A tumor is an abnormal growth of body tissue. Tumors can be cancerous (malignant) or noncancerous (benign).
Causes, incidence, and risk factors
In general, tumors occur when cells divide and grow excessively in the body. Normally, cell growth and division is strictly controlled. New cells are created to replace older ones or to perform new functions. Cells that are damaged or no longer needed die to make room for healthy replacements.
If the balance of cell growth and death is disturbed, a tumor may form.
Problems with the body's immune system can lead to tumors. Tobacco causes more deaths from cancer than any other environmental substance. Other causes include:
- Benzene and other chemicals and toxins
- Drinking too much alcohol
- Environmental toxins, such as certain poisonous mushrooms and a type of poison that can grow on peanut plants (aflatoxins)
- Excessive sunlight exposure
- Genetic problems
Types of tumors known to be caused by viruses are:
Some tumors are more common in one gender than the other. Some are more common among children or the elderly. Others are related to diet, environment, and family history.
Symptoms depend on the type and location of the tumor. For example, lung tumors may cause coughing, shortness of breath, or chest pain. Tumors of the colon can cause weight loss, diarrhea, constipation, iron deficiency anemia, and blood in the stool.
Some tumors may not cause any symptoms. Others, such as pancreatic cancer, do not usually cause symptoms until the disease has reached an advanced stage.
The following symptoms may occur with tumors:
Signs and tests
Your doctor or nurse might see a tumor, such as skin cancer. However, most cancers cannot be seen during an exam because they are deep inside the body.
When a tumor is found, a piece of the tissue is removed and examined under a microscope. This is called a biopsy. It is done to determine if the tumor is noncancerous (benign) or cancerous (malignant). Depending on the location of the tumor, the biopsy may be a simple procedure or a serious operation.
Other tests that may be done include:
- Blood tests
- Bone marrow biopsy (most often for lymphoma or leukemia)
- Chest x-ray
- Complete blood count (CBC)
- Liver function tests
Treatment varies based on:
- Type of tumor
- Whether it is cancer or not
- Location of the tumor
You may not need treatment if the tumor is benign (noncancerous) and in a "safe" area where it will not cause symptoms or cause problems with the way an organ works.
Sometimes benign tumors may be removed for cosmetic reasons. Benign tumors of the brain may be removed because of their location or harmful effect on the surrounding normal brain tissue.
If a tumor is cancer, possible treatments include:
- A combination of these methods
If a cancerous tumor is in one location, surgery is usually performed. Surgery may also be done if the tumor has spread only to nearby lymph nodes.
If all of the cancer cannot be removed with surgery, treatment includes radiation or chemotherapy, or both. Some patients need a combination of surgery, radiation, and chemotherapy.
A cancer diagnosis often causes a lot of anxiety and can affect a patient's entire life. There are many resources for cancer patients. See: Cancer resources
The outlook varies greatly for different types of tumors. If the tumor is benign, the outlook is generally very good. However, there are some instances where a benign tumor can cause significant problems, such as in the brain.
If the tumor is malignant, the outcome depends on the type and stage of the tumor at diagnosis. Some cancers can be cured. Some that are not curable can still be treated, and patients can live for many years with the cancer. Still other tumors are quickly life-threatening.
Complications can occur if a tumor is located in a region of the body where it affects the function of the normal organ. If the tumor is malignant, it can also cause complications if it spreads (metastasizes).
You can reduce the risk of cancerous (malignant) tumors by:
- Eating a healthy diet
- Exercising regularly
- Limiting alcohol
- Maintaining a healthy weight
- Minimizing exposure to radiation and toxic chemicals
- Not smoking or chewing tobacco
- Reducing sun exposure, especially if you burn easily
Moscow JA, Cowan KH. Biology of cancer. In Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 185.
Last reviewed 9/3/2012 by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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