FACT SHEET covering top issues on fibroids
- 1Fibroids are a hormone dependent tumor – both estrogen and progesterone is necessary for the fibroid to grow
- 2Women may begin to develop fibroids as young as the early twenties
- 3Fibroids may cause reproductive problems
- 4Some fibroids grow in multiple numbers they often look like a single fibroid due to their tendency to grow in a cluster
- 5The most common symptom of fibroids is abnormal periods
What Causes Fibroids
As we know, our cells are renewed at certain intervals – after sexual intercourse or when a woman’s monthly cycle is completed. The new cells, which are called stem cells, form and replace the old cells.
During these periods of renewal there are genetic changes that happen in the muscle cells as the new ones form. It is these genetic changes that cause fibroids to develop. Some data suggests that genetics play a significant role in the origination of the fibroid tumors due to the tumors being relatively common in particular groups of women.
Fibroids are a hormone dependent tumor which means both estrogen and progesterone is needed for the fibroid to grow. More commonly, fibroids are the product of progesterone derived tumors rather than tumors that depend on estrogen.
Some believe the role of steroid hormones contribute to fibroid formation.
Until recently, the steroid hormones, estrogen and progesterone were considered the most important regulators of fibroid growth. This would explain why fibroids appear during a woman's middle reproductive years (when estrogen levels are high) and stop growing after the menopause (when estrogen levels drop)
Women who weigh over 70kg may be more likely to have fibroids than lighter women. This is thought to be due to higher estrogen levels in heavier women.
In the past, the contraceptive pill was thought to increase the risk of fibroids, however, the pill no longer contains the same high levels of estrogen than it used to. Some studies suggest that the newer combined pill (estrogen and progestogen) and the mini pill (progestogen only) may actually help prevent or slow the growth of fibroids.
Growth hormones (GH) and prolactin (PRL) are also thought to promote fibroid growth; however their role is less well defined. More recently, growth factors (small proteins that affect cell growth), have been shown to mediate the growth-promoting effects of estrogen and to play an important role in the development of fibroid tumors.
Estrogen, progesterone and growth factors certainly promote the growth of the tumors; however their roles occur after the initiation of the fibroid formation. The initiating event remains unknown, however many believe there are genetic factors associated with the formation of fibroids.
Fibroids are at least twice as common in African-American women as in white women. Although racial differences in socioeconomic status and access to health care may contribute to this finding, these factors do not completely explain the discrepancy. Further, there is a genetic predisposition for hysterectomy; this operation is two-fold higher in identical versus fraternal twins. There also exists a rare heritable form of uterine fibroids in association with fibroids of the skin called Reed's syndrome. Most importantly, women whose close relatives have fibroids are more likely to develop symptoms. This means women with a family history of fibroids are twice as likely to develop fibroids as women with no family history.