Tumor
Tumor
A tumor (also known as a neoplasm) is an abnormal tissue growth. Neoplasm means new formation. Tumors can be either malignant (cancerous) or non-malignant (benign) but either type may require therapy to remove it or reduce its size. In either case the tumor’s growth is unregulated by normal body control mechanisms. Usually the growth is not beneficial to the organ in which it is developing and may be harmful.
It is not known what triggers this abnormal growth. Normally cells are generated at a rate needed to replace those that die or are needed for an individual’s growth and development. Muscle cells are added as one grows as are bone cells and others. Genetic controls modulate the formation of any given cells. The process of some cells becoming muscle cells, some becoming nerve cells, and so on is called cell differentiation. Tumor formation is an abnormality in cell differentiation.
A benign tumor is a well-defined growth with smooth boundaries. This type of tumor simply grows in diameter. A benign growth compresses adjacent tissues as it grows. A malignant tumor usually has irregular boundaries and invades the surrounding tissue. This cancer also sheds cells that travel through the bloodstream implanting themselves elsewhere in the body and starting new tumor growth. This process is called metastasis.
It is important that the physician determine which kind of tumor is present when one is discovered. In some cases this is not a simple matter. It is difficult to determine whether the growth is benign without taking a sample of it and studying the tissue under the microscope. This sampling is called a biopsy. Biopsy tissue can be frozen quickly, sliced thinly, and observed without staining (this is called a frozen section); or it can be sliced, stained with dyes, and
observed under the microscope. Cancer tissue is distinctly different from benign.
A benign tumor can be lethal if it compresses the surrounding tissue against an immovable obstacle. A benign brain tumor compresses brain tissue against the skull or the bony floor of the cranium and results in paralysis, loss of hearing or sight, dizziness, and/or loss of control of the extremities. A tumor growing in the abdomen can compress the intestine and interfere with digestion. It also can prevent proper liver or pancreatic function. The benign tumor usually grows at a relatively slow pace and may stop growing for a time when it reaches a certain size.
A cancer may grow quite rapidly or slowly, but usually is irregular in shape. It invades the neighboring tissue instead of pressing it aside. Most importantly, a cancer sheds cells, that is, metastasizes, so that new cancer growths can spring up in areas distant from the original cancer. The cancerous cells also can establish a cancer in tissue that is different from the original cancer. A breast cancer could spread to bone tissue or to liver.
Tumor removal is a surgical procedure to remove an abnormal growth. A tumor, an uncontrolled growth of cells, can be either benign, like a wart, or malignant, in which case it is a cancer. Benign tumors are well circumscribed and are generally easy to
KEY TERMS
Biopsy —The surgical removal of a small part of a tumor. The excised tissue is studied under the microscope to determine whether it is benign or malignant.
Chemotherapy —Use of powerful drugs to kill cancer cells in the human body.
Differentiation —The process by which cells take the form of a given type of tissue. That is, basic cells become muscle cells, neurons, stomach lining, kidney, or other cell types.
Metastasis —Spreading of a cancerous growth by shedding cellsthat grow in other locales.
remove completely. In contrast, cancers pose some of the most difficult problems in all of surgery. A benign tumor can be removed surgically if it is in a location that a surgeon can reach. A tumor growing in an unreachable area of the brain can be treated using radiation. It can also be treated by inserting thin probes through the brain tissue into the tumor and circulating liquid nitrogen through the probe to freeze the tumor. This operation is called cryosurgery.
A malignancy requires steps to remove it but consideration must be given to the possibility that the tumor has begun to metastasize. The main or primary tumor may be removed surgically but if the tumor has been growing for some time the patient also may require treatment with powerful drugs to kill any stray cells. This treatment is called chemotherapy. Chemotherapy allows the anti-tumor drug to be circulated throughout the body to counter any small tumor growths. Currently about 40% of all cancers are treated with surgery alone. In 55% of all cancers, surgery is combined with other treatments—usually radiation therapy or chemotherapy.
Resources
BOOKS
King, Roger, J.B., and Mike W. Robins. Cancer Biology. Harlow, UK, and New York: Pearson/Prentice Hall, 2006.
Souhami, Robert L. Oxford Textbook of Oncology. Oxford, UK, and New York: Oxford University Press, 2002.
Tannock, Ian F., ed. The Basic Science of Oncology. New York: McGraw-Hill Medical Publishing Division, 2005.
Larry Blaser
Tumor
Tumor
How Are Tumors Diagnosed and Treated?
A tumor (Too-mor) is an abnormal growth of new tissue that can occur in any of the body’s organs. Many people automatically associate tumors with the disease called cancer*, but that is not always the case.
- * cancer
- is any tumorous (TOO-mor-us) condition, the natural (untreated) course of which is fatal.
KEYWORDS
for searching the Internet and other reference sources
Cancer
Neoplasm
What Is a Tumor?
The human body is made up of many types of cells that are constantly dividing to produce new, younger cells that can “take over” for aging or damaged cells. Through this process, the body heals its injuries and keeps tissues healthy. Sometimes, this process gets out of control, and new cells continue to be produced even when they are not needed, forming a clump of extra tissue, a tumor.
