Fibroid growth differs in black and white women

NEW YORK (Reuters Health) - Differences in the growth of fibroid tumors may explain why black women typically have more symptoms than white women, according to a study in the Proceedings of the National Academy of Sciences.

Fibroids, also known as leiomyomata, are growths within the walls of the uterus. Although almost always benign, these tumors can become quite large and produce heavy menstrual periods, pelvic pain, and other symptoms. They occur in about 25 percent of all women and are the leading cause of hysterectomy, or removal of the uterus, in the United States.

Dr. Donna Day Baird, at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina, and her associates conducted the Fibroid Growth Study, designed to measure fibroids in women with symptoms.

Included were 262 tumors in 72 women, ages 24 to 54 years. Thirty-eight subjects were African American and 34 were Caucasian. Fibroid volume was documented by MRI performed four times over a 1-year period.

Typically, the fibroids grew by about 9 percent every 6 months. However, 7 percent of tumors regressed by more than 20 percent.

Growth rates varied even within the same woman and "were not influenced by tumor size, location, body (weight or number of prior pregnancies)," Baird's team reports.

Before age 35, rates of fibroid growth were not associated with subject's race. However, growth rates declined with age only among white women who were older than 35 years of age.

Aside from age and race, the only other factor affecting the growth rate was the number of tumors, with single tumors growing much faster than multiple fibroids.

Based on their findings, the researchers suggest that "it may be possible to extend the follow-up time for assessment of fibroid growth" beyond the current clinical practice of evaluation at 6-month intervals.

"In addition," they write, "if further research supports our findings that tumor growth rates decline in white women as they age, those approaching perimenopause might chose to delay treatment and wait for menopause when tumors are likely to shrink."

SOURCE: Proceedings of the National Academy of Sciences, online December 1, 2008.