This is a result of a number of factors. Malignant tumors of the ovaries develop quickly, often times involving both ovaries, and they shed malignant cells relatively early in the disease. These cells, which frequently land on the uterus, bladder, and bowel, can begin forming new tumor growths before cancer is ever even suspected. In addition to the rapid rate of development, there is not a screening test for ovarian cancer and symptoms of early disease are minimal, if even present. For these reasons, over 50 percent of women with ovarian cancer are in the advanced stages of the disease at the time of diagnosis.
Ovarian cancer is more common in industrialized nations, with the exception of Japan.
The incidence is higher in older women. More than half of the deaths from ovarian cancer occur in women between 55 and 74 years of age. Approximately one quarter of ovarian cancer deaths occur in women between 35 and 54 years of age. Studies have shown that there may be a lower risk of ovarian cancer in patients who have used the oral contraceptive pill. After five or more years of use, there is a 60 percent reduction in the risk of ovarian cancer.