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What’s the difference? Benign vs. malignant tumors

What's the difference in benign and malignant tumors?
While it may seem easy to categorize benign tumors as harmless and malignant tumors as harmful, the distinctions are often more of a gray area. Yet the importance of differentiating the two is critical.

There’s no such thing as a good tumor. These masses of mutated and dysfunctional cells may cause pain and disfigurement, invade organs and, potentially, spread throughout the body. But not all tumors are malignant, or cancerous, and not all are aggressive.

A tumor is a collection of cells that form an abnormal mass of tissue. If you’re diagnosed with a tumor, your doctor will first determine whether it’s benign or malignant.

Benign tumors, while sometimes painful and potentially dangerous, don’t pose the same threat as malignant tumors. While benign tumors generally don’t invade and spread, malignant cells are more likely to metastasize, or travel to other areas of the body. They also grow faster.

While it may seem easy to categorize benign tumors as harmless and malignant tumors as harmful, the distinctions are often more of a gray area. Yet the importance of differentiating the two is critical.

In this article, we’ll explore:

If you’re interested in learning more about your diagnosis and treatment options, or if you’re looking for a second opinion of your cancer diagnosis and treatment plan, how we diagnosis and treat colorectal cancer at Cancer Treatment Centers of America® (CTCA) call us or chat online with a member of our team.

What's the difference in benign and malignant tumors?

What’s a benign tumor?

Benign tumors aren’t cancerous and are usually not life-threatening. But like their malignant cousins, they develop when cells grow abnormally, and they may form anywhere in the body, though benign cells don’t typically invade nearby tissue or spread—they’re contained to the tumor.

Do benign tumors require treatment?

In general, benign tumors grow slowly, and some never need treatment. Others may cause serious health risks when they press on nearby organs, nerves or blood vessels, or grow in the brain or on the spinal cord. These kinds of tumors typically require surgery to remove. Once they are removed, most benign tumors don’t grow back.

The doctor may decide to closely watch a benign tumor to see whether it grows to the point that it causes problems before it’s surgically removed. This approach, called active surveillance, helps delay or even avoid surgery completely.

Can benign tumors become cancers?

Some benign tumors also have the potential to become cancerous when abnormal cells continue to divide out of control. These kinds of tumors are also carefully watched. If normal-looking cells are reproducing faster than normal—a process called hyperplasia—for example, the tumor will be closely monitored. If abnormal-looking cells reproduce faster than normal and but may appear abnormal—called dysplasia—the tumor will be watched even more carefully.

Types of benign tumors

Common types of benign tumor include:

  • Adenomas: These bumps most commonly form on the surfaces of the gastrointestinal, or GI, tract.
  • Fibromas: These connective tissue tumors may be found in any organ. Fibroid tumors are named for where they form in the body, such as uterine fibroids.
  • Desmoid tumors: These are often more aggressive than most benign tumors and may invade nearby tissue and organs. But they don’t metastasize.
  • Hamartomas: These tumors may develop in the lungs, heart, skin, brain or breast.
  • Hemangiomas: These tumors are a collection of blood vessel cells in the skin or internal organs. They may appear on the skin as a birthmark-like discoloration and often disappear on their own.
  • Lipomas: These soft, round, fatty tumors are often found on the neck or shoulders.
  • Leiomyomas: The most common gynecologic tumors in the United States, these may be found in the uterus. Their growth is fueled by hormones.
  • Myomas (fibroids): These common tumors are often found in the uterus, developing in the smooth tissue lining.
  • Papillomas: These tumors grow from tissue lining the skin and organs. They usually grow outward and form lesions.

What’s a malignant tumor?

Malignant tumors form when cancerous cells multiply and develop into a mass. Unlike benign tumors, cancer cells may invade nearby tissue. They may also break off from tumors and spread throughout the body, in a process called metastasis.

When cancer does spread, it’s important to know where it originated because this behavior affects treatment decisions. “Is it primary lung cancer or metastatic disease from somewhere else?” says Peter Baik, DO, FACOS, FACS, Thoracic Surgeon at CTCA® in Phoenix and Chicago. “The treatment is definitely different depending on the answer.”

If cancerous tumors detected in the chest wall began there, for example, the doctor may be able to be remove the cancer with surgery. But if the tumors spread there after forming somewhere else in the body, the patient may need a systemic (whole-body) treatment like chemotherapy first, Dr. Baik says.

Common malignant tumor types include:

  • Carcinomas: These are the most common malignant tumor types. They develop in epithelial cells, which line the inner surface of the body. Carcinomas include different types, including adenocarcinomas, basal cell carcinomas and squamous cell carcinomas.
  • Sarcomas: These malignant tumors form in the bones and in soft and fibrous tissues, including tendons, ligaments, fat and muscle.
  • Germ cells: These tumors begin in cells that produce eggs or sperm. They most often occur in the ovaries or testicles, but they may also develop in the abdomen, brain or chest.
  • Blastomas: Blastomas form in embryonic tissue and developing cells in the eyes, brain or nervous system.

Benign vs. malignant tumors: The key differences

The main differences between most benign and malignant tumors include those below.

Benign tumors Malignant tumors
Not cancerous Cancerous
Don't invade surrounding tissue May invade surrounding tissue
Don't spread to other parts of the body May spread to other parts of the body
Grow slowly Grow quickly
Are not likely to recur Are more likely to recur
Have a smooth, regular shape May have an uneven shape
Move around when pushed on Don't move around when pushed on
May or may not require treatment Require treatment

How do you know if a tumor is cancerous?

A doctor may perform a physical exam and order blood tests if they suspect cancer, but the only way to confirm the presence of disease is with a biopsy.

During a biopsy, the doctor will take a small tissue sample from the tumor, then send the sample to a laboratory so it can be tested for cancer or other signs of disease. A pathologist will analyze the sample under a microscope and determine whether cancer has been detected and whether it’s spread in the body. The pathologist may also help identify features of the tumor that help guide treatment decisions.

“It’s not always straightforward,” Dr. Baik says. “That’s the reason why, if we have questions, we talk to other specialists on our team to make sure we’re recommending appropriate treatment options.”

If you’re interested in learning more about your diagnosis and treatment options, or if you’re looking for a second opinion of your cancer diagnosis and treatment plan, how we diagnosis and treat colorectal cancer at CTCA, call us or call us or chat online with a member of our team.