Topics of Interest

Fibroids and Cancer

Do Growing Fibroids Mean Cancer?

Fibroids are benign uterine growths. Furthermore, fibroids do not turn into cancer. Genetic studies of fibroids and uterine muscle cancer (sarcoma) show that they have very different genetic mutations and that sarcomas do not develop from fibroids. However, a leiomyosarcoma, an extremely rare malignant tumor of the uterine muscle, also causes enlargement of the uterus. But only 1 out of every 1,000 women admitted to the hospital for surgery because of problems thought to be from fibroids will be found to have a sarcoma. And since 80 percent of women with fibroids are never admitted to a hospital for surgery, the incidence of sarcoma in all women with fibroids is extraordinarily low. The average age of women who develop fibroids is 38. Although sarcoma can rarely occur in young women, the average age of a woman who develops a sarcoma is 63. So, if you have fibroids, there is not much reason to worry about sarcoma.

Most gynecologic textbooks teach physicians that if a woman has a rapidly growing uterus, she should have surgery to see if she has a uterine sarcoma. Surgery would be needed to remove tissue for microscopic analysis. However, during the course of my training and years in practice, I have never seen a “rapidly growing fibroid” actually turn out to be a sarcoma.

To study this issue, I did a clinical study at the hospitals where I practice and reviewed the charts of 1,332 women admitted for surgery because of fibroids. Only three women (two tenths of 1%) were found to have a sarcoma. Of the 371 patients admitted because of rapidly growing fibroids, only one (three tenths of 1%) had a sarcoma. This study showed that the risk of developing a sarcoma is extremely low, even if your fibroids are rapidly growing.

I am including the abstract from our article:

Uterine sarcoma in patients operated on for presumed leiomyomas and rapidly growing leiomyomas.
Authors: Parker W, Berek J, Fu YS.
Obstetrics and Gynecology 1994; 83:414-8

Objective: To determine the incidence of uterine sarcoma in patients operated on for symptomatic uterine leiomyomas or “rapidly growing” leiomyomas.

Methods: Medical records of 1332 women admitted to either of two community hospitals between 1988-1992 for hysterectomy or myomectomy for uterine leiomyomas were reviewed. The incidence of leiomyosarcoma, endometrial stromal sarcoma and mixed mesodermal tumor was calculated. Patient ages, admitting symptoms, operative and pathologic findings were analyzed. Included in the study were 371 women (28%) operated on for “rapidly growing” leiomyomas. All patients operated on during the same interval and found to have a uterine sarcoma were reviewed.

Results: One of 1332 patients (.07%) operated on for presumed leiomyoma was found to have a leiomyosarcoma This woman was the only patient found to have a sarcoma among 371 (0.27%) women operated on for “rapid growth” of the uterus. None of 198 patients who met a published definition of rapid growth had a uterine sarcoma. Two women (0.15%) were found to have endometrial stromal sarcoma and none was found to have a mixed mesodermal tumor. During the same interval, nine additional patients were found to have uterine sarcomas, and for these the preoperative diagnosis was sarcoma in four, endometrial cancer in three, ovarian cancer in one, and prolapsed uterus in one.

Conclusions: The total incidence of uterine sarcoma (leiomyosarcoma, endometrial stromal sarcoma, and mixed mesodermal tumor) among patients operated on for uterine leiomyoma is extremely low (0.23%). The incidence of sarcoma among patients operated on for “rapidly growing” leiomyoma (0.27%), or those who met published criteria for rapid growth (0%) does not substantiate the concept of increased risk of sarcoma in these women.

Can the Diagnosis of Sarcoma be Made Without Surgery?

Uterine sarcoma, a cancer of the uterine muscle, is extremely rare, occurring in less than 1 patient per 1,000 who have surgery for fibroids. And since 80 percent of women with fibroids never even have surgery, the incidence of this cancer is extraordinarily low. Also, most patients determined to have sarcomas are postmenopausal women in their sixties or seventies, whereas most patients with fibroids are in their thirties and forties. Almost all pre-menopausal women with growing fibroids have benign uterine fibroids. Therefore, most patients with rapidly growing fibroids may be followed with frequent pelvic examinations. If you are postmenopausal and not on estrogen, growth of the uterus is more concerning and may be an indication for surgery.

However, a recent study found that by using a combination of an MRI and a blood test called LDH, the diagnosis of uterine sarcoma could be reliably made. At the time of the MRI, a liquid dye called Gadolinium is injected into a vein. The MRI picture of the fibroids should be taken 40-60 seconds after injection. If a sarcoma is present the dye will light up on the MRI. This is because the sarcoma contains more blood vessels than normal uterine muscle and the blood vessels carry the dye. The other part of the testing, the LDH blood test, measures an enzyme made in muscle cells. It turns out that sarcoma makes more LDH iso-enzyme 3 and this can be measured by the lab (but your doctor must ask for this test specifically). So, the combination of an abnormal MRI and increased LDH-3 can mean that a sarcoma is present. But, if either of these tests is normal, it is unlikely that you have a sarcoma. I am including the abstract of this article below.
Usefulness of Gd-DTPA contrast-enhanced dynamic MRI and serum determination of LDH and its isozymes in the differential diagnosis of leiomyosarcoma from degenerated leiomyoma of the uterus

