The monthly period or menstruation ceases because the ovaries stop making enough hormones. It is a time when a woman can no longer bear children.
Natural menopause is a gradual process that can take several years.
Surgery and radiation to the ovaries cause immediate and severe menopause. The powerful drugs in the chemotherapy treatments can cause cessation of ovary functions, reduction of estrogen and progesterone levels and loss of periods temporarily or permanently. One of the signs of menopause is not having menstruation for six to twelve months. It can be confirmed by a blood test. Women already diagnosed with breast cancer should discuss other non hormonal options with their doctor, oncologist, gynecologist or endocrinologist.