Many diseases have their symptoms at different stages, and ovarian cancer is no exception. What is the significance of clinical staging of ovarian cancer? According to the different stages of ovarian cancer and patients’ own conditions, different treatments can be chosen. Ovarian cancer staging can be divided into the following four stages: stage I, stage II, stage III and stage IV. Below is a brief introduction of the differences of each stage of ovarian cancer. Stage I: lesion location: confined to ovary For advanced ovarian cancer patients with extensive metastasis, tumor cytoreduction or lumpectomy with chemotherapy can still achieve ideal results based on accurate ovarian cancer staging. Stage Ⅰa: the lesion is confined to one ovary, with intact peritoneum, no tumor on the surface and no ascites; Stage Ⅰb: the lesion is confined to both ovaries, with intact peritoneum, no tumor on the surface and no ascites; Stage Ⅰc: the lesion of Stage Ⅰa or Stage Ⅰb has already penetrated out of the surface of the ovary or the peritoneum is ruptured, or malignant cells can be found in ascites or peritoneal lavage fluid. Stage II: lesion location: involving one or both ovaries with pelvic metastasis The accuracy of clinical surgery in staging ovarian cancer is easily affected by subjective factors, while abdominopelvic CT scan can make up for the shortcomings of surgical staging, and the accuracy of preoperative staging can reach 70% to 90%. Stage IIa: lesion extension or metastasis to the uterus or fallopian tube; Stage IIb: lesion extension to other pelvic tissues; Stage IIc: Stage IIa or IIb lesion, with the tumor penetrating the surface of the ovary; or rupture of the peritoneal membrane; or malignant cells are found in the ascites or peritoneal lavage. Stage III Lesion location: involvement of one or both ovaries with extra-pelvic implants Stage IIIa: lesion grossly seen confined to the pelvis, lymph node-negative, but microscopically there is an implant tumor on the peritoneal surface of the peritoneum; Stage IIIb: abdominal peritoneal implant tumor <2 cm in diameter, lymph node-negative; Stage IIIc: abdominal peritoneal implant tumor ≥2 cm in diameter, or accompanied by metastasis to the retroperitoneum or inguinal lymph nodes. Stage IV Lesion location: distant metastasis Malignant cells need to be found in the presence of ascites; Liver metastasis (involving liver parenchyma).