Short-term change in growth of uterine leiomyoma: tumor growth spurts.

OBJECTIVE: To describe the short-term changes in growth of uterine leiomyomas (fibroids). DESIGN: Prospective observational study. SETTING: University research center. PATIENT(S): Premenopausal women with fibroids (18 blacks and 18 whites) recruited through a physician network and community outreach. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURE(S): The volumes of 101 fibroids were measured at enrollment, 3, 6, and 12 months with magnetic resonance imaging, resulting in three interval-specific growth rates. Growth spurts were defined by interval growth rates≥30% per 3 months and substantially greater than during other intervals of observation. An overall measure of short-term change in fibroid growth was calculated as the variance of the three interval-specific growth rates. RESULT(S): Growth spurts were observed in 37 of the 101 fibroids, a prevalence nearly tenfold higher than that attributable to potential measurement error. Fibroids from the same woman did not have similar short-term growth, nor were woman-specific factors (age, race/ethnicity, parity, body mass) or the fibroid position in the uterus important. However, large fibroids (>5 cm diameter) had less short-term change than smaller fibroids. CONCLUSION(S): Short spurts of growth are common for fibroids, suggesting that tumor biology may change rapidly.