Risk factors (1) Age of onset: Different types of ovarian malignant tumors occur in women of different ages. In women before 20 years old, germ cell tumors are predominant; in women around 30-40 years old, junctional tumors are common; and ovarian epithelial cancer is common in women over 50 years old. (2) Risk factors: For ovarian epithelial carcinoma, the known risk factors include: increasing age, failure to give birth or the use of ovulation-promoting drugs. The incidence is twice as high in women who have not given birth as compared to menstruating women. Early childbearing, early menopause and the use of oral contraceptives can reduce the risk of ovarian cancer. (3) Genetic factors: About 10% of ovarian cancer cases have genetic factors. Women carrying mutant BRCA1 and BRCA2 have a 10%-50% increased risk of ovarian cancer with a lower age of onset. The risk of incidence increases with age. In particular, patients carrying the BRCA1 mutation have a median age of onset of only about 45 years. Prevention The following points are mentioned in the 2015 SGO recommendations for ovarian cancer prevention: (1) Oral contraceptives can reduce the risk of type I and type II ovarian cancer and are safe for use in patients carrying mutant BRCA1 and BRCA2. (2) Tubal ligation can reduce the incidence of ovarian cancer in both the general population and high-risk groups. (3) Prophylactic tubal oophorectomy reduces the incidence of BRCA1 and BRCA2 mutation carriers by 80%. (4) Genetic testing is recommended for patients with a high-risk family history. (5) The use of tubectomy as a sterilization procedure or prophylactic tubectomy during other pelvic surgery such as hysterectomy can reduce the incidence of ovarian cancer in the general population. About screening At present, there is still a lack of effective screening means for ovarian cancer worldwide. Some researchers have proposed to use CA125 and pelvic and abdominal ultrasound in combination with gynecologic examination for screening, but only 50% of early-stage ovarian cancers have elevated CA125 levels, and ultrasound is limited by the examination means, so it is difficult to detect lesions <1 cm and lesions in the pelvic floor. Even when combined screening is performed, its sensitivity and specificity are still unsatisfactory. 2014 WHO Histopathological Classification of Ovarian Cancer