Ovarian cancer begins in the ovaries. Ovaries are reproductive glands found only in females (women). The ovaries produce eggs (ova) for reproduction. The eggs travel through the fallopian tubes into the uterus where the fertilized egg implants and develops into a fetus. The ovaries are also the main source of the female hormones estrogen and progesterone. One ovary is on each side of the uterus in the pelvis.
- Epithelial tumors start from the cells that cover the outer surface of the ovary. Most ovarian tumors are epithelial cell tumors.
- Germ cell tumors start from the cells that produce the eggs (ova).
- Stromal tumors start from structural tissue cells that hold the ovary together and produce the female hormones estrogen and progesterone.
Most of these tumors are benign (non-cancerous) and never spread beyond the ovary. Benign tumors can be treated by removing either the ovary or the part of the ovary that contains the tumor.
Malignant (cancerous) or low malignant potential ovarian tumors can spread (metastasize) to other parts of the body and can be fatal. Their treatment is discussed later in this document.
Epithelial ovarian tumors
Malignant epithelial ovarian tumors
Cancerous epithelial tumors are called carcinomas. About 85% to 90% of ovarian cancers are epithelial ovarian carcinomas. When someone says that they had ovarian cancer, they usually mean that they had this type of cancer. These tumor cells have several features (when viewed under a microscope) that can be used to classify epithelial ovarian carcinomas into different types. The serous type is by far the most common, but there are other types of a mucinous, endometrioid, and clear cell.
If the cells don’t look like any of these four subtypes, the tumor is called undifferentiated. Undifferentiated epithelial ovarian carcinomas tend to grow and spread more quickly than the other types. These subtypes classify epithelial ovarian carcinomas, but they are also given a grade and a stage.
The grade classifies the tumor based on how much it looks like normal tissue on a scale of 1, 2, or 3. Grade 1 epithelial ovarian carcinomas look more like normal tissue and tend to have a better prognosis (outlook). Grade 3 epithelial ovarian carcinomas look less like normal tissue and usually have a worse outlook. Grade 2 tumors look and act in between grades 1 and 3.
The tumor stage describes how far the tumor has spread from where it started in the ovary. Epithelial ovarian cancers tend to spread to the lining and organs of the pelvis and abdomen (belly) first. It may lead to the build-up of fluid in the abdominal cavity (called ascites). As it becomes more advanced, it may spread to the lung and liver, or, rarely, to the brain, bones, or skin. Staging is explained in detail in a later section.
Other cancers that are similar to epithelial ovarian cancer
Primary peritoneal carcinoma
Primary peritoneal carcinoma (PPC) is rare cancer closely related to epithelial ovarian cancer. At surgery, it looks the same as an epithelial ovarian cancer that has spread through the abdomen. Under a microscope, PPC also looks just like epithelial ovarian cancer. Other names for this cancer include extra-ovarian (meaning outside the ovary) primary peritoneal carcinoma (EOPPC) and serous surface papillary carcinoma.
PPC seems to develop from cells in the lining of the pelvis and abdomen. This lining is called the peritoneum. These cells are very similar to the cells on the surface of the ovaries. Some experts believe that PPC may start in the cells lining the fallopian tubes.
Like ovarian cancer, PPC tends to spread along the surfaces of the pelvis and abdomen, so it is often difficult to tell exactly where cancer first started. This type of cancer can occur in women who still have their ovaries, but it is of more concern for women who have had their ovaries removed to prevent ovarian cancer. This cancer does rarely occur in men.
Symptoms of PPC are similar to those of ovarian cancer, including abdominal pain or bloating nausea, vomiting, indigestion, and a change in bowel habits. Also, like ovarian cancer, PPC may elevate the blood level of a tumor marker called CA-125.
Women with PPC usually get the same treatment as those with widespread ovarian cancer. It could include surgery to remove as much of cancer as possible (a process called debulking that is discussed in the section about surgery), followed by chemotherapy like that given for ovarian cancer. Its outlook is likely to be similar to widespread ovarian cancer.
Fallopian tube cancer
It is another rare cancer that is similar to epithelial ovarian cancer. It begins in the tube that carries an egg from the ovary to the uterus (the fallopian tube). Like PPC, fallopian tube cancer and ovarian cancer have similar symptoms. The treatment for fallopian tube cancer is much like that for ovarian cancer, but the outlook (prognosis) is slightly better.
Symptoms & Types
Ovarian cancer often starts silently, not showing symptoms until its later stages. What should you watch for, and what are the stages of ovarian cancer? Ovarian cancer warning signs include ongoing pain or cramps in the belly or back, abnormal vaginal bleeding, nausea, and bloating. Depending on the cancer stage, ovarian cancer treatment includes surgery and chemotherapy.
Treatment & Care
Surgery, chemotherapy, and radiation may be used to treat ovarian cancer, depending on the disease’s stage.