Hello and welcome to the community. Sorry for the late response and about the loss of your mother to ovarian cancer. I too have lost a loved one due to that particular form of cancer so my heart goes out to you. And yes, it brings up worries about yourself. I'm sure they are looking into your uterine mass quite seriously.
While both start in a woman's reproductive organs, they are a bit different. They have different side effect profiles and characteristics to the cancer. With uterine cancer, a woman typically has unusual vaginal bleeding which is not the case with ovarian cancer. And ovarian cancer is often detected later due to the commonality of the symptoms of it at first like bloating and abdominal pain.
So, those differences were always there but in the 80's, it was likely harder to differentiate given the less advanced diagnosistic procedures.
Have you had a follow up on your uterine mass? I'm sure that is worrying for you. Let us know how that goes.