Cancer that forms in tissues of the ovary (one of a pair of female reproductive glands in which the ova, or eggs, are formed). Most ovarian cancers are either ovarian epithelial carcinomas (cancer that begins in the cells on the surface of the ovary) or malignant germ cell tumors (cancer that begins in egg cells).

The Ovaries
The ovaries are part of a woman's reproductive system . They are in the pelvis . Each ovary is about the size of an almond.

The ovaries make the female hormones - estrogen and progesterone . They also release eggs. An egg travels from an ovary through a fallopian tube to the womb ( uterus ).

When a woman goes through her "change of life" ( menopause ), her ovaries stop releasing eggs and make far lower levels of hormones.

Understanding Cancer
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.

Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.

Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Tumors can be benign or malignant :

•  Benign tumors are not cancer:

• Benign tumors are rarely life-threatening.
• Generally, benign tumors can be removed. They usually do not grow back.
• Benign tumors do not invade the tissues around them.
• Cells from benign tumors do not spread to other parts of the body.

•  Malignant tumors are cancer:

• Malignant tumors are generally more serious than benign tumors. They may be life-threatening.
• Malignant tumors often can be removed. But sometimes they grow back.
• Malignant tumors can invade and damage nearby tissues and organs.
• Cells from malignant tumors can spread to other parts of the body. Cancer cells spread by breaking away from the original (primary) tumor and entering the lymphatic system or bloodstream. The cells invade other organs and form new tumors that damage these organs. The spread of cancer is called metastasis .