What Is a Tumor?

A tumor, also known as a neoplasm, is an abnormal lump or growth that forms in or on the body. This abnormal mass of tissue forms when cells grow and divide too quickly or do not die quickly enough. Tumors can form anywhere in the body. 

Tumors are considered either noncancerous (benign) or cancerous (malignant). Benign tumors are usually not serious and do not spread to other areas of the body. Malignant tumors often spread quickly and can invade other areas of the body. 

A tumor is usually diagnosed by a physical exam and biopsy. Treatment options can vary widely and depend on the type of the tumor and its size and location. 

Types of Tumors

A tumor can be cancerous, noncancerous, or precancerous. The treatment plan will depend on which type of tumor you have and how advanced it is. 

Malignant Tumors

Malignant tumors are cancerous. Cancer is relatively common and affects up to 1 in 3 people in the United States. There are many types of cancer, which are classified depending on where the cancer cells are located. 

Malignant tumors tend to grow quickly and have irregular borders. They invade surrounding tissues and can spread throughout the body through the blood or lymph system. 

Malignant tumors can grow anywhere in the body. Common sites include:

• Skin (basal or squamous cell carcinoma)
• Brain (glioblastoma)
• Bones (osteosarcoma)
• Colon 
• Breasts
• Lungs
• Pancreas 
• Ovaries 
  

Premalignant Tumors

Premalignant tumors are tumors that are benign but could become cancerous over time. Once identified, premalignant tumors are either monitored closely or removed. 

Common sites for premalignant tumors include:

• Colon (colon polyps) 
• Skin (actinic keratosis)
• Breast (ductal carcinoma in situ)

Benign Tumors

Benign tumors are noncancerous and are often not serious. They tend to grow slowly and do not invade surrounding tissues or areas of the body. 

A benign tumor may need to be removed if it presses on or compresses an area of the body. For example, if a tumor presses on your windpipe (trachea), it needs to be removed because it can affect your ability to breathe. 

Common areas where benign tumors grow include:

• Bones (osteoma)
• Brain 
• Uterus (uterine fibroids)
• Soft tissue (lipomas)

Causes

Tumors form when a mass of cells clump together and grow in or on the body. This can occur when certain cells grow and divide more than they should. It may also occur when cells do not die and be replaced when they should. 

Normally, the body is able to control when cells form, grow, and die. New cells are supposed to replace older ones. When this balance is thrown off, a tumor can form. 

Risk factors for developing a tumor include:

• Tobacco use
• Autoimmune disorder (a condition caused by the immune system attacking healthy cells in the body)
• Chemical exposures, such as to benzene and other toxins
• Environmental exposures, such as to poisonous plants or poor air quality
• Radiation exposure
• Viruses 
• Genetic disorders
• Heavy alcohol use
• Excessive sunlight exposure 
  

Symptoms of Tumors

Symptoms of tumors vary by their type, location, and size. Some tumors do not cause symptoms until they have grown to an advanced stage. Examples include esophageal cancer and pancreatic cancer. Other types of tumors cause symptoms early on. 

Possible symptoms of tumor include:

• A lump or a thickening, hard area under the skin
• Fever
• Chills
• Fatigue
• Pain or discomfort
• Loss of appetite 
• Unexplained weight loss
• Night sweats 
• Skin changes, such as yellowing or darkening of the skin or sores that are slow to heal

Diagnosis

A tumor may be detected during a physical exam. Your healthcare provider may be able to see a tumor on your skin or in your mouth. They may also be able to feel (palpate) it during an exam. 

Once your provider suspects a tumor, they will likely send you for a biopsy. 

A biopsy is a medical test that removes cells or tissue to be examined under a microscope. A biopsy may be performed by a surgeon or other specialist. For example, a skin biopsy is usually performed by a dermatologist, a medical doctor who specializes in the diagnosis and management of skin diseases. 

Once your cells or tissue has been removed, the sample will be examined by a pathologist, a medical doctor who specializes in the diagnosis of laboratory techniques to study diseases. The purpose of a biopsy is to determine if your tumor is cancerous. 

Other diagnostic tests that you may require include:

• Blood tests 
• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• Positron emission tomography (PET) scan
• Chest X-ray
• Liver function tests
• Bone marrow biopsy 

How Are Tumors Treated?

Treatment for a tumor depends on the type of tumor, as well as its size, location, and how advanced it is. Most benign tumors are not treated unless they are causing symptoms. For example, if a benign tumor is large enough to compress an organ, it may need to be removed. 

Precancerous tumors are often removed to ensure that they do not become cancerous. Malignant tumors usually require treatment to prevent further spread and damage. 

Treatment for malignant tumors may include:

• Chemotherapy: A powerful drug treatment used to kill cancerous cells. The drugs are cytotoxic, meaning they can kill tumor cells.
• Radiation therapy: This therapy uses beams of intense radiation—usually X-rays—to kill cancerous cells.
• Surgery: Surgery can be performed to remove the cancerous cells from your body. Normally a secondary treatment, such as chemotherapy or radiation therapy, is recommended in order to ensure all the cancer cells have been eliminated.
• Immunotherapy: This type of biological therapy uses substances to help fight the cancer.
• Targeted cancer therapy: This therapy targets and attacks the proteins in cancer cells that help them grow and spread.

Outlook

The outlook for a tumor depends on several factors. When determining your prognosis, your healthcare provider will consider the type of tumor, whether it is malignant, its location, and its size. 

Small, benign tumors often have an excellent outlook and usually do not require any treatment other than monitoring. A benign tumor that is growing may require intervention to prevent it from affecting other organs and tissues. 

The outlook for a malignant tumor depends on which type of cancer is causing it and how advanced the disease is. Some forms of malignant tumors can be safely removed and cured. Others may have already spread and will be more difficult to treat. Talk with your healthcare provider about your individual prognosis and which steps to take. If you have a malignant tumor, you will likely be referred to an oncologist—a doctor who specializes in cancer.

A Quick Review

A tumor is an abnormal mass of tissue that forms in or on the body. It forms when cells grow too quickly or do not die normally. Tumors can form anywhere in the body. They are usually grouped into one of two types: benign or malignant. Benign tumors are noncancerous and often harmless. Malignant tumors are cancerous and may grow and spread quickly. 

Tumors are usually diagnosed with a physical exam, biopsy, and other medical tests. The treatment plan depends on the type of tumor and its size and location.