Malignant vs. Benign Tumors: What Are the Differences?

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

Once your healthcare provider knows if your tumor is benign or malignant, they will develop a treatment plan.

This article provides an 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 or growth of tissue 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 don't threaten to invade other tissues. The tumor cells are contained within the tumor and aren't abnormal or very different from surrounding cells.

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
  • Causing excess hormone production

Common benign tumors include:

Doctors may need to surgically remove benign tumors. While they are not cancerous, some of these masses can grow very large if left untreated—sometimes up to several pounds.

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

Malignant (Cancerous) Tumors

Malignant tumors are made of cancer cells that can grow uncontrollably and invade nearby tissues. The cancer cells in a malignant tumor tend to be abnormal and very different from the normal surrounding tissue.

Cancerous tumors can occur anywhere in the body. The most frequently diagnosed malignant tumors worldwide include:

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

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 not caught and treated early enough. Once this occurs, 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, tumors in the lungs might show characteristics of the original breast cancer tumor.

Differences Between Malignant vs. Benign Tumors

Here's a snapshot of the main differences between the two types of tumors:

Malignant Tumors Benign Tumors
Cancerous Not cancerous
May invade surrounding tissue Doesn’t invade surrounding tissue
Most grow rapidly* Most grow slowly*
Irregular shape Smooth shape
Needs treatment May not need treatment

*There are some exceptions.

Can a Benign Tumor Turn Malignant?

Benign tumors only very rarely transform into malignant tumors. Specific tumors can, however, become malignant over time.

Colon polyps are one example. These benign tumors can be surgically removed during a colonoscopy before turning malignant if identified and treated early. Removing polyps is one way to prevent colon cancer.

It is also possible that a tumor thought to be benign turns out to be malignant as it grows and develops.

Tumor Diagnosis and Next Steps

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.

This is the most definitive way to determine tumor status, and the answer is usually clear-cut. But sometimes, the diagnosis is uncertain. It's also possible that cancer could be present, but the biopsy missed the area with malignant cells.

Additional tests like blood work or imaging (such as an MRI or X-ray) can be used to determine the characteristics of the tumor.

The information gathered from these tests guides the treatment plan.

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.

Treating Malignant vs. Benign Tumors

In many cases, benign tumors are merely observed and do not require removal. When they do, surgery is usually the only treatment required.

Malignant tumors may or may not be surgically removed. This depends on several factors, including tumor size and location, patient age, stage of cancer, and overall patient health.

These tumors may also require additional treatments like radiation and chemotherapy.


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.

Though it's possible for a benign tumor to turn malignant, this is not common.

5 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.
  1. Patel A. Benign vs malignant tumors. JAMA Oncol. 2020;6(9):1488. doi:10.1001/jamaoncol.2020.2592

  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. World Cancer Research Fund International. Worldwide cancer data.

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

  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

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