Could Abnormal Vaginal Bleeding Be A Sign Of Endometrial Cancer?

I m 60 years old and have had light to moderate bleeding for 2 1/2 weeks. I had some lighter bleeding almost 4 years ago, had a biopsy, vaginal ultrasound but I don t remember exactly what the diagnosis was, just that it wasn t bad. Now that it s happening again, only heavier, I saw my primary physician this week. She told me that I was told 4 years ago that I needed to come back every 6 months and get re-checked. I ve been seeing her for 10 years, had annual paps, checkups every three months for thyroid and blood pressure meds, but no one has ever mentioned anything since the original biopsy about getting it done again so I thought everything was okay. Now she wants me to go see an OBGYN next Wed. My question is: what are the chances of it being endometrial cancer? I KNOW it doesn t do anygood to worry at this point, but I m not sleeping well.