Endometriosis Cancerous and Fibroids: What to Know

Endometriosis, Cancer Risk, and Fibroids: What to Know

Endometriosis and uterine fibroids are two common, benign gynecologic conditions that can cause significant pain, heavy bleeding, and fertility challenges. They are not the same disease, and most cases are not cancer. Still, many people worry about cancer risk, especially when symptoms persist or change. Here’s what the evidence says—and how to talk with your clinician about diagnosis, treatment, and when to consider further evaluation.

Quick definitions

  • Endometriosis: Tissue similar to the uterine lining grows outside the uterus (e.g., ovaries, peritoneum), causing inflammation and pain. It is benign but can be chronic and progressive. Learn more from the NIH and NICHD: NICHD: Endometriosis and OWH: Endometriosis.
  • Uterine fibroids (leiomyomas): Benign smooth muscle tumors of the uterus. They can be single or multiple, and vary widely in size. See ACOG: Uterine Fibroids and MedlinePlus: Uterine Fibroids.

Are endometriosis and fibroids cancerous?

In almost all cases, no.

  • Endometriosis is noncancerous. Rarely, endometriotic cysts on the ovary (endometriomas) can undergo changes associated with ovarian cancer, but this is uncommon.
  • Fibroids are benign. The cancer that can arise in the uterus’s muscle layer is called leiomyosarcoma. It is very rare, and evidence suggests most leiomyosarcomas arise de novo (not from pre-existing fibroids). ACOG notes that the chance of an unexpected uterine sarcoma in surgery for presumed fibroids is low, but not zero.

The U.S. Food and Drug Administration (FDA) has issued safety communications about surgical tools called laparoscopic power morcellators because they can spread an undiagnosed sarcoma if present. This does not mean fibroids are cancer; it highlights the importance of careful patient selection and technique. Read the FDA’s guidance: FDA Morcellation Safety Communication.

What is the actual cancer risk?

  • Endometriosis and ovarian cancer: People with endometriosis have a modestly increased relative risk of certain ovarian cancers (notably clear cell and endometrioid subtypes). Importantly, the absolute risk of ovarian cancer remains low for most individuals. See NCI’s overview of ovarian cancer risk factors: NCI: Ovarian Cancer Prevention (PDQ).
  • Fibroids and cancer: Having fibroids does not increase your risk of uterine cancer, and fibroids do not “turn into” cancer. Uterine sarcomas are rare and typically unrelated to existing fibroids. See ACOG guidance: ACOG: Uterine Fibroids.

Symptoms: How endometriosis and fibroids differ—and overlap

  • Endometriosis commonly causes painful periods, pelvic pain between periods, pain with sex, pain with bowel movements or urination (especially around menstruation), and infertility. Some people also report bloating and fatigue. See ACOG: Endometriosis.
  • Fibroids frequently cause heavy or prolonged menstrual bleeding, pelvic pressure, frequent urination, constipation, back pain, and reproductive issues (depending on fibroid size and location). See OWH: Uterine Fibroids.

Because symptoms overlap and can co-exist, a thorough evaluation is key.

Diagnosis: What to expect

  • History and exam: Your clinician will review symptoms, menstrual patterns, reproductive goals, and perform a pelvic exam.
  • Imaging: Pelvic ultrasound is first-line for suspected fibroids and may identify ovarian endometriomas. MRI can help map fibroids or deeply infiltrating endometriosis.
  • Endometriosis confirmation: Many cases are diagnosed clinically, but laparoscopy with biopsy remains the definitive test when needed for diagnosis or treatment. See ACOG: Endometriosis.

Treatment options

Plans are individualized based on symptoms, size and location of lesions, age, and fertility goals. Choices often start conservatively and escalate as needed.

Endometriosis

  • Pain control: NSAIDs can help with dysmenorrhea and pelvic pain.
  • Hormonal therapy: Combined estrogen-progestin contraceptives, progestin-only methods (including levonorgestrel IUD), and newer gonadotropin-releasing hormone (GnRH) analogs can suppress endometriotic activity and improve pain. FDA-approved options include GnRH agonists (e.g., leuprolide) and antagonists (e.g., elagolix). See FDA: Endometriosis Treatments.
  • Surgery: Laparoscopic excision or ablation of endometriosis and lysis of adhesions can reduce pain and improve fertility in selected cases.

Fibroids

  • Watchful waiting: Appropriate when symptoms are mild and anemia is absent.
  • Medications: NSAIDs for cramps; hormonal contraceptives or the levonorgestrel IUD to reduce bleeding; tranexamic acid for heavy menses; short-term GnRH agonists or newer GnRH antagonists with add-back therapy (e.g., relugolix combination therapy, elagolix combinations) to shrink fibroids and control bleeding. See FDA approvals for fibroid therapies.
  • Minimally invasive procedures: Uterine artery embolization (UAE) to shrink fibroids by cutting off blood supply; MRI-guided focused ultrasound in select candidates.
  • Surgery: Myomectomy to remove fibroids while preserving the uterus; hysterectomy for definitive treatment when childbearing is complete or other options fail. If considering laparoscopic approaches, discuss morcellation risks and containment strategies per the FDA.

Fertility and pregnancy

  • Endometriosis can impair fertility by causing inflammation, adhesions, and altered pelvic anatomy. Medical suppression treats pain but does not improve fertility while in use. Surgical treatment may improve spontaneous conception in selected patients; assisted reproductive technologies are often considered. See NICHD: Endometriosis Treatment.
  • Fibroids may affect fertility and pregnancy outcomes when they distort the uterine cavity or are very large. Submucosal fibroids are most associated with miscarriage and infertility. Myomectomy can improve outcomes in specific scenarios; discuss individualized risks and benefits with your clinician. See ACOG.

When to seek care—and when to ask about cancer

Most people with endometriosis or fibroids do not have cancer. Still, prompt evaluation is wise if you have:

  • Heavy bleeding causing anemia (fatigue, dizziness) or soaking pads/tampons hourly
  • Pelvic pain that disrupts daily life or worsens over time
  • New pelvic mass, persistent bloating, early satiety, or unexplained weight loss
  • Bleeding after menopause
  • Rapidly enlarging uterine mass, especially after menopause

There is no recommended routine screening for ovarian cancer in average-risk individuals; attention to persistent symptoms and appropriate imaging is key. See NCI: Ovarian Cancer Prevention (PDQ).

Key takeaways

  • Endometriosis and fibroids are benign, common causes of pelvic pain and bleeding.
  • Endometriosis confers a small, increased relative risk of certain ovarian cancers, but the absolute risk is low.
  • Fibroids do not turn into cancer; uterine sarcomas are rare and typically unrelated to fibroids.
  • Effective treatments exist—from medications and minimally invasive procedures to surgery—tailored to your symptoms and fertility plans.
  • Discuss surgical approaches and morcellation considerations with your surgeon, per FDA guidance.

If you’re experiencing symptoms or have concerns about cancer risk, make an appointment with a gynecologist. Bringing a symptom diary and your goals (pain relief, bleeding control, fertility) can help you and your clinician craft a plan grounded in current evidence.

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