Ovarian cancer occurs when normal ovarian cells grow abnormally and produce tumors in one or both ovaries. An ovarian tumor can be either noncancerous (also called ‘benign’) or cancerous (also called ‘malignant’).
The most common type of ovarian cancer is called ovarian epithelial cancer. It begins in the tissue that covers the ovaries. Cancersometimes begins at the end of the fallopian tube near the ovary and spreads to the ovary. Cancer can also begin in the peritoneum and spread to the ovary. The stages and treatment are the same for ovarian epithelial, fallopian tube, and primary peritoneal cancers.
Another type of ovarian cancer is ovarian germ cell tumor, which is much less common. It begins in the germ (egg) cells in the ovary. Ovarian low malignant potential tumor (OLMPT) is a type of ovarian disease in which abnormal cells form in the tissue that covers the ovaries. OLMPT rarely becomes cancer.
National Cancer Institute