- Epithelial ovarian cancer begins in the epithelium: the outer cells that cover the ovary. This is the most common type of ovarian cancer, accounting for about 90% of cases.
- Germ cell ovarian cancer begins in the cells that produce the eggs.
- Stromal tumours start from structural tissue cells that hold the ovary together and produce the female hormones; estrogen and progesterone. These tumours can affect women of any age.