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 an overview of benign and malignant tumors, including their differences, causes, and how they're treated.

What Is a Tumor?

A tumor is an abnormal mass or growth 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 tumor cells are contained within the tumor. The cells generally aren't very different from the surrounding cells, and they aren't highly abnormal.

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:

• Fibroids
• Lipomas
• Adenomas
• Hemangiomas

Doctors may need to surgically remove benign tumors. While benign tumors are not cancerous, some of them 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. The cancer cells in a malignant tumor tend to be abnormal, and very different from the normal surrounding tissue.

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

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.

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.

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

Can a Benign Tumor Turn Malignant?

Benign tumors only very rarely transform into malignant tumors. But some types, such as adenomatous polyps or adenomas in the colon, have a higher risk of becoming cancer. That is why polyps are removed during a colonoscopy. Removing them is one way of preventing colon cancer.

Uncertain Diagnosis

It's usually clear-cut whether a tumor is benign or malignant, but not always. Your healthcare provider may use several tests to diagnose it as one or the other. Sometimes, the diagnosis is uncertain.

Also, it is possible that a biopsy finds precancerous cells or misses the area with 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

The determination of whether a tumor is benign or malignant 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.

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.