What are Uterine Fibroids (UFs)?

(a.k.a. Uterine leiomyoma, myoma, fibromyoma, leiofibromyoma, fibroleiomyoma, and fibroma)

Uterine fibroids are BENIGN i.e. non-cancerous), usually clusters of TUMORS in, on or within the uterine walls

Originate from and are composed of SMOOTH MUSCLE cells (myocytes) of the uterine wall's muscle layer (called the myometrium, the middle layer of the uterine wall used for contracting the uterus) and its accompanying connective tissue;

• It is RARE for benign uterine leiomyomas to progress to cancerous leiomyosarcomas (1.7 women per 100,000 women are diagnosed annually with uterine sarcoma, which includes leiomyosarcoma) (National Cancer Institute)

Vary in size - from microscopic to very large (can weigh several pounds).

Fibroids are often described by their location in the uterus:

• Myometrial - in the muscle wall of the uterus
• Submucosal - just under the surface of the uterine lining
• Subserosal - just under the outside covering of the uterus
• Pendunculated - occurring on a long stalk on the outside of the uterus or inside the cavity of the uterus

Called DIFFUSE uterine leiomyomatosis - when there are too many fibroids to count.

Diagnosis of uterine fibroids

Diagnosis can be wrong - pelvic examination may show an irregularly shaped, lumpy, or enlarged uterus, but in obese women it is difficult to diagnose fibroids, which may be mistaken for:

• Pregnancy
• Ovarian tumors
• Inflammation of the fallopian tubes
• Uterine adenomyosis (a condition in which the uterine lining grows into the muscle wall of the uterus)

Fibroids can be confirmed - by a transvaginal ultrasound, a pelvic ultrasound or a pelvic MRI.

Who gets uterine fibroids?

UFs are the most common pelvic tumor in females, typically found during the mid- to late-reproductive years

• Uterine fibroid incidence rate is 70% by age 50 in U.S. white women and 80% in African-American women - with a staggering half of reproductive age U.S. women having fibroids. Typically affects women over 30, but not under 20; (Baird et al, 2003)
• More common in African-American women than Caucasian women - ~25% of white women and 50% of black women have symptomatic uterine fibroids. (Wise, 2005)
• More common in overweight women - perhaps because of increased estrogen from adipose aromatase enzyme activity that converts the androgens ANDROSTENEDIONE and Testosterone to estrogens
• UFs often have a growth spurt before menopause -and then become quiescent
• Higher UF incidence in women who have not given birth or had early menarche or have a UF history in first degree relatives
• Smokers have LESS risk of UFs
• Physical activity seems to protect against having UFs (Baird et al, 2007) (Flake et al, 2003)

What are the symptoms of uterine fibroids

What are the symptoms of uterine fibroids?

What causes uterine fibroids?

Hormonal influences and growth factors are involved in UF growth and development:

Causes of uterine fibroids

Estrogen and PROGESTERONE generally promote uterine fibroid growth

How to treat uterine fibroids

Mainstream treatments for uterine fibroids

Alternative therapies for uterine fibroids

References

Baird DD, Dunson DB, Hill MC, et al. (2003)  High cumulative incidence of uterine leiomyoma in balack and white women: ultrasound evidence. Am J Obstet Gynecol; 188: 100-107

Baird DD, et al. (2007) Association of physical activity with development of uterine leiomyoma. Am. J. Epidemiol. (2007) 165 (2): 157-163. Study

Flake GP, Andersen J, Dixon D.  (Jun. 2003) Review Etiology and pathogenesis of uterine leiomyomas: a review. Environ Health Perspect. Environ Health Perspect.111(8):1037-54. PubMed

Ishikawa, H.; Reierstad, S.; Demura, M.; Rademaker, A. W.; Kasai, T.; Inoue, M.; Usui, H.; Shozu, M. et al. (2009). "High Aromatase Expression in Uterine Leiomyoma Tissues of African-American Women". Journal of Clinical Endocrinology & Metabolism 94 (5): 1752. PubMed

Wise, L., Palmer, J., Bernard, H., Stewart, E., Rosenberg, L., (2005) Age-Specific Incidence rates for Self-Reported Uterine Leiomyomata in the Black Women's Health Study Obstet Gynecol 105(3): 563-568