Can Uterine Fibroids Turn Into Cancer?

Are Uterine Fibroids Cancerous?

Uterine fibroids, also called leiomyomas, are benign tumors made of smooth muscle and fibrous tissue. Benign means the growth stays contained and does not spread to other parts of the body. Having fibroids also does not raise your risk of developing other uterine cancers, such as endometrial cancer, later on.

What Are the Chances of Fibroids Turning Into Cancer?

The chance that a growth diagnosed as a fibroid is actually cancer is extremely low, affecting fewer than 1 in 1,000 women with fibroids.^[1] This rare cancer is called leiomyosarcoma, and it develops independently rather than evolving from an existing benign fibroid. Even though fibroids and leiomyosarcoma form in the same type of uterine tissue, researchers have not confirmed that a benign fibroid can transform into this cancer over time.^[2]

What Are the Signs That Fibroids Might Be Cancerous?

Most fibroid symptoms, like heavy periods, pelvic pressure, and frequent urination, overlap heavily with ordinary benign fibroids, which can make it difficult to spot a concerning change. However, a few patterns should be discussed with a specialist, such as rapid growth over weeks rather than months, a uterus that keeps enlarging after menopause, new bleeding that occurs after menopause, and pelvic pain that worsens quickly instead of staying stable. Having one of these symptoms does not mean cancer is present, but it is a reason to ask for a closer look.

Persistent heavy bleeding and related anemia are common with ordinary fibroids, but any sudden change in pattern should be evaluated.

First Signs of Uterine Cancer

Uterine cancer, including the rare leiomyosarcoma, often announces itself through abnormal bleeding rather than silence. Patients frequently describe bleeding between periods, bleeding after menopause, or a noticeably heavier period than usual as the first thing that sent them to a doctor. Pelvic pain or a feeling of pressure that develops quickly, rather than gradually over years, is another commonly reported early sign. Because these symptoms can also come from ordinary fibroids, the only way to know which one is happening is through evaluation, not through symptoms alone.

Can an Ultrasound Tell If a Fibroid Is Cancerous?

An ultrasound can help a specialist see the size, location, and general shape of a growth, but it cannot definitively confirm whether that growth is benign or cancerous. MRI can add more detail about blood flow and tissue characteristics and may raise suspicion if something looks atypical, but even MRI cannot rule out leiomyosarcoma with certainty. The only test that can confirm a cancerous fibroid diagnosis is a biopsy, where a small tissue sample is examined directly. This is why a specialist may recommend a biopsy as part of the fibroid diagnosis process even when imaging looks reassuring, particularly if a fibroid is growing unusually fast.

When Should You Get a Second Opinion?

A second opinion is reasonable any time a growth behaves differently than a typical fibroid. Consider asking for one if a mass is growing rapidly, if new symptoms appear after menopause, if bleeding patterns change suddenly, or if your first provider has not discussed imaging limitations or next steps with you. For a closer look at how fibroids and cancer are distinguished, see the difference between fibroids and cancer. Seeking a second opinion does not mean something is wrong. It means you are making sure every question has been answered before moving forward with a treatment plan.