A cyst is usually a fluid filled sac on one or both ovaries. It sounds like you are talking about a fibroid that grew from 3 cm to 10 cm in 6 months. Fibroids grow in response to estrogen in your system. They are generally not removed unless they are causing symptoms. Pressure from fibroids can be felt on organs close to the uterus and cause symptoms of constipation, urinary frequency, incontinence and very rarely, kidney function problems.
Fibroids sometimes cause excessive bleeding from the uterus when located inside the uterus.
In a menopausal woman who chooses not to take hormonal replacement therapy, existing fibroids usually shrink because the body is producing less estrogen. New fibroids are unlikely. Fibroids typically grow attached directly to the inside or outside wall of the uterus. I recently had very excessive vaginal bleeding from fibroids, which required a myomectomy and blood transfusions. In some cases, fibroids can return, even after a myomectomy.