Are Thick Uterine Lining And Closed Uterus Sings Of Cancer?

Hi, I am 62 years old. I went for my first pep after eight years( my husband died eight years ago) and was told that the lining in my uterus has thicken. I had cancer in my right breast and had it removed. I was put on tamoxifen and have one year left to take this medication. I was then sent to see a gynaecologist and was told the same thing about the thicken in my uterus and also that my uterus had closed over. He had to open it and take a piece of it to send away to be checked. Does this mean that I have cancer again in my uterus or does it mean that I will need a hysterectomy? Thankyou for your time.