What Is the Difference Between a Malignant and a Benign Tumor?

One diagnosis signals cancer, while the other doesn't.

Dividing cancer cell
Dividing cancer cell. STEVE GSCHMEISSNER/Science Photo Library/Getty Images

If you have been diagnosed with a tumor—a growth or lump on a part of your body—it is important to find out whether the tumor is malignant or benign, as this will affect your treatment plan. These are medical terms that can be difficult to decipher. In short, malignant means cancerous and benign means noncancerous. Learn more about how either diagnosis affects your health.

What Is a Tumor?

A tumor can be cancerous or non-cancerous.

Cancer occurs when abnormal cells in the body grow uncontrollably, preventing normal cells from growing and performing their function. Cancer can occur anywhere in the body including the breast, intestines, lungs, reproductive organs, blood, and skin

Cancer cells lump together to form a growth called a tumor. But not all tumors are cancerous. To determine whether a tumor is cancerous, a doctor can take a sample of the cells (called a biopsy). Then the biopsy is analyzed under a microscope by another doctor who is called a pathologist. If the cells are cancerous, the tumor is malignant. If the cells are noncancerous and have normal features, the tumor is benign. 

Malignant Tumors

What does "malignant" mean? Malignant means that the tumor can invade nearby tissues and even move into the bloodstream or lymph nodes, where it can spread to other tissues within the body—this 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 to other areas of the body, like the liver or bones. The breast cancer cells can then form tumors in the liver or bone.

This is called breast cancer with liver and bone metastasis. So if a doctor took a biopsy of a liver tumor in a woman with breast cancer, the cells of that tumor would resemble those seen in breast tissue (but have cancer-like features). 

Benign Tumors

What does "benign" mean? If the cells are not cancerous, the tumor is benign, which means that it cannot invade nearby tissues (or metastasize), and the cells have normal features. A benign tumor is not usually worrisome and is generally considered harmless unless it compresses tissues or nearby nerves or blood vessels and causes damage. Fibroids in the uterus or lipomas are examples of benign tumors. 

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, whereas later-stage cancers have spread to more areas of the body). Determining the stage of cancer may require biopsies, surgery, and/or imaging tests.

Once the cancer stage is determined, you can proceed with therapy, which usually entails surgery, radiation, and/or chemotherapy

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 compromising an important organ in your body).

A Word From Verywell

Being diagnosed with a tumor can be an anxiety-ridden experience. Be sure to discuss your concerns with your doctor and ask whether there are any support groups that you can join. And remember, the earlier that you or your doctor 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 doctor. 

Sources:

American Cancer Society. (December 2015). What is cancer?: A guide for patients and families. 

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