A tumor is a solid mass of tissue that forms when abnormal cells group together. Tumors can affect bones, skin, tissue, organs and glands. Many tumors are not cancer (they’re benign). But they still may need treatment. Cancerous, or malignant, tumors can be life-threatening and require cancer treatment.


What is a tumor?

A tumor is a mass or group of abnormal cells that form in the body. If you have a tumor, it isn’t necessarily cancer. Many tumors are benign (not cancerous).

Tumors can form throughout the body. They can affect bone, skin, tissues, glands and organs. Neoplasm is another word for tumor.


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What’s the difference between a tumor and a cyst?

A tumor is a solid mass of tissue. It may or may not be cancerous.

A cyst is a small sac that may contain fluid, air or solid material. The majority of cysts are not cancerous.

What are the types of tumors?

A tumor may be:

  • Cancerous: Malignant or cancerous tumors can spread into nearby tissue, glands and other parts of the body. The new tumors are metastases (mets). Cancerous tumors can come back after treatment (cancer recurrence). These tumors can be life-threatening.
  • Noncancerous: Benign tumors are not cancerous and are rarely life-threatening. They’re localized, which means they don’t typically affect nearby tissue or spread to other parts of the body. Many noncancerous tumors don’t need treatment. But some noncancerous tumors press on other body parts and do need medical care.
  • Precancerous: These noncancerous tumors can become cancerous if not treated.

Types of malignant tumors

Types of cancerous tumors include:

Types of benign tumors

Common noncancerous tumors include:

Types of precancerous tumors

Precancerous tumors include:


Symptoms and Causes

What causes a tumor?

Your body is constantly making new cells to replace old or damaged ones that die off. Sometimes, the cells don’t die off as expected. Or, new cells grow and multiply faster than they should. The cells start to pile up, forming a tumor.

What are the risk factors for tumors?

Tumors affect people of all ages, including children. Factors that increase the chances of developing a tumor include:


What are the symptoms of a tumor?

Symptoms of a tumor vary depending on where the tumor develops and whether it’s cancerous. You may be able to feel the mass, as with a breast lump.

You may experience:

Diagnosis and Tests

How are tumors diagnosed?

Your healthcare provider performs a biopsy to determine whether a tumor is cancer. A biopsy involves removing cell samples from a tumor. A pathologist (a medical doctor who studies diseases) examines the samples in a lab to make a diagnosis. If a tumor is in an area that’s difficult to reach, your provider may remove the entire tumor and then do a biopsy.

You may also get one or more of these tests:

Management and Treatment

How are tumors treated?

Treatments for a tumor depend on many factors, including the tumor type (malignant or benign) and location.

Many noncancerous tumors don’t need treatment. But some benign tumors can continue to grow. For example, benign brain tumors can press against healthy tissue, affecting vision or speech. Your healthcare provider may recommend surgery to remove the tumor.

Treatments for cancerous tumors include:

  • Surgery to remove the tumor.
  • Chemotherapy to shrink the tumor before surgery or destroy lingering abnormal cells after surgery.
  • Immunotherapy to engage the immune system to fight cancer.
  • Radiation therapy to destroy abnormal cells.
  • Targeted therapy to slow or stop the growth of cancer cells.


How can I prevent tumors?

Most tumors occur for no known reason. Still, these steps may lower your risk of developing a tumor:

Outlook / Prognosis

What are the complications of tumors?

Benign tumors may grow and put pressure on organs like the brain. Endocrine tumors may not be cancerous but may cause your body to overproduce hormones. You may need surgery to remove the tumor.

Cancer cells can break away from the original tumor. The cells may travel in the bloodstream (circulatory system) or lymphatic system. When cells settle in a new location like an organ or gland, they start multiplying again, creating a new tumor (metastatic cancer). Cancer that spreads can be more challenging to treat.

Living With

When should I call my doctor?

You should call your healthcare provider if you experience:

  • Extreme fatigue.
  • Lump or mass anywhere on the body.
  • Severe pain that interferes with sleep or daily activities.
  • Unexplained weight loss.

What questions should I ask my doctor?

You may want to ask your healthcare provider:

  • Is the tumor malignant or benign?
  • What type of tumor do I have?
  • What is the best treatment for me?
  • What are the treatment risks and side effects?
  • Should I look out for signs of complications?

A note from Cleveland Clinic

It can be upsetting to learn that you have a tumor. You should know, though, that many tumors are benign and don’t need treatment. If a tumor is cancerous, there are a lot of treatment options. Receiving prompt treatment can make a big difference. Cancer therapies can destroy cancer cells, prevent them from spreading and lower the risk of cancer coming back. Often, people live many years after receiving treatment for cancerous tumors. Your healthcare provider can discuss your treatment options with you.

Medically Reviewed

Last reviewed on 10/05/2021.

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