Are Fibroids Cancerous? What Every Woman Should Know (and How to Ease Your Mind)

Hearing you have uterine fibroids can be unsettling, and it’s natural to wonder: could they be cancer? Here’s the reassuring truth grounded in evidence from trusted sources like the NIH, AHRQ, and FDA: fibroids are almost always benign (noncancerous). In fact, fibroids are incredibly common—most women develop them at some point, often without ever knowing it.

This article explains what fibroids are, how rare cancer truly is, when to seek extra evaluation, and practical steps to feel more at ease.

What are uterine fibroids?

Uterine fibroids (also called leiomyomas or myomas) are growths made of smooth muscle and connective tissue that develop in the wall of the uterus. They can be as small as a seed or large enough to distort the uterus. Many cause no symptoms; when they do, common issues include heavy menstrual bleeding, pelvic pressure, frequent urination, or fertility challenges. According to the National Institutes of Health, fibroids are very common, affecting a large proportion of women by age 50.^NIH/NICHD

Are fibroids cancerous?

Almost never. Fibroids are benign tumors. A different and rare disease called uterine sarcoma (including leiomyosarcoma) is cancerous, but it is not the same as a fibroid. Research suggests uterine leiomyosarcoma typically arises de novo (on its own), not by transforming from a benign fibroid.^NCI

How rare is cancer in women with presumed fibroids?

• The FDA’s 2014 safety communication estimated about 1 in 350 women undergoing surgery for presumed fibroids might have an unsuspected uterine sarcoma.^FDA
• Subsequent government analyses suggest the true risk is lower. A 2017 report from the Agency for Healthcare Research and Quality (AHRQ) estimated the risk of unexpected leiomyosarcoma in surgeries for presumed fibroids ranges from about 1 in 770 to less than 1 in 10,000 procedures, with risk increasing with age.^AHRQ

Bottom line: while no risk is zero, cancer in the setting of typical fibroids is rare, especially in premenopausal women.

Can doctors tell the difference between a fibroid and cancer before surgery?

There is no single test that definitively rules out uterine sarcoma before surgery. Here’s what clinicians use:

• Pelvic exam & history: To understand symptoms, size changes, and bleeding patterns.
• Ultrasound: First-line imaging to confirm fibroids and map location.
• MRI: Offers more detail; certain imaging features may raise suspicion, but MRI cannot diagnose sarcoma with certainty.
• Endometrial biopsy: Samples the uterine lining (helpful if abnormal bleeding is present), but it typically does not sample tissue deep in the uterine wall where fibroids live—so it can’t rule out sarcoma within a fibroid.

Definitive diagnosis of leiomyosarcoma usually requires examination of tissue after surgical removal.^NCI

When should you ask more questions?

Most changes in fibroid size or symptoms are benign and related to hormones. However, speak with your clinician if you notice:

• New or worsening symptoms after menopause (for example, a growing uterine mass or new bleeding when you’ve been period-free).
• Unexplained, persistent pelvic pain or pressure that is rapidly worsening.
• Abnormal uterine bleeding that is heavy or prolonged, especially if you are over 45.
• Systemic symptoms such as unexplained weight loss or fever (these are uncommon and have many possible causes).
• Risk factors like prior pelvic radiation or certain hereditary cancer syndromes (e.g., Li-Fraumeni, hereditary retinoblastoma).^NCI

Important: Rapid growth alone is not a reliable predictor of cancer in premenopausal women. Still, any concerning change should prompt a conversation and possibly updated imaging.

Evidence-based options for managing fibroids

Your plan depends on symptoms, age, fertility goals, and overall health. Options include:

• Watchful waiting: Many fibroids shrink after menopause. If symptoms are mild, monitoring with periodic check-ins may be all that’s needed.^NIH/NICHD
• Medications to control bleeding and pain: nonsteroidal anti-inflammatory drugs (NSAIDs), hormonal contraceptives, progestin-releasing IUD, tranexamic acid, or short-term use of GnRH agonists/antagonists to shrink fibroids and reduce bleeding.^{MedlinePlus (NIH)}
• Procedures for symptom relief: uterine artery embolization, MRI-guided focused ultrasound, myomectomy (removing fibroids), or hysterectomy (removing the uterus) when appropriate.^NIH/NICHD

If surgery is considered, ask your surgeon about how tissue will be removed. The FDA advises that power morcellation (a technique to fragment tissue inside the abdomen) should be used only with a legally marketed tissue containment system and generally not in women who are postmenopausal or candidates for tissue removal through the vagina or a mini-laparotomy. This is to reduce the small risk of spreading an unsuspected cancer.^FDA

How to ease your mind today

• Ground yourself in the numbers: Fibroids are benign the vast majority of the time; cancer is rare, particularly before menopause.^AHRQ
• Track your symptoms: Keep a simple log of bleeding days, pad/tampon use, pain, and pressure. This helps you and your clinician spot patterns and respond early.
• Ask focused questions: “Do my imaging results look typical for fibroids?” “When should I be re-checked?” “What are the risks and benefits of each treatment for someone my age and goals?”
• Seek a second opinion if you’re unsure about a recommendation—especially before major procedures affecting fertility.
• Prioritize overall health: While lifestyle changes don’t eliminate fibroids, maintaining a healthy weight, managing blood pressure, and treating anemia can improve how you feel day to day.

Key takeaways

• Fibroids are common and almost always benign.
• Uterine sarcoma is rare; most leiomyosarcomas do not arise from benign fibroids.
• No single preoperative test can rule out sarcoma, but your clinician can use history, imaging, and—when indicated—biopsy of the uterine lining to guide next steps.
• Treatment is individualized and ranges from watchful waiting to medications and procedures. FDA guidance helps reduce rare risks during surgery.
• If anxiety is high, focus on the facts, track symptoms, and partner closely with a trusted clinician.

This article is for educational purposes and is not a substitute for personal medical advice. If you have new or concerning symptoms, consult your healthcare professional.

Trusted sources

• National Institutes of Health (NIH), Eunice Kennedy Shriver National Institute of Child Health and Human Development: Uterine Fibroids Overview – nichd.nih.gov
• MedlinePlus (NIH): Uterine Fibroids – medlineplus.gov
• National Cancer Institute (NCI): Uterine Sarcoma Treatment (PDQ) – Patient Version – cancer.gov
• Agency for Healthcare Research and Quality (AHRQ): Management of Uterine Fibroids (2017) – effectivehealthcare.ahrq.gov
• U.S. Food and Drug Administration (FDA): Laparoscopic Power Morcellators—Safety Communication (updated) – fda.gov

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