Doctor Decoded: Malignant vs. Benign Tumors

Your doctor says you have a tumor — but it’s benign. This may raise a lot of questions for you: What are benign tumors? Do you have cancer or not? Is it dangerous? Will you need surgery?

In general, a tumor is any abnormal mass of tissue. Tumors develop when cells grow and divide out of control, causing them to build up into large masses. Surprisingly, tumors do not always signify cancer. When it’s cancerous, it’s known as malignant. Otherwise, it’s benign.

Benign tumors

Benign tumors are abnormal masses of tissue that are not cancerous. One of the key characteristics of these non-cancerous tumors is that they don’t spread or invade the nearby tissue. Plus, they don’t often grow back after a surgeon removes them. These characteristics are what makes them less dangerous.

That said, benign tumors aren’t always harmless. Depending on their location, they can pose a threat to the body, including compressing nearby body parts or affecting the body’s normal function. A non-cancerous tumor in the brain can even be life-threatening, according to the National Cancer Institute.

Malignant tumors

Malignant tumors are cancerous tumors. These abnormal masses can grow large, but they can also invade nearby tissue. When cancer cells get into the blood or lymphatic systems, they can travel to distant parts of the body. This is known as cancer metastasis.

Additionally, malignant tumors can control the microenvironment near the tumor, influencing other molecules and blood vessels to help the malignant tumor grow. They can even cause blood vessels to form around the tumor to help it get oxygen and nutrients from the blood. They may also subtly steal nutrients that the body needs to function or release toxic material.

The treatment for benign and malignant tumors may be very different. In some cases, a benign tumor may require surgical removal, whereas malignant tumors may need additional treatments, including chemotherapy, radiation therapy, or immunotherapy. Regardless—whether benign or malignant — both types of tumors deserve medical attention.