There are two types of tumors:
- malignant (ma-LIG-nant), or cancerous, tumors are made up of abnormally shaped cells that grow quickly, invade nearby healthy tissues, and often make their way into the bloodstream. When these cells travel to other parts of the body, they form additional tumors.
- Benign (be-NINE) tumors are not cancer. They grow slowly and are self-contained; that is, they do not invade and destroy the tissue around them, nor do they spread to other parts of the body. Their cells are usually normally shaped.
Who Gets Tumors?
People of all ages can develop tumors, but generally they are more common as people grow older. Researchers believe that malignant tumors result from a combination of causes, the most important being genetic and environmental. People may inherit a tendency to develop certain kinds of tumors from their parents. Also, repeated exposure to harmful substances such as cigarette smoke, pollutants, and too much sunlight can damage cells and trigger the process of tumor formation.
When a tumor first starts to develop, it is so small that it does not cause symptoms. As it grows, it usually causes symptoms that vary according to its location. For instance, a tumor in the lung may cause a feeling of irritation or a nagging cough. People with brain tumors may experience headaches, dizziness, blurry vision, or lack of coordination. A person with a tumor in the colon* may notice that going to the bathroom is painful or produces blood.
- * colon
- is part of the large intestine where waste is formed and moved to the rectum, which stores it until it passes out of the body.
How Are Tumors Diagnosed and Treated?
A doctor can usually diagnose a tumor with one of many tests that create images of the inside of the body, such as x-rays, ultrasound*, CT scans*, or MRI*. The next step is to figure out whether the tumor is benign or malignant through a process called biopsy (BY-op-see). Surgeons remove part or all of the tumor and examine a sample under the microscope. The appearance of the cells will indicate whether a tumor is cancerous or not.
- * ultrasound
- is a painless procedure in which sound waves passing through the body create images on a computer screen.
- * CT scans
- or CAT scans are the shortened names for computerized axial tomography (to-MOG-ra-fee), which uses computers to view structures inside the body.
- * MRI,
- which is short for magnetic resonance imaging, produces computerized images of internal body tissues based on the magnetic properties of atoms within the body.
Even though a benign tumor is not harmful, it may have to be removed if it causes pain, pressure, or other symptoms. In many cases of a malignancy, the tumor and any affected surrounding tissue will be removed. Sometimes, radiation therapy (directed high-energy x-rays) or chemotherapy (cancer-fighting drugs) may be used to shrink the tumor.
See also
Cancer
Tobacco-Related Diseases
Resource
The National Cancer Institute, part of the U.S. National Institutes of Health (NIH), has a fact sheet, What You Need to Know about Cancer, and a book, When Someone in Your Family Has Cancer, available by phone or on its website at the pages given below. For the latter, from the Publication Index, follow the link Living with Cancer/Supporting People with Cancer. Telephone 800-422-6237 http://cancernet.nci.nih.gov/wyntk_pubs/cancer.htm http://rex.nci.nih.gov/NCI_PUB_INDEX/PUB_INDEX_DOC.html
Tumor
Tumor
A tumor (also known as a neoplasm) is an abnormal tissue growth. Neoplasm means "new formation." Tumors can be either malignant (cancerous) or nonmalignant (benign) but either type may require therapy to remove it or reduce its size. In either case the tumor's growth is unregulated by normal body control mechanisms. Usually the growth is not beneficial to the organ in which it is developing and may be harmful.
It is not known what triggers this abnormal growth. Normally cells are generated at a rate needed to replace those that die or are needed for an individual's growth and development. Muscle cells are added as one grows as are bone cells and others. Genetic controls modulate the formation of any given cells. The process of some cells becoming muscle cells, some becoming nerve cells, and so on is called cell differentiation. Tumor formation is an abnormality in cell differentiation.
A benign tumor is a well-defined growth with smooth boundaries. This type of tumor simply grows in diameter. A benign growth compresses adjacent tissues as it grows. A malignant tumor usually has irregular boundaries and invades the surrounding tissue. This cancer also sheds cells that travel through the bloodstream implanting themselves elsewhere in the body and starting new tumor growth. This process is called metastasis.
It is important that the physician determine which kind of tumor is present when one is discovered. In some cases this is not a simple matter. It is difficult to determine whether the growth is benign without taking a sample of it and studying the tissue under the microscope . This sampling is called a biopsy. Biopsy tissue can be frozen quickly, sliced thinly, and observed without staining (this is called a frozen section); or it can be sliced, stained with dyes, and observed under the microscope. Cancer tissue is distinctly different from benign.
A benign tumor can be lethal if it compresses the surrounding tissue against an immovable obstacle. A benign brain tumor compresses brain tissue against the skull or the bony floor of the cranium and results in paralysis, loss of hearing or sight, dizziness, and/or loss of control of the extremities. A tumor growing in the abdomen can compress the intestine and interfere with digestion. It also can prevent proper liver or pancreatic function. The benign tumor usually grows at a relatively slow pace and may stop growing for a time when it reaches a certain size.
