What is the ruling on purity and prayer for a woman suffering from cancer who is undergoing hormonal treatment to prevent menstruation, but it has nevertheless occurred? Should it be treated as menstruation or as irregular bleeding (istihada)?

If a woman sees blood during a time suitable for menstruation, meaning its duration and the clean periods interspersed within it do not exceed fifteen days, then it is menstruation. With it, she must abstain from prayer, fasting, and sexual intercourse. When the bleeding stops, she should perform ghusl and pray. However, if the duration of the blood and the clean periods interspersed within it exceeds fifteen days, then she is a mustahadah (experiencing irregular bleeding), and the rulings for a mustahadah apply to her.