What Is a Benign vs. Malignant Tumor?

If you have been diagnosed with a tumor, your healthcare provider will first determine whether it's a benign vs. malignant tumor. Benign tumors are noncancerous. Malignant tumors are cancerous.

Benign tumors can appear in the form of lipomas, fibroids, or adenomas. Malignant tumors are cancerous tumors such as breast, lung, or colorectal cancer. There's a wide range of treatment options depending on your specific tumor.

Once your healthcare provider knows if your tumor is benign or malignant, they will develop a treatment plan for you. This article provides a comprehensive overview of benign and malignant tumors, including their differences, causes, and how they're treated.

Benign vs. Malignant Tumors
Verywell / Joshua Seong

What Is a Tumor?

A tumor is an abnormal mass of tissue in the body that serves no specific purpose. It can develop when cells grow and divide too quickly.

Tumors can be located anywhere in the body. They grow and behave differently depending on whether they are benign (noncancerous) or malignant (cancerous).

Benign (Noncancerous) Tumors

A benign tumor is made up of cells that aren't a threat to invade other tissues, and the cells are contained within the tumor.

Usually, benign types of tumors are harmless unless they are:

  • Pressing on nearby tissues, nerves, or blood vessels
  • Taking up space in the brain
  • Causing damage 

Common benign tumors include:

Doctors may need to surgically remove benign tumors. While benign tumors are not cancerous, they can grow very large (sometimes up to several pounds) if left untreated.

Tumors that take up space become dangerous when they compress critical structures like the airway (trachea) or inside the brain, pushing on essential areas enclosed in the skull.

Malignant (Cancerous) Tumors

Malignant means that the tumor is made of cancer cells that can grow uncontrollably and invade nearby tissues.

Some cancer cells can travel through the bloodstream or lymph system to other parts of the body. This spreading process is called metastasis.

For example, breast cancer begins in the breast tissue and may spread to lymph nodes in the armpit if it's not caught early enough and treated. Once breast cancer has spread to the lymph nodes, the cancer cells can travel (metastasize) to the liver, bones, or other parts of the body.

The breast cancer cells can then form tumors in those locations. For example, a biopsy of these tumors in the lungs might show characteristics of the original breast cancer tumor.

Cancerous tumors can occur anywhere in the body. The most frequently diagnosed worldwide for both women and men include:

  1. Breast cancer
  2. Lung cancer
  3. Colorectal cancer
  4. Prostate cancer
  5. Stomach cancer

Differences in Benign vs. Malignant Tumors

Most malignant tumors grow rapidly, and most benign ones do not. But there are examples of both slow-growing cancerous tumors and noncancerous ones that grow quickly.

The main differences between the two types of tumors are clear and consistent. Here's a snapshot of the main ones:

Benign Tumors
  • Causes compression of surrounding areas without invasion into tissue

  • Slow-growing

  • Does not metastasize (spread) to other parts of the body

  • Tends to have clear boundaries

  • May not require treatment if not health-threatening

  • Treated with surgery

Malignant Tumors
  • Invades surrounding and distant tissues

  • Fast-growing

  • Can spread (metastasize) to other parts of the body

  • Recurrence possible after surgery

  • Treated with surgery, radiation, chemotherapy, or immunotherapy medications

Can a Benign Tumor Turn Malignant?

Some types of benign tumors only very rarely transform into malignant tumors.

But some types, such as adenomatous polyps or adenomas in the colon, have a greater risk of becoming cancer. That is why polyps are removed during a colonoscopy. Removing them is one way of preventing colon cancer.

It's not always clear-cut whether a tumor is benign or malignant. And your healthcare provider may use several factors to diagnose it as one or the other. You may end up with an uncertain diagnosis.

Also, it is possible that a biopsy finds precancerous cells or misses the area with more cancerous cells. In these cases, what was thought to be benign might turn out to be malignant as it further grows and develops.

What Your Tumor Diagnosis Means

A healthcare provider can take a sample of the cells with a biopsy procedure to determine whether a tumor is benign or cancerous.

Then a pathologist (a doctor who specializes in examining tissues) will run tests on the cells. This includes looking at the sample under a microscope.

Malignant Tumor Diagnosis

If you have been diagnosed with a malignant tumor, your oncologist (cancer doctor) will devise a treatment plan with you based on the stage of cancer. Early-stage cancers haven't spread much, if at all. Later-stage cancers have spread to more areas of the body.

Once the cancer stage is determined, you can proceed with treatment. Determining the stage of cancer may require:

  • Biopsies
  • Surgery
  • Imaging tests

Benign Tumor Diagnosis

If you have been diagnosed with a benign tumor, your doctor will provide reassurance that you do not have cancer.

Depending on the type of benign tumor, your doctor may recommend observation or removal for cosmetic or health purposes. For instance, the tumor may be affecting an important organ in your body.

Summary

When your doctor diagnoses you with a tumor, they will first determine if it's benign or malignant. Benign tumors are noncancerous. Malignant tumors are cancerous. Once your doctor determines what type of tumor you have, they can decide what treatment plan is best for you.

A Word From Verywell

Being diagnosed with a tumor is incredibly stressful. Discuss your concerns with your healthcare provider and ask whether there are any support groups that you can join.

Remember, the earlier you or your healthcare provider detects a lump, the more likely the tumor is treatable. So if you notice something unusual on your body, don't wait to tell your healthcare provider.

Frequently Asked Questions

  • How long can someone survive with a benign brain tumor?

    The average five-year survival rate for patients with any type of brain tumor is 75%. But this varies by age, tumor type, and exact location in the brain. For benign tumors, the five-year survival rate is 91%. This rate drops to 36% for malignant tumors.

  • How does treatment differ for benign vs. malignant tumors?

    Surgical tumor removal is often used for both benign and malignant tumors. Usually, this is the only treatment needed for benign tumors. In many cases, benign tumors are merely observed and do not require removal.

    Malignant tumors may or may not be removed. They may also require additional treatments like radiation and chemotherapy. However, treatment of each type can vary depending on tumor size, location, patient age, stage of cancer for malignant tumors, and overall patient health.

  • What are the chances of a benign tumor turning malignant?

    Specific tumors can become malignant over time, such as colon polyps. These benign tumors can be surgically removed before turning malignant if they are identified and treated with early detection.

  • Can you tell if a tumor is benign without a biopsy?

    A biopsy is the most definitive way to determine if a tumor is benign or malignant. Additional tests like blood work or imaging (such as an MRI or x-ray) can be used to determine the characteristics of the tumor.

  • Is a malignant tumor always cancer?

    Yes, malignant means cancerous.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Wan Z, Yin T, Chen H, Li D. Surgical treatment of a retroperitoneal benign tumor surrounding important blood vessels by fractionated resection: a case report and review of the literature. Oncol Lett. 2016;11(5):3259-3264. doi:10.3892/ol.2016.4395

  3. Institute for Quality and Efficiency in Health Care. How do cancer cells grow and spread?

  4. World Cancer Research Fund International. Worldwide cancer data.

  5. Coleman HG, Loughrey MB, Murray LJ, et al. Colorectal cancer risk following adenoma removal: a large prospective population-based cohort study. Cancer Epidemiol Biomarkers Prev. 2015;24(9):1373-80. doi:10.1158/1055-9965.EPI-15-0085

  6. National Brain Tumor Society. Quick brain tumor facts.

Additional Reading

By Blyss Splane
Blyss Splane is a certified operating room nurse working as a freelance content writer and former travel nurse. She works as a freelance content writer for healthcare blogs when she's not spending time with her husband and dog.

Originally written by Lisa Fayed