Is There Cancer in My Fibroid?
You may wonder: Can my fibroid lead to cancer?
It’s a good question. Media attention has recently become pandemic about women having fibroid surgery who ended up with widespread cancer, including a 2014 safety communication from the U.S. Food and Drug Administration (FDA). For those living with uterine fibroids, this can certainly provoke anxiety.
A fibroid, also known as leiomyoma, is a benign (non-cancerous) tumor of muscle arising from the uterus. It is the most common pelvic tumor in women, and the majority of women will develop them within their lifetime. But can they lead to cancer? Possibly, but don’t panic. There’s more…
By definition, leiomyomas are benign but they may actually harbor cancer, which we refer to as leiomyosarcoma. The cells in a fibroid are clones of the same original cell that decided to rebel and multiply unchecked by the body. This eventually results in a ball of muscle.
Dividing cells undergo a process called mitosis. The nuclei of mitotic cells appear differently than normal cells. Pathologists look at fibroids under a microscope and count the dividing cells, called mitotic figures. When they see at least ten mitotic figures under a high-power lens, the fibroid is said to be a cancer.
If a cancer is hiding in your fibroid, the ramifications can be catastrophic. Fibroid uteri (that's like uterus, but more than one) are often quite large and may need to be broken apart to be removed. If a gynecologist morcellates, or takes apart, your fibroid uterus and it's harboring cancer, then little pieces may spread and grow, worsening your prognosis. (i.e. you would be less likely to survive the cancer or would need more intensive treatment).
So even though the chance your fibroid has cancer may be low, you might choose not to undergo the risk of morcellation or myomectomy (fibroid removal), and instead choose a hysterectomy with a traditional belly incision. Certainly, if you have reason to suspect cancer, then a traditional hysterectomy is really the only way to go.
But let’s put leiomyosarcoma in perspective:
Based on the FDA analysis, the risk of a fibroid uterus harboring cancer at the time of hysterectomy is approximately 1 in 400.
See that pink circle in the midst of so many yellow ones? That represents the one woman that has a sarcoma in her fibroid uterus, next to the 399 that don’t. The other yellow circles are women who have non-cancerous fibroids. So the pink circle graphically represents the odds that there is a cancer in your fibroid uterus when you undergo hysterectomy.
However, many experts disagree with this estimate and believe for various reasons that the risk is actually lower. Some estimate it to be approximately 1 in 2000.
It’s pretty safe to say that the risk of cancer in this situation is pretty low either way. Now, you can see that the number of women who would have to undergo hysterectomy to find one cancer is quite high. You can use either of these estimates-the point is that the odds of your fibroid having cancer are pretty low. Look at it this way: All those yellow dots show the odds that your fibroid is NOT cancer. Feel better?
Now here is where a little more doctoring can help you decide what your individual risk might be. There are certain factors that increase the chance that your fibroid is cancerous. The most important seems to be age. As you age, the risk of cancer in fibroids increases. Being under the age of 50 reduces the likelihood that your fibroid has cancer. Factors that may increase the risk of cancer are anemia, fibroid size, or suspicion based on imaging, in addition to increasing age.
Now back to the original question - is there cancer in your fibroid?
If you believe you are at risk of fibroid cancer, seek the advice of an experienced gynecologic surgeon. But remember the overall odds - it’s pretty unlikely.
Last Updated: December 18, 2017