Ovarian Cancer Types and Stages
Types of Ovarian Tumors
Many types of tumors can start growing in the ovaries. Most of these are benign (non-cancerous) and never spread beyond the ovary. Benign tumors can be treated successfully by removing either the ovary or the part of the ovary that contains the tumor. Ovarian tumors that are not benign are malignant (cancerous) and can spread (metastasize) to other parts of the body. Their treatment is more complex and is discussed later in this document.
In general, ovarian tumors are named according to the kind of cells the tumor started from and whether the tumor is benign or cancerous. There are 3 main types of ovarian tumors:
*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.
Epithelial ovarian tumors
Benign epithelial ovarian tumors
Most epithelial ovarian tumors are benign, don’t spread, and usually don’t lead to serious illness. There are several types of benign epithelial tumors including serous adenomas, mucinous adenomas, and Brenner tumors.
Tumors of low malignant potential
When looked at under the microscope, some ovarian epithelial tumors don’t clearly appear to be cancerous. These are called tumors of low malignant potential (LMP tumors). They are also known as borderline epithelial ovarian cancer. These are different from typical ovarian cancers because they don’t grow into the supporting tissue of the ovary (called the ovarian stroma). Likewise, if they spread outside the ovary, for example, into the abdominal cavity, they may grow on the lining of the abdomen but don’t grow into it.
LMP tumors tend to affect women at a younger age than the typical ovarian cancers. These tumors grow slowly and are less life-threatening than most ovarian cancers. LMP tumors can be fatal, but this isn’t common.
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. When these tumors are looked at under the microscope, the cells have several features 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 like mucinous, endometrioid, andclear cell.
If the cells don't look like any of these 4 subtypes, the tumor is called undifferentiated. Undifferentiated epithelial ovarian carcinomas tend to grow and spread more quickly than the other types. Epithelial ovarian carcinomas are classified by these subtypes, 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. Staging is explained in detail in a later section.
Primary peritoneal carcinoma
Primary peritoneal carcinoma (PPC) is a 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. Primary peritoneal carcinoma develops in cells from 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. Like ovarian cancer, PPC tends to spread along the surfaces of the pelvis and abdomen, so it is often difficult to tell exactly where the 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. This could include surgery to remove as much of the cancer as possible (a process called debulking that's discussed in the "Surgery" section), followed by chemotherapy like that given for ovarian cancer. Its outlook is likely to be similar to widespread ovarian cancer.
Fallopian tube cancer
This is another rare 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 and outlook (prognosis) is slightly better for fallopian tube cancer than for ovarian cancer.
Germ cell tumors
Germ cells are the cells that usually form the ova or eggs. Most germ cell tumors are benign, but some are cancerous and may be life threatening. Less than 2% of ovarian cancers are germ cell tumors. Overall, they have a good outlook, with more than 9 out of 10 patients surviving at least 5 years after diagnosis. There are several subtypes of germ cell tumors. The most common germ cell tumors are teratoma, dysgerminoma, endodermal sinus tumor, and choriocarcinoma. Germ cell tumors can also be a mix of more than a single subtype.
Teratomas are germ cell tumors with areas that, when viewed under the microscope, look like each of the 3 layers of a developing embryo: the endoderm (innermost layer), mesoderm (middle layer), and ectoderm (outer layer). This germ cell tumor has a benign form called mature teratoma and a cancerous form called immature teratoma.
The mature teratoma is by far the most common ovarian germ cell tumor. It is a benign tumor that usually affects women of reproductive age (teens through forties). It is often called a dermoid cyst because its lining resembles skin. These tumors or cysts can contain different kinds of benign tissues including, bone, hair, and teeth. The patient is cured by surgically removing the cyst.
Immature teratomas are a type of cancer. They occur in girls and young women, usually younger than 18. These are rare cancers that contain cells that look like those from embryonic or fetal tissues such as connective tissue, respiratory passages, and brain. Tumors that are relatively more mature (grade 1 immature teratoma) and haven’t spread beyond the ovary are cured by surgical removal of the ovary. When they have spread beyond the ovary and/or much of the tumor has a very immature appearance (grade 2 or 3 immature teratomas), chemotherapy is recommended in addition to surgery to remove the ovary.
This type of cancer is rare, but it is the most common ovarian germ cell cancer. It usually affects women in their teens and twenties. Dysgerminomas are considered malignant (cancerous), but most don’t grow or spread very rapidly. When they are limited to the ovary, more than 75% of patients are cured by surgically removing the ovary, without any further treatment. Even when the tumor has spread further (or if it comes back later), surgery and/or chemotherapy is effective in controlling or curing the disease in about 90% of patients.
Endodermal sinus tumor (yolk sac tumor) and choriocarcinoma
These very rare tumors typically affect girls and young women. They tend to grow and spread rapidly but are usually very sensitive to chemotherapy. Choriocarcinoma that starts in the placenta (during pregnancy) is more common than the kind that starts in the ovary. Placental choriocarcinomas usually respond even better to chemotherapy than ovarian choriocarcinomas.
About 1% of ovarian cancers are ovarian stromal cell tumors. More than half of stromal tumors are found in women older than 50, but about 5% of stromal tumors occur in young girls. The most common symptom of these tumors is abnormal vaginal bleeding. This happens because many of these tumors produce female hormones (estrogen). These hormones can cause vaginal bleeding (like a period) to start again after menopause. In young girls, these tumors can also cause menstrual periods and breast development to occur before puberty. Less often, stromal tumors make male hormones (like testosterone). If male hormones are produced, the tumors can cause normal menstrual periods to stop. They can also cause facial and body hair to grow. Another symptom of stromal tumors can be sudden, severe, abdominal pain. This occurs if the tumor starts to bleed. Types of malignant (cancerous) stromal tumors include granulosa cell tumors (the most common type), granulosa-theca tumors, and Sertoli-Leydig cell tumors, which are usually considered low-grade cancers. Thecomas and fibromas are benign stromal tumors. Cancerous stromal tumors are often found at an early stage and have a good outlook, with more than 75% of patients surviving long-term.
An ovarian cyst is a collection of fluid inside an ovary. Most ovarian cysts occur as a normal part of the process of egg release (ovulation) -- these are called "functional" cysts. These cysts usually go away within a few months without any treatment. If you develop a cyst, your doctor may want to check it again after your next cycle (period) to see if it has gotten smaller. An ovarian cyst can be more concerning in a female who isn't ovulating (like a woman after menopause or girl who hasn't started her periods), and the doctor may want to do more tests. The doctor may also order other tests if the cyst is large or if it does not go away in a few months. Even though most of these cysts are benign (not cancer), a small number of them could be cancer. Sometimes the only way to know for sure if the cyst is cancer is to take it out with surgery. Benign cysts can be observed (with repeated physical exams and imaging tests), or removed with surgery.
How is ovarian cancer staged?
Staging is the process of finding out how widespread a cancer is. Most ovarian cancers that are not obviously widespread are staged at the time of surgery. One of the goals of surgery for ovarian cancer is to obtain tissue samples for diagnosis and staging. In order to stage the cancer, samples of tissues are taken from different parts of the pelvis and abdomen and examined under the microscope.
Staging is very important because ovarian cancers have a different prognosis at different stages and are treated differently. The accuracy of the staging may determine whether or not a patient will be cured. If the cancer isn’t properly staged, then cancer that has spread outside the ovary may be missed and not treated. Once a stage has been given it does not change, even when the cancer comes back or spreads to new locations in the body.
Ask your cancer care team to explain the staging procedure. Also ask them if they will perform a thorough staging procedure. After surgery, ask what your cancer's stage is. In this way, you will be able to take part in making informed decisions about your treatment.
Ovarian cancer is staged according to the AJCC/TNM System. This describes the extent of the primary Tumor (T), the absence or presence of metastasis to nearby lymph Nodes (N), and the absence or presence of distant Metastasis (M). This closely resembles the system that is actually used by most gynecologic oncologists, called the FIGO system. Both rely on the results of surgery for the actual stages. Fallopian tube cancer is staged like ovarian cancer, but with different "T" categories. Primary peritoneal cancer (PPC) is staged like ovarian cancer, with all cases being either stage III or IV depending on whether the cancer has spread to distant sites.
What the stages of ovarian cancer mean
The cancer is still contained within the ovary (or ovaries). It has not spread outside the ovary.
Stage IA (T1a, N0, M0): Cancer has developed in one ovary, and the tumor is confined to the inside of the ovary. There is no cancer on the outer surface of the ovary. Laboratory examination of washings from the abdomen and pelvis did not find any cancer cells.
Stage IB (T1b, N0, M0): Cancer has developed within both ovaries without any tumor on their outer surfaces. Laboratory examination of washings from the abdomen and pelvis did not find any cancer cells.
Stage IC (T1c, N0, M0): The cancer is present in one or both ovaries and one or more of the following are present:
- Cancer is on the outer surface of at least one of the ovaries.
- In the case of cystic tumors (fluid-filled tumors), the capsule (outer wall of the tumor) has ruptured (burst)
- Laboratory examination found cancer cells in fluid or washings from the abdomen.
The cancer is in one or both ovaries and has involved other organs (such as the uterus, fallopian tubes, bladder, the sigmoid colon, or the rectum) within the pelvis. It has not spread to lymph nodes, the lining of the abdomen (called the peritoneum), or distant sites.
Stage IIA (T2a, N0, M0): The cancer has spread to or has invaded (grown into) the uterus or the fallopian tubes, or both. Laboratory examination of washings from the abdomen did not find any cancer cells.
Stage IIB (T2b, N0, M0): The cancer has spread to other nearby pelvic organs such as the bladder, the sigmoid colon, or the rectum. Laboratory examination of fluid from the abdomen did not find any cancer cells.
Stage IIC (T2c, N0, M0): The cancer has spread to pelvic organs as in stages IIA or IIB and cancer cells were found when the fluid from the washings from the abdomen were examined under a microscope.
The cancer involves one or both ovaries, and one or both of the following are present: (1) cancer has spread beyond the pelvis to the lining of the abdomen; (2) cancer has spread to lymph nodes.
Stage IIIA (T3a, N0, M0): During the staging operation, the surgeon can see cancer involving the ovary or ovaries, but no cancer is visible to the naked eye in the abdomen and the cancer has not spread to lymph nodes. However, when biopsies are checked under a microscope, tiny deposits of cancer are found in the lining of the upper abdomen.
Stage IIIB (T3b, N0, M0): There is cancer in one or both ovaries, and deposits of cancer large enough for the surgeon to see, but smaller than 2 cm (about 3/4 inch) across, are present in the abdomen. Cancer has not spread to the lymph nodes.
Stage IIIC: The cancer is in one or both ovaries, and one or both of the following are present:
- Cancer has spread to lymph nodes (any T, N1, M0)
- Deposits of cancer larger than 2 cm (about 3/4 inch) across are seen in the abdomen (T3c, N0, M0).
Stage IV (any T, any N, M1)
This is the most advanced stage of ovarian cancer. In this stage the cancer has spread to the inside of the liver, the lungs, or other organs located outside of the peritoneal cavity. (The peritoneal cavity, or abdominal cavity is the area enclosed by the peritoneum, a. membrane that lines the inner abdomen and covers most of its organs.). Finding ovarian cancer cells in the fluid around the lungs (called pleural fluid) is also evidence of stage IV disease.
Recurrent ovarian cancer: This means that the disease went away with treatment but then came back (recurred).
Information provided by the American Cancer Society