Fast Growing Fibroid Cancer and Fibroids: What to Know

Fast Growing Fibroid Cancer and Fibroids: What to Know

Hearing that a fibroid is “fast growing” can be alarming, especially when internet searches bring up the word cancer. The good news: uterine fibroids (leiomyomas) are common benign growths, and even when they enlarge quickly, they rarely represent cancer. Still, it’s important to understand when growth warrants closer evaluation, what symptoms to watch for, and which tests and treatments are appropriate. This guide brings together current evidence and recommendations from trusted sources to help you make informed decisions.

What are uterine fibroids?

Uterine fibroids are noncancerous tumors of the muscle of the uterus. They can be as small as a seed or as large as a melon, and women may have one or many. Most fibroids do not cause problems, but some can lead to heavy menstrual bleeding, pelvic pressure or pain, urinary frequency, constipation, painful sex, or fertility issues. Risk factors include age during reproductive years, family history, early menarche, and Black race, among others. Fibroids typically shrink after menopause as estrogen and progesterone levels fall. For an overview, see the National Institutes of Health (NIH) resource on fibroids (NIH/NICHD).

How fast do fibroids grow?

Fibroid growth is variable. Some remain stable for years; others enlarge gradually. It’s also normal for fibroids to grow more quickly when hormone levels are higher, such as during pregnancy or while using certain hormone therapies, and to shrink after menopause. Short-term increases in size may reflect transient changes like fluid shifts or bleeding within the fibroid (degeneration), not cancer.

Because fibroid size can fluctuate and ultrasound measurements can vary slightly between exams, a single “jump” in size is not definitive. Your clinician will usually look for consistent trends and consider your age, symptoms, and life stage (for example, nearing menopause or pregnant) before recommending further steps.

Does a fast-growing fibroid mean cancer?

Almost always, no. The cancer that can arise in the uterus’s muscle layer is called uterine leiomyosarcoma (LMS). LMS is rare, and it typically develops independently—not by a fibroid “turning into” cancer. Major organizations emphasize that there is no reliable way to distinguish a benign fibroid from LMS based on speed of growth alone.

  • How rare is it? The American College of Obstetricians and Gynecologists (ACOG) notes that the risk of finding an unexpected uterine sarcoma in surgery for presumed fibroids ranges from roughly 1 in 770 to less than 1 in 10,000 cases (ACOG).
  • Can imaging rule out cancer? Ultrasound and MRI can describe features of a mass and suggest benign fibroids, but they cannot definitively rule out LMS. A sure diagnosis typically requires surgical removal and examination by a pathologist (NCI).
  • Do fibroids become cancer? Fibroids are benign; they do not “transform” into LMS. Instead, LMS arises de novo. The overall probability remains very low (NCI).

Red flags: When growth deserves prompt evaluation

While most enlarging fibroids are still benign, seek medical attention if you experience:

  • Postmenopausal growth of a uterine mass (fibroids usually shrink after menopause).
  • New or worsening abnormal bleeding, particularly bleeding after menopause.
  • Rapidly increasing pelvic pain that is persistent and not related to periods.
  • Unexplained anemia, fatigue, or weight loss.
  • Fever with pelvic pain, or severe, sudden pain (may also indicate fibroid degeneration or torsion).

These symptoms don’t mean cancer is present, but they do warrant timely evaluation to identify the cause and tailor treatment.

How clinicians evaluate a fast-growing mass

  • History and pelvic exam: Assessment of bleeding patterns, pain, pressure symptoms, and a physical exam to estimate uterine size and tenderness.
  • Imaging: Transvaginal and transabdominal ultrasound are first-line. MRI is helpful when ultrasound is inconclusive, to map fibroids before procedures, or to better characterize a mass (NIH/NICHD).
  • Endometrial sampling: If abnormal bleeding is present—especially after age 45 or postmenopause—sampling the uterine lining can rule out endometrial hyperplasia or cancer (distinct from fibroids).
  • Laboratory tests: Complete blood count to check for anemia; pregnancy test when appropriate. There is no blood test that reliably distinguishes fibroids from LMS.

No single test perfectly differentiates fibroids from LMS before surgery. Decisions integrate symptoms, imaging findings, age, reproductive plans, and overall risk profile. Shared decision-making is key.

Treatment options for symptomatic fibroids

If a fibroid is growing but not causing symptoms, watchful waiting with periodic follow-up is often reasonable. When symptoms affect quality of life, options include:

  • Medications (NIH/NICHD):
    • Hormonal birth control (pills, IUDs) can reduce bleeding and cramps.
    • Tranexamic acid helps control heavy menstrual bleeding.
    • GnRH agonists/antagonists temporarily shrink fibroids and reduce bleeding; often used short term or to optimize before procedures.
    • NSAIDs for pain relief.
  • Minimally invasive procedures:
    • Uterine artery embolization (UAE): Blocks blood flow to fibroids to shrink them; effective for bleeding and bulk symptoms.
    • Radiofrequency ablation: Uses heat to shrink fibroids via laparoscopic or transcervical approaches.
    • MRI-guided focused ultrasound (MRgFUS): Noninvasive energy ablation for select patients.
  • Surgery:
    • Myomectomy: Removes fibroids while preserving the uterus; preferred if future pregnancy is desired.
    • Hysterectomy: Removes the uterus; definitive treatment when childbearing is complete or symptoms are severe.

The choice of therapy depends on your symptoms, fibroid size and location, desire for fertility, age, and medical conditions. Discuss benefits, risks, recovery time, and likelihood of symptom relief with your clinician.

What about power morcellation and cancer risk?

When large fibroids are removed minimally invasively, surgeons sometimes use a technique called morcellation to cut tissue into smaller pieces. The U.S. Food and Drug Administration (FDA) warns that if an unsuspected cancer like LMS is present, morcellation can spread cancer cells inside the abdomen. The FDA recommends that when power morcellation is considered, it be performed only with an approved tissue containment system and in carefully selected patients, with thorough informed consent (FDA; ACOG).

Fertility and pregnancy considerations

Some fibroids can interfere with fertility or pregnancy, depending on their size and location (for example, submucosal fibroids projecting into the uterine cavity). If you’re trying to conceive, ask about treatments that preserve the uterus and minimize scarring. Myomectomy is often considered in select infertility cases; medical therapies like GnRH analogs may be used short term but are contraceptive while taken. Individualized guidance from a reproductive specialist can help align treatment with family-building goals.

Key takeaways

  • Most fibroids are benign. Rapid growth alone rarely signals cancer.
  • Postmenopausal growth, new or worsening abnormal bleeding, and persistent, unexplained pain merit prompt evaluation.
  • Imaging and biopsies help guide care, but definitive distinction between fibroids and leiomyosarcoma usually requires surgical pathology.
  • Effective treatments range from medications to minimally invasive procedures and surgery—tailored to your symptoms and goals.
  • Discuss surgical technique and risks, including morcellation, with your surgeon if an operation is planned.

If you’re worried about a “fast-growing” fibroid, a consultation with a gynecologist can put your risk in perspective and map out a plan that fits your life.

This article is for educational purposes and does not replace professional medical advice. If you have concerning symptoms, please seek care promptly.

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