Probiotics and cancer - The Probiotic Solution - Excerpt

Townsend Letter for Doctors and Patients, June, 2002 by Mark A. Brudnak

From the forthcoming book: The Probiotic Solution

Cancer is a group of many related diseases that begin in cells, the body's basic unit of life. To understand cancer, it is helpful to know what happens when normal cells become cancerous.

The body is made up of many types of cells. Normally, cells grow and divide to produce more cells only when the body needs them. This orderly process helps keep the body healthy. Sometimes, however, cells keep dividing when new cells are not needed. These extra cells form a mass of tissue called a growth or tumor.

Tumors can be benign or malignant.

* Benign tumors are not cancer. They can often be removed and, in most cases, they do not come back. Cells from benign tumors do not spread to other parts of the body. Most important, benign tumors are rarely a threat to life.

* Malignant tumors are cancer. Cells in these tumors are abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer spreads from the original cancer site to form new tumors in other organs. The spread of cancer is called metastasis. Leukemia and lymphoma are cancers that arise in blood-forming cells. The abnormal cells circulate in the bloodstream and lymphatic system. They may also invade (infiltrate) body organs and form tumors.

Most cancers are named for the organ or type of cell in which they begin. For example, cancer that begins in the lung is lung cancer, and cancer that begins in cells in the skin known as melanocytes is called melanoma.

When cancer spreads (metastasizes), cancer cells are often found in nearby or regional lymph nodes (sometimes called lymph glands). If the cancer has reached these nodes, it means that cancer cells may have spread to other organs, such as the liver, bones, or brain. When cancer spreads from its original location to another part of the body, the new tumor has the same kind, of abnormal cells and the same name as the primary tumor. For example, if lung cancer spreads to the brain, the cancer cells in the brain are actually lung cancer cells. The disease is called metastatic lung cancer (it is not brain cancer).

Possible Causes and Prevention of Cancer

The more we can learn about what causes cancer, the more likely we are to find ways to prevent it. In the laboratory, scientists explore possible causes of cancer and try to determine exactly what happens in cells when they become cancerous. Researchers also study patterns of cancer in the population to look for risk factors, conditions that increase the chance that cancer might occur. They also look for protective factors, things that decrease the risk.

Although doctors can seldom explain why one person gets cancer and another does not, it is clear that cancer is not caused by an injury, such as a bump or bruise. In addition, although being infected with certain viruses may increase the risk of some types of cancer, cancer is not contagious; no one can "catch" cancer from another person.

Cancer develops over time. It is a result of a complex mix of factors related to lifestyle, heredity, and environment. A number of factors that increase a person's chance of developing cancer have been identified. Many types of cancer are related to the use of tobacco, what people eat and drink, exposure to ultraviolet (UV) radiation from the sun, and, exposure to cancer-causing agents (carcinogens) in the environment and the workplace. Some people are more sensitive than others to factors that can cause cancer.

Still, most people who get cancer have none of the known risk factors. In addition, most people who do have risk factors do not get the disease.

Some cancer risk factors can be avoided. Others, such as inherited factors, are unavoidable, but it may be helpful to be aware of them. People can help protect themselves by avoiding known risk factors whenever possible. They can also talk with their doctor about regular 'checkups and about whether cancer-screening tests could be of benefit.

These are some of the factors that increase the likelihood of cancer:

* Tobacco. Smoking tobacco, using smokeless tobacco, and being regularly exposed to environmental tobacco smoke are responsible for one-third of all cancer deaths in the United States each year. Tobacco use is the most preventable cause of death in this country.

Smoking accounts for more than 85% of all lung cancer deaths. For smokers, the risk of getting lung cancer increases with the amount of tobacco-smoked each day, the number of years they have smoked, the type of tobacco product, and how deeply they inhale. Overall, for those who smoke one pack a day, the chance of getting lung cancer is about 10 times greater than for nonsmokers. Cigarette smokers are also more likely than nonsmokers to develop several other types of cancer, including oral cancer and cancers of the larynx, esophagus, pancreas, bladder, kidney, and cervix. Smoking may also increase the likelihood of developing cancers of the stomach, liver, prostate, colon, and rectum. The risk of cancer begins to decrease soon after a smoker quits, and the risk continues to decline gradually each year after quitting.