The incidence of malignant tumors of the ovary varies from country to country and region to region, with the highest incidence in Northern Europe and North America and a lower incidence in China. The incidence rate is higher among urban women than rural women, and the incidence rate is higher among economically well-off groups of women than those who are economically disadvantaged. In terms of race, the incidence rate is higher in the white race than in other races of color. Endocrine disorders Ovarian tumors occur in women who are celibate, infertile, or have fewer children; the incidence of delayed menarche and premature menopause increases; and the incidence of ovarian cancer increases with severe premenstrual dysphoric disorder, dysmenorrhea, repeated miscarriages, unusual breast distension, history of breast cancer, and history of endometriosis. Number and frequency of ovulation Cyclic ovulation of ovary is an adverse stimulus to the mesenchyme on the surface of ovary, and repeated damage repair may be a high-risk factor for inducing ovarian cancer. According to the statistics of Peking Union Medical College Hospital, the incidence of ovarian cancer is prone to increase when the number of ovarian ovulation increases. Full-term delivery and longer breastfeeding and oral contraceptive pills can reduce the occurrence of ovarian cancer, which is attributed to the reduction of the number of ovulation. Genetic factors: Women without family history of ovarian cancer have a lifetime risk of 1/70; if one first-degree relative has the disease, the risk increases to 5%; if two first-degree relatives have the disease, the risk is 7%; if there is a first-degree relative with hereditary ovarian cancer syndrome, the risk is as high as 50%, and the risk increases with the increase of age.