung Cancer?
The primary risk factor for lung cancer is cigarette smoking, and exposure to cigarette smoke. Eighty-seven percent of patients with lung cancer have a history of tobacco exposure. The exposure can be either from smoking cigarettes, or from inhaling second hand smoke. The risk of lung cancer goes up with the number of cigarettes smoked per day, and the duration of use of tobacco. This is measured typically as pack-years, or the number of packs per day, times the number of years of smoking.
Other risk factors for lung cancer include exposure to environmental agents such as asbestos and radon, and exposure to other industrial products. Asbestos exposure is linked to a tumor of the pleura called mesothelioma. However, the combination of smoking and asbestos exposure generates a risk factor for lung cancer that is greater than the simple sum of the relative risks. Asbestos was used in the past as an insulation material, and in automobile brake pads, and was frequently used in shipyards. Radon is a naturally occurring gas, a byproduct of the breakdown of uranium. Radon can be found in up to six percent of homes in the US. It is most frequently found in unventilated basements, and in concrete buildings. Home tests for radon are commercially available.
There are a number of other carcinogens (cancer causing agents) that are believed to be associated with lung cancer, and are reviewed elsewhere.
What is the Incidence of Lung Cancer?
Lung cancer is the most frequent cause of death from cancer in both men and women. Lung cancer is responsible for more cancer deaths in men than all other cancers combined. In the late 1980’s, the incidence of lung cancer in women surpassed the incidence of breast cancer due to the increasing use of tobacco by women.
The incidence of lung cancer can be reduced in large populations by reducing the use of cigarettes. In England, the lung cancer rate in men from ages 35 – 54 has dropped 50% in 30 years due to the development of non-smoking programs. An individual can reduce his or her own risk by 50% by not smoking for 10 years.
What are the Symptoms of Lung Cancer?
Most patients early in the course of lung cancer have no symptoms. The cancer grows silently when it is very small. However, some patients will develop symptoms of a persistent cough, hemoptysis (coughing up blood), recurrent pneumonia, weight loss, wheezing, fever, or pain. Sometimes a lump develops in the neck or armpit. A few lung cancers secrete hormones or proteins that cause signs or symptoms.
By the time most lung cancers are discovered, 85% have spread beyond the ability of the surgeon to remove them. Therefore, prevention, or early detection, when the cancer can still be removed, is important.
What are the Different Categories of Lung Cancer?
There are two general categories of lung cancer: small cell and non-small cell. The categories are divided this way because they act differently and are treated differently.
Small cell carcinoma
• One basic type
• Usually spreads early in the course
• Stages: limited or extensive
• Treated with chemotherapy
Non-small cell carcinoma
• Three basic types – Adenocarcinoma, Squamous cell carcinoma, Large cell carcinoma
• Usually spreads later in the course
• Stages: I, II, III, IV
• Treated with surgery, chemotherapy, and/or radiation therapy, depending on the stage
What are the Stages of Lung Cancer?
The amount a cancer has “spread” in the lung is measured by its “stage.” The further cancer cells have spread from the original mass, or the larger the cancer, then the higher the stage.
The stage of a cancer determines the treatment that is selected for that particular cancer, and the prognosis. The higher the stage, the greater the spread. The greater the spread, the worse the prognosis.
Non-small cell cancer is staged using the TNM staging system. TNM refers to T for tumor size, N for node status, and M for the presence or absence of metastases. In general, there are Stages I, II, III, and IV.
- Stage I is a tumor that is localized to the lung, and has no lymph node involvement.
- Stage II is a tumor that has lymph node involvement inside the lung only, or a tumor which has grown directly into another nearby structure, such as the chest wall.
- Stage III is a tumor that has spread to the lymph nodes in the mediastinum (the center of the chest between the lungs.)
- Stage IV is a tumor that has spread anywhere outside the confines of the chest. That is, tumor which has spread to the adrenal glands, bones, ribs, brain, or elsewhere.
How is Lung Cancer Diagnosed?
The true diagnosis of lung cancer can only be made by looking at cells from a mass or lymph node under a microscope. There are a number of diagnostic tests that are performed in preparation or in pursuit of making a tissue diagnosis.
Chest X-ray: The chest x-ray, also known as a chest radiograph or CXR, is a screening test for lung cancer. Many cancers are initially detected on a routine chest radiograph that is taken for an annual physical or in the process of evaluating another medical problem.
CT scan of the chest: The CT scan is also known as a CAT scan, or computerized axial tomography. This scan takes only a few minutes to perform, and gives a very detailed image of the anatomy of the chest and lungs. It is used to evaluate the location and size of tumors in the chest, and is used to evaluate the size and location of lymph nodes in the chest. In addition, the adrenal glands are usually evaluated with this test, because the adrenal glands are an area where lung cancer can spread early in its course.
PET Scan: A PET scan is a test using injectable radioactive material which is detected by a special camera. The most frequent PET scan used for the lung measures the relative metabolism of glucose by tissues in the body. Infections, inflammation, and cancers use more glucose than surrounding tissues. This area of increased utilization of glucose appears to the camera as more intense radioactivity than surrounding areas on the scan (a “hot spot.”). The PET scan is not perfect at predicting cancer. It only creates significant suspicion of cancer. In contrast, a PET scan that does not show increased activity in a lung tumor is very reliable. The chance of the nodule being a cancer in such a scan is very, very low.
Bone Scan: A bone scan is a test using injectable radioactive material that is detected by a special camera. The bone scan is used to detect abnormal areas in the bones of the body. Sometimes these areas are abnormal due to arthritis or other changes, and sometimes due to spread of cancer to the bone. If an abnormality is detected by bone scan, then further investigation into the abnormal area may be necessary.
CT Directed Needle Biopsy: When a lung tumor is located far away from the airways, and cannot be reached by bronchoscopy and biopsy, another test may be performed. This test is performed by a Radiologist with the use of a CT scanner. The tumor is precisely located by using a CT scan. With the patient still in the CT scanner, local anesthesia (numbing medicine) is injected into the patient’s skin. Then, a small needle is advanced directly into the lung tumor, and tumor cells are aspirated into a syringe, and then examined under a microscope. In the vast majority of cases, there are no complications from a CT directed needle biopsy. Occasionally a small amount of air leaks from the lung into the chest, and the air must be removed by placing a small drain into the chest for several hours or a for a day.
What Surgical Techniques are Available for the Treatment of Lung Cancer?
Depending on the stage of Lung Cancer different operations can be performed. A Thoracis Surgeon, is a surgeon who specializes in these types of procedures. Such operations include: