If you had both ovaries removed it will cause immediate menopause. You stated that you had an ovarian tumor but did not state if both ovaries were removed. If one ovary was left in place then you will still menstruate.
This article explains everything including the function of the ovaries and the hormones they release that start the menstrual cycle:
If you go to page 2 of the article and scroll down towards the bottom you will see menopause.
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