Can Fibroids Turn Into Cancer?
Why This Matters
One of the first questions many women ask after being diagnosed with fibroids is:
"Could it be cancer?"
It's an understandable fear.
Hearing that you have a growth inside your uterus can be frightening, and it's natural to worry about what it might mean for your health.
The reassuring news is that fibroids are almost always benign (non-cancerous).
Although there is a rare type of cancer that develops in the muscle of the uterus, current evidence suggests it usually develops independently rather than from an existing fibroid.
Understanding the difference between fibroids and uterine cancer can help reduce unnecessary anxiety while ensuring you know when medical assessment is important.
Quick Summary
Fibroids are benign (non-cancerous) growths.
The vast majority of fibroids remain benign throughout a woman's life.
A rare cancer called uterine leiomyosarcoma develops in the muscle of the uterus.
Current evidence suggests leiomyosarcoma usually develops independently rather than from an existing fibroid.
Rapid growth, particularly after menopause, should always be assessed.
Most women with fibroids never develop uterine cancer.
What Are Fibroids?
Fibroids (also called uterine leiomyomas) are non-cancerous growths that develop from the smooth muscle of the uterus.
They are incredibly common.
In fact, up to 70–80% of women will develop fibroids during their lifetime, although many never know they have them because they cause no symptoms.
Fibroids can vary greatly in:
size
number
location
Some are no bigger than a pea, while others can grow much larger.
Despite their size, they remain benign tumours, meaning they do not spread to other parts of the body.
Can Fibroids Turn Into Cancer?
This is one of the biggest myths surrounding fibroids.
The reassuring answer is that the vast majority do not.
For many years, doctors questioned whether fibroids could become cancerous over time.
Current evidence suggests that uterine leiomyosarcoma usually develops independently rather than from an existing fibroid. While it isn't possible to say that transformation never occurs, it appears to be exceptionally rare, and most experts consider leiomyosarcoma to be a separate disease rather than a cancer that develops from a benign fibroid.
In other words, women with fibroids are not considered to be simply waiting for one of their fibroids to become cancerous.
What Is Leiomyosarcoma?
Leiomyosarcoma is a rare cancer that develops from the smooth muscle of the uterus.
Unlike fibroids, it:
grows aggressively
can spread to other parts of the body
requires specialist treatment
Fortunately, it is very uncommon.
Most women diagnosed with fibroids will never develop leiomyosarcoma.
How Common Is It?
Leiomyosarcoma is extremely rare.
The exact number varies between studies, but it affects only a very small proportion of women compared with the millions who have fibroids.
This is why healthcare professionals generally reassure women that fibroids themselves are not considered precancerous.
How Can Doctors Tell the Difference?
Unfortunately, there isn't a single scan that can always distinguish a fibroid from a leiomyosarcoma with complete certainty before surgery.
Doctors use several pieces of information together, including:
your symptoms
your age
whether you've reached menopause
ultrasound findings
MRI scans (in some situations)
how quickly the growth appears to be changing
In many cases, the diagnosis can only be confirmed by examining tissue under a microscope after surgery.
When Might Doctors Be More Concerned?
Most fibroids are straightforward to diagnose and monitor.
However, your healthcare provider may recommend further investigations if:
a fibroid appears to be growing rapidly, particularly after menopause
you develop new symptoms after menopause
there is unexplained vaginal bleeding after menopause
scans show unusual features
symptoms are changing unexpectedly
These situations do not mean you have cancer, but they do warrant further assessment.
What Symptoms Might Suggest Further Investigation?
Many of the symptoms of fibroids and uterine cancers overlap.
These include:
pelvic pain
abdominal swelling
pressure symptoms
abnormal bleeding
This is why healthcare providers consider your overall clinical picture rather than relying on one symptom alone.
Remember, having these symptoms does not mean you have cancer.
Can Fibroids Increase My Risk of Cancer?
Current evidence suggests that having fibroids does not significantly increase your risk of developing uterine leiomyosarcoma.
Fibroids are extremely common.
Leiomyosarcoma is extremely rare.
If fibroids routinely became cancerous, leiomyosarcoma would be far more common than it is.
What Does This Mean for You?
Being diagnosed with fibroids can understandably feel frightening.
However, it's important to remember that fibroids are one of the most common benign conditions affecting women.
The vast majority remain benign throughout a woman's life.
