Differences Between a Malignant and Benign Tumor

If you have been diagnosed with a tumor, the first step your healthcare provider will take is to find out whether it is malignant or benign. This will affect your treatment plan. Put simply, malignant means cancerous and benign means noncancerous.

This article will discuss how either diagnosis affects your health.

Benign vs. Malignant Tumors
Verywell / Joshua Seong

What Is a Tumor?

A tumor is an abnormal lump or growth of cells. Sometimes a tumor is made up of cells that aren't a threat to invade other tissues. This is considered benign.

When the cells are abnormal and can grow uncontrollably and spread to other parts of the body, they are cancerous cells. That means the tumor is malignant. This spreading process is called metastasis.

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

Benign Tumors: Noncancerous

If the cells are not cancerous, the tumor is benign. A benign tumor is less worrisome unless it is:

  • Pressing on nearby tissues, nerves, or blood vessels
  • Causing damage 

Fibroids in the uterus or lipomas are examples of benign tumors.

Doctors may need to remove benign tumors through surgery. These tumors can grow very large, sometimes weighing pounds. They can also be dangerous. Dangerous benign tumors may occur in the brain and crowd the normal structures in the enclosed space of the skull. They can press on vital organs or block channels.

Some types of benign tumors, such as intestinal polyps, are considered precancerous. They are removed to prevent them from becoming malignant. Benign tumors usually don't come back once removed. But if they do, they return to the same place.

Recap

Benign tumors are not cancerous. But they may still need to be removed. That's because benign tumors sometimes press on nearby organs, tissues, nerves, or blood vessels. Some benign tumors may grow very large. This can be dangerous, especially if they occur in the brain or near other vital organs.

Malignant Tumors: Cancerous

Malignant means that the tumor is made of cancer cells. These cells can invade nearby tissues. Some cancer cells can move into the bloodstream or lymph nodes. From there, they can spread to other tissues within the body.

Cancer can occur anywhere in the body, including the following areas:

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 to the liver, bones, or other parts of the body.

The breast cancer cells can then form tumors in those locations. A biopsy of these tumors might show characteristics of the original breast cancer tumor.

Differences Between Benign and 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:

Characteristics of Benign Tumors
  • Cells tend not to spread

  • Most grow slowly

  • Do not invade nearby tissue

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

  • Tend to have clear boundaries

  • Under a pathologist's microscope, shape, chromosomes, and DNA of cells appear normal

  • Do not secrete hormones or other substances (an exception: pheochromocytomas of the adrenal gland)

  • May not require treatment if not health-threatening

  • Unlikely to come back if removed or require further treatment such as radiation or chemotherapy

Characteristics of Malignant Tumors
  • Cells can spread

  • Usually grow fairly rapidly

  • Often invade nearby healthy tissue

  • Can spread via bloodstream or lymphatic system, or by sending "fingers" into nearby tissue

  • May recur after removal, sometimes in areas other the original site

  • Cells have abnormal chromosomes and DNA; may have abnormal shape

  • Can secrete substances that cause fatigue and weight loss (paraneoplastic syndrome)

  • May require aggressive treatment, including surgery, radiation, chemotherapy, and 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 transforming into 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 different 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 where there are more cancerous cells. In these cases, what was thought to be benign might turn out to be malignant as it further grows and develops.

Recap

Many benign tumors never turn malignant. But some benign tumors, such as colon polyps, have a greater risk of turning into cancer. So removing them is one way to prevent cancer. It's not always clear whether a tumor is benign or malignant, so a doctor may need to change the diagnosis as the tumor develops.

What Your Tumor Diagnosis Means

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.

Determining the stage of cancer may require:

  • Biopsies
  • Surgery
  • Imaging tests

Once the cancer stage is determined, you can proceed with treatment.

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. If you have a malignant tumor, your doctor will devise treatment depending on the stage of cancer you have.

A Word From Verywell

Being diagnosed with a tumor can cause a huge amount of anxiety. Be sure to discuss your concerns with your healthcare provider and ask whether there are any support groups that you can join. And remember, the earlier that 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 removal of the tumor is often used for both benign and malignant tumors. Often, 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, age of the patient, stage of the cancer for malignant tumors, and overall health of the patient.

Was this page helpful?
4 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. 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

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

  3. 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

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

Additional Reading