Benign vs. Malignant Tumors

If you’ve been diagnosed with a tumor, the first thing your doctor will do is determine whether it’s malignant or benign. A malignant tumor is cancerous, and a benign tumor is non-cancerous. Here, we’ll outline the characteristics and differences between benign and malignant tumors.

What’s a Benign Tumor?

Benign tumors aren’t cancerous, so they won’t invade surrounding tissue or spread elsewhere. Benign tumors can cause serious problems, though, when they grow near vital organs, press on a nerve, or restrict blood flow. Fortunately, benign tumors usually respond well to treatment. These are the most common types of benign tumors:

  • Adenomas. These tumors, or polyps, develop in glandlike cells in epithelial tissue, a thin layer of tissue covering glands, organs, and other structures. The size and location of these tumors will dictate the treatment. Some colon polyps are adenomas and should be removed in case they become malignant.
  • Fibroids. These tumors grow in fibrous tissue. Uterine fibroids are common and affect 20-80% of women by age 50. Fibroids don’t necessarily need treatment, but a doctor can remove them if they’re causing pain or other problems.
  • Hemangiomas. Hemangiomas are tumors made up of extra blood vessels. They’re the most common tumors in children and tend to grow on the skin and liver. On the skin, these tumors may initially look like a red birthmark. Over time, it’ll start to form a red lump. These tumors should be monitored, but they usually don’t cause problems and tend to fade away without treatment. 
  • Lipomas. Lipomas are slow-growing tumors that form in the fatty tissue under the skin. They typically grow in the neck, shoulders, armpit, or trunk, but they can occur anywhere. They’re most common between the ages of 40-60. Treatment isn’t always necessary, but lipomas can be removed if they bother you. 

What’s a Malignant Tumor?

Malignant tumors are cancerous. Our bodies constantly produce new cells to replace old ones. Sometimes, DNA gets damaged during this process and new cells develop abnormally. Instead of dying off, they continue to multiply faster than our immune system can handle, which forms a tumor. Cancer cells can break away from these tumors and travel through the bloodstream or lymphatic system to other parts of the body. Types of malignant tumors include:

  • Carcinoma. The most common cancers, carcinomas develop in epithelial cells. They include the following:
    • Adenocarcinoma. This forms in cells that produce mucus. This includes many breast, colon, and prostate cancers.
    • Basal cell carcinoma. This starts in the lowest layer of the epidermis.
    • Squamous cell carcinoma. This forms in the cells just beneath the outer surface of the skin, as well as organs like the bladder, kidneys, intestines, or stomach.
    • Transitional cell carcinoma. This develops in tissue called the epithelium or urothelium. Bladder, kidney, and ureter cancers may be this type. 
  • Sarcoma. Sarcomas begin in bones, soft tissues, and fibrous tissues. This includes:
    • Tendons
    • Ligaments
    • Fat
    • Muscle
    • Blood and lymph vessels
  • Germ cell. These tumors begin in cells that produce eggs or sperm. They’re usually found in the ovaries or testicles, but they can also develop in the abdomen, chest, or brain. 
  • Blastoma. Blastomas start in embryonic tissue and developing cells in the brain, eyes, or nervous system. Children are more likely to develop blastomas than adults. 

What’s the Difference Between a Benign and a Malignant Tumor?

A tumor is an abnormal lump or growth of cells. If the cells in the tumor are normal, it’s benign. If they’re abnormal and grow uncontrollably, they’re cancerous cells and the tumor is malignant. Below, we outline the main characteristics of benign and malignant tumors.

Characteristics of Benign TumorsCharacteristics of Malignant Tumors
– Cells usually don’t spread
Most grow slowly
– They don’t invade nearby tissue
– They don’t spread to other parts of the body
– They tend to have clear boundaries
– Through a microscope, the shape, chromosomes, and DNA of cells appear normal
– They don’t secrete hormones or other substances (an exception: pheochromocytomas of the adrenal gland)
– They may not require treatment if not health-threatening
– They’re unlikely to recur if removed or require further treatment, like radiation or chemotherapy 
– Cells can spread
– They usually grow rapidly
– They often invade the basal membrane that surrounds healthy tissue
– They can spread through the bloodstream or lymphatic system, or by sending “fingers” into nearby tissue
– They can recur after removal, sometimes in areas other than the original site
– Cells have abnormal chromosomes and DNA characterized by large, dark nuclei.
– They can also have an abnormal shape
– They can secrete substances that cause fatigue and weight loss (paraneoplastic syndrome)
– They may require aggressive treatment, including surgery, radiation, chemotherapy, and immunotherapy medication

Can a Benign Tumor Become Malignant?

While rare, some benign tumors can become malignant. Some of these benign tumors, such as adenomatous polyps in the colon have a greater risk of transforming into cancer, which is why they’re removed during a colonoscopy. 

Is a Malignant Tumor More Dangerous Than a Benign Tumor?

Malignant tumors can be life-threatening. Many benign tumors are harmless and don’t require treatment, but others can cause serious problems or become cancerous. If you feel a lump anywhere on your body, see a doctor as soon as you can. 

Learn More About Tumors

If you think you may have a tumor, either benign or malignant, make sure to see your doctor quickly to get a diagnosis. The earlier a tumor is diagnosed, the more treatment options you’ll have, which increases your chance for a better outcome.

If you have additional questions about tumors, reach out to a Baptist Health cancer care provider near you. 

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