If your healthcare provider recommends monitoring your fibroids, this is usually because they want to ensure they remain stable—not because they believe they are likely to become cancer.
If anything changes, your healthcare team will arrange the appropriate investigations.
You Are Not Alone
Many women hear the word "tumour" and immediately think "cancer."
It's an entirely natural reaction.
Remember that tumour simply means an abnormal growth.
Tumours can be benign (non-cancerous) or malignant (cancerous).
Fibroids are benign tumours.
If you're feeling anxious after your diagnosis, don't hesitate to ask your healthcare provider to explain your scan results and why they're confident your fibroids are benign.
Sometimes understanding the difference is enough to ease a great deal of worry.
Questions to Ask Your Doctor
Are you confident these are fibroids?
Do I need any further scans?
Why do you think my fibroids are benign?
Should they be monitored?
Are there any warning signs I should look out for?
If I develop new symptoms, when should I seek medical advice?
Could my HRT affect my fibroids?
Myth vs Fact
Myth
Fact
Fibroids eventually become cancer.
Current evidence suggests the vast majority remain benign throughout a woman's life.
Every tumour is cancer.
A tumour can be benign or malignant. Fibroids are benign tumours.
Large fibroids are more likely to become cancerous.
Size alone does not determine whether a growth is cancerous.
Fibroids mean I'll get uterine cancer.
Most women with fibroids never develop uterine cancer.
When to Seek Urgent Medical Advice
Arrange a prompt medical assessment if you experience:
vaginal bleeding after menopause
rapidly increasing abdominal swelling
persistent or worsening pelvic pain
unexplained weight loss
difficulty passing urine or opening your bowels because of increasing pelvic pressure
any new or concerning symptoms that don't have an obvious explanation
These symptoms are far more likely to have causes other than cancer, but they should always be assessed.
Your Next Step
If you've recently been diagnosed with fibroids:
Ask your healthcare provider to explain where your fibroids are located.
Find out whether any follow-up scans are recommended.
Don't be afraid to ask why they're confident the growths are benign.
If you've reached menopause, report any vaginal bleeding promptly.
Remember that the vast majority of fibroids remain benign throughout a woman's life.
Understanding the facts can help replace fear with reassurance and allow you to make informed decisions about your care.
Key Takeaways
Fibroids are benign (non-cancerous) growths.
The vast majority of fibroids remain benign and are not thought to develop into cancer.
Leiomyosarcoma is a rare cancer that is generally thought to develop independently rather than from an existing fibroid.
Most women with fibroids never develop uterine cancer.
New symptoms, particularly after menopause, should always be assessed.
Regular follow-up may be recommended depending on your individual circumstances.
Frequently Asked Questions
Can fibroids become cancer?
Current evidence suggests that the vast majority of fibroids remain benign and are not thought to develop into cancer. Leiomyosarcoma is considered a separate disease that usually develops independently.
What is uterine leiomyosarcoma?
Leiomyosarcoma is a rare cancer of the smooth muscle of the uterus. It is considered a separate condition from fibroids.
Can an ultrasound tell the difference?
Ultrasound can often identify fibroids, but it cannot always distinguish a benign fibroid from a rare cancer with complete certainty. Sometimes additional imaging, such as an MRI scan, is recommended.
Should I worry if my fibroid is growing?
Fibroids commonly grow before menopause because they are influenced by hormones. However, if a fibroid appears to be growing after menopause, your healthcare provider will usually recommend further assessment.
Should every fibroid be removed to rule out cancer?
No. Most fibroids do not require surgery simply because of concerns about cancer. Treatment decisions are based on symptoms, size, location and your individual circumstances.
Related Articles
Fibroids Explained
Symptoms of Fibroids
Treatment Options for Fibroids
Fibroids After Menopause
When Should You See a Gynaecologist?(future article)
Understanding Postmenopausal Bleeding(future article)
Understanding Pelvic Ultrasound Scans(future article)
References
National Institute for Health and Care Excellence (NICE). Heavy Menstrual Bleeding: Assessment and Management (NG88).
Royal College of Obstetricians and Gynaecologists (RCOG). Fibroids: Information for You.
American College of Obstetricians and Gynecologists (ACOG). Uterine Fibroids.
Stewart EA, et al. Uterine Fibroids.Nature Reviews Disease Primers.
Bulun SE. Uterine Fibroids.New England Journal of Medicine.
World Health Organization (WHO). Classification of tumours of the female reproductive organs.