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It is very unlikely that this is a recurrence of endometrial cancer, so not to worry. Less than 1% chance. You will want to make a Drs appointment as soon as possible for an exam and pap smear. The most likely cause of the bleeding is atrophic vaginitis. This is thinning of the vaginal lining due to lack of hormones. It is very common. Get in as soon as possible but try not to worry.