Lung cancer

Lung cancer is a swift killer. Of the 172,570 people who were diagnosed with lung cancer in the United States in 2005 only 15 percent will survive for five years.

Lung cancer is the third most common type of cancer in the United States (after prostate cancer and breast cancer). Yet due to its bleak outcome, it is the number-one killer among cancer patients. According to the American Lung Association, lung cancer caused an estimated 160,440 deaths in 2004, accounting for 28.5 percent of all cancer-related deaths.

These statistics are even more shocking when we consider that at the beginning of the twentieth century lung cancer was virtually an unknown disease.

But lung cancer can be stopped.

Unlike other forms of cancer that strike seemingly at random or are linked to a genetic susceptibility (hereditary trait) we can do nothing about—at least not for the moment, many studies have demonstrated the direct correlation between smoking and lung cancer. The American Lung Association estimates that smoking causes 90 percent of cases of lung cancer. This means that the power to stop lung cancer before it starts is quite literally in our hands.

What is Cancer?

The word cancer comes from the Greek word karkinos meaning crab. Hippocrates, the great Greek physician (460-370 B.C.) who is considered the father of modern medicine, gave it this name because the tumors that are the visible evidence of many types of cancer reminded him of a crab, with a central body (the tumor or lump) from which several rays— the legs—spread into the surrounding tissue.

Cancer is an ancient disease. Mummies some 2,500 years old have been discovered in Peru with lumps that clearly suggest cancer as the cause of death. Pictures found in the walls of ancient Egyptian tombs depict human figures with tumors.

Yet until the twentieth century cancer was a rare disease. One of the reasons for this is that cancer needs time to grow, which means that it appears predominantly in older people. Until recently, not many people lived to old age. They were more likely to die young from accidents, malnutrition, hard physical work, infectious diseases, and, in the case of women, childbirth.

During the twentieth century the discovery of antibiotics, better nutrition, and general improvement in work conditions and health care helped eliminate many of these causes of death. With more people living longer, the number of cases of cancer increased.

Types of Cancers

Cancer is a general term for abnormal cell division and growth. This means cancer is not a single disease but many— as many as there are different types of cells in the human body. In medical terms, the 150 or so different cancers that have been found to date are grouped into five types, according to the kind of tissue in which they develop. These types are carcinoma, sarcoma, leukemia, lymphoma, and myeloma.

Carcinomas are cancers that develop in the epithelial cells that cover the skin, mouth, nose, throat, and lung airways, as well as the genitourinary and gastrointestinal (GI) tracts. They also cover glands such as the breast and thyroid. Carcinomas are tumors. The most common carcinomas are in the lung, breast, prostate, skin, stomach, and colon.

Sarcomas form in bones or in soft connective and supportive tissues such as cartilage, muscles, tendons, fat, and the outer lining of the lungs, abdomen, heart, central nervous system, and blood vessels. Since soft tissues can be found in every organ, sarcomas can occur anywhere in the body. Sarcomas are also tumors.

Leukemias, lymphomas, and myelomas are not tumors.

Leukemias are a group of cancers of the cells of the blood and bone marrow (the soft part inside the bones where blood cells originate). There are three types of blood cells: red blood cells that transport oxygen; platelets that protect against bruising and bleeding; and white blood cells, or leukocytes, that fight infections. Leukemias are characterized by an abnormal production of leukocytes. Depending on the type of leukocytes that become cancerous, leukemias are classified as myeloid or lymphoid, terms which derive from two types of leukocytes, the neutrophils and lymphocytes.

Myeloid cells help form neutrophils, which are the leukocytes that play a role in the early stages of the body’s defense against microorganisms. Neutrophils are macrophages; that is, they engulf and eliminate foreign matter, bacteria, and debris from cells that have been destroyed by infection. Lymphoid cells give rise to lymphocytes, the leukocytes that make up the second line of the body’s defense against foreign molecules.

Lymphomas, as you’ll learn below, usually occur when lymphocytes grow out of control. Leukemias are also classified as acute or chronic. Acute leukemias are more aggressive and can quickly lead to death. Without rapid treatment, most patients will die in days or weeks. Chronic leukemias grow more slowly and may not cause obvious problems for years. Lymphomas are cancers that develop in the lymphatic system, a basic part of the immune system defending the body against disease. The lymphatic system consists of a complex network of channels that carries lymph, a fluid rich in different types of leukocytes, or white blood cells. The lymphocytes are found either clustered in lymph nodes, or glands, or circulating through the bloodstream and in lymphatic vessels. When a lymphoma develops, the lymph glands or other organs swell where healthy lymphocytes are normally found, and lumps appear throughout the body.

One specific kind of lymphoma is called Hodgkin’s disease. All other kinds are referred to as non-Hodgkin’s lymphomas. There are many varieties of both Hodgkin’s disease and non-Hodgkin’s lymphomas.

Multiple myeloma is a cancer of the plasma cell, a type of B lymphocyte responsible for producing antibodies (complex proteins that fight infection).Myeloma is a rare disease (1 percent of all cases of cancer) characterized by the growth of malignant plasma cells, mostly in the bone marrow.

Lung cancer is a carcinoma that affects the lungs. The role of the lungs is to draw oxygen from the air and to expel toxic carbon dioxide. Every cell in our body needs oxygen to stay alive. Without oxygen, we would die in minutes. When the lungs do not work properly, every part of the body suffers. That is why lung cancer is such a deadly disease.

Is a tumor always cancer?

Not all tumors are cancer. A tumor is a mass of cells that does not belong to the tissue where it is growing and has no function. Some, like freckles, moles, and warts, are harmless. Harmless tumors are called benign. Cells in a benign tumor look and act more like normal cells. They are differentiated, which means they become a specific type of cell and will grow and spread more slowly than undifferentiated cells. Benign tumors grow slowly and do not move from the place where they have formed. Because they are usually encapsulated by connective tissue, they have smooth edges.

Cancers are malignant tumors: tumors with no clear-cut borders, in which the cells divide with no control, invade surrounding tissues, develop a network of blood vessels to get nourishment, and eventually spread to other places in the body.

Not all types of cancer form tumors. In leukemias, for instance, the cancer cells are abnormal white blood cells, or leukocytes, that circulate freely in the bloodstream.

This entry was posted on Sunday, August 1st, 2010 at 10:12 am and is filed under Lung Cancer. You can follow any comments to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.