Authors -A. Goto, S. Takeuchi , K. Sugimura, T. Maruo
International Journal of Gynecological Cancer, Volume 12, Page 354, July 2002

This prospective study was conducted to identify the magnetic resonance imaging (MRI) characteristics of uterine leiomyosarcoma (LMS) and to evaluate the diagnostic accuracy of conventional MRI and dynamic MRI with or without serum measurement of lactate dehydrogenase (LDH) levels. Two hundred ninety-eight consecutive patients were entered in this study. In eligible 227 patients, ten patients with LMS and 130 patients with uterine degenerated leiomyoma (DLM) were included for the present study. Precontrast T1, T2 weighted images were obtained in all patients. Serum LDH and its isozymes were also measured. Dynamic MRI by Gd-DTPA was obtained in all patients with LMS and 32 patients with DLM in whom elevated LDH levels were observed. The contrast enhancement at 60 s after administration of Gd-DTPA was detected in all LMS, but absent in 28 of 32 DLM patients. Concerning serum LDH isozymes, both total LDH and LDH isozyme type 3 were elevated in all 10 patients with LMS. The sensitivity for determination of LMS with MRI alone, dynamic MRI alone, and combined use of MRI (including dynamic MRI) and serum LDH levels was 100% in each group. The specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 93.1%, 52.6%, 100%, and 93.1% with MRI alone, and 93.8%, 83.3%, 100%, and 95.2% with dynamic MRI alone, and 100%, 100%, 100%, 100% with combined use of LDH and MRI, respectively. In conclusion, the combined use of dynamic MRI and serum measurement of LDH (isozymes) seems to be useful in making a differentiated diagnosis of LMS from DLM before treatment.

Although the study is very convincing, these tests will need to be confirmed in other studies before they should be given total acceptance.

What Should You Do if You have a Growing Fibroid?

If you have a growing fibroid, it is perfectly reasonable to be followed by having a pelvic examination every one to three months. If the fibroid begins to cause bothersome symptoms, then surgery may be considered. If the fibroid continues to grow very rapidly, doubling in size in a few weeks or months, then surgery may be indicated. However, because of the rarity of sarcomas (especially in women younger than fifty), we found no justification for assuming that growth in a fibroid means that cancer is developing. And, as stated before, there is no evidence to suggest that fibroids turn into cancer. Therefore, surgery is not usually indicated.

If you are a woman in her fifties or sixties, the issue of growth of fibroids is different. Published reports show that sarcomas may occur in women in their fifties and sixties. If you are postmenopausal and not on estrogen replacement therapy, any growth in your uterus may be cause for concern. Until there is further confirmation of the MRI/LDH tests, surgery may be needed to remove the growing fibroid. A pathologist performs an examination of the tissue under a microscope to conclusively show if cancer is present.

Do Birth Control Pills Cause Fibroids to Grow?

Birth control pills do not appear to cause the growth of fibroids. Three studies have tried to answer this question; one study found a slightly increased risk of fibroids, another study found no increased risk and the third study found a slightly decreased risk. However, these studies are retrospective and may contain selection bias.

Does Menopausal Hormone Therapy Cause Fibroids to Grow?

Postmenopausal hormone therapy does not normally cause fibroid growth. A few studies have tried to answer this question. After three years, only 8% of postmenopausal women with fibroids who were taking hormones had any increase in fibroid size. If any increase in uterine size is noted, it is likely related to the dose of progestins. A study found that for women taking oral estrogen plus a low dose of synthetic progesterone for one year, 23% had a slight increase in size (about 1 inch in diameter) while 50% of the women taking a higher dose had an increase in size. Estrogen patches or skin creams (with synthetic progesterone) may cause slight (1/4 inch) increase in the diameter of fibroids while oral estrogen (with synthetic progesterone) caused no increase in size.

In our fibroid study, we found that in the small number of postmenopausal women (7 women) who were taking estrogen and were noted to have growing fibroids, none was found to have a sarcoma during surgery. Therefore, a reasonable option for these women might be to discontinue the estrogen and see if the uterus shrinks back to its previous size. If the fibroids do shrink (because the estrogen and progestin is no longer present), then you could stay off the hormones and avoid surgery. Or, if the hormones are necessary for bothersome menopausal symptoms, you can restart them with the knowledge that surgery will probably be necessary if the fibroids grow again. If you stop taking hormones and your uterus does not shrink, or especially if it continues to grow, then surgery should be performed because of the possibility of uterine sarcoma.

William H. Parker, MD
Clinical Professor, Reproductive Medicine, UC San Diego School of Medicine

Page last updated: January, 2018


Disclaimer: The ideas, procedures and suggestions contained on this web site are not intended as a substitute for consulting with your physician. All matters regarding your health require medical supervision.

Fibroid Doctor William H. Parker

Dr. William H. Parker is a board-certified Fellow in the American College of Obstetricians and Gynecologists. Dr. Parker is an internationally recognized expert in fibroid surgery and research. Based in San Diego, California, he is considered one of the best fibroid surgeons for abdominal and laparoscopic myomectomy in the United States and abroad. He has been chosen for Best Doctors in America and Top Doctors every year beginning in the late 90's.

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