are well-differentiated (Grade 1), moderately differentiated (Grade 2) and poorly differentiated (Grade 3). Well-differentiated tumors have a better prognosis than poorly differentiated tumors. Clear cell carcinoma and especially undifferentiated carcinoma have a poorer prognosis than the other cell types.
The two other major kinds of ovarian cancer—germ cell tumors, which arise from the eggs, and ovarian stromal tumors, which arise from supportive tissue—are relatively uncommon and account for less than 10 percent of all ovarian malignancies ( see "Ovarian Germ Cell Tumors" ).
How It Spreads Ovarian cancer spreads early by shedding malignant cells into the abdominal cavity. The cells implant on the lining of the abdominal cavity (peritoneum) and can grow on the surface of the liver, the fatty tissue attached to the stomach and large intestine (omentum), the small and large intestines, the bladder and the diaphragm.
Disease on the diaphragm may at times result in impaired drainage of fluid from the abdominal cavity, resulting, for some women, in a large collection of abdominal fluid known as ascites . The cancer cells can occasionally cross the diaphragm and spread to the surface of the lungs and chest cavity, resulting in a collection of fluid around the lungs known as a pleural effusion .
Ovarian cancer may also spread to the pelvic, aortic, groin and neck lymph nodes ( see Diagram in Cervical Cancer ).
