What is the ruling on prayer and fasting while bleeding continues due to a tumor in the uterine lining, and is this blood considered menstrual blood that prohibits prayer?

If the bleeding exceeds 15 days, then you are in a state of istihadah (non-menstrual bleeding). You must refer to your previous habit, if you know it, and count that as menstruation. Then, you perform ghusl (ritual bath) and wudu (ablution) for every prayer, and you pray and observe all the rulings applicable to ritually pure women. If you do not have a habit, then rely on differentiation: dark, thick blood accompanied by pain is menstruation, and anything else is istihadah. If you have neither a habit nor the ability to differentiate, then consider six or seven days as menstruation, then perform ghusl. The remainder is istihadah, during which you perform wudu for every prayer.