A cancer may grow quite rapidly or slowly, but usually is irregular in shape. It invades the neighboring tissue instead of pressing it aside. Most importantly, a cancer sheds cells, that is, metastasizes, so that new cancer growths can spring up in areas distant from the original cancer. The cancerous cells also can establish a cancer in tissue that is different from the original cancer. A breast cancer could spread to bone tissue or to liver.
A benign tumor can be removed surgically if it is in a location that a surgeon can reach. A tumor growing in an unreachable area of the brain can be treated using radiation . It can also be treated by inserting thin probes through the brain tissue into the tumor and circulating liquid nitrogen through the probe to freeze the tumor. This operation is called cryosurgery.
A malignancy requires steps to remove it but consideration must be given to the possibility that the tumor has begun to metastasize. The main or primary tumor may be removed surgically but if the tumor has been growing for some time the patient also may require treatment with powerful drugs to kill any stray cells. This treatment is called chemotherapy. Chemotherapy allows the antitumor drug to be circulated throughout the body to counter any small tumor growths.
Resources
periodicals
Carpi, J. "Progress Against Cancer." American Health 13 (October 1994): 15-16+.
DeVita, E. "Conquering Cancer." American Health 13 (November 1994): 66-73.
Xu, D., et al. "Downregulation of Telomerase Reverse Transcriptase mRNA Expression by Wild Type in Human Tumor Cells." Oncogene 19 (26 October 2000): 53.
Larry Blaser
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Biopsy
—The surgical removal of a small part of a tumor. The excised tissue is studied under the microscope to determine whether it is benign or malignant.
- Chemotherapy
—Use of powerful drugs to kill cancer cells in the human body.
- Differentiation
—The process by which cells take the form of a given type of tissue. That is, basic cells become muscle cells, neurons, stomach lining, kidney, or other cell types.
- Metastasis
—Spreading of a cancerous growth by shedding cells that grow in other locales.
Tumor
Tumor
A tumor is an abnormal growth of tissue. Also known as a neoplasm (meaning "new formation"), a tumor can be either benign (not serious or harmful) or malignant (cancerous or deadly). Either type may require therapy to remove it or reduce its size.
It is not known what triggers a tumor's abnormal growth. The body normally creates cells only at a rate needed to replace those that die or to aid an individual's growth and development. The growth of a tumor, however, is unregulated by normal body control mechanisms.
Benign and malignant tumors
A benign tumor is a well-defined growth with smooth boundaries that simply grows in diameter. This can be harmful if the tumor compresses the surrounding tissue against a hard surface in the body. A benign brain tumor that compresses brain tissue against the skull or the bony floor of the cranium can result in paralysis, loss of hearing or sight, dizziness, and other ailments. A tumor growing in the abdomen can compress the intestine and interfere with digestion. It also can prevent the proper functioning of the liver or pancreas. The benign tumor usually grows at a relatively slow pace and may stop growing for a time when it reaches a certain size.
Words to Know
Benign: A slow-growing, self-contained tumor that is not seriously harmful.
Biopsy: The surgical removal of a small part of a tumor, which is then studied under a microscope to determine whether it is benign or malignant.
Chemotherapy: Use of powerful chemicals to kill cancer cells in the human body.
Malignant: A usually fast-growing, often fatal tumor that invades surrounding tissue and sheds cells that spread throughout the body, creating new tumors.
Metastasis: Spreading of a cancerous growth by shedding cells that grow in other locations.
Radiation therapy: Use of radioactive substances to kill cancer cells in the human body.
A malignant tumor may grow quite rapidly and can be fatal. It usually has irregular boundaries and invades the surrounding tissue instead of pressing it aside. Most important, this cancer also sheds cells that travel through the bloodstream, starting new tumor growth at other locations in the body. This process is called metastasis (pronounced me-TAS-ta-sis). The cancerous cells can establish a cancer in tissue that is different from the original cancer. A breast cancer could spread to bone tissue or to liver tissue.
Medical approaches
Benign tissue is distinctly different from cancer tissue. However, it is difficult to determine whether a tumor is benign or malignant without surgically removing a sample of it and studying the tissue under the microscope. This sampling is called a biopsy (pronounced BY-op-see).
A benign tumor can be removed surgically if it is in a location that a surgeon can reach. A tumor growing in an unreachable area of the body can be treated using radiation (by which the patient is administered radioactive substances that target a specific area and destroy cells there). Another method is to insert thin probes into the tumor and freeze it with liquid nitrogen. This operation is called cryosurgery (pronounced cry-o-SUR-jer-ee).
A malignant tumor may be removed surgically. However, if the tumor has been growing for some time and has begun to metastasize or spread, the patient also may require treatment with powerful chemicals
to kill any stray cells. This treatment is called chemotherapy (pronounced key-moe-THER-a-pee).
[See also Cancer ]
tumor
tu·mor / ˈt(y)oōmər/ (Brit. tu·mour) • n. a swelling of a part of the body, generally without inflammation, caused by an abnormal growth of tissue, whether benign or malignant. ∎ archaic a swelling of any kind.DERIVATIVES: tu·mor·ous / -mərəs/ adj.
tumour
Stuart Judge
See cancer.