The term "ovarian cancer" includes several different types of cancer that all arise from cells of the ovary. Most commonly, tumors arise from the epithelium, or lining cells, of the ovary. These include epithelial ovarian (from the cells on the surface of the ovary), fallopian tube, and primary peritoneal (the lining inside the abdomen that coats many abdominal structures) cancer. These are all considered to be one disease process. There is also an entity called borderline ovarian tumors that have the microscopic appearance of a cancer, but tend not to spread much.
However, there are also less common forms of ovarian cancer that come from within the ovary itself, including germ cell tumors and sex cord-stromal tumors. All of these diseases will be discussed, as well as their treatment.
Epithelial ovarian cancer
Epithelial ovarian cancer (EOC) accounts for a majority of all ovarian cancers. It is generally thought of as one of three types of cancer that include ovarian, fallopian tube, and primary peritoneal cancer that all behave, and are treated the same way, depending on the type of cell that causes the cancer. The four most common cell types of epithelial ovarian cancer are serous, mucinous, clear cell, and endometrioid. These cancers arise due to DNA changes in cells that lead to the development of cancer. Serous cell type is the most common variety. It is now thought that many of these cancers actually come from the lining in the fallopian tube, and fewer of them from the cells on the surface of the ovary, or the peritoneum. However, it is often hard to identify the sources of these cancers when they present at advanced stages, which is very common.
Borderline ovarian tumors
Borderline ovarian tumors account for a small percentage of epithelial ovarian cancers. They are most often serous or mucinous cell types. They often have large masses, but they only rarely metastasize, that is, spread to other areas. Often, removal of the tumor, even at more advanced stages, can be a cure.
Germ cell ovarian cancers
Germ cells tumors arise from the reproductive cells of the ovary. These are uncommon. They include dysgerminomas, yolk sac tumors, embryonal carcinomas, polyembryomas, non-gestational choriocarcinomas, immature teratomas, and mixed germ cell tumors. They tend to occur more often in younger-aged women.
Stromal ovarian cancers
Another category of ovarian tumor is the sex cord-stromal tumors. These arise from supporting tissues within the ovary itself. As with germ cell tumors, these are uncommon. These cancers come from various types of cells within the ovary. They are much less common than the epithelial tumors. These include granulosa-stromal tumors and Sertoli-Leydig cell tumors.
What are ovarian cancer statistics?
According to the National Cancer Institute (NCI), in 2013 there will be an estimated 22,240 new cases of ovarian cancer and 14,030 deaths from the disease. The vast majority of the cases are EOC and are found at stage 3 or later, meaning the cancer has spread beyond the pelvis or to the lymph nodes. This is mostly due to the lack of definite symptoms at the early stages of development of the disease process. An individual woman has a lifetime risk of 1.37%, thus it is an uncommon disease. The median age of diagnosis is 63. However, approximately 25% of cases are diagnosed between ages 35 and 54. Caucasian women have the highest rate of diagnosis.
Like many other cancers, when ovarian cancer is found at an early stage (for example, localized to the ovary or fallopian tube) the survival at five years is very good. Most women at stage 1 will still be alive at five years. However, the five-year survival for all women diagnosed with ovarian cancer is only 45%. This is because it is often found at an advanced stage in which the disease has already spread within the abdomen.
Survival is also dependent on the type of care the patient receives. Unfortunately, approximately half of all women with the disease are never referred to a gynecologic oncologist. These are physicians with special training in gynecologic (ovarian, uterine, cervical, vulvar, and vaginal) cancers. If a woman does not involve a doctor with this specialized training in her care, then studies show very clearly that her survival is significantly worse, often by many years. For this reason, every woman with this disease ideally will obtain a referral to a gynecologic oncologist before she starts any treatment or has any